ASCIDIAN NEWS*

 

Gretchen Lambert 

12001 11th Ave. NW, Seattle, WA 98177

206-365-3734   gretchen.lambert00@gmail.com

home page:  http://depts.washington.edu/ascidian/

 

Number 69                                                                                                                                                                         June 2012

 

Thanks to all of you who sent the many contributions for this issue. There are 145 new publications listed at the end of this newsletter, many abstracts from recent meetings, announcements of upcoming meetings in 2012 and 2013, and much more. I hope you find it interesting.

     

*Ascidian News is not part of the scientific literature and should not be cited as such.

 

NEWS AND VIEWS

 

1. From Gretchen: It has been a busy year ascidiologically (and otherwise) for me. In February I taught an ascidian identification workshop at the Moss Landing Marine Lab in California, and in April I taught another one in Nelson, New Zealand, at the Cawthron Institute, which concluded with a very interesting boat ride out into the Marlborough Sounds to visit two green-lipped mussel farms, watch them being harvested, and examine the lines for ascidian fouling. I continue to identify ascidians for individuals and institutions. I greatly miss my other half though.

   It is now 1 year since Charles’s death June 1, 2011. You can find a biography of Charles, that I was invited to write, at http://onlinelibrary.wiley.com/doi/10.1002/mrd.21384/pdf .

   I set up two scholarship funds in his name last year, and they have received a number of contributions. I am very happy to report that the first awards have been made, to very deserving students. If you would like to continue to honor his memory, and his accomplishments as a researcher and teacher, your contributions will be greatly appreciated.

a) http://depts.washington.edu/fhl/help_endowments.html The Charles Lambert Memorial Endowment. Provides assistance to graduate students for research and/or coursework at the Univ. of Washington Friday Harbor Labs that includes cell or developmental biology of marine invertebrates, or any aspect of ascidian biology. Charley and I met at the Labs in 1964, when we went there to take summer classes. Without scholarship help we could not have attended, and we would not have met! We soon transferred to UW where we continued our graduate work. Charley received his Ph.D. in 1970, and we returned to the Labs many times for research and teaching. We have been very dedicated to helping others attend this fine institution.

b) http://www.fullerton.edu/foundation/direct/nsm/nsm-scholarships.asp The Charles Lambert Memorial Scholarship fund. Charley taught in the Calif. State Univ. Fullerton Biol. Dept. for 28 years, was the campus Outstanding Professor for 1986 and earned other awards as well.  

 

We also set up an online photo album: http://charlesclambertmemorial.shutterfly.com/ . You can click on an album photo and then scroll through for larger images with labels. There are many recent additions I hope you will enjoy viewing. You can add a comment or photos if you wish; they will be much appreciated.

 

2. From Hitoshi Sawada: Director, Sugashima Marine Biological Laboratory, Sugashima, Toba, Japan. hsawada@bio.nagoya-u.ac.jp

The International Symposium on the Mechanisms of Sexual Reproduction in Animals and Plants, a joint meeting of the 2nd Allo-authentication meeting and the 5th Egg-coat Meeting (MCBEEC), will be held November 12-16, 2012, in Nagoya, Japan.

Deadlines for registration and abstract submission: Early: July 31, 2012; Regular: August 31, 2012. http://allo-authentication.net/5thMCBEEC/index.html

 

The official URL of the 4th Egg-coat (MCBEEC) meeting, which was held in 2004 in Ise-Shima, Japan, was also up-loaded at the following website:

 http://www.bio.nagoya-u.ac.jp/~SugashimaMBL/4thMCBEEC/index.html   There is a photo album in this website. Please enjoy.

 

3. Dr. Patricia Mather (published as Patricia Kott), passed away on Wednesday 4 January 2012 in Brisbane, Australia. She published many monographs on the ascidians of Australia and worked for many years at the Queensland Museum in Brisbane. A press release can be seen at http://www.couriermail.com.au/ipad/obituary-patricia-mather/story-fn6ck8la-1226251460148 . A full length biography with photos is forthcoming in Memoirs of the Queensland Museum - Nature 2012 56(1):237-255. In Memorium Patricia Mather (née Kott) (1925–2012) by Peter J.F. Davie. (Peter.Davie@qm.qld.gov.au). http://www.qm.qld.gov.au/About+Us/Publications/Memoirs+of+the+Queensland+Museum

 

4. From Gretchen: I recently donated my large collection of worldwide samples of Didemnum vexillum to Dr. Sarah Cohen at the Romberg Tiburon Center for Environmental Studies, San Francisco State University. There are 70 samples in 95% ethanol from the east and west coasts of the U.S. including Alaska, Pacific Canada, France, Netherlands, Ireland, Italy, New Zealand, and Japan. There are also 42 samples in 10% buffered seawater formalin from most of the same locations; these latter may ultimately be housed at the Calif. Academy of Sciences in San Francisco. Anyone wishing to borrow or obtain a small sample should contact Dr. Cohen, as this was the arrangement for the donation. sarahcoh@rtc.sfsu.edu

 

5. From Christina Simkanin, Univ. of Victoria, British Columbia, Canada and Graduate Research Fellow, Smithsonian Environmental Research Center, Edgewater, Maryland. csimkanin@gmail.com

I have been working with Greg Ruiz's Marine Invasions Lab at the Smithsonian Environmental Research Center on a database of the introduced marine and estuarine invertebrate species in the continental U.S., Alaska and Hawaii (The National Estuarine and Marine Exotic Species Information System - NEMESIS). The tunicate portion of the database, which includes 30 species, was launched publicly at the beginning of March http://invasions.si.edu/nemesis/browseDB/GroupSummary.jsp?GRP=Tunicates. It provides information on the invasion history and current distribution of each species, and summarizes key information on the ecology and known impacts of each invader. I hope it will be useful for some of your work. If you see something that you think is an omission or mistake, please let me know.

 

6. From Gemma Quilez-Badia (gquilez@atw-wwf.org ), Barcelona, Spain:

a. The next International Conference on Marine Bioinvasions will be held at the end of August 2013 in Vancouver, Canada.  We look forward to seeing you there and plan to issue a call for special sessions this fall. 

b. New journal, BioInvasions Records: http://www.reabic.net/journals/bir/2012/Issue1.aspx

This is an open access, peer-reviewed international journal focusing on applied research on alien species and biological invasions in aquatic and terrestrial ecosystems of Europe, North America and other regions. The journal provides the opportunity of timely publication of first records of aquatic and terrestrial invaders and other relevant information needed for risk assessments and early warning systems. Also, relevant technical reports and conference proceedings can be considered for publication in this journal.  We welcome submissions to the journal and of course encourage you to use it as a resource.  Frances Lucy lucy.frances@itsligo.ie and Vadim Panov bir_editor@reabic.net, vepanov@gmail.com

 

7. From David Kipling, Cardiff University, UK. kiplingd@cardiff.ac.uk

One thing of note this year is that there are now Facebook Groups for people interested in Tunicates. There is a general Tunicata group, plus a NE Atlantic Tunicates group.  If you use Facebook do have a look and join!

  [From the editor: the Tunicata listserv has been ongoing for many years, is easy to join, and continues to be a valuable means of communication: Tunicata email discussion forum  http://www.jiscmail.ac.uk/lists/tunicata.html]

 

8. From Noa Shenkar, Zoology Department, Tel-Aviv University, Israel.

The “Ascidiacea World Database of Marine Species” (WoRMS) http://www.marinespecies.org/ascidiacea/ is being updated and revised constantly. In order to keep it up to date please e-mail PDF files of new species publications to noa.shenkar@gmail.com.  Any comments and corrections are greatly appreciated.

   Congratulations to Noa! She won the Marie Curie reintegration grant, 150,000 euros for 3 years! She will use it to establish her new ascidian lab.

 

9. From Geoff Nette, Director, Independent Marine Bio-Chemistry Research Pty Ltd, Point Lookout, Queensland, Australia (geoffnette@imbcr.com.au) . 

    Geoff reports the death of Dr. Silvia Scippa, of the Stazione Zoologica Anton Dohrn in Naples, on April 4. “I had the extremely good fortune to work in Naples with Silvia from 1996 to 1998. It was the marine taxonomists of the19th century, Cuvier of course comes to mind, and a few intrepid investigators of the blood chemistry of these enigmatic organisms [the ascidians], such as Harless and Winterstein, who must surely have fired the imagination of one Martin Henze at the Stazione Zoologica 'Anton Dohrn' at the turn of the last century. His own studies precipitated a generous portion of research into ascidian chemistry right through the twentieth century, all from his discovery of the Vanadium Assimilation phenomenon in the blood of ascidians, and in particular within the so called morula cells of Phallusia mammillata, or so we all thought. Little question of the animal, big question of the blood cells!

   After some seventy years of research into the accumulation of vanadium, by groups all around the globe, it was Professoressa Scippa and her stalwart mentor and colleague Professor Mario de Vincentiis and their co-workers who laid to rest the question of which cell type actually assimilated the vanadium - the Signet Ring Cell! It is a natural phenomenon poorly understood and even now Silvia's research does not receive the recognition her discovery deserves, even though it is reflective of her lifelong dedication to the study of these animal.  Thank you Silvia for the opportunity... and I know this to be a sentiment echoed by too many researchers to name individually right here and right now. Vale Professoresa.”

 

WORK IN PROGRESS

1. From Juan Bellas, Centro Oceanografico de Vigo, Spain (juan.bellas@vi.ieo.es): Last year we were granted the following patent in Spain: Procedure for assessing the efficacy of antifouling compounds by using the larval settlement bioassay with ascidians. Inventors: Juan Bellas and Ricardo Beiras. Application number: ES 2333573 B1. Award date: 01/04/2011. Publication date: 04/05/2011. Priority country: Spain. Holder entity: Universidade de Vigo.  This invention is related to the use of the ascidian larval settlement bioassay in assessing the efficacy of antifouling compounds used to prevent undesirable growth of organisms on the surface of boat hulls and other submerged artificial structures. This biological assay is easy to carry out in the laboratory and presents a rapid response (48 h), allowing to evaluate the effectiveness of antifouling compounds before the application on surfaces submerged in the marine environment. The ascidian larval settlement bioassay has been successfully applied to the evaluation of the efficacy of the two most widely used antifouling compounds, TBT and copper. This bioassay could be used by the maritime industry in routine or pre-industrial evaluation of the efficacy of new antifouling biocides. The invention is also applicable to environmental risk studies and to the monitoring of the pollution caused by the use of antifouling paints in port areas.

2.  From Christian Sardet, BioMarCell group UMR 7009 BioDev CNRS / Univ P. et M. Curie, Villefranche sur Mer, France. csardet@gmail.com , http://www.biologymultimedia.com

   I retired last August but with emeritus status which allows me to continue working in the Villefranche laboratory.  I have participated actively in the Tara Oceans Expedition and in that context started the Plankton Chronicles project mixing art and science: http://www.planktonchronicles.org. One episode (videos and photos) concerns larvaceans:

http://www.planktonchronicles.org/en/episode/new-larvaceans-their-houses-are-nets

   I also pursue some research on the egg cortex with Japanese colleagues and hope to complete a map of the egg cortex and of its changes after fertilization.

 

3. Temporal and spatial variation in ascidian settlement within fouling communities in Mission Bay, San Diego, California Brianna M. Tracy and N. Reyns. Univ. of San Diego, Dept. of Marine Science and Environmental Studies, San Diego, CA 92108. briannamtracy@gmail.com

   Ascidians are ecologically important members of fouling communities, and often dominant organisms on Southern California docks. While previous studies have documented the presence of native and non-indigenous ascidians in the region, generally little is known about their spatial and temporal settlement patterns, and how such variability influences population dynamics and overall fouling community development. The purpose of this study was to examine weekly ascidian settlement on replicate PVC plates deployed at five locations in Mission Bay, an urbanized estuary in San Diego, CA. Sampling locations were selected to represent the range of environmental conditions in Mission Bay. Settlement was related to weekly measures of sea surface temperature, salinity, turbidity, and flow. While this study is ongoing, our preliminary results suggest that settlement rates may be highest at sites that receive greatest tidal flushing. Additionally, ascidian die-offs have occurred within one week of increased freshwater exposure following rain events.  This study will provide valuable insight about population dynamics in coastal environments, and will serve as a valuable comparison to studies documenting ascidian settlement in other California regions.

 

ABSTRACTS FROM RECENT MEETINGS

 

1. California State Univ. Biotechnology Symposium, January 7, 2012, Santa Clara, CA.

 

The Rho GTPase Cdc42 is a physiological switch in the integrin-triggered signaling pathway of ascidian sperm activation. Bridgett A. Santos, Lamar Blackwell, Katie Richards, Adilene Sandoval and Robert A. Koch, Dept. of Biol. Sci., Calif. State Univ. Fullerton.

  The phylogenetic proximity to vertebrates of the sea squirt, Ascidia ceratodes, makes it a good model for studying fertilization. Activation of ascidian sperm cell to penetrate the egg

barriers permitting fusion with the oocyte involves actin-dependent motility. In ascidians sperm binds eggs via sperm â1-like integrin triggering focal adhesion kinase to initiate an actin polymerization signaling cascade known in non-sperm mammalian cell motility to require Rho GTPases (Cdc42, Rac1, RhoA). In this study we investigated ascidian sperm cell activation using constitutively active (ca) and dominant negative (dn) Cdc42 to test its role in ascidian integrindependent signaling. Cdc42ca and Cdc42dn were presented to live sperm cells by liposomal delivery and livecell permeabilization. Liposomes loaded with Cdc42 protein variants (1mg/ml) were tested against “empty” liposomes filled with 140mM KCl to mimic cytosol. Sperm cells that fused with Cdc42dn liposomes were subsequently challenged with integrin-activating mAb12G10 (10μM). Live-cell permeabilization was achieved by incubating sperm cells with octyl-betaglucopyranoside and were then incubated with Cdc42 variants (1.33 nM) in an intracellular buffer. Cells incubated with Cdc42dn will be challenged with mAb12G10 as above. Sperm cells exposed to Cdc42ca liposomes exhibited 50% of maximum activation, a percentage equivalent to mAb12G10-initiated activation, whereas sperm cells incubated with empty liposomes showed %-activation equal to naturally occurring spontaneous activation. Only a small percentage (15%) of sperm cells previously exposed to Cdc42dn liposomes could be activated by mAb12G10, thus exhibiting a 70% inhibition. Permeabilized live sperm cells incubated with Cdc4ca were activated at 106.2±30% (n=6) of maximum responsivity. That liposomal delivery of Cdc42ca induced sperm cell activation established a potential role for Cdc42. That mAb12G10-initiated activation was inhibited by Cdc42dn showed that wild type Cdc42 is necessary for the process. That infusion of Cdc42ca (1.33nM) induced activation of sperm cells established that physiological levels are sufficient to switch-on the process. We predict that exposure to Cdc42dn and challenge with mAb12G10 will show inhibition similar to that found in liposomal delivery experiments. We conclude that Cdc42 is physiologically involved in the â1-like integrin-initiated pathway of ascidian sperm cells activation.

 

2. Lower Invertebrate Symbiosis With Microorganisms. 25 February to 2 March 2012, Tel Aviv and Eilat, Israel.

 

a. A case of sponge-envy? An emerging picture of ascidian-associated bacterial communities. Susanna López-Legentil, Dept. of Animal Biology (Invertebrates), Univ. of Barcelona, Barcelona, Spain. slopez@ub.edu

   Sponges (Porifera) and ascidians (Chordata) have followed distinct evolutionary trajectories, however, both taxa have converged to similar ecological lifestyles. Ascidians resemble sponges as sessile filter-feeding organisms that disperse by motile larva, contain mineral spicules and produce defensive secondary metabolites. In addition, the few studies investigating ascidian microbial diversity have suggested rich and diverse bacterial communities in their tissues. Here, we review the current status of ascidian microbiology and compare the diversity, composition and stability of the ascidian microbiota with symbiotic bacteria in sponges. Similarly to sponges, the Proteobacteria (Alpha, Gamma and Delta) appear to be the predominant bacterial group in ascidians, with Actinobacteria and Cyanobacteria also present in many ascidian species. Other bacterial phyla such Bacteroidetes, Chloroflexi, Spirochaetes and Verrucomicrobia are only retrieved occasionally. Phylogenetic analyses indicate that most ascidian-associated bacteria are closely related to sponge symbionts, with the remaining microbes clustering with seawater and marine sediment bacteria. We also present the first data on the temporal stability of ascidian bacterial symbionts, by characterizing and monitoring the microbial community in the Mediterranean ascidian Didemnum fulgens. D. fulgens harbors a bacterial consortium typical of ascidians, including numerous  Proteobacteria, and a few Cyanobacteria and Acidobacteria. The overall bacterial community in D. fulgens had a distinct signature from the surrounding seawater and, as found for

Mediterranean sponges, was stable over time. Finally, both sponges and ascidians have often been reported to form obligate symbiotic relationships with cyanobacteria. Undoubtedly, the most emblematic and well-studied symbiotic relationship in ascidians is with Prochloron (Prochlorales) and Synechocystis (Chroococcales), a genus closely related to Prochloron. Our own research on the cyanobacterial populations of didemnid species from the Bahamas confirmed the prevalence of these symbionts, with most of the photosymbionts belonging to these two cyanobacterial genera. In addition, didemnid species from the genus Lissoclinum harbored unique cyanobacteria related to Acaryochloris, which uses the recently described chlorophyll d as a predominant photosynthetic pigment. Similar to observations of Prochloron, Acaryochloris-like symbionts also appear to be vertically transmitted to progeny. As described for sponges, the photosymbiont communities investigated were mainly structured by host phylogeny, with some evidence of structuring by sampling location. In conclusion, results to date suggest that the overall bacterial diversity in ascidians is similar to sponges, with symbiont communities mostly host-specific and stable over time. However, some

compositional differences are evident, for example at the cyanobacterial level, where ascidians mostly harbor symbionts from the genus Prochloron and sponges from the genus Synechococcus.

b. Not so lower: Bacterial diversity in ascidians from the Great Barrier Reef.  Mari Carmen Pineda1, Nicole Webster2, Xavier Turon3, Susanna López-Legentil1 1 – Animal Biology Dept., Univ. of Barcelona, Barcelona, Spain ; 2 – Australian Institute of Marine Science (AIMS), Townsville, Australia; 3 - Centre for Advanced Studies of Blanes (CEAB, CSIC), Blanes, Spain. mcpineda@ub.edu

   Ascidians or sea-squirts are sessile filter-feeding organisms within the sub-phylum Tunicata. Similar to other marine invertebrates, ascidians are known to harbor microbial symbionts but have received much less research attention than  sponges and corals. Here, 19 species of ascidians from the Great Barrier Reef (order Aplousobranchia n=15, Phlebobranchia n=2, and Stolidobranchia n=21) were studied to characterize the bacterial diversity hosted in their tunics. Denaturing gradient gel electrophoresis (DGGE) profiles of 16S rRNA revealed a high diversity of microbes in most of the collected ascidians. Multidimensional Scaling (MDS) plots based of banding pattern similarities showed that Rhopalaea sp. and Eudistoma amplum had bacterial profiles similar to seawater samples. The symbiont communities of the Didemnidae species (Aplousobranchia) Lissoclinum badium and Lissoclinum patella were somewhat set apart from the rest of the ascidians investigated in the MDS plot, while replicates from the same species generally grouped closely together. Amplification and sequencing of DGGE bands revealed 82 different OTU’s (99% sequence identity), with Proteobacteria (Alpha, Gamma and Delta) roughly representing 75% of the recovered microbes. Actinobacteria and Cyanobacteria were present in most (n=14) of the species, while Bacteroidetes, Chloroflexi, Spirochaetes and Verrucomicrobia were unevenly distributed among the ascidian hosts. Further in-depth analyses using massively parallel 16S rRNA gene tag pyrosequencing are currently underway. Here, we demonstrated that like other marine invertebrates, ascidians harbor rich microbial communities that exhibit varying levels of diversity and host-specificity.

 

3. Ocean Sciences Meeting, Salt Lake City, Utah, February 20-25, 2012.

 

Seasonal variability in settlement and abundance of the non-indigenous ascidian, Botryllus schlosseri, in a subarctic harbor.  Kevin C. K. Ma (kevin.ma@mun.ca), J. Ben Lowen, Don Deibel, and Cynthia H. McKenzie, Ocean Sciences Centre, Memorial University of Newfoundland, St. John’s, Canada.

   Population dynamics remain enigmatic for the non-indigenous temperate ascidian, Botryllus schlosseri, which was identified on the south coast of Newfoundland in 2006. This represents a unique opportunity to study B. schlosseri in subarctic waters characterised by a short productive season. The seasonal cycles of colony abundance and larval settlement rates were determined in Arnold’s Cove, Newfoundland, by (1) deploying an experimental array of artificial settlement plates and (2) surveying a transect of 140 wharf pilings using HD video. Coincident with maximum seasonal temperatures, peak settlement was at 30-40 m⁻²d⁻¹ in September and peak cover of colonies was 3% in October. Settlement rate was greater at 1 and 2.5 m than 4 m depths and on PVC in preference to aluminum and wood substrates. These results have ecological, economic, and management implications as they address competition of space in subtidal benthic communities, potential threats to sustainable bivalve aquaculture, and the implementation of monitoring and mitigation efforts.

 

4. 41st Benthic Ecology meeting, Norfolk, Virginia, March 23-25, 2012.

 

Life-history constraints affecting invasion success in Botryllus schlosseri. Lowen, Ben1(jlowen@mun.ca); Deibel, Don1; Ma, Kevin1; McKenzie, Cynthia H.2; Thompson, Ray J.1 1Ocean Sciences Centre, Memorial Univ. of Newfoundland, St. John's, Canada;  2Northwest Atlantic Fisheries Centre, Dept. of Fisheries and Oceans, St. John's, Canada.

   The reproductive success of ectotherms in temperate seasonal environments is constrained by temperature limits for growth and sexual reproduction. Botryllus schlosseri (class Ascidiacea) is a temperate ectotherm that disrupts benthic communities and mariculture operations. Its dispersal from temperate to colder subarctic waters raises the question as to how it could adapt to an increasingly short season for growth and reproduction, and a longer overwintering period. To answer this question, we followed cohorts of marked colonies in Arnold's Cove, Newfoundland. B. schlosseri grew and reproduced within the thermal limits described in studies of temperate populations. Consequently, temporal windows for growth and reproduction were shorter by 3 months in colder sub-arctic waters than in temperate waters, indicating that the life cycle was time constrained. Compared with colonies in temperate waters, these time constraints selected for enhanced early reproductive effort (during 1-3 cycles), thereby shortening generation time at the expense of future growth and reproduction of the parent colony. This strategy is adaptive, as fitness in ectotherms is maximized by their producing as many generations as possible within a season. Coupled with high overwintering survival in autumn born colonies, these results help explain the persistence of temperate B. schlosseri in sub-arctic waters.

 

5. VI Intl. Meeting of the Latin American Society for Developmental Biology, Montevideo, Uruguay, 26-29 April 2012.

 

Limited sex but lots of buds in the colonial chordates or Budding in colonial chordates. A. Stefania Gutierrez, P. Endara, Billie J. Swalla, Federico D. Brown (Universidad de los Andes, Bogotá, Colombia). fedavidbrown@googlemail.com, fd.brown46@uniandes.edu.co

   Tunicates show a great plasticity in propagation mechanisms. Solitary species only reproduce sexually, whereas colonial species reproduce sexually by internal fertilization and brooding or asexually by budding. Different adult tissues in colonial species generate new clonal individuals. We study the transition of a solitary ancestral species into several colonial species in the Styelidae, in which the evolution of budding and regenerative abilities can be reconstructed. By the use of recent molecular phylogenetic data, and direct observations of budding in different Styelid colonial species, we demonstrate how more recent clades show a higher integration in the development of zooids and buds, whereas more basal clades show a higher independence in the development of their zooids. Botryllus and Botrylloides have long been known to regenerate complete bodies from remnant colony vasculature and circulatory progenitor cells after complete zooid removal. By stem cell marker expression and cell labeling studies we provide further evidence for stem cell like features in circulatory blood cells of the derived Botryllus and Botrylloides. Systemic removal of buds or zooids in these species show synchrony or size defects in the development of the colony, suggesting signaling between differentiated and undifferentiated individuals. In contrast, zooid or bud removal in Symplegma rarely shows an effect in the development of the colony upon ablation of either buds or zooids demonstrating a higher independence in a more basal species. Additionally, we find that vascular budding is the most common mechanism for asexual propagation in Symplegma, in contrast to palleal (lateral epidermis of zooids) budding in Botryllus and Botrylloides. Our results from comparative studies in different species allow us to reconstruct the steps for the evolution of coloniality in the chordates, in which a release of stem cells into the vasculature allowed the evolution of vascular budding, and a higher integration in the development of individuals in the colony allowed the evolution of palleal budding. Mechanistic developmental changes that occurred during the evolution of budding in colonial chordates set the framework for understanding stem cell function in other animals, including vertebrates.

 

6. 8th Intl. Vanadium Symposium: Chemistry, Biological Chemistry, & Toxicology will be held August 15-18, 2012 in Crystal City, VA, USA. Dr. Tatsuya Ueki will give a talk on Vanabins.

Older meetings:

7. BIOLIEF 2011 – 2nd World Conference on Biological Invasions and Ecosystem Functioning, Mar del Plata, Argentina, November 21-24, 2011.

Ascidians (Tunicata, Ascidiacea) colonizing hard substrates at Patagonian harbours. Marcos Tatián, Cristian Lagger, Evangelina Schwindt. mtatian@com.uncor.edu

   Harbours are primary areas of invasion for invertebrate benthic marine species. Depletion of succesional plates along 6 major harbours of Patagonia in Argentina allowed the analysis of the ascidian community and the detection of those considered invasive species.

 

8. 2011 Joint annual meeting, Italian Society of Immunology, Clinical Immunology and Allergology (SIICA) and German Society for Immunology (DGfI) – Riccione (Italy) September, 28 – October 1, 2011.

 

Immune roles of a rhamnose-binding lectin from the colonial urochordate Botryllus schlosseri. Ballarin L., Dept. of Biology, University of Padova, Padova, Italy. ballarin@bio.unipd.it

   Differently from gnatostome vertebrates, invertebrate chordates rely only on innate immunity for immune surveillance and lectins exert a pivotal role in invertebrate immune defence. Here, we describe the immune roles played by a recently identified member of the rhamnose-binding lectin (RBL) family from a basal chordate, the colonial ascidian Botryllus schlosseri. B. schlosseri RBL (BsRBL) can activate phagocytes through: (i) induction of their directional movement towards the source of the molecule; (ii) modification of cytoskeleton, required for shape changes; (iii) stimulation of the respiratory burst, and consequent production of reactive oxygen species (ROS) with microbicidal activity, including superoxide anions and peroxides; and (iv) increase in the ability to phagocytose foreign particles. BsRBL also induces the synthesis and release, by cytotoxic morula cells (MCs), of cytokines recognised by anti-ILla and anti-TNFa antibodies. At high concentrations, BsRBL induces degranulation of MCs and cell death consequent to the release of the cytotoxic enzyme phenoloxidase into the medium. Results are consistent with the existence of cross-talk between B. schlosseri immunocytes (phagocytes and MCs). In addition, a three-dimensional model for BsRBL is presented.

 

THESIS ABSTRACTS

 

1. Lauren Marie Stefaniak.  Didemnum vexillum: identity, origin, and life history of an invasive ascidian.  University of Connecticut, 2012. Ph.D. thesis advisor Dr. Robert Whitlatch.  lauren.stefaniak@uconn.edu

   Over the past forty years, an increasing number of previously unrecorded populations of a colonial ascidian belonging to the genus Didemnum have been documented in most temperate coastal regions of the world, impacting aquaculture operations, natural rocky habitats, cobble/gravel substrates, and eelgrass beds.  Recent morphological analyses identified the populations as Didemnum vexillum Kott, 2002.  However, because of incomplete historical records and the numerous mis-identifications of this species, the native range of D. vexillum has not been conclusively known.  Also, little is known about the life history cycle, population biology, and native ecology of the species.  The goals of this dissertation are four-fold.  First, support the morphological identification of D. vexillum using molecular characters.  Second, use population genetics to determine the native region of this now cosmopolitan species.  Third, describe observations on the distribution and ecology of D. vexillum in Japan, a region where there is a dearth of information on the species.  And fourth, quantify aspects of D. vexillum’s life history cycle to examine the relative importance of sexual and asexual pathways to reproduction and dispersal of D. vexillum. [Editor’s note: much of this work has been published or is in press and in preparation.]

 

2. Studies on some ascidians of Tuticorin coast [Phallusia nigra]. D. Shanmuga Priya, A.P.C. Mahalaxmi College  for Women, Thoothukudi-628 002, India. Ph.D thesis, Manonmaniam Sundaranar Univ., Tirunelveli; advisors Drs. S. Gopalakrishnan and V.K. Meenakshi.

   The scope of the present investigation was to perform pharmacognostical and phytochemical determinations, antibacterial and antifungal activities studies, pharmacological studies such as anti-inflammatory, antipyretic, analgesic, anaesthetic and wound healing activities of Phallusia nigra Sav. from Tuticorin coast, in addition to its macroscopic and microscopic characters. The results of physico-chemical properties, the fluorescence analysis of the various solvent extracts such as petroleum ether (400 - 600C), benzene, chloroform, methanol and water are discussed. Major phytochemical constituents such as alkaloids, steroids, flavonoids, quinones, saponins and anthraquinones are present in almost all the extracts. Thin layer chromatographic studies of the various extracts of P. nigra were carried out in different solvent systems using Silica gel ‘G’ plate. Paper chromatographic studies were performed for aqueous extract. The fluorescing spots were located using UV-fluorescence viewing cabinet (365 nm) and the Rf values of the spots were measured and compared. GC-MS analysis of the methanolic extract of P. nigra identified eleven chemical constituents; the major are methyl 3-bromo-1-adamantaneacetate (24.65%), n-hexadecanoic acid (24.45%), (Z)-11-hexadecen-1-ol, (17.64%) and 2,6-dimethyl-6-trifluoroacetoxyoctane (9.82%). In HPTLC studies, six peaks were observed: gallic acid, ferulic acid, caffeic acid and the flavonoids rutin, isoquercitrin and quercetin. A maximum peak area (27773.44) corresponding to quercetin was observed with 221.89 μg/g concentration. These pharmacognostical and phytochemical characters of Phallusia nigra can be used as a diagnostic tool for the correct identification of the animal species.

   Anti-bacterial and anti-fungal screening of extracts of P. nigra were performed against five gram positive bacteria, Bacillus cereus, Bacillus subtilis, Bacillus megaterium, Sarcina lutea and Staphylococcus aureus, six gram negative bacteria, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Salmonella typhi, Proteus mirabilis and Pseudomonas pyocyanus and three fungi, Candida albicans, Aspergillus niger and Saccharomyces cerevisiae. The antibiotics ofloxacin and nystatin were used as standard for bacteria and fungi respectively. Antimicrobial activity was measured by Disc Diffusion method. Highly significant activity was noticed in methanol and water extracts against both bacteria and fungi. The minimum inhibitory concentration (MIC) of the methanolic extract of P. nigra is 2-3 µg/ml. Phallusia nigra displayed good antimicrobial potential and showed inhibition over the growth of the test organisms used. The methanolic extract of P. nigra was also screened for acute and chronic anti-inflammatory activity (carrageenan induced paw edema, cotton pellet granuloma). The reduction in paw volume was highly significant in Group V treated with 150 mg/kg bw followed by Group IV (100 mg/kg bw), indicating a dose dependent activity compared to that of the standard drug, Indomethacin (10 mg/kg bw). A highly significant inhibition in the antiproliferative activity of the granulomatous tissue was observed with 150 mg/kg bw in chronic inflammatory studies. Studies on biochemical parameters of the serum, liver and exudates indicated lower lipid peroxide content and γ-glutamyl transpeptidase activity. The crude extracts were observed to decrease the increased acid and alkaline phosphatase activity and decrease the serum albumin content during chronic inflammation. Methanolic extract of P. nigra was subjected to antipyretic and analgesic activity by Brewer’s yeast-induced pyrexia method and Eddy’s hot plate and tail immersion methods respectively. The extract, when administered at a dose of 150 mg/kg bw caused significant antipyretic activity by lowering the body temperature at fourth hour when compared to that of the standard drug, paracetamol (10 mg/kg bw). Groups treated with 100 mg/kg bw and 150 mg/kg bw had highly significant analgesic activity in both the methods when compared to that of the standard drug, diclofenac sodium (10 mg/kg bw). Methanolic extract of  P. nigra was subjected to anaesthetic activity by intracutaneous wheal method. The extract, when administered at a dose of 10% and 15% caused highly significant anaesthetic activity when compared to that of the standard drug, xylocaine (1%). The mean sleeping time and percentage relaxation of muscle was also highly significant in the extract treated groups compared to that of the standard drug, aminobarbitone. The methanolic extract of  P. nigra was screened for wound healing activity (Incision wound model, Excision wound model and dead space model). In excision and incision wound models, the wound contraction was highly significant in Group V treated with 15% followed by Group IV (10%) indicating a dose dependent activity compared to that of the standard drug, framycetin sulphate (2%). Epithelialization period was also found to be highly significant when compared with that of the standard, in both models. In the dead space model, significant increase in the wet and dry weight of the granulation tissues, tensile strength and hydroxyproline content of the granulation tissue was observed in the animals treated with the methanolic extract of P. nigra. The findings reveal the presence of bioactive components in P. nigra which can be important in the synthesis of new drugs.  [some editorial shortening]

 

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