home page: http://depts.washington.edu/ascidian/
Number 72 December 2013
This is the largest newsletter ever! Thanks very much to all of you who submitted contributions. There are 131 new publications listed at the end of this newsletter, plus abstracts from recent meetings, announcements of two upcoming ascidian workshops, and thesis abstracts.
Ascidiologists were treated to two excellent meetings this year: the Tunicata meeting in Naples in July and the Intl. Marine Bioinvasions meeting in Vancouver in August. It was a pleasure to see many friends at both, and exciting to hear so much new research on ascidians. See below for the websites where you can find the entire agendas; some of the abstracts are included in this newsletter.
The Ascidian News website lists newsletters going back to 1991 (when I started putting them online), 42 counting this one. I am considering making pdf’s of all the earlier issues but only if there is some interest, so please let me know if you would be interested! There are many new publications listed in each one, over 100 in all the later ones, so you all have easy access to the titles of many thousands of publications on all aspects of ascidian biology and taxonomy. Thus it irritates me greatly when I review manuscripts, and read new papers, with inadequate bibliographies that reference relevant prior research. This happens all too frequently. I urge all of you to take another look at the New Publications section of all the newsletters on the AN website, including the older ones for papers you may have forgotten about, and for faculty members to require that your graduate students go through all the newsletter New Publications, a very worthwhile expenditure of only a few hours’ time.
*Ascidian News is not part of the scientific literature and should not be cited as such.
1. The 7th Intl. Tunicata meeting was held in Naples, Italy July 22-26. Please see the website for the agenda.
The 8th Intl. Tunicata meeting will be held in Japan in 2015, possibly sometime between July and September, the location not yet decided. The organizers are Kazuo Inaba, Director,
Shimoda Marine Research Center, University of Tsukuba, and Gaku Kumano,Tohoku University.
2. The 8th Intl. Conference on Marine Bioinvasions was held 20-22 August at the Biodiversity Research Centre at the University of British Columbia (UBC) in Vancouver, Canada. There were many talks and posters on ascidians (unfortunately!). Here is the website for a downloadable pdf of the agenda: http://icmb.info/sites/default/files/Program_ICMBVIII_v3_07162013.pdf
The 9th Intl. Conference will be held in Sydney, Australia, January 2016; Emma Johnston will be the local organizer. email@example.com
3. From Mary Carman: The next Intl. Invasive Sea Squirt Conference (IISSC4) will be held at Woods Hole, Massachusetts Oct 29-31, 2014. Please save the date! firstname.lastname@example.org
4. A two week ascidian workshop will be offered June 17-July 1, 2014 at the Smithsonian Tropical Research Institute (STRI) at Bocas del Toro, Panama. This is an intensive field course covering all aspects of the taxonomy and biology of ascidians worldwide, including ecology, embryology, and physiology. The course will be taught by Rosana Rocha (Universidade Federal do Parana Departamento de Zoologia, Curitiba, Brasil) and Gretchen Lambert (Univ. of Washington Friday Harbor Labs). This will be the 4th time this popular course has been offered at Bocas. For more information and application details see http://www.stri.si.edu/sites/taxonomy_training/future_courses/2014/2014_Taxonomy_Biology_Tunicates.html Application deadline is February 1, 2014. Contact person: Rachel Collin, director of the STRI Bocas lab. email@example.com
5. From Noa Shenkar, Zoology Dept., Tel-Aviv Univ., Israel. firstname.lastname@example.org
An Ascidian Taxonomy Workshop will be held March 17-21, 2014 at the Inter-University Institute in Eilat, Red Sea coast of Israel. The workshop is organized by Gretchen Lambert and Noa Shenkar and is supported by the Israel Taxonomy Initiative. The workshop will combine lectures, lab work and field observations. There are a few spots for international participants. Please visit the website for more information.
The WoRMS Ascidiacea World Database is being updated and revised constantly. Please e-mail PDF files of new species publications to email@example.com. Any comments and corrections to the database are greatly appreciated.
6. From Christian Sardet, CNRS/Univ. P. et M. Curie Paris 6, Villefranche: I have been retired for 2 years now but just completed the book "Plancton - aux origines de la vie" which will also be published in English in 2014. http://www.planktonchronicles.org/livre/ firstname.lastname@example.org We also added 4 new episodes of plankton chronicles: http://www.planktonchronicles.org
7. From Marc Rius (M.Rius@soton.ac.uk): have recently moved to the University of Southampton where I am starting my research group. I will develop my research program as part of the School of Ocean and Earth Science (http://www.southampton.ac.uk/oes/index.page?), the National Oceanography Centre (http://noc.ac.uk/), the Institute for Life Sciences (http://www.southampton.ac.uk/ifls/) and the Southampton Marine and Maritime Institute (http://www.southampton.ac.uk/smmi/). Students are expected to start in October 2014.
8. From Motonori Hoshi: I started working from October at a new institute: Administrative Director, Earth-Life Science Institute (ELSI), Tokyo Institute of Technology, Japan email@example.com
We had the Presentation Ceremony of the International Prize for Biology 2013; the awardee was Joseph Felsenstein. In October, Robert Treat Paine was honored with Cosmos Prize 2013. So, two scholars of the University of Washington received two major prizes in Japan in a month! [AN editor’s note: I agree with you, Ghen, a truly major honor for the Univ. of Washington]
WORK IN PROGRESS
Carlos San Vicente and Françoise Monniot:
A reexamination of many Corella specimens from the southern hemisphere has shown that species commonly attributed to Corella eumyota Traustedt actually belong to 3 different species: C. eumyota Traustedt and C. antarctica Sluiter (Alurralde, G., Torre, T., Schwindt, E., Castilla, J. C. and Tatian, M. 2013. A re-evaluation of morphological characters of the invasive ascidian Corella eumyota reveals two different species at the tip of South America and in the South Shetland Islands, Antarctica. Polar Biol. 36: 957-968) and a new species C. brewinae Monniot 2013. (Monniot, F. 2013. The genus Corella (Ascidiacea, Phlebobranchia, Corellidae) in the Southern Hemisphere with description of a new species. Zootaxa 3702: 135–149). A new kind of symbiotic crustaceans for ascidians has been discovered in several specimens of C.brewinae from the Macquacie region, inside the branchial sac. These Mysida represent a new genus and a new species which study is in progress. firstname.lastname@example.org ,
2. From Gastón Alurralde: Bentho-pelagic coupling in an Antarctic coastal ecosystem affected by thaw: an ecological approach. Ecología Marina, Instituto de Diversidad y Ecología Animal, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Argentina email@example.com
The project started during the last Antarctic Summer Campaign (January 2013) and focuses on the study of benthic-pelagic coupling in an Antarctic coastal ecosystem (Potter Cove) affected by melting of surrounding glaciers. The ongoing work addresses the analysis of environmental variables, different food sources and the trophic ecology of filter feeder species under different seston amounts and composition. Through aquaria experiments, using the ascidian Cnemidocarpa verrucosa and the Antarctic krill Euphausia superba, processes related to the trophic ecology (time of passage through the digestive tract, assimilation efficiency, faeces production rate) were studied under different diets (phytoplankton, detritus, krill and ascidian feces) and increasing concentrations of inorganic material. First outcomes were presented at the XI SCAR Biology Symposium. (July 2013, Barcelona, Spain) and at the 7th Tunicate Meeting (July 2013, Naples, Italy). Particulate matter (food source) was monthly collected and fixed in a sediment trap and then examined through microscopic analysis. Stable isotope analysis (δ13C, δ15N) will be carried out in best-representative filtering species, other community associated species, water and sediment samples. This will serve to find out about the origin and transfer patterns of organic matter, and determine the relative contribution of the various sources of food. This project framed on ECLIPSE (Effects of Climate Change in Polar Shallow benthic Ecosystems), a project supported by the TOTAL foundation (France). More information about the project: http://www.eclipseproject.org/ (Ph.D. thesis project. Advisers: Dr. Marcos Tatián and Dr. Verónica L. Fuentes)
3. Ascidians from the southern South America and the Antarctic Peninsula. Cristian Lagger. Universidad Nacional de Córdoba, Argentina. firstname.lastname@example.org
The Southwestern Atlantic ascidian fauna has scarcely been studied and has rarely been sampled, especially the Patagonian region. The general objective of my thesis is to study the ascidians of southern South America (Argentine and Chilean sea) and Antarctica Peninsula from a multidisciplinary approach, using morphological, biogeographic and genetic analysis. The project has three specific research objectives. First, a contribution to the knowledge of the diversity and distribution of ascidians in that area, a taxonomic line that meant the examination of material loaned at the most important museums of Argentina (with specimens labeled since 1914!). Also, the determination of specimens collected in different samplings along the SW Atlantic, Argentine Sea (by SCUBA diving and aboard on scientific ships), the Chilean fjords (in cooperation with San Ignacio del Huinay Foundation) and material from several argentine Antarctic expeditions. The bulk of those determinations and the literature citations, allow to establishing the biogeographic relationship among the studied and adjacent areas. Another specific point of my research is the detection and colonization of invasive species at the major harbor areas along Patagonia, Argentina. Recruitment on successional plates allows qualitative and quantitative analysis. The last objective focusses on evolution studies on deep ascidians using molecular analysis. As a result, the phylogenetic position of tunicates, formerly classified inside Hexacrobylidae or Sorberacea, are now related with the Family Molgulidae. Ph.D. thesis advisor: Dr. Marcos Tatián.
4. Systematic and population structure of deep ascidians along a bathymetric gradient, at the Southwestern Ocean. Tamara Maggioni, Instituto de Diversidad y Ecología Animal (CONICET-UNC) and Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina. email@example.com
Since 2012, the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Argentina) has initiated the first series of exploratory deep ocean campaigns (RV A.R.A. Puerto Deseado) nucleating a group of scientists, each specialized in different taxa. The area under study hitherto, navigated twice, is located in the Argentinean shelf around 38°S. It included the submarine Mar del Plata Canyon (MdPC) and comprised a bathymetric range from 200 m to 3,500 m (partial results of the biodiversity found were communicated at the VIII National working days of Marine Sciences, 2012, Chubut, Argentina). Next year, it is planned to expand the expeditions into the south, down to 44°S. In the frame of my Ph.D. thesis, I collected 25 ascidian morphospecies during the MdPC expeditions, 15 of which were colonial and 10 solitary. Actually, I am working on ascidian determinations expecting the finding of new species for science, as happened with other taxa e.g., amphipods, echinoids and cnidarians. The next step will consist of studies on ascidian community structure and gut content analysis, along the bathymetric gradient explored. Many interesting and exciting conclusions are hoped to be inferred since the area, especially at these depths, is known to be highly underexplored.
a. Morphological and molecular characterization of a worldwide--distributed Botrylloides species. Gretchen Lambert, Carmela Gissi1, Elizabeth Sheets2, Francesca Griggio3, C. Sarah Cohen2, Riccardo Brunetti4, Francesco Mastrototaro5, Rosana M. da Rocha6
Friday Harbor Laboratories, Univ. of Washington, USA firstname.lastname@example.org
1 Dip. Bioscienze, Univ. degli Studi di Milano, Milano, Italy email@example.com
3 Dip. Bioscienze, Università degli Studi di Milano, Milano, Italy firstname.lastname@example.org
4 Museo di Storia Naturale di Venezia, Venezia, Italy email@example.com
5 Dip. Biologia, Università di Bari, Bari, Italy firstname.lastname@example.org
6 Dep Zoologia, Universidade Federal do Paraná, Curitiba, Brazil email@example.com
Botrylloides colonies recorded in the Taranto’s harbour (Southern Italy) during 2001-2011 were described as Botrylloides pizoni n. sp. Brunetti & Mastrototaro, 2012. Similar Botrylloides colonies were also sampled in Southern California since 1997 and Southeast Brazil since 1993, and attributed to B. perspicuum Herdman, 1886 and B. giganteum (Pérès, 1949), respectively. Here we report the detailed molecular and morphological comparison of these widely distributed Botrylloides colonies in order to define their possible identity. Sequences of COI, a reliable molecular marker used for species identification, are identical or 99% identical between Italian, Californian, and Brazilian colonies, clearly indicating these specimens as conspecific. As for morphology, specimens from California emerged to be indistinguishable from the Italian and the Brazilian ones. Species name assignment according to nomenclatural precedence will be widely discussed in the presentation. Indeed, morphological comparison of B. giganteum specimens from California, Senegal and Brazil with B. perspicuum colonies from Papua New Guinea and Malaysia showed enough difference to consider both as valid species. Moreover, a re-examination of the holotype of Botryllus firmus, a junior synonym of B. perspicuum, showed that pizoni is synonymous with firmus: the limited description of B. firmus, due to the poor condition of the material, induced Brunetti & Mastrototaro to erect the new species. If firmus is a jr. syn. of perspicuum will require further analyses of the Herdman’s species. We here underline that properly analyzed molecular and morphological characters lead to identical results. Our report also suggests this species is spreading around the world and could become invasive.
b. The Botryllinae subfamily: first evidence of invariant mitochondrial genome architecture in a sea of ascidian variability. Francesca Griggio1, Adriana Giumbo1, Nicola Franchi2, Graziano Pesole3,4, Francesco Mastrototaro5, Carmela Gissi1
2 Dip. Biologia, Università di Padova, Padova, Italy, firstname.lastname@example.org
3 Istituto di Biomembrane e Bioenergetica, CNR, Bari, Italy, email@example.com
4 Dip. Bioscienze, Biotecnologie e Biofarmaceutica, Università di Bari, Bari, Italy
5 Dip. Biologia, Università di Bari, Bari, Italy, firstname.lastname@example.org
The mitochondrial (mt) genome of ascidians has been so far analyzed in 19 species representatives of 8 families and distributed among all three major groups of Aplousobranchia, Phlebobranchia and Stolidobranchia. These genomes highlighted the extreme variability of many mitogenomic features, including gene order, tRNA gene content, position/sequence of the largest non-coding region, and nucleotide substitution rate. This overall fast mt evolutionary dynamics was also observed at level of congeneric species and even cryptic Ciona intestinalis species show a different gene order. In order to verify the existence of slow-evolving ascidian lineages, we sequenced the complete/partial mt genome of 5 additional species (Aplidium tabarquensis, Clavelina phlegraea, Botrylloides leachii, Botrylloides pizoni sensu Brunetti&Mastrototaro 2012, Botrylloides violaceus, and Halocynthia papillosa) sampled so that, together with already-known mtDNAs, we obtained two closely related species for most families. The new data allowed the identification of the subfamily Botryllinae (Styelidae) as the first ascidian group showing slow evolution of at least some mitogenomic features. Indeed, the three analyzed Botrylloides species share exactly the same genome organization, which can be also easily converted between Botryllus and Botrylloides species. Size and positions of non-coding regions were also largely comparable between different Botryllinae. However, no concomitant slow-down of the nucleotide substitution rate was observed, as estimated by phylogenetic reconstructions. Detailed analyses on a possible correlation between nucleotide substitution rate and gene order rearrangement rate will be presented in the poster. Our results suggest that slow-evolving lineages are more appropriate for investigating the peculiar mechanisms of ascidian mt evolution.
c. A phytochelatin synthase gene in the solitary tunicate Ciona. Nicola Franchi1, Diana Ferro2, Barbara Spolaore3, Gianfranco Santovito2, Loriano Ballarin2.
1Department of Biological, Chemical and Pharmacological Science and Technology, Univ. of Palermo, Palermo, Italy, email@example.com; 2Dept. of Biology, Univ. of Padova, Padova, Italy; 3C.R.I.B.I., Univ. of Padova, Padova, Italy.
The major thiol-containing molecules involved in controlling the level of intracellular ROS in eukaryotes, acting as a nonenzymatic detoxification system, are metallothioneins (MTs), glutathione (GSH) and phytochelatins (PCs). Both MTs and GSH are well-known in the animal kingdom. PC was considered a prerogative of the plant kingdom but, in 2001, a phytochelatin synthase (PCS) gene was described in the nematode Caenorhabditis elegans; additional genes encoding this enzyme were later described in the earthworm Eisenia fetida and in the parasitic nematode Schistosoma mansoni but scanty data are available, up to now, for deuterostomes.
Here, we describe the molecular characterisation and transcription pattern, in the presence of Cd, of a PCS gene from the invertebrate chordate Ciona intestinalis, a ubiquitous solitary tunicate and demonstrate the presence of PCs in tissue extracts. We also studied mRNA localization by in situ hybridization. In addition, we analysed the behaviour of hemocytes and tunic cells consequent to Cd exposure as well as the transcription pattern of the Ciona orthologous for PCNA, usually considered a proliferation marker, and observed that cell proliferation occurs after 96 h of Cd treatment. This matches the hypothesis of Cd-induced cell proliferation, as already suggested by our previous data on the expression of a metallothionein gene in the same animal.
d. Phenoloxidase, melanin and amyloid fibrils in the compound ascidian Botryllus schlosseri. Rossana Girardello1, Stefano Tasselli1, Magda de Eguileor1, Nicola Franchi2, Loriano Ballarin3.
1Dept. of Biotechnology and Molecular Science, Univ. of Insubria, Varese, Italy firstname.lastname@example.org; 2Dept. of Biological, Chemical and Pharmacological Sci. and Technology, Univ. of Palermo, Palermo, Italy email@example.com; 3Dept. of Biology, Univ. of Padova, Padova, Italy firstname.lastname@example.org
In invertebrates, the recognition of non-self molecules frequently leads to the release of phenoloxidase (PO) by circulating granulocytes, in the form of its precursor, pro-PO, which is quickly activated by soluble serine proteases. This response represents a powerful weapon against potentially pathogenic microorganisms and, in several taxa, independently of their phylogenetic position, the pro-PO activation system is responsible of a massive production of melanin. The latter is supported by the formation of amyloid fibrils as well as other concurrent events, such as ACTH production, NEP overexpression and α-MSH formation. In the colonial ascidian Botryllus schlosseri, allorecognition between contacting, genetically incompatible colonies, leads to the recruitment of haemocytes in the contact region and their degranulation with the consequent release of PO and the production of melanin which is deposited in the necrotic spots along the colony contacting border.
Here, we present a morphological study of activated circulating hemocytes of B. schlosseri showing that they are able to produce a huge amount of amyloid fibrils driving the melanin pigment accumulation. In addition, we stress that amyloid fibrils production and melanin synthesis are sustained by a change in cytoplasmic pH, and by an interaction between immune and neuroendocrine system.
e. A novel platform for gene expression study. Davide Campagna, Nicola Franchi, Fabio Gasparini, Lucia Manni, Giorgio Valle, Loriano Ballarin. Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italy.
The recent development of high-throughput sequencing technologies allows the expanding of RNA-seq experiments especially for gene expression analyses at different levels and for various purposes. This allowed the production of great amount of data to be analyzed using bioinformatics analyses. Gene expression data, gene annotation and KEG information can be used to discover the putative genetic controls involved in different pathways. So, gene expression analysis represents a base step to understand the role of genes in RNA-seq experiments. Here we present a new platform for gene expression analyses that allows to analyze gene expression data with hight flexibility and at various statistical significance. The platform allows the selection of differentially expressed genes on the basis of two possible criteria: i) the selection based on gene-ontology categories that enables the focusing of the genes involved in the pathways of interest; ii) the selection based on sequence similarity of known protein or nucleotide sequences. The selected genes are compared for their differential expression levels in different experimental conditions in order to follow and/or focus their role in the observed phenotypes. Results are presented in a well-designed way and can be checked at different levels of the analysis. This platform was tested using several SOLiD RNA-seq libraries coming from 3 stages of the colonial blastogenetic cycle of B. schlosseri and all information has been included in an ad hoc database for fast accessing which interacts with the platform in all aspects of the analysis.
f. Introduced ascidians in Catalan harbors (NE Spain). Miquel L. Legentil1, Xavier Turon2, Patrick M. Erwin1, Susanna López-Legentil1. 1Dept. of Animal Biology, Univ. of Barcelona, Barcelona, Spain email@example.com, firstname.lastname@example.org, email@example.com, 2Center for Advanced Studies of Blanes (CEAB-CSIC), Girona, Spain firstname.lastname@example.org
Harbors and marinas are well known gateways for species introductions, including numerous ascidians that travel attached to ship hulls or in ballast waters. However, to date there are few inventories of ascidian species in harbors and marinas, limiting our knowledge of these artificial habitats as vectors for species introductions. Here, we sampled 32 harbors along 300 km of the Catalan coast (NE Spain) and identified all ascidian species up to 3 meters depth. A fragment of the mitochondrial gene Cytochrome Oxidase I (COI) was used to barcode each species and assess the genetic diversity of three common ascidians (Ciona intestinalis, Ascidiella aspersa and Aplidium sp.). In total, over 20 species were identified in harbor habitats, with some species recorded in nearly all harbors (e.g. C. intestinalis, Clavelina lepadiformis, Botryllus schlosseri, A. aspersa, and Diplosoma listerianum), while others were rarely found (e.g. Polyandrocarpa zorritensis, Phallusia ingeria, Molgula bleizi, and Polycarpa pomaria). This inventory uncovered an unexpected diversity of introduced ascidians in Catalonia. Genetic diversity within the three investigated species was low, indicating a slow arrival of new genetic variants or selection for specific genotypes better adapted to the environmental conditions that characterize these habitats. This study highlights the importance of cataloguing harbor ascidiofauna in order to establish baselines for monitoring non-native species, understand their spreading capacity, investigate their invasive potential and, if necessary, develop adequate management and contingency plans.
g. Deep sequencing of the ascidian microbiome. Patrick M. Erwin1, M. Carmen Pineda1, Nicole Webster2, Xavier Turon3, Susanna López-Legentil1
2Australian Institute of Marine Science, Townsville, Australia email@example.com
2Center for Advanced Studies of Blanes (CEAB-CSIC), Blanes, Girona, Spain firstname.lastname@example.org
Ascidian-associated microbes may play a critical role in the metabolic needs of their host and in nutrient cycles of the environments they inhabit; however, the ascidian microbiome remains largely unexplored beyond a few model species. Here, we provide the most comprehensive characterization to date of the ascidian microbiome by investigating the diversity, structure and specificity of microbial symbionts in 42 Great Barrier Reef ascidians using 16S rRNA gene tag pyrosequencing. Results revealed high bacterial biodiversity (3,217 OTU0.03) and the widespread occurrence of ammonia-oxidizing Archaea in ascidians. The ascidian microbiota was clearly differentiated from free-living seawater microbial communities and included symbiont lineages shared with other invertebrate hosts as well as unique, ascidian-specific phylotypes. Several rare seawater microbes were markedly enriched in the ascidian microbiota, suggesting that the rare biosphere of seawater may act as a conduit for horizontal symbiont transfer among hosts. However, most OTUs (71.2%) were rare and specific to a single host while core communities were comprised of only 7 OTUs, indicating an overall high degree of host-specificity. Recent studies indicate steep physico-chemical gradients within the ascidian tunic and we hypothesize that the complex ascidian microbiota revealed herein is maintained by this dynamic tunic microenvironment, offering periodic windows of optimal conditions for different metabolic pathways. For example, ample chemical substrate (ammonia-rich host waste) and physical habitat (high oxygen, low irradiance) that support nitrification processes. Thus, ascidian hosts provide unique and fertile niches for diverse marine microorganisms and may represent an important habitat for nitrite/nitrate regeneration in coral reef ecosystems.
h. Life beyond death: renewal of Styela plicata introduced populations
after die-off episodes in North Carolina, USA. M.Carmen Pineda1, Xavier Turon2, Rocío Pérez-Portela2, Susanna López-Legentil1. 1Dep. de Biologia Animal, Facultat de Biologia, Univ. de Barcelona, Spain email@example.com, firstname.lastname@example.org
2Centre d’Estudis Avançats de Blanes, CSIC, Spain, email@example.com,
Styela plicata is a solitary ascidian introduced all around the world by ship traffic and presents many of the required features to become invasive. We aimed to describe the genetic structure between and within cohorts of S. plicata, in order to determine whether it remains genetically constant over time or whether a periodic generational renewal occurs. To address this goal, we sampled 12-14 individuals of S. plicata every 2 months for 2.5 years in Wilmington (NC, USA), and analyzed a mitochondrial marker (COI) and seven nuclear microsatellites. Population genetics analyses showed similar results for both types of genetic markers. The AMOVA showed that most of the genetic variation was found within time periods and not among them. However, for the microsatellites significant differences among time periods were also detected. Specifically, September-October 2007 was genetically different from most of the other time periods. The inbreeding coefficient showed two major drops in July-October 2007 and September-October 2008, suggesting the arrival of migrants. Moreover, around June every year we observed massive die-offs in the population, leaving free substratum that could be recolonized by recruits arriving from other populations, and which were only detected 2-3 months later in its adult stage. In conclusion, the studied population of S. plicata was mainly stable over time, as shown by the low variation among time periods found with all markers. However, there was also evidence for a potential renewal of the population after massive dieoffs which perpetuated the presence of this species in the study area.
i. Global introduction or cryptic speciation? You can have it both ways: genetic patterns of the widespread ascidian Diplosoma listerianum (Milne-Edwards, 1841). Pérez-Portela R., Arranz V., Rius M., Turon X. firstname.lastname@example.org, M.Rius@soton.ac.uk, email@example.com.
The existence of widespread benthic species with low dispersal capabilities is a paradox that has been explained by human-driven range shifts (introductions) and by hidden diversity in the form of unrecognized cryptic species. Both factors are not mutually exclusive. Here we analyze the genetic patterns of the colonial ascidian Diplosoma listerianum, a species described from NE Atlantic and nowadays distributed globally, in both natural and artificial substrates. The study of a fragment of the COI gene in 14 localities worldwide revealed four genetic clades differentiated >16%, suggesting the existence of multiple cryptic species. There is a complex geographic structure, as in 4 localities more than one clade exist in sympatry. One of the clades (Clade A) is globally distributed (both sides of the Atlantic, both sides of the Pacific, and Indian Ocean). This clade is also the only one present in European waters and the one with the highest genetic diversity. This clade is thus assignable to the original nominal species Diplosoma listerianum (Milne-Edwards, 1841). Another clade (C) was also found at both sides of the Atlantic and in the Indian Ocean, while Clade B and Clade D were restricted to their presumably native ranges. Further analyses of the 11 populations where Clade A specimens were found revealed strong population structure irrespective of geographical distances, which is coherent with stochastic dispersal linked to human transport.
j. Adverse effect of antifouling compounds on the reproductive mechanisms of the ascidian Ciona intestinalis. Alessandra Gallo and Elisabetta Tosti, Animal Physiology and Evolution Laboratory, Stazione Zoologica Anton Dohrn, Napoli, Italy. firstname.lastname@example.org
is the biological process by which a living organism gives rise to one or more
descendants ensuring the conservation of the species. In marine organisms with
external fertilization, sperm, oocytes and embryos may be exposed to
environmental pollutants from human activities that may alter the physiological
functions giving rise to a reduced reproductive success. The oocytes are
electrogenic cells i.e. capable of changing the electrical properties of the
plasma membrane in response to different stimuli. With the electrophysiological
technique of whole cell voltage clamp, we evaluated and compared the influence
of two antifouling biocides, tributyl tin and diuron, on reproductive
mechanisms in the marine invertebrate Ciona
intestinalis by measuring conductance and membrane ionic currents,
electrical events of fertilization. With different toxicity assays, we
evaluated the effect of the two biocides on gamete and embryo development.
The results obtained demonstrated that both tributyl tin and diuron affect the electrical properties of the plasma membrane, by increasing the conductance and reducing in a dose dependent manner the sodium currents that characterize mature oocytes in this ascidian. The tributyl tin but not diuron also influences the frequency and amplitude of the fertilization current. Pre-treatment with tributyltin and diuron of oocytes and sperm does not affect the fertilization and embryonic development. However fertilized oocytes in sea water containing tributyl tin, but not diuron, undergo a reduced fertilization and an abnormal development.
This study suggests that: i) the two biocides affect either the electrical properties of the plasma membrane and the reproductive processes representing a risk factor for the survival of this species when it is exposed to pollution, ii) the ascidian Ciona intestinalis may be considered a good model organism to test the toxicity of pollutants; iii) the reproduction may be considered as a good biomarker and an indicator of the level of toxicological risk to which a given natural population is subjected.
k. T-type Ca2+ current activity during oocyte growth and maturation in the ascidian Styela plicata. Alessandra Gallo1, Gian Luigi Russo2, Elisabetta Tosti1.
1Animal Physiology and Evolution Laboratory, Stazione Zoologica Anton Dohrn, Napoli, Italy email@example.com; 2Institute of Food Sciences, National Research Council, Avellino, Italy.
Voltage-dependent calcium currents play a fundamental role during oocyte maturation, mostly L-type calcium currents, whereas T-type calcium currents are involved in sperm physiology and cell growth. In this study, using an electrophysiological and pharmacological approach, we demonstrated, for the first time in oocytes, that T-type calcium currents are present with functional consequences on the plasma membrane of growing immature oocytes of the ascidian Styela plicata. We classified three subtypes of immature oocytes at the germinal vesicle stage on the basis of their size, morphology and accessory cellular structures. These stages were clearly associated with an increased activity of T-type calcium currents and hyperpolarization of the plasma membrane. We also observed that T-type calcium currents oscillate in the post-fertilization embryonic stages, with minimal amplitude of the current in the zygote and maximal at 8-cell stage. In addition, chemical inhibition of T-type calcium currents, obtained by applying specific antagonists, induced a significant reduction in the rate of cleavage and absence of larval formation. We suggest that calcium entry via T-type calcium channels may act as a potential pacemaker in regulating cytosolic calcium involved in fertilization and early developmental events. [ Dedicated to the dear memory of Prof. Charles Lambert]
In comparative immunology and evolution of the chordate immune system, tunicates hold an important phylogenetic position as sister group of vertebrates. However, knowledge of the tunicate immune system is limited to the class Ascidiacea, in which some species are now considered model organisms. In the class Thaliacea, represented by fragile pelagic species, the few studies on their haemocytes go back to several decades ago and do not consider comparative aspects with ascidian haemocytes. In this study, we identified various haemocyte types and their distribution in the common salp Thalia democratica by comparative observations under light and electron microscopy and by histochemical, histoenzymatic and immunohistochemical techniques. By comparing specialisations with those of ascidian haemocytes, we detected an undifferentiated cell type (lymphocyte-like cell) and three categories with four cell types, i.e. i) phagocytic line (hyaline amoebocyte and amoebocyte with large vacuoles), ii) mast cell-like line (granular cell), and iii) storage cells (nephrocyte). Both phagocytes and granular cells appear to migrate in the tunic. Phagocytes adhere to the tunic which internally covers the oral siphon, where they probably function as sentinel cells of the pharynx. Results show the variety of haemolymph cells in the salp similar to phlebobranch ascidians.
m. Budding and ncRNAs during the evolution of coloniality in ascidians. Gutierrez, S. (1), Velandia, C.A. (1,2), Bermudez, C. I. (2), Gittenberger, A. (3), Brown, F.D. (1,4). (1)Universidad de los Andes; (2)Universidad Nacional de Colombia; (3)Gimaris, The Netherlands; (4)Universidade de Sao Paulo. firstname.lastname@example.org
To reconstruct developmental transitions, and to explore ncRNA regulation during the evolution of coloniality, we study two species of colonial ascidians, i.e. Symplegma brakenhielmi and Didemnum vexillum. One well-supported transition from a solitary ancestor into a colonial clade occurs in the Botryllidae. In this clade, basal species are solitary or social (i.e. individuals in aggregates), and derived species are colonial (i.e. individuals share a common tunic). Phylogenetic reconstructions provide evidence for an increase in the degree of individual integration of the colonies during evolution. Basal colonial botryllid S. brakenhielmi does not synchronize budding and their buds generally develop independently at extracorporeal vessels that connect the individuals of the colony, whereas derived Botryllus and Botrylloides individuals bud synchronously, and generally develop by evagination of the lateral epidermis of adult individuals. To show that S. brakenhielmi individuals show complete independence in development, we carried systemic bud or zooid removal in the colony and compared our results to previous observations in Botryllus schlosseri. Next, we studied hemocytes and analyzed proliferation in S. brakenhielmi to identify putative circulatory progenitor cells. Budding in ascidians requires a permanent supply of progenitor cells likely regulated by ncRNA pathways. Using Didemnum vexillum genome, we search for ncRNA predictions and search for colonial ascidian specific signatures. Our results support a stepwise integration of budding synchrony and developmental interaction of individuals during the evolution of coloniality. Our study raises new questions about the origins of cell signaling between individuals, and its involvement in the developmental integration of coloniality.
n. First records of Didemnum vexillum in a tropical region. Leda Restrepo(1), M. Gabriela Agurto(2), Irma Betancourt(2), Yesennia Pozo(2), Federico D. Brown(1,2,3).
(1)Universidad de los Andes; (2)Escuela Escuela Superior Politécnica del Litoral; (3)Universidade de Sao Paulo. email@example.com
Didemnum vexilum is an invasive ascidian that can displace native species and affect oyster cultures by rapid overgrowth. In recent years, reports of D. vexillum invasions in the Mediterranean, Pacific, and Atlantic Oceans have raised scientific concern, and initial action has been taken to control its spread. In this study, we provide molecular evidence for the first tropical occurrence of D. vexillum on warm tropical waters. Colonies were collected from cultured oysters at the Centro Nacional de Acuicultura e Investigaciones Marinas (CENAIM) in San Pedro, Prov. of Santa Elena, Ecuador. Reported cases of D. vexillum invasions have occurred mostly in temperate regions, therefore we examined whether this species was adapted to propagate exclusively in cold temperatures. We found higher growth rates of colonies maintained at colder temperatures than those generally observed off the coast of Ecuador. To evaluate native Didemnum species distribution, we collected several colonies at undisturbed benthic sites (5-15m) nearby. Colonies were identified morphologically, and species relationships were analyzed using mitochondrial COI and nuclear tho markers. We suggest two possible indirect migration routes: (a) by boat traffic from Asia via North America, or (b) by oyster culture introduction from Japan via Chile. Using laboratory oyster culture assays, we provide evidence that the presence of Didemnum colonies on oyster shells affects oyster filtration rates and growth negatively. We raise concerns about future propagation of D. vexillum in tropical waters, and provide experimental evidence of negative physiological effects on oysters associated to Didemnum infestation.
o. The ontology of the colonial ascidian Botryllus schlosseri. Manni L, Gasparini F, Hotta K, Ishizuka KJ, Ricci L, Tiozzo S, Voskoboynik A, Dauga D. firstname.lastname@example.org Dipartimento di Biologia, Università di Padova, Padova, Italy.
The coloniaI ascidian Botryllus schlosseri represents a model organism for studying diverse aspects of colonial lifestyle including: 1) natural chimerism and allorecognition; 2) sexual versus asexual reproduction; 3) stem cell mediated regeneration plasticity and 4) apoptosis. For several decades the biology of B. schlosseri has been studied around the world, and a considerable amount of data has been collected. Its transcriptome is available and its genome is about to be published. To facilitate studies on tunicates, the tunicate community is working on the reorganization of the current data base systems in order to provide different types of data related to several model tunicate species. Advanced model organism databases represent embryonic anatomy via a hierarchical textual ontology defined for each developmental stage. Since description was lacking for B. schlosseri, we created an Open Biomedical Ontologies (OBO)-compliant anatomical ontology for each stage, based on the ontology of Ciona intestinalis. The B. schlosseri ontology defines a vocabulary of coloniaI specific anatomical entities (e.g., colony, single zooids, primary and secondary buds), and it represents the tissue lineages and the developmental timing of specific tissues during blastogenesis. This ontology is based on Sabbadin's blastogenesis staging method (Sabbadin, 1955) but also incorporates staging methods employed by others. The B. schlosseri anatomical ontology represents an implementable resource and an important tool for the tunicate scientific community.
p. Morphological differentiation of the ascidian coronal organ and molecular characterization of its secondary sensory cells. Rigon F, Shimeld SM, Gasparini F, Caicci F, Manni L. email@example.com Dipto. di Biologia, Università di Padova, Padova, Italy.
Among sensory organs present in tunicates, the coronal organ is the only one based on secondary sensory cells (SSCs).It was morphologically described in species of all tunicate classes, thus representing a plesiomorphic feature of the subphylum. The coronal organ has a mechanosensory function related to feeding behavior, being the first filtering barrier in the mouth. Its sensory cells are provided with an apical bundle bearing cilia and microvilli (or stereovilli) and lack an axonal prolongation, as typical of SSCs. Considering that tunicates and vertebrates are believed to be sister groups, it has been hypothesized a cell homology between the coronal organ sensory cells and the vertebrate SSCs, i.e. hair cells of ear and lateral line. To validate this hypothesis, we studied in metamorphosing larvae and juveniles of the ascidian Ciona intestinalis the morphological changes occurring during the coronal organ development using SEM and TEM. We also analyzed the pattern of celi proliferation using antibodies against Phospho Histone H3. We further verified, by means of ISH, the expression of typical molecular markers involved in vertebrate hair cell differentiation (Notch, Delta, Hairy, Atoh, Musashi) finding that they are shared between ascidian and vertebrate SSCs. We found that also functional aspects related to neurotransmission are common, e.g. the presence of ionic channels, such as TRPA, and of neurotransmitters, such as glutamate and acetylcholine. Our data support the hypothesis that tunicate and vertebrate SSC evolved from a SSC cell present in the common ancestor of the two sister groups.
q. Testing an useful in vivo vessel network model: impact of anti-angiogenic drugs and vertebrate angiogenic factors on the propagation of Botryllus schlosseri circulatory system. Gasparini F, Manni L, Bortolin F, Burighel P, Zaniolo G. firstname.lastname@example.org Dipto. di Biologia, Università di Padova, Padova, Italy.
The process of vessel formation in vertebrates occurs during embryogenesis and in adult regenerative-renewal conditions. Angiogenesis, the main vessel formation mechanism, has received increased attention as related to cancer progression.
We have recently evidenced that the mechanism of vessel formation in ascidians shows correspondences with vertebrates. In particular, the colonial circulatory system (CCS) of Botryllus schlosseri, an intricate network of vessels originated by extensions of epidermis and embedded in the tunic external to zooids, forms and regenerates through the sprouting mechanism characterizing also vertebrate angiogenesis. This opens interesting consideration on vertebrate angiogenesis evolution. In order to investigate on B. schlosseri CCS the effect of molecules stimulating or inhibiting human angiogenesis, we defined an experimental protocol and data analysis procedure for testing injected solutes. Pairs of colony pieces (subclones) were operated to remove the CCS, injected in parallel with the molecule of interest and, as control, with its solvent, and then examined after three days. Appropriate statistical tests for paired samples were chosen to test the effect of injected factors on CCS regeneration. Our data indicate that human endogenous molecules promoting angiogenesis (i.e., VEGF and EGF) injected into CCS significantly impact on its propagation. Contrarily, the drugs Sorafenib and Vatalanib, known to have anti-angiogenetic effects on human blocking VEGF and related pathways, do not inhibit this process in B. schlosseri.
These discrepancies between the effects of promoting factors and drugs in B. sch/osseri with respect to human open interesting questions about the mechanisms of action of these molecules in different species.
2. 8th Intl. Conference on Marine Bioinvasions, Univ. of British Columbia, Vancouver, Canada, 20-22 August, 2013. Program and Abstract book: https://www.dropbox.com/s/u57e1shuq083nh3/ICMBVIII_Abstract_Book_Draft_III.pdf
See #33, 41, 44, 45, 49, 50, 70, 74, 77, 79, 81, 85, 88, 90, 92.
Evidence of ascidian community homogenization in less than 10 years. Rosana Rocha1, Gretchen Lambert2, Isabela Neves1 and James Roper3
1 Dep Zoologia, Universidade Federal do Paraná, CP 19020, 81531-980, Curitiba, PR, Brazil email@example.com 2 Univ. of Washington Friday Harbor Laboratories, Friday Harbor, Washington, USA, 3 Centro Universitário Vila Velha, R. Mercúrio s/n, CEP 29102-623, Vila Velha, ES, Brazil.
Ascidians are often a major component of fouling communities, especially in marinas and on piers. In these habitats introduced species are common and often shared among them, which can result in an increase in similarity between sites. This “homogenization” is one of several negative effects that may result from bioinvasion. We used data from Rapid Assessment Surveys (RAS) performed at the same sites on two consecutive dates: 2000 and 2010 in New England (5 sites), 1997 and 2004 in San Francisco Bay (8 sites), 1994 and 2000 in southern California (12 sites). We calculated Jaccard similarity between pairs of sites within years in each of these regions to test the hypothesis that similarity (= homogenization) increases over time because of introductions. We used paired t-tests to compare similarity over time (the two dates). Species richness increased over time as well, and similarity increased as predicted in both San Francisco Bay (t = 2.34, p = 0.01) and southern California (t = 6.6, p <0.001), even though the time intervals between surveys were only 7 and 6 years, and 10 in New England. Both regions had the greatest proportion of introduced species in relation to total richness (89 and 83%), while New England had fewer at 73% (and lower species richness), which may explain the lack of effect there. Thus, homogenization is ocurring rapidly and since marinas and piers are the first step for natural habitat invasions, homogenization of natural habitats is likely to occur faster on the Pacific coast.
3. 15th Intl. Congress of Immunology, Milan, August 22-27, 2013.
a. Phenoloxidases and cytotoxicity in ascidians: an overview. L. Ballarin1, N. Franchi2, F. Schiavon1, S. C. E. Tosatto1. 1Dept. of Biol., Univ. of Padova, Padova, Italy; 2Dept. of Biological, Chem. and Pharmaceut. Sci. and Technol., Univ. of Palermo, Palermo, Italy. firstname.lastname@example.org
Phenoloxidases (POs) belong to a family of copper-containing proteins (including also hemocyanins) widely distributed among invertebrates. They are able to convert polyphenols to quinones and induce cytotoxicity through the production of reactive oxygen species, a fundamental event in many immune responses. In ascidians, PO activity has been described and studied in both solitary and colonial species and the enzyme is involved in inflammatory and cytotoxic reactions against foreign cells or molecules, and in the formation of the cytotoxic foci which characterize the nonfusion reaction of botryllid ascidians. Expressed genes for putative POs have been recently identified in the solitary ascidian C. intestinalis (CiPO1 and CiPO2) and the compound ascidian Botryllus schlosseri. Multiple sequence alignments evidenced the similarity between the sequences of ascidian POs and crustacean proPOs whereas the analysis of the three-dimensional structure reveals high similarity with
arthropod haemocyanins, which share common precursors with arthropod proPOs. Botryllus and Ciona POs grouped in the same cluster, and all of them share the full conservation of the six histidines at the two copper-binding sites as well as of other motifs, also found in arthropod haemocyanin subunits, involved in the regulation of enzyme activity. In situ hybridisation indicated that the Botryllus PO is transcribed inside morula cells, a characteristic cytotoxic haemocyte type. This research was supported by the Italian MIUR (PRIN 2010-2011).
b. Evolution of the complement system: ancient molecules and new evidences from tunicates. N. Franchi1, L. Ballarin2, N. Parrinello1; 1Univ. of Palermo, Palermo, Italy; 2Univ. of Padova, Padova, Italy. email@example.com
The complement system is a key player in innate immunity but, recently, it is becoming even more evident that complement plays also important roles in adaptive immunity.
Components of the human complement system possess unique domain structures and are classified in protein families: C3, factor B (Bf), mannan-binding protein-associated serine protease (MASP), C6 and factor I (If) family. These complement families probably derive from exon shuffling, which created the unique domain structures of each family, and gene
duplication and subsequent functional divergence, which increased the number of members in each family. Accumulating information on the complement system of vertebrates indicates that these gene duplications, which played a pivotal role in establishing the classical and the lytic pathway, occurred in jawed vertebrates. In contrast, information on complement genes of invertebrate chordates is limited and, so far, only the ascidians, such as Ciona intestinalis and Halocinthia roretzi, and the cephalochordate Branchiostoma floridae have an almost complete set of the complement gene families: C3-, Bf-, MASP-, and C6-like genes.
In the present work we demonstrate the presence of C6-, C3-, MASP-, MBL- and Bf-like genes in the colonial ascidian Botryllus schlosseri and the enhanced transcription after zymosan infection, which indicates their involvement in the ascidian immunity. The observation of a transcribed C6 gene suggest that the presence of the lytic pathway predates the appearance of the vertebrates. We are now carrying out new investigation to demonstrate a complement-related lytic activity in B. schlosseri. This work was supported by the Italian MIUR (PRIN 2010-2011)
4. First Intl. Conf. of Fish and Shellfish Immunology. June 25-28, 2013, Vigo, Spain.
Zinc pyrithione induces immunotoxicity in the colonial ascidian Botryllus schlosseri.
F. Cima, L. Ballarin. Department of Biology, Univ. of Padova, Padova, Italy. firstname.lastname@example.org
After TBT ban by many countries in the world, due to its severe impact to coastal ecosystems, mainly related to immunosuppressive effects on both invertebrates and vertebrates, alternative biocides have been massively introduced in formulations of antifouling paints. Zinc pyrithione (ZnP) is one of these new generation biocides, used in dermatology for its antidandruff and antimycotic action. However, up to now, no data are available concerning its potential target organisms, long-term toxic effects on biocoenoses, mechanisms of action, bioaccumulation and environmental fate.
Our interest in the study of ascidian defence reactions led us to investigate the effects of ZnP on cultured phagocytes of the colonial ascidian Botryllus schlosseri, a model organism for immunobiology investigations, widespread in shallow waters, already used in the study of tributyltin (TBT) immunotoxicity. We set up short-term haemocyte cultures (60 min at 20°C) exposed to various concentrations (0.1 to 10 µM) of ZnP (LC50 = 82.5 µM). The fraction of cells with amoeboid morphology, expressed as the amoebocytic index, and the percentage of haemocytes containing phagocytized yeast cells were significantly (p < 0.05) reduced after exposure to 0.1 and 0.5 µM ZnP, respectively. These effects were dose- and time-dependent, and irreversible, similarly to those reported for TBT. Detection of microfilaments and microtubules at fluorescence microscope by FITC-phalloidin and anti-a-tubulin antibody, respectively, revealed thorn-shaped, cytoplasmic projections due to cytoskeletal alterations only in the actin component. Isodynamic mixtures of ZnP and TBT showed an antagonistic interaction on their effects on the amoebocytic index, although no cytoskeletal disassembly was observed, and a significant (p < 0.05) detachment of cells from the substrate occurred after incubation at 0.5 µM. Moreover, like TBT, ZnP induced apoptosis which was detected both as chromatin condensation with acridine orange at 0.1 mM and chromatin fragmentation with TUNEL reaction at 0.5 mM. The latter concentration also significantly (p < 0.001) affected both oxidative phosphorylation and lysosomal activities through the inhibition of cytochrome-c-oxidase and acid phosphatase activity, respectively. Differently to TBT, no effect was observed on Ca2+ homeostasis, since no decrement in Ca2+-ATPase activity occurred, although a small increase in cytosolic Ca2+ was detected after incubation at the highest concentration. In conclusion, our results demonstrate that ZnP shows a strong toxicity on cultured haemocytes at very low concentrations and interferes with fundamental cell activities. Therefore, this substituent biocide results as much toxic as TBT and, since many of its mechanisms of action are unknown, it represents a potential risk for the environmental health.
4. Coastal and Estuarine Research Foundation, 3-7 November 2013, San Diego, CA.
a. The effects of environmental conditions on growth rates of the invasive ascidian Botrylloides violaceus in a southern California bay. Reyns, N., Martinez, D., and Tracy, B. email@example.com
Fouling communities within southern California harbors are often dominated by ascidians, many of which are non-indigenous species that persist and out-compete native species. In Mission Bay, a relatively shallow mesotidal estuary in San Diego, the non-indigenous species Botrylloides violaceus settles along man-made structures such as marina docks and can be locally abundant. We hypothesized that spatial differences in environmental conditions would impact B. violaceus growth rates. PVC plates (13 x13 cm) were deployed at four Mission Bay locations for one year (Fall 2011- Fall 2012) and photographed weekly to identify the spatial and temporal settlement patterns of ascidian species. Temperature, salinity, water clarity, and flow were measured at the time photographs were taken. ImageJ was used to calculate % area cover and growth rates of B. violaceus. Although B. violaceus growth was spatially variable, temperature and salinity measures were within the reported tolerances for this species. In general, growth rates were greatest when temperature and salinity were relatively low. An understanding of how B. violaceus responds to changing environmental conditions will allow us to better predict the potential biotic impacts this species might have outside of its native range.
b.Spatiotemporal patterns of native and invasive ascidian assemblages in Mission Bay, San Diego, CA, USA. Tracy, B., and Reyns, N., firstname.lastname@example.org
Spatial and temporal patterns of ascidian community assemblages were examined within fouling communities of Mission Bay, San Diego, California, USA. We hypothesized that ascidian communities would be structured by spatial differences in environmental parameters between sampling locations. Settlement patterns of native and invasive ascidian species were monitored weekly from September 2011 through November 2012 using settlement plates deployed on floating docks at four sampling locations. Environmental parameters (temperature, salinity, visibility and DO) were measured concurrently. In total, eleven of the fifteen ascidian species observed on settlement plates were invasive species. Sampling locations within the bay differed significantly in ascidian community composition and spatial differences in visibility, salinity, and temperature were correlated to community dissimilarity. Additionally, we observed seasonal persistence of invasive ascidians; below average rainfall in a region of mild climate likely prevented winter cessation. As such, a shifting global climate may be advantageous to invasive species, not only with regard to mediating their persistence, but also in terms of facilitating the establishment, spread, and dominance of future invaders.
5. 94th Annual Meeting of the Western Society of Naturalists, Oxnard, California.
Distribution modelling using maximum entropy approach and open access biodiversity data: a case study of 31 ascidian species. Crafton R.E., Rius M.1 1M.Rius@soton.ac.uk Ocean & Earth Sciences, Univ. of Southampton, UK.
While understanding species distributions and niches has historically been a central tenet of ecological research, improvements in computational technologies, software creation, and data availability have increased focus on these topics over the last two decades. Species distribution models are used to inform academic understanding of what influences range limits and management and conservation activities regarding climate change and invasive species, among many other topics. However, there are both benefits and concerns in utilizing these resources. To illustrate the power and potential dangers of using freely available modeling packages (in this case Maximum Entropy Modeling Software - Maxent) and open access species occurrence data sets (Global Biodiversity Information Facility and literature review), results for global distribution models for 31 ascidian (Phylum Chordata, Class Ascidiacea) species are presented. Results for both current distributions and modeled plausible distributions are compared to identify areas that are modeled as suitable yet lack reported occurrence records. Global port locations are used as a proxy to identify areas with potentially higher propagule pressure, which when combined with habitat suitability, can be used to illustrate invasion risk. The potential for geographic bias based on data sampling is also considered.
6. IV Simposio Colombiano de Biología Evolutiva, Universidad Central, Bogotá. 24-26 July 2013
a. Developmental coloniality in Symplegma brakenhielmi and evolutionary implications. Gutierrez, S. (1), Brown, F.D. (1,2). (1) Universidad de los Andes; (2) Universidade de Sao Paulo. email@example.com
Coloniality is a life history that consists of individuals in permanent turnover, in which modular development has evolved. Only some taxa of Metazoans have the capacity to form colonies by asexual reproduction of individuals. Within tunic bearing sessile marine chordates, i.e. Tunicata, colonial and solitary life histories evolved by convergence. One well-supported transition from a solitary ancestor to coloniality occurs in the Styelidae. All basal species in the group are solitary, whereas derived genera such as Symplegma, Botryllus, and Botrylloides are colonial. Phylogenetic reconstructions of related genera show a stepwise evolution of colonial characters, i.e. higher integration and independence of zooids and buds during blastogenesis. Botryllus and Botrylloides zooids bud in a highly synchronous and periodic manner, whereas Symplegma is asynchronous. Therefore, Symplegma shows an intermediate state between basal solitary species and derived colonial species. Progenitor undifferentiated hemocytes are involved in asexual reproduction in Botryllus and Botrylloides. In this research we describe blastogenesis in Symplegma brakenhielmi and test independence of individuals in the colony by systemic bud or zooid removals. Our results showed less integration and more independence of blastogenesis in S. brakenhielmi as expected in a stepwise evolution scenario. However, we observed acceleration in the development of new buds in budectomized colonies that suggests a certain level of colony-wide control in this species. Next, we characterize hemocytes in S. brakenhielmi colonies. Macrophage-like cells involved in zooid resorption and colony turnover are maintained as the most abundant hemocytes throughout blastogenesis, in contrast to the highly cyclic abundance of macrophages in Botryllus schlosseri blastogenesis. We identified two distinct proliferating hemocytes using mitotic marker Phospho-histone H3 that may serve as putative progenitor cells involved in blastogenesis. Orchestrated blastogenesis implies a constant communication of individuals within the colony, therefore we propose that highly synchronous and periodic blastogenesis in derived Styelids may be accompanied by the evolution of novel and cyclic paracrine or endocrine morphogens signaling. Our findings raise new questions about cell signaling and communication of modules within a colony. These processes could promote body innovations during the evolution of coloniality.
b. Búsqueda y validación computacional de ARNs no codificantes homólogos en el genoma del tunicado. Velandia, C.(1), Brown, F.D. (2,3), Gittenberger A. (4), Bermudez, C. I.(1). (1) Universidad Nacional de Colombia; (2) Universidad de los Andes; (3) Universidade de Sao Paulo; (4) Gimaris, The Netherlands. firstname.lastname@example.org
La secuencia primaria de los RNA no codificantes (ncRNAs) tienen, en términos evolutivos, un alto grado de conservación. Por medio de estrategias de homología y alineamiento estructural, se buscó integrar la información a nivel de estructura primaria y secundaria, con el fin de validar los ncRNAs encontrados en el genoma del tunicado Didemnum vexillum. La detección por homología representa una herramineta clave en genómica, debido a que permite relacionar secuencias en un organismo con otro de forma rápida y con un alto grado de confianza. Como punto de partida de esta búsqueda, se obtuvieron secuencias de ncRNAs anotadas sobre genomas de especies evolutivamente relacionadas y por medio de herramientas basadas en alineamientos de secuencia y estructura secundaria, se obtuvieron los posibles candidatos que fueron evaluados mediante parámetros de descubrimiento de falsos positivos (del ingles: False discovery rate). Esta estrategia permitió encontrar secuencias candidatas significativas para todos los grupos de ncRNAs (microRNAs, RNAs de transferencia, small nuclear RNAs, small nucleolar RNAs y RNAs ribosomales). Cada secuencia fue clasificada con respecto a su familia de ncRNA especifica. Se reportan las coordenadas genómicas, longitud, sentido, valores de identidad y estructura secundaria de los ncRNAs en el primer genoma de una ascidia colonial. Con estos resultados y comparaciones genómicas se puede especular acerca de la relación de ncRNAs y la evolución de los cordados. Los tunicados son los únicos cordados coloniales, por lo que este estudio comparativo de los ncRNAs podría tener implicaciones importantes para entender cómo se mantiene el estado no diferenciado de las células madre adultas involucradas en la gemación y reproducción asexual.
7. TWAS 24th General Meetings, Buenos Aires, Argentina, 1-4 October, 2013.
Stem cell lineages guide the evolution of budding and clonality in our own phylum. Federico D. Brown(1,2,3). (1)Universidade de Sao Paulo; (2)Universidad de los Andes;
(3)Escuela Escuela Superior Politécnica del Litoral. email@example.com
A colony is an aggregate of clonal individuals in permanent turnover that propagate by budding. Only some Metazoans have the capacity to form colonies. Within the Chordata, tunicates have evolved colonial and solitary life histories multiple times independently. To reconstruct developmental transitions, and to explore non-coding RNA (ncRNA) regulation during the evolution of coloniality, we study two species of colonial ascidians, i.e. Symplegma brakenhielmi and Didemnum vexillum. One well-supported transition from a solitary ancestor into a colonial clade occurs in the colonial Styelidae. In this clade, basal species are solitary or social (i.e. individuals in aggregates), and derived species are colonial (i.e. individuals that share a common tunic). Phylogenetic reconstructions of species within this clade show a stepwise evolution of colonial characters. Most recently derived species show a higher dependence and synchrony between individuals during budding cycles of the colony. Our studies show that basal colonial botryllid S. brakenhielmi does not synchronize budding cycles, and buds generally develop in vessels that connect individuals of the colony in an independent manner, in contrast to the well-studied and more derived Botryllus and Botrylloides genera. To show that S. brakenhielmi individuals show complete independence in budding, we carried systemic bud or zooid removal in the colony and compared our results to previous observations in Botryllus schlosseri. To test whether synchrony in budding cycles occurs in S. brakenhielmi we counted types of blood cells in colonies of different size or developmental stage. Macrophage-like cells were invariably abundant in all analyzed colonies, suggesting permanent tissue resorption and turnover in the colony, in contrast to cyclic abundance of Macrophage-like cells in B. schlosseri. Using mitotic marker Phospho-histone H3, we identified two populations of proliferating blood cells that may act as putative progenitor cells for S. brakenhielmi vascular budding. Progenitor stem cells remain undifferentiated and can be replenished via highly sophisticated mechanisms of RNA regulation. To address involvement of RNA regulation for the maintenance of progenitor stem cells for budding, we used the genome of colonial ascidian Didemnum vexillum to search for specific signatures of ncRNAs only present in colonial ascidians. We compared our predictions to other solitary tunicate genomes such as Ciona intestinalis, Ciona savignyi, and Oikopleura dioica. We found C/D box snoRNAs or miRNAs candidates involved in silencing, methylation, and stem cell regulation that will allow us to test for specific expression in stem cell porgenitors in buds of colonial ascidians. Our study raises new questions about the origins synchronous developmental integration between individuals of the colony by novel signaling pathways, and the involvement of RNA regulation during the evolution of budding in colonial chordates.
8. Conferência “Avanços e Perspectivas da Ciência no Brasil, América Latina e Caribe” at the Academia Brasileiras de Ciencias, Rio de Janeiro, Brasil. 28-30 October, 2013.
Origen evolutivo de las células madre en nuestro propio filo: implicaciones en la regeneración y reproducción clonal. Federico D. Brown (1,2). (1)Universidade de São Paulo; (2)Universidad de Los Andes. firstname.lastname@example.org
Dentro de nuestro propio filo, los tunicados exhiben una gran plasticidad en los mecanismos de reproducción, y también muestran un potencial de regenerar cuerpos completos a partir de tejidos adultos. En estos cordados marinos, que incluye a las ascidias, especies solitarias sólo se reproducen sexualmente, mientras que las especies coloniales pueden reproducirse sexual y asexualmente. Después de una remoción completa de todos los individuos - o zooides - de la colonia, células progenitoras del sistema vascular remanente regeneran nuevos individuos completos. Para entender el grado de dependencia en el desarrollo de los individuos coloniales (i.e. zooides), se realizaron remociones de zooides o yemas en varias colonias de S. brakenhielmi, y se registraron datos detallados del desarrollo de nuevas yemas o de la diferenciación de los zooides en las colonias manipuladas. Los géneros coloniales más recientes de la familia Styelidae, a la que pertenece S. brakenhielmi, muestran una sincronía y dependencia en el desarrollo de los zooides, mientras que los géneros basales muestran una mayor independencia en su desarrollo. S. brakenhielmi muestra un estado intermedio, sin sincronización en el desarrollo de sus individuos, pero con un mínimo grado de dependencia ya que colonias en las que fueron extraídos las yemas generan nuevas yemas más rápidamente que el control. Además, se identificaron caracterizaron las células de la sangre y se usaron caracteres morfologicos y moleculares para identificar células progenitores putativas involucradas en la regeneración de individuos de colonias adultas. Ya que la gemación y regeneración de individuos en ascidias coloniales requiere de una fuente permanente de células madre no diferenciadas, se está explorando la posibilidad de que ncRNAs estén involucrados en mantener el estado no diferenciado en células circulatorias de la sangre. Se realizaron predicciones de distintos tipos de ncRNAs, incluyendo miRNAs, y se presenta una hipótesis con candidatos específicos de miRNAs que podrían estar involucrados en la regulación de los estados de determinación de células madre progenitoras importantes para la evolución de la gemación y la colonialidad. Entender los cambios necesarios en el desarrollo que fueron necesarios durante la evolución de la gemación en las ascidias pueden darnos pistas importantes acerca del funcionamiento y origén de células madre en otros cordados, incluyendo al humano.
9. Sixth Intl. Symposium of Developmental Biology, Paraty, Brasil. 1-4 November, 2013.
Bud like your progenitors! Federico D. Brown(1,2), Arianna S. Gutierrez(2), Leda Restrepo(2), Cristian A. Velandia(2,3), and Arjan Gittenberger(4,5), Clara Bermudez-Santana(3). (1)Universidade de São Paulo; (2)Universidad de Los Andes; (3)Universidad Nacional de Colombia; (4)GiMaRIS Netherlands; (5)Leiden University. email@example.com
Within our own phylum, tunicates exhibit a great plasticity in reproduction mechanisms, and also show complete adult regeneration potential. Solitary species only reproduce sexually, whereas colonial species reproduce both sexually and clonally. Species of colonial ascidians have long been known to regenerate complete bodies from remnant colony vasculature and circulatory progenitor cells after complete removal of all individuals or zooids of the colony. To reconstruct developmental transitions, and to explore ncRNA regulation during the evolution of coloniality, we study two species of colonial ascidians, i.e. Symplegma brakenhielmi and Didemnum vexillum. We study the transition of a solitary ancestral species into several colonial species by direct observations of budding in different Styelid colonial species. We demonstrate how more recent clades show a higher integration in the development of individuals, whereas more basal clades show a higher independence. S. brakenhielmi does not synchronize budding and their buds generally develop independently at extracorporeal vessels that connect the individuals of the colony, whereas derived Botryllus and Botrylloides generally present synchronous budding by evagination of the lateral epidermis of adult individuals. To show that S. brakenhielmi individuals show complete independence in development, we carried systemic bud or zooid removal in the colony and compared our results to previous observations in Botryllus schlosseri. Next, we studied hemocytes and analyzed proliferation in S. brakenhielmi to identify putative circulatory progenitor cells. Budding in ascidians requires a permanent supply of progenitor cells likely regulated by ncRNA pathways. Using Didemnum vexillum genome, we search for ncRNA predictions and search for colonial ascidian specific signatures. Our results support a stepwise integration of budding synchrony and developmental interaction of individuals during the evolution of coloniality. Mechanistic developmental changes that occurred during the evolution of budding in marine colonial chordates set the framework for understanding stem cell function in other animals, including vertebrates.
1. Marine bioinvasions in anthropogenic and natural habitats: an investigation of nonindigenous ascidians in British Columbia. Christina Simkanin. Ph.D. thesis, Univ. of Victoria, Canada. Advisors John Dower, Tom Therriault and Glen Jamieson. firstname.lastname@example.org
The simultaneous increase in biological invasions and habitat alteration through the building of coastal infrastructure is playing an important role in reshaping the composition and functioning of nearshore marine ecosystems. This thesis examined patterns of marine invasions across anthropogenic and natural habitats and explored some of the processes that influence establishment and spread of invaders. The goals of this thesis were four-fold. First, I examined the habitat distribution of marine nonindigenous species (NIS) spanning several taxonomic groups and geographical regions. Second, I conducted systematic subtidal surveys in anthropogenic and natural habitats and investigated the distribution of nonindigenous ascidians on Southern Vancouver Island, British Columbia, Canada. Third, I tested methods for in-situ larval inoculations and utilized these techniques to manipulate propagule supply and assess post-settlement mortality of ascidians across habitat types. Fourth, I investigated the role of biotic resistance, through predation by native species, on the survival of ascidian colonies in anthropogenic and natural habitats.
Results from this research showed that anthropogenic habitats are hubs for marine invasions and may provide beachheads for the infiltration of nearby natural sites. Specifically, a literature review of global scope showed that most NIS are associated with anthropogenic habitats, but this pattern varied by taxonomic group. Most algal and mobile invertebrate NIS were reported from natural habitats, while most sessile NIS were reported from artificial structures. Subtidal field surveys across both anthropogenic and natural habitats showed that nonindigenous ascidians were restricted largely to artificial structures on Southern Vancouver Island and that this pattern is consistent across their global introduced ranges. Field manipulations using the ascidian Botrylloides violaceus as a model organism, showed that post-settlement mortality is high and that large numbers of larvae or frequent introduction events are needed for successful initial invasion and successful infiltration of natural habitats. Experiments also showed that predation by native species can limit the survival of B. violaceus in anthropogenic and natural habitats. This dissertation contributes knowledge about the patterns and processes associated with habitat invisibility; provides insight into factors affecting colonization; and supplies valuable information for predicting and managing invasions.
2. Population dynamics of a non-indigenous colonial ascidian tunicate in a subarctic harbour. Kevin C. K. Ma, MS thesis, Memorial University of Newfoundland, Canada.
Botryllus schlosseri (Subphylum Tunicata: Class Ascidiacea) is a nonindigenous
ascidian species of global and national interest, which has extensive populations along the south coast of insular Newfoundland. Economically, this species has been of concern to industry, management, and policymakers because non-indigenous ascidian species have been a severe and costly nuisance for bivalve aquaculture. Ecologically, the presence of this temperate-adapted species in Newfoundland represents an expansion of its global range into subarctic waters. Thus, I aimed to describe the population dynamics of B. schlosseri in Arnold’s Cove, Placentia Bay, Newfoundland and Labrador, Canada, by determining the temporal and spatial patterns of recruitment and the seasonal cycle of colony abundance. In
addition, I aimed to compile a checklist of extant indigenous and non-indigenous ascidian species of eastern Canada with an emphasis on species from Newfoundland and Labrador.
Artificial plates were used to determine recruitment rates among three sites, depths (1.0, 2.5, and 4.0 m from the water surface), and substrate types (aluminum, PVC, and wood in 2010; only PVC in 2011), in Arnold’s Cove. Concurrently, density and cover of colonies were determined from the analysis of high-definition video surveys of a belt transect of wharf pilings. Seasonal biomass production was estimated from carbon to nitrogen (C:N) ratios and dry weight per unit area of dissected tissue subsamples.
The seasonal window for recruitment was from early August to mid-October. Recruitment rates were greater near the water surface than at other depths, and on PVC in comparison to aluminum and wood substrates. Maximum recruitment rates on PVC at 1.0 m were 29.3 and 43.5 m⁻²d⁻¹ in September of 2010 and 2011, respectively, coincident with maximum seasonal seawater temperatures of 16-17°C. Colonies were present year-round on pilings. In the upper subtidal zone, monthly mean cover ranged from an annual minimum of 0.6% in May to a maximum of 2.8% in October. Colony size and biomass, though not C:N ratios, had a significant seasonal signal.
These findings suggest that recruitment was predominantly constrained by seawater temperature within the short productive season, and that the population was sustained from one year to the next because of high cover of overwintering colonies. The efficacy of utilising PVC to track recruitment of Botryllus schlosseri, and perhaps other closely related ascidian species is supported by my data. Future management of B. schlosseri should target mitigation efforts before the annual onset of sexual reproduction and recruitment in July and within the upper 3-4 m of the water column.
3. Temporal and spatial variation in native and non-indigenous ascidian settlement within fouling communities in Mission Bay, San Diego, California. Brianna Tracy. MS degree in Marine Science, Univ. of San Diego 2013. Advisors: Dr. Nathalie Reyns, Dr. Jeff Crooks, and Dr. Drew Talley. email@example.com.
The results were structured into two main chapters:
- Spatial and Temporal Patterns of Native and Invasive Ascidian Assemblages in Mission Bay, San Diego, California, USA
- Fouling Community Composition, Taxonomic Richness, and Diversity in Mission Bay, San Diego, California, USA
In total, eleven of the fifteen ascidian species observed during this study were invasive species. Sampling locations within the bay differed significantly in ascidian community composition and spatial differences in visibility, salinity, and temperature were correlated to community dissimilarity. Three invasive ascidian species (Botrylloides violaceus, Botryllus schlosseri, Ciona intestinalis) and one cryptogenic species (Diplosoma listerianum) were identified as significant contributors to fouling community assemblages at the sampling locations. Although these species visually appeared dominant on the settlement plates, we did not measure a statistical difference in taxonomic richness in the presence or absence of any of these main ascidian fouling community contributors. We observed seasonal persistence of invasive ascidians, however; below average rainfall in a region of mild climate likely prevented winter cessation. As such, a shifting global climate may be advantageous to invasive species, not only with regard to mediating their persistence, but also in terms of facilitating the establishment, spread, and dominance of future invaders.
4. Budding in Symplegma brakenhielmi and the evolution of coloniality in botryllid ascidians. Stefania Gutiérrez (1,2) Master Thesis, Universidad de los Andes, Bogotá, Colombia. June, 2013. (1)Laboratorio de Biología del Desarrollo Evolutiva (EvoDevo), Departamento de Ciencias Biológicas, Univ. de los Andes, Bogotá D.C., Colombia.
(2) Smithsonian Tropical Research Institute, Bocas del Toro, Panamá. firstname.lastname@example.org
Coloniality is a life history that consists of individuals in permanent turnover, in which modular development has evolved. Only some taxa of Metazoans have the capacity to form colonies by asexual reproduction of individuals. Within tunic bearing sessile marine chordates, i.e. Tunicata, colonial and solitary life histories evolved by convergence. One well-supported transition from a solitary ancestor to coloniality occurs in the Styelidae. All basal species in the group are solitary, whereas derived genera such as Symplegma, Botryllus, and Botrylloides are colonial. Phylogenetic reconstructions of related genera show a stepwise evolution of colonial characters, i.e. higher integration and independence of zooids and buds during blastogenesis. We describe blastogenesis in Symplegma brakenhielmi and test independence of individuals in the colony by systemic bud or zooid removals. Our results show less integration and more independence of blastogenesis in Symplegma than in Botryllus or Botrylloides as expected in a stepwise evolution scenario. However, we observed acceleration in the development of new buds in budectomized colonies that demonstrates some level of colony-wide regulation in this species. To test whether circulatory hemocytes provided evidence for cyclic and highly synchronous development in Symplegma, we characterized hemocytes in several S. brakenhielmi colonies. Macrophage-like cells involved in zooid resorption and colony turnover were the most abundant hemocytes in different colonies at different stages, in contrast to Botryllus schlosseri colonies that show higher abundance of macrophage-like cells only during the stage of tissue recycling. Using mitotic marker Phospho-histone H3, we identified two populations of proliferating hemocytes that may act as putative progenitor cells. Synchronized and cyclic blastogenesis can only be accomplished by permanent communication of individuals in the colony, therefore we propose that novel mechanisms of orchestrated paracrine or endocrine signaling between individuals evolved in derived Styelid ascidians. Our findings raise new questions on how modular development may serve as a preadaptation for the evolution of coloniality.
5. First record of the invasive tunicate Didemnum vexillum in a tropical region. Leda Restrepo(1, 2). Master Thesis, Universidad de los Andes, Bogotá, Colombia. December, 2013. Advisor Federico Brown. 1Dept. of Biol. Sci., Universidad de los Andes, Bogotá, Colombia; 2Centro Nacional de Acuicultura e Investigaciones Marinas, Escuela Superior Politécnica del Litoral, San Pedro, Ecuador. email@example.com
Didemnum vexillum is an invasive ascidian that rapidly overgrows and dominates benthic communities displacing native species and seriously impacting oyster cultures and other aquaculture facilities. In recent years, reports of Didemnum vexillum invasions in the Mediterranean, Pacific, and Atlantic Oceans have raised concerns. In this study we report the first tropical occurrence of D. vexillum on the coast of Ecuador based on morphological and molecular evidence. To evaluate native Didemnum species composition, we collected ascidian colonies, from cultured oysters at the Centro Nacional de Acuicultura e Investigaciones Marinas (CENAIM) in San Pedro, Prov. of Santa Elena and at several benthic sites (5-15m) nearby. All colonies were identified morphologically and assessed by molecular analyses, using mitochondrial marker COI. To help determine how ascidian fouling affects oyster growth and filtration, we grew C. gigas oysters alone and compared them to oysters implanted with Didemnum. We found the growth of this ascidian on oysters affect significantly the filtration rate of the oyster, and subsequently the optimal growth and development. A mostly temperate distribution of Didemnum vexillum suggests that its propagation may be favored by cold temperatures, thereby we examined whether Didemnum growth was positively affected by colder water temperatures than those generally found off the coast of Ecuador. We present molecular data on mitochondrial genes from colonies sampled from Ecuador and compare with samples of New Zealand, Japan, and North America. These data indicate that Didemnum sp. found in Ecuador is possibly native to the northwestern Pacific Ocean.
Ahn, C. H., Won, T. H., Kim, H., Shin, J. and Oh, K. B. 2013. Inhibition of Candida albicans isocitrate lyase activity by cadiolides and synoilides from the ascidian Synoicum sp. Bioorg. & Med. Chem. Lett. 23: 4099-4101.
Al-Sofyani, A. A., Marimuthu, N. and Wilson, J. J. 2013. Tunicate bloom in the Obhur creek of Jeddah coast, Red Sea. Curr. Sci. India 104: 1274-1275.
Aoki, M. N., Matsumoto-ohshima, C., Hirose, E. and Nishikawa, J. 2012. Mother–young cohabitation in Phronimella elongata and Phronima spp. (Amphipoda, Hyperiidea, Phronimidae). J. Mar. Biol. Ass. U.K. 93: 1553–1556.
Arrigoni, C., Schroeder, I., Romani, G., Van Etten, J. L., Thiel, G. and Moroni, A. 2013. The voltage-sensing domain of a phosphatase gates the pore of a potassium channel. J. Gen. Physiol. 141: 389-395.
Baghdiguian, S., Martinand-Mari, C., Maury, B., Lorman, V. and Mangeat, P. 2013. Would D'Arcy Thompson have predicted a topological control of apoptosis? Med. Sci. (Paris) 29: 411-5.
Barnes, D. K. A. and Conlan, K. E. 2007. Disturbance, colonization and development of Antarctic benthic communities. Phil. Trans. Roy. Soc. B 362: 11-38.
Barnes, P. B., Roberts, D. E. and Davis, A. R. 2013. Biodiversity in saline coastal lagoons: patterns of distribution and human impacts on sponge and ascidian assemblages. Diversity and Distributions 19: 1394-1406.
Bonnet, N. Y. K., Rocha, R. M. and Carman, M. R. 2013. Ascidiidae Herdman, 1882 (Tunicata: Ascidiacea) on the Pacific coast of Panama. Zootaxa 3691: 351–364.
Bontemps, N., Gattacceca, F., Long, C., Thomas, O. P. and Banaigs, B. 2013. Additional cytotoxic pyridoacridine alkaloids from the ascidian Cystodytes violatinctus and biogenetic considerations. J. Nat. Prod. 76: 1801-1805.
Cahill, P. L., Heasman, K., Jeffs, A. and Kuhajek, J. 2013. Laboratory assessment of the antifouling potential of a soluble-matrix paint laced with the natural compound polygodial. Biofouling 29: 967-975.
Cañete, J. I. and Rocha, R. M. 2013. Modiolarca lateralis (Pteryomorphia: Mytilidae): bivalve associated to six species of ascidians from Bocas del Toro, Panama. Lat. Am. J. Aquat. Res. 41: 1030-1035.
Canning-Clode, J., Fofonoff, P., McCann, L., Carlton, J. T. and Ruiz, G. 2013. Marine invasions on a subtropical island: fouling studies and new records in a recent marina on Madeira Island (Eastern Atlantic Ocean). Aquatic Invasions 8 (3): 261-270.
Cima, F. and Ballarin, L. 2013. A proposed integrated bioindex for the macrofouling biocoenosis of hard substrata in the lagoon of Venice. Estuarine, Coastal & Shelf Sci. 130: 190-201.
Cima, F., Caicci, F. and Sordino, P. 2013. The haemocytes of the salp Thalia democratica (Tunicata, Thaliacea): an ultrastructural and histochemical study in the oozoid. Acta Zool. epub:
Collin, S. B., Edwards, P. K., Leung, B. and Johnson, L. E. 2013. Optimizing early detection of non-indigenous species: estimating the scale of dispersal of a nascent population of the invasive tunicate Ciona intestinalis (L.). Mar. Pollution Bull. 73: 64-69.
Crooks , J. A., Chang, A. L. and Ruiz, G. M. 2011. Aquatic pollution increases the relative success of invasive species. Biol. Invasions 13: 165-176.
Danks, G., Campsteijn, C., Parida, M., Butcher, S., Doddapaneni, H., Fu, B., Petrin, R., Metpally, R., Lenhard, B., Wincker, P., Chourrout, D., Thompson, E. M. and Manak, J. R. 2013. OikoBase: a genomics and developmental transcriptomics resource for the urochordate Oikopleura dioica. Nucleic Acids Res. 41: D845-D853.
Denker, E., Bocina, I. and Jiang, D. 2013. Tubulogenesis in a simple cell cord requires the formation of bi-apical cells through two discrete Par domains. Development 140: 2985-2996.
Dumollard, R., Hebras, C., Besnardeau, L. and McDougall, A. 2013. Beta-catenin patterns the cell cycle during maternal-to-zygotic transition in urochordate embryos. Dev. Biol. epub
Erwin, P., Pineda, M. C., Webster, N., Turon, X. and López-Legentil, S. 2013. Down under the tunic: Bacterial biodiversity hotspots and widespread ammonia-oxidizing Archaea in Great Barrier Reef ascidians. ISME J. epub: 1-14.
Ettensohn, C. A. 2013. Encoding anatomy: developmental gene regulatory networks and morphogenesis. Genesis 51: 383-409.
Ferro, D., Franchi, N., Mangano, V., Bakiu, R., Cammarata, M., Parrinello, N., Santovito, G. and Ballarin, L. 2013. Characterization and metal-induced gene transcription of two new copper zinc superoxide dismutases in the solitary ascidian Ciona intestinalis. Aquatic Toxicol. 140– 141: 369– 379.
Fitridge, I., Dempster, T., Guenther, J. and de Nys, R. 2012. The impact and control of biofouling in marine aquaculture: a review. Biofouling 28: 649-669.
Fong, H. K. and Copp, B. R. 2013. Synthesis, DNA binding and antitumor evaluation of styelsamine and cystodytin analogues. Mar. Drugs 11: 274-299.
Frank, P., Hedman, B. and Hodgson, K. O. 2013. XAS spectroscopy, sulfur, and the brew within blood cells from Ascidia ceratodes. J. Inorg. Biochem. in press:
Freestone, A. L., Ruiz, G. M. and Torchin, M. E. 2013. Stronger biotic resistance in tropics relative to temperate zone: effects of predation on marine invasion dynamics. Ecology 94: 1370-1377.
Galil, B. S. 2012. Truth and consequences: the bioinvasion of the Mediterranean Sea. Integrative Zool. 7: 299-311.
Gallo, A. and Tosti, E. 2013. Adverse effect of antifouling compounds on the reproductive mechanisms of the ascidian Ciona intestinalis. Mar. Drugs 11: 3554-3568.
Gasparini, F., Caicci, F., Rigon, F., Zaniolo, G., Burighel, P. and Manni, L. 2013. Cytodifferentiation of hair cells during the development of a basal chordate. Hearing Res. 304: 188-199.
Gomathy, S., Meenakshi, V. K., Senthamarai, S., Paripooranaselvi, M., Chamundeswari, K. P. and Delighta Mano Joyce, M. I. 2013. Chemical screening of the simple ascidian Microcosmus exasperatus. Proc. 2nd Intl. Conf. Kanniyakumari Acad. Arts & Sci. 17-21.
Gomathy, S., Meenakshi, V. K., Senthamarai, S., Shanmugapriya, D., Paripooranaselvi, M. and Chamundeswari, K. P. 2012. Studies on the distribution of ascidians. Proc. 8th all India Conference of KAAS -2012 3: 23-31.
Gopalakrishnan, S., Meenakshi, V. K. and Shanmuga Priya, D. 2012. Anaesthetic activity of Phallusia nigra Savigny, 1816. Annals Biol. Res. 3: 1863-1865.
Gopalakrishnan, S., Shanmuga Priya, D. and Meenakshi, V. K. 2012. Wound healing activity of the methanolic extract of Phallusia nigra Sav. Intl. J. Chem. Pharmaceut. Sci. 3: 45-51.
Gopalakrishnan, S., Shanmuga Priya, D. and Meenakshi, V. K. 2012. Antimicrobial activity of the methanolic extract of Phallusia nigra Sav. J. Nat. Prod. & Plant Resources 2: 579-583.
Gopalakrishnan, S., Shanmuga Priya, D. and Meenakshi, V. K. 2013. Anti- inflammatory activity of simple ascidian, Phallusia nigra Sav. Intl. J. Pharmaceut. Sci. Rev. & Res. 22: 162-167.
Gopalakrishnan, S., Shanmuga Priya, D. and Meenakshi, V. K. 2013. Pharmacognostical and preliminary phytochemical evaluation of Phallusia nigra Sav. Global J. Pharmacol. 7: 39-44.
Gutt, J., Cape, M., Dimmler, W., Fillinger, L., Isla, E., Lieb, V., Lundalv, T. and Pulcher, C. 2013. Shifts in Antarctic megabenthic structure after ice-shelf disintegration in the Larsen area east of the Antarctic Peninsula. Polar Biol. 36: 895-906.
Han, Q.-H., Fan, C.-Q., Lu, Y.-N., Wu, J.-P., Liu, X. and Yin, S. 2013. Chemical constituents from the ascidian Aplidium constellatum. Biochem. Syst. & Ecol. 48: 6-8.
Harada, Y. 2013. Allorecognition between compound ascidian colonies. Zool. Sci. 30: 694-698.
Haupaix, N., Stolfi, A., Sirour, C., Picco, V., Levine, M., Christiaen, L. and Yasuo, H. 2013. p120RasGAP mediates ephrin/Eph-dependent attenuation of FGF/ERK signals during cell fate specification in ascidian embryos. Development 140: 4347-4352.
Haye, P. A. and Munoz-Herrera, N. C. 2013. Isolation with differentiation followed by expansion with admixture in the tunicate Pyura chilensis. BMC Evol. Biol. 13:
Hillock, K. A. and Costello, M. J. 2013. Tolerance of the invasive tunicate Styela clava to air exposure. Biofouling 29: 1181-1187.
Hirose, E. and Hirose, M. 2013. Photosymbiotic ascidians from oceanic islands in the tropical Pacific as candidates of long-dispersal species: morphological and genetic identification of the species. Aquatic Invasions 8 (3): 271-280.
Hirose, E., Mayama, H. and Miyauchi, A. 2013. Does the aquatic invertebrate nipple array prevent bubble adhesion? An experiment using nanopillar sheets. Biol. Lett. 9: 1-5.
Horikawa, Y., Matsumoto, H., Yamaguchi, F., Ishida, S. and Fujiwara, S. 2013. Transcriptional regulation in the early ectodermal lineage of ascidian embryos. Dev. Growth Differ. epub: 1-12.
Irvine, S. Q. 2013. Study of Cis-regulatory elements in the ascidian Ciona intestinalis. Curr. Genomics 14: 56-67.
Janiak, D. S., Osman, R. W. and Whitlatch, R. B. 2013. The role of species richness and spatial resources in the invasion success of the colonial ascidian Didemnum vexillum Kott, 2002 in eastern Long Island Sound. J. Exp. Mar. Biol. Ecol. 443: 12-20.
Jin, H., Zhang, P., Bijian, K., Ren, S., Wan, S., Alaoui-Jamali, M. A. and Jiang, T. 2013. Total synthesis and biological activity of marine alkaloid Eudistomins Y1-Y7 and their analogues. Mar. Drugs 11: 1427-1439.
Jones, M. R. L. and Breen, B. B. 2013. Food and feeding relationships of three sympatric slickhead species (Pisces: Alepocephalidae) from northeastern Chatham Rise, New Zealand. Deep Sea Res. 79: 1-9.
Jute, A. H. C., Gobin, J. F. and Rocha, R. M. 2013. A preliminary list of ascidians for the island of Trinidad, West Indies. Mar. Biodiversity Rec. 6: e62 (4 pages).
Kabalah-Amitai, L., Mayzel, B., Kauffmann, Y., Fitch, A. N., Bloch, L., Gilbert, P. U. and Pokroy, B. 2013. Vaterite crystals contain two interspersed crystal structures. Science 340: 454-457.
Kabalah-Amitai, L., Mayzel, B., Zaslansky, P., Kauffmann, Y., Clotens, P. and Pokroy, B. 2013. Unique crystallographic pattern in the macro to atomic structure of Herdmania momus vateritic spicules. J. Struct. Biol. 183: 191-198.
Kanda, M., Ikeda, T. and Fujiwara, S. 2013. Identification of a retinoic acid-responsive neural enhancer in the Ciona intestinalis Hox1 gene. Dev. Growth Differ. 55: 260-269.
Katikala, L., H., A., Passamaneck, Y. J., Gazdoiu, S., Jose'-Edwards, D. S., Kugler, J. E., Oda-Ishii, I., Imai, J. H., Nibu, Y. and Di Gregorio, A. 2013. Functional Brachyury binding sites establish a temporal read-out of gene expression in the Ciona notochord. PLoS Biol. 11: e1001697.
Kawamura, K., Shiohara, M., Kanda, M. and Fujiwara, S. 2013. Retinoid X receptor-mediated transdifferentiation cascade in budding tunicates. Dev. Biol. in press:
Kawamura, K. and Sunanaga, T. 2013. Senescence-associated superoxide dismutase influences mitochondrial gene expression in budding tunicates. Dev. Growth & Differ. 55: 606-614.
Kohila Subathra Christy, H., Jothibai Margret, R. and Meenakshi, V. K. 2013. Infrared and gas chromatogram-mass spectral studies of the ethanolic extract of Phallusia arabica Savigny, 1816. Arch. Applied Sci. Res. 5: 17-23.
Kumagai, A., Ito, H. and Sasaki, R. 2013. Detection of the kinetoplastid Azumiobodo hoyamushi, the causative agent of soft tunic syndrome, in wild ascidians Halocynthia roretzi. Dis. Aquat. Organ. 106: 267-271.
Kumagai, A. and Kamaishi, T. 2013. Development of polymerase chain reaction assays for detection of the kinetoplastid Azumiobodo hoyamushi, the causative agent for soft tunic syndrome in the ascidian Halocynthia roretzi. Fish Pathol. 48: 42-47.
Lee, S. S. C., Teo, S. L. M. and Lambert, G. 2013. New records of solitary ascidians on artificial structures in Singapore waters. Mar. Biodiversity Rec. 6: 1-18.
Levasseur, M., Dumollard, R., Chambon, J. P., Hebras, C., Sinclair, M., Whitaker, M. and McDougall, A. 2013. Release from meiotic arrest in ascidian eggs requires the activity of two phosphatases but not CaMKII. Development 140: 4583-4593.
Li, J. L., Kim, E. L., Wang, H., Hong, J., Shin, S., Lee, C. K. and Jung, J. H. 2013. Epimeric methylsulfinyladenosine derivatives from the marine ascidian Herdmania momus. Bioorg. & Med. Chem. Lett. 23: 4701-4704.
Litman, G. W. and Dishaw, L. J. 2013. Histocompatibility: clarifying fusion confusion. Curr. Biol. 23: R934.
Matsumae, H., Hamada, M., Fujie, M., Niimura, Y., Tanaka, H. and Kawashima, T. 2013. A methodical microarray design enables surveying of expression of a broader range of genes in Ciona intestinalis. Gene 519: 82-90.
Matsuoka, T., Ikeda, T., Fujimaki, K. and Satou, Y. 2013. Transcriptome dynamics in early embryos of the ascidian, Ciona intestinalis. Dev. Biol. epub:
Meenakshi, V. K., Delighta Mano Joyce, M. I., Paripooranaselvi, M. and Gomathy, S. 2013. CNS depressant activity of the simple ascidian Microcosmus exasperatus Heller, 1878. Intl. J. Curr. Microbiol. & Applied Sci. 2: 16-25.
Meenakshi, V. K., Gomathy, S., Paripooranaselvi, M. and Chamundeswari, K. P. 2012. Antidiabetic activity of the ethanol extract of simple ascidian, Microcosmus exasperatus Heller, 1878. Int. J. Chem. Pharmaceut. Sci. 3: 33-39.
Meenakshi, V. K., Gomathy, S., Senthamarai, S., Paripooranaselvi, M. and Chamundeswari, K. P. 2012. GC-MS determination of the bioactive components of Microcosmus exasperatus Heller, 1878. J. Curr. Chem. Pharmaceut. Sci. 2: 271-276.
Meenakshi, V. K., Gomathy, S., Senthamarai, S., Paripooranaselvi, M. and Chamundeswari, K. P. 2012. Analysis of vitamins by HPLC and phenolic compounds, flavonoids by HPTLC in Microcosmus exasperatus. Eur. J. Zool. Res. 1: 105-110.
Meenakshi, V. K., Gomathy, S., Senthamarai, S., Paripooranaselvi, M. and Chamundeswari, K. P. 2013. Hepatoprotective activity of the ethanol extract of simple ascidian, Microcosmus exasperatus Heller, 1878. Eur. J. Zool. Res. 2: 32-38.
Meenakshi, V. K., Paripooranaselvi, M., Gomathy, S. and Chamundeswari, K. P. 2012. Antiproliferative activity of Phallusia nigra Savigny, 1816 against Dalton's Lymphoma ascites. Intl. J. Chem. Pharmaceut. Sci. 3: 70-75.
Meenakshi, V. K., Paripooranaselvi, M., Gomathy, S. and Chamundeswari, K. P. 2012. Antitumor and immunomodulatory activity of Phallusia nigra Savigny, 1816 against Ehrlich Ascites carcinoma. Intl. J. Pharmaceut. Sci. 1: 7-12.
Meenakshi, V. K., Paripooranaselvi, M., Gomathy, S. and Chamundeswari, K. P. 2013. Immunomodulatory activity of ethanol extracts of Phallusia nigra Savigny 1816, against Dalton's lymphoma ascites. Eur. J. Applied Engin. & Sci. Res. 2: 20-24.
Meenakshi, V. K., Paripooranaselvi, M., Sankaravadivu, S., Gomathy, S. and Chamundeeswari, K. P. 2013. Immunomodulatory activity of Phallusia nigra Savigny, 1816 against S-180. Intl. J. Curr. Microbiol. & Applied Sci. 2: 286-295.
Meenakshi, V. K., Paripooranaselvi, M., Senthamarai, S., Gomathy, S., Sankaravadivu, S. and Chamundeswari, K. P. 2014. Antitumor effect of ethanolic extract of Phallusia nigra Savigny, 1816 on S-180 tumor bearing mice. Intl. J. Exp. Pharmacol. in press:
Meenakshi, V. K. and Senthamarai, S. 2012. New records of two species of colonial ascidians - Aplidium distaplium Kott, 1992 and Aplidium brevilarvacium Kott, 1963 from Indian waters. Eur. J. Zool. Res. 1: 65-69.
Meenakshi, V. K. and Senthamarai, S. 2013. Diversity of ascidians from the Gulf of Mannar. In: Venkataraman, K., Sivaperuman, C. and Raghunathan, C. (ed.), Ecology and Conservation of Tropical Marine Faunal Communities. Heidelberg, New York, Dordrecht, London, Springer, pp. 213-229.
Meenakshi, V. K. and Senthamarai, S. 2013. On the occurrence of one new species and three new records of the genus Aplidium from Indian waters. J. Chem. Biol. & Phys. Sci. 3: 2712-2721.
Meenakshi, V. K., Senthamarai, S., Paripoorana Selvi, M., Gomathy, S., Shanmuga Priya, D. and Chamundeswari, K. P. 2012. Antibacterial activity of simple ascidian Ascidia sydneiensis (Family: Ascidiidae) against human pathogens. J. Microbiol. Biotech. Res. 2: 894-899.
Meenakshi, V. K., Senthamarai, S., Paripooranaselvi, M., Gomathy, S., Sankaravadivu, S. and Chamundeswari, K. P. 2013. In vitro and in vivo antitumor and immunomodulatory studies of Microcosmus exasperatus against DLA bearing mice. Eur. J. Applied Engin. & Sci. Res. 2: 18-25.
Meenakshi, V. K. and Shanmuga Priya, D. 2012. HPLC and FTIR spectral studies of the simple ascidian Phallusia nigra. Arch. Applied Sci. Res. 4: 2145-2148.
Meenakshi, V. K., Veerabahu, C. and Roselin, K. F. 2013. GC-ms and IR studies of ethanolic extract of colonial ascidian Polyclinum madrasensis Sebastian, 1952. Intl. J. Pharma & Bio Sci. 4: 1187-1198.
Monniot, F. 2013. The genus Corella (Ascidiacea, Phlebobranchia, Corellidae) in the Southern Hemisphere with description of a new species. Zootaxa 3702: 135–149.
Moody, W. J. and Okamura, Y. 2013. Neural development in simpler embryos: A retrospective of Dr. Kunitaro Takahashi's work-- Obituary. Neurosci. Res. 75: 167-170.
Nakamura, M. J., Hotta, K. and Oka, K. 2013. Raman spectroscopic imaging of the whole Ciona intestinalis embryo during development. PLOS One 8:
Nakamura, Y., Kato, H., Nishikawa, T., Iwasaki, N., Suwa, Y., Rotinsulu, H., Losung, F., Maarisit, W., E., M. R., Morioka, H., Yokosawa, H. and Tsukamoto, S. 2013. Siladenoserinols A-L: new sulfonated serinol derivatives from a tunicate as inhibitors of p53-Hdm2 interaction. Org. Lett. 15: 322-325.
Nakazawa, K., Yamazawa, T., Moriyama, Y., Ogura, Y., Kawai, N., Sasakura, Y. and Saiga, H. 2013. Formation of the digestive tract in Ciona intestinalis includes two distinct morphogenic processes between its anterior and posterior parts. Dev. Dyn. 242: 1172-1183.
Ogura, Y. and Sasakura, Y. 2013. Ascidians as excellent models for studying cellular events in the chordate body plan. Biol. Bull. 224: 227-236.
Omotezako, T., Nishino, A., Onuma, T. A. and Nishida, H. 2013. RNA interference in the appendicularian Oikopleura dioica reveals the function of the Brachyury gene. Dev. Genes & Evol. 223: 261-267.
Ordóñez, V., Pascual, M., Rius, M. and Turon, X. 2013. Mixed but not admixed: a spatial analysis of genetic variation of an invasive ascidian on natural and artificial substrates. Mar. Biol. 160: 1645–1660.
Ordóñez, V., Rius, M., McQuaid, C. D., Pineda, M. C., Pascual, M. and Turon, X. 2013. Early biotic interactions among introduced and native benthic species reveal cryptic predation and shifts in larval behaviour. Mar. Ecol. Prog. Ser. 488: 65-79.
Oren, M., Paz, G., Douek, J., Rosner, A., Amar, K. O. and Rinkevich, B. 2013. Marine invertebrates cross phyla comparisons reveal highly conserved immune machinery. Immunobiology 218: 484-495.
Otsuka, K., Yamada, L. and Sawada, H. 2013. cDNA cloning, localization, and candidate binding partners of acid-extractable vitelline-coat protein Ci-v-Themis-like in the ascidian Ciona intestinalis. Molec. Repro. & Develop. 80: 840-848.
Padua, A., Lanna, E. and Klautau, M. 2013. Macrofauna inhabiting the sponge Paraleucilla magna (Porifera: Calcarea) in Rio de Janeiro, Brazil. J. Mar. Biol. Ass. U.K. 93: 889-898.
Paripooranaselvi, M. and Meenakshi, V. K. 2012. Screening of a few chosen ascidians of Tuticorin coast for larvicidal activity. Annals Biol. Res. 3: 3849-3852.
Paripooranaselvi, M., Meenakshi, V. K., Senthamarai, S., Gomathy, S., Chamundeeswari, K. P. and Sankaravadivu, S. 2013. Cytotoxicity of Phallusia nigra Savigny, 1816 to human cell lines. Proc. Second Intl. Conf. of Kanniyakumari Acad.Arts & Sci. 22-27.
Paripooranaselvi, M., Meenakshi, V. K., Shanmuga Priya, D., Gomathy, S., Senthamarai, S. and Chamundeswari, K. P. 2012. Ascidian biofouling. Proc. 8th all India Conference of KAAS -2012 3: 6-13.
Park, K. H., Zeon, S. R., Lee, J. G., Choi, S. H., Shin, Y. K. and Park, K. I. 2013. In vitro and in vivo efficacy of drugs against the protozoan parasite Azumiobodo hoyamushi that causes soft tunic syndrome in the edible ascidian Halocynthia roretzi (Drasche). J. Fish Diseases epub:
Pérez-Portela, R., Arranz, V., Rius, M. and Turon, X. 2013. Cryptic speciation or global spread? The case of a cosmopolitan marine invertebrate with limited dispersal capabilities. Sci. Reports 3: 1-10.
Ramos-Espla, A. A., Izquierdo Munoz, A. and Cinar, M. E. 2013. Microcosmus exasperatus (Ascidiacea: Pyuridae), current distribution in the Mediterranean Sea. Mar. Biodiversity Rec. 6: 1-5.
Raslan, A. A., Lee, J. H., Shin, J., Shin, Y. K. and Sohn, Y. C. 2013. Transcriptional activity and expression of liver X receptor in the ascidian Halocynthia roretzi. Zool. Sci. 30: 731-741.
Ravinesh, R. and Bijukumar, A. 2013. Comparison of intertidal biodiversity associated with natural rocky shore and sea wall: A case study from the Kerala coast, India. Indian J. Geo-Mar. Sci. 42: 223-235.
Rigon, F., Stach, T., Caicci, F., Gasparini, F., Burighel, P. and Manni, L. 2013. Evolutionary diversification of secondary mechanoreceptor cells in tunicata. BMC Evol. Biol. 13 (112): 1-14.
Rius, M. and Teske, P. R. 2013. Cryptic diversity in coastal Australasia: a morphological and mitonuclear genetic analysis of habitat-forming sibling species. Zool. J. Linn. Soc. 168: 597–611.
Rivero, N. K., Dafforn, K. A., Coleman, M. A. and Johnston, E. L. 2013. Environmental and ecological changes associated with a marina. Biofouling 29: 803-815.
Rosner, A., Moiseeva, E., Rabinowitz, C. and Rinkevich, B. 2013. Germ lineage properties in the urochordate Botryllus schlosseri - From markers to temporal niches. Dev. Biol. epub:
Rubenstein, N. D., Feldstein, T., Shenkar, N., Botero-Castro, F., Griggio, F., Mastrototaro, F., Delsuc, F., Douzery, E. J. P., Gissi, C. and Huchon, D. 2013. Deep sequencing of mixed total DNA without barcodes allows efficient assembly of highly plastic ascidian mitochondrial genomes. Genome Biol. Evol. 5: 1185-1199.
Sams, M. A. and Keough, M. J. 2013. Effects of early recruits on temperate sessile marine community composition depend on other species recruiting at the time. Oecologia 173: 259-268.
Sankaravadivu, S., Meenakshi, V. K. and Jothibai Margret, R. 2013. Nutritive value of a colonial ascidian Ecteinascidia venui Meenakshi, 2000. Proc. Second Intl. Conf. of Kanniyakumari Acad.Arts & Sci. 28-31.
Saperas, N. and Ausio, J. 2013. Sperm nuclear basic proteins of tunicates and the origin of protamines. Biol. Bull. 224: 127-136.
Senthamarai, S., Meenakshi, V. K., Gomathy, S., Paripooranaselvi, M., Shanmuga Priya, D. and Chamundeswari, K. P. 2012. Antibacterial activity of ascidian Microcosmus exasperatus against human pathogens. Proc. 8th all India Conference of KAAS -2012 3: 14-22.
Shanmuga Priya, D., Meenakshi, V. K., Paripooranaselvi, M., Gomathy, S., Senthamarai, S. and Chamundeswari, K. P. 2012. Phytochemical investigation of the simple ascidian Phallusia nigra Savigny, 1816 of Tuticorin coast. Proc. 8th all India Conference of KAAS -2012 3: 1-5.
Shanmuga Priya, D., Meenakshi, V. K., Sankaravadivu, S., Kohila Subathra Christy, H. and Stella Packiam, C. 2013. Total flavonoid and phenolic content in a simple ascidian Phallusia nigra. Proc. Second Intl. Conf. of Kanniyakumari Acad.Arts & Sci. 36-38.
Smitha, D., Kumar, M. M., Ramana, H. and Rao, D. V. 2013. Rubrolide R: a new furanone metabolite from the ascidian Synoicum of the Indian Ocean. Nat. Prod. Res. epub:
Smoothey, A. F. 2013. Habitat-associations of turban snails on intertidal and subtidal rocky reefs. PLos One 8: e61257.
Spinelli, M., Guerrero, R., Pajaro, M. and Capitanio, F. 2013. Distribution of Oikopleura dioica (Tunicata, Appendicularia) associated with a coastal frontal system (39 degrees-41 degrees S) of the SW Atlantic Ocean in the spawning area of Engraulis anchoita anchovy. Brazil. J. Oceanog. 61: 141-148.
Sri Kumaran, N., Bragadeeswaran, S. and Meenakshi, V. K. 2013. Mitochondrial cytochrome oxidase I (COI) DNA sequencing of the ascidians Didemnum granulatum (JQ013198) and D. psammathodes (JN624758). Mitochondrial DNA epub:
Sri Kumaran, N., Bragadeeswaran, S. and Meenakshi, V. K. 2013. Mitochondrial cytochrome oxidase I (COI) DNA sequencing of the ascidians Didemnum granulatum (JQ013198) and D. psammathodes (JN624758). Mitochondrial DNA 1-4.
Stella Packiam, C., Jothibai Margret, R. and Meenakshi, V. K. 2013. Infrared and gas chromatogram-mass spectral studies of the ethanolic extract of Ascidia sydneiensis. Intl. Res. J. Pharmaceut. Sci. 3: 271-277.
Stella Packiam, C., Meenakshi, V. K. and Jothibai Margret, R. 2013. Studies on the chemical constituents of a simple ascidian, Ascidia sydneiensis. Proc. Second Intl. Conf. of Kanniyakumari Acad.Arts & Sci. 32-35.
Su, S.-W., Hirose, E., Chen, S. L. S. and Mok, M. H.-K. 2013. Photosymbiotic ascidians in Singapore: turbid waters may reduce living space. Zookeys 305: 55–65.
Tang, W. J., Chen, J. S. and Zeller, R. W. 2013. Transcriptional regulation of the peripheral nervous system in Ciona intestinalis. Dev. Biol. 378: 183-193.
Ueda, N. and Degnan, S. M. 2013. Nitric oxide acts as a positive regulator to induce metamorphosis of the ascidian Herdmania momus. PLoS One 8: e72797.
Veerabahu, C., Meenakshi, V. K. and Roselin, K. F. 2013. Infra red and gas chromatogram/mass spectral studies on ethanolic extract of Didemnum psammathodes. J. Curr. Chem. Pharmaceut. Sci. 3: 196-202.
Voskoboynik, A., Neff, N. F., Sahoo, D., Newman, A. M., Pushkarev, D., Koh, W., Passarelli, B. and al., e. 2013. The genome sequence of the colonial chordate, Botryllus schlosseri. eLife 2: 1-24.
Voskoboynik, A., Newman, A. M., Corey, D. M., Sahoo, D., Pushkarev, D. et al. 2013. Identification of a colonial chordate histocompatibility gene. Science 341: 384-387; 1-44 suppl. pages.
Wainwright, B. J., Arlyza, I. S. and Karl, S. A. 2013. Isolation and characterization of twenty-one polymorphic microsatellite loci for Polycarpa aurata using third generation sequencing. Conservation Genet. Resour. 5: 671-673.
Whitaker, M. 2008. Calcium signalling in early embryos. Phil. Trans. Roy. Soc. B 363: 1401-1418.
Yoshida, M., Hiradate, Y., Sensui, N., Cosson, J. and Morisawa, M. 2013. Species-specificity of sperm motility activation and chemotaxis: a study on ascidian species. Biol. Bull. 224: 156-165.
Zhao, S. M., Lu, Y. N., Tian, X. Q., Yang, Q., Yu, H. J. and Fan, C. Q. 2013. Purine and carboline alkaloids from ascidian Symplegma oceania [in Chinese with English abstract]. Zhongguo Zhong Yao Za Zhi 38: 1018-1020.
Zhou, Y., Lewallen, M. and Xie, T. 2013. Stem cells’ exodus: A journey to immortality. Dev. Cell 24: 113-114.