ASCIDIAN NEWS*
Gretchen Lambert
12001 11th Ave. NW,
206-365-3734 glambert@fullerton.edu or gretchen.lambert00@gmail.com
home page: http://depts.washington.edu/ascidian/
Number
68 November
2011
Thanks so
much for the many emails and letters of condolence I received after Charles’s
death June 1; they have been a great source of comfort to me and to our
daughters, to hear from so many friends and colleagues. Please see below the
link to a short biography. Thanks also to all of you who sent the many
contributions for this issue and also for your words of encouragement for
continuing AN; I am happy to know that AN is still an important resource. There
are 162 new publications
listed at the end of this newsletter, many abstracts from recent meetings,
announcements of upcoming meetings in 2012, and much more! This is the largest
issue ever.
*Ascidian News is not part of the scientific
literature and should not be cited as such.
1. Charley Lambert’s
last publication, a remarkable summing up of his past 20+ years of
research, can be found in the special
issue of Molecular
Reproduction and Development, Vol. 78, issues 10-11 (Oct. – Nov.), which contains the proceedings of the symposium Mechanisms of egg
maturation and fertilization: From sea to land, held at the Friday Harbor
Laboratories Sept. 2010. You can download the article from http://onlinelibrary.wiley.com/doi/10.1002/mrd.21349/pdf
. Signaling
pathways in ascidian oocyte maturation: The roles of cAMP/Epac, intracellular
calcium levels, and calmodulin kinase in regulating GVBD (pages 726–733).
I was invited to write a short biography of
Charley for this issue; you can find it at http://onlinelibrary.wiley.com/doi/10.1002/mrd.21384/pdf
and download it if you wish. It includes 2 of my favorite photos I took of him,
as well as just a few of the many memorable tributes I received from former
students, colleagues and friends.
The issue also contains
several other ascidian papers (see list of Recent Publications at the end of
this newsletter).
2. Two scholarship funds
have been set up in Charley’s name:
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; the rest is history! So 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 at Calif. State
Univ. Fullerton Biol. Dept. for 28 years, was the campus Outstanding Professor
for 1986 and earned other awards as well. The scholarship provides an annual
graduate student award for research in Invertebrate Cell and Developmental
Biology, or any aspect of ascidian biology.
We also set up an
online photo album with many photos old and new. It’s also a site where you can
add a tribute if you wish. http://charlesclambertmemorial.shutterfly.com/
. You can click on an album and then on Slideshow for larger images with
labels. We hope that some of you will be inspired to add comments/photos.
3. From Kevin Heasman, Cawthron Institute, Nelson, New Zealand: the next International Invasive Sea Squirt
Conference will be held in Nelson April
11-14, 2012. Kevin.Heasman@cawthron.org.nz
Invasive ascidians are impacting ecosystems, creating a nuisance for the
aquaculture industry, and are a major component of fouling communities. The aim
of the fourth conference is to further our knowledge, address the problems
associated with invasive species of tunicates and investigate avenues of
exclusion and mitigation.
Details can be found at http://www.cawthron.org.nz/sea-squirt-conference-2012/index.html. Abstract
due date is 1 February 2012. The Conference will start on April the 11th
with a Taxonomy workshop held by Gretchen Lambert. The following two days (12th
and 13th April) will each start with a plenary speaker with the rest of each
day focused on presentations and evening poster sessions. On Saturday 14th
April a field trip to the Marlborough Sounds to look at fouling, aquaculture
and enjoy a day in the spectacular Marlborough Sounds.
4. From Ken Hastings,
The Sixth International Tunicate Meeting was held in Montréal, Québec, Canada, at McGill University, July 3-7, 2011.
Abstract details are at http://apps.mni.mcgill.ca/tunicate/. A number of the abstracts are included below
in this newsletter. Click on Program Book from the left-hand menu of the
website for the complete list of talks and posters with abstracts. This pdf is
downloadable.
Lifetime
Achievement Awards were given to Nori
Satoh and Christian Sardet at the final banquet. Both were given
personalized copies of Berrill's "The Origin of Vertebrates" in honor
of John Berrill who taught at McGill Univ. for many years and published many
classic papers on ascidian biology, especially embryology.
The next ITM meeting is tentatively
scheduled for sometime in 2013.
5. The 7th Intl. Conference on Marine
Bioinvasions was held 23-25 August in Barcelona, Spain. The meeting included a
number of talks on ascidians; the program can be viewed at http://www.icmb.info/. Two of the abstracts
are included in this newsletter.
6. From Mary Carman,
Biology Dept., Woods Hole Oceanographic Institution, Woods Hole, MA. mcarman@whoi.edu
The papers from the International Invasive
Sea Squirt Conference III (held at Woods Hole MA April 2010) have now been
published in Aquatic Invasions and can be downloaded from the Open Access
website. http://www.aquaticinvasions.net/2011/issue4.html. Many thanks to the guest editors Andrea Locke
and Mark Hanson.
7. From Christina
Simkanin and Greg Ruiz: The National Exotic Marine and Estuarine
Species Information System (NEMESIS) Exotic Tunicate Database.
NEMESIS was developed by
the Marine Invasions Lab at the Smithsonian Environmental Research Center. The database includes detailed information on
approximately 500 different non-native species that have invaded marine and
estuarine environments in the continental
8. The third
edition of the Ascidian Workshop in Bocas del Toro Smithsonian Tropical
Research Institute (STRI), Panama was held last June 9-30. The workshop
was called Advanced Tunicate Biology: Integrating Modern and Traditional Techniques
for the Study of Ascidians. Eighteen advanced undergrad, and graduate
students, pos-docs, and researchers attended the workshop, funded by the NSF
Pan American Advanced Studies Institute (PASI). Because of the nature of the
grant, half of the participants were from the U.S., and the rest from other
American countries (Canada, Mexico, Brazil, Colombia, Chile, Argentina), The
workshop also included one student from Singapore and another from South Africa
who obtained other funding.
Activities included field collecting,
taxonomy labs, lectures on recent advances in many aspects of ascidian biology
(symbiosis, chemical ecology, evo-devo, population genetics, regeneration, and
invasion biology), and plenty of hands-on lab time. Field collecting was carried out by
snorkeling almost every other day at various sites including coral reefs,
mangroves, seagrass beds and harbor docks. One optional scuba dive trip was
also included. In the laboratory, each participant was provided with a stereo
dissecting microscope, and a compound microscope was shared by every two
participants. This allowed us to study ascidian structures and internal
morphological characters, particularly important for taxonomic keys. The last days were reserved for research projects on many
interesting subjects, such as larval choice mediated by environmental cues,
larval pigment development, the role of artificial substrates in species
introduction, climate change effects on introduced species, the use of the
ascidian tunic by bivalves, bacteria associated with the tunic, morphological
comparison of distant populations of Phallusia nigra (Dr. Hirose brought some samples from
Okinawa e.g.), antifeedant properties of ascidian extracts, and variation of egg size in Ascidia curvata and Ascidia
sydneiensis from different populations.
The workshop was very successful in
promoting future research collaborations among attendants and instructors of
the course, which was one of its main goals. We are thankful to the staff at
Bocas Research Station and its director Rachel Collin for such a warm welcome
and being such good hosts! Last
but not least, we´d like to mention that the meals at Bocas Station were always
good and provided us with the energy to withstand the long schedules of the
course. We had
an enjoyable time and great logistics for field and lab activities. We
hope to see some of you in the next edition already planned for 2014!
Rosana Rocha
(rmrocha@ufpr.br), Xavier
Turon (xturon@ceab.csic.es), Euichi Hirose (euichi@sci.u-ryukyu.ac.jp), Federico Brown (fd.brown46@uniandes.edu.co), Billie Swalla (bjswalla@u.washington.edu).
More information on the STRI lab and this and
other courses can be found at http://www.stri.si.edu/sites/taxonomy_training/past_courses/2011/2011_PASI_Advanced_Tunicate_Biology.html
WORK
IN PROGRESS
1.
Billie Swalla’s Lab at the University of Washington is working on a comprehensive phylogeny
of the molgulid ascidians. If you have a molgulid species that you would like
identified and/or sequenced, please contact me, and send a voucher specimen
fixed in 4% formaldehyde (10% seawater formalin) and one sent in 95% ethanol to
Professor Billie J. Swalla, Dept. of Biology, 238 Kincaid Hall, Univ. of
Washington, Seattle, WA 98195. bjswalla@u.washington.edu.
2. Ecuadorean
Ascidian Studies. Gabriela
Agurto1, Stefania Gutierrez2, & Federico Brown1,2. 11Centro Nacional de Acuicultura e
Investigaciones Marinas (CENAIM), San Pedro, Ecuador; 2Universidad
de los Andes, Bogotá, Colombia. fd.brown46@uniandes.edu.co
Taking advantage of biological diversity in
Ecuador, and funded by the Ecuadorean Council for Science and Technology
(SENESCYT), we are currently collecting and describing species in continental
and insular Ecuadorean coastlines. Ascidian studies in Ecuador are scarce or
absent due mainly to a lack of local taxonomic experts. Therefore we plan to
begin a survey and broad sampling of ascidian species in El Oro, Guayas, Santa
Elena, Manabí, Esmeraldas, and Galápagos Provinces. We are focusing on
morphological descriptions of budding in collected colonial ascidians, and
studying regeneration abilities of colonial ascidians in culture. The
objectives of this project are: (1) collecting and describing ascidian
diversity in Ecuador, both morphologically and molecularly; (2) morphological
descriptions of budding and regeneration in selected colonial ascidians; (3)
establishing a colonial ascidian developmental model system for stem
cell and regeneration studies.
3. From Carmen
Primo, National
Centre for Marine Conservation and Resource Sustainability, Australian Maritime
College, Univ. of Tasmania, Launceston, Tasmania, Australia. c.primo@amc.edu.au
Elsa Vazquez and I are preparing the
Ascidiacea section for the "CALM/SCAR-MarBIN Biogeographic Atlas of the
Southern Ocean". This will take the form of a collection of maps and
synthetic texts presenting the key biogeographic patterns, and their causal
processess, of the main benthic and pelagic/nektonic taxa in the Southern Ocean
south of the Subtropical Convergence. There will be a hard copy in large
format, as well as a dynamic online version on SCAR-MarBIN. Illustrative maps
will be the key elements of the AAtlas, which is not intended to be a Treatise
of the Southern Ocean Biogeography.
4.
From
Tom Ermak, Sea Peach BioScience, 65 Hagen Road, Newton Centre, MA tomermak@rcn.com
I started two ascidian websites this year.
The first one is my consulting/microscopy website, Sea Peach Bioscience (www.seapeachbio.com), and the other is an image library called
Tunicarium (www.tunicarium.com)
containing a collection of my histology and EM
micrographs. My autoradiography/histology slide set from the 1970s is
still in excellent condition and I have started to digitally re-photograph many
of the images from the slides. In late spring, I set up a photo-microscopy
facility in my home office with bright field and stereo-zoom
photomicroscopes. During the summer, I participated in the Massachusetts
marine invasive species monitoring program (http://www.mass.gov/czm/invasives/monitor/mimic.htm)
surveying invasive invertebrates (including 6
ascidian species) and algae at marinas in Salem Sound and Cape Cod Bay,
MA. Some of the stereo-zoom microscopic images of live colonial
ascidians have been added to Tunicarium.
5. From Edwin L. Cooper and David Yao, Lab. of Comp. Neuroimmunology, Dept. of
Neurobiology, David Geffen School of Medicine, UCLA, Los Angeles, CA cooper@mednet.ucla.edu
Diving for drugs: marine
tunicate anticancer compounds
The marine biosphere boasts tremendous biodiversity replete with
structurally-unique, active and selective secondary metabolites. Bioprospecting
for anti-tumor compounds has been rewarding, and tunicates have been especially
successful in yielding prospective cancer therapies. These compounds are now
subjected to clinical trials in Europe and the US. With the ongoing search for
potent and specific cancer drugs, this review redirects attention to this
promising – yet still novel and unexplored – source of potential
pharmaceuticals. We discuss marine-derived anti-tumor drugs, their structures,
and their various types and levels of anti-tumor activities. [submitted to Drug
Discovery Today]
5. From Christina
Simkanin, Dept. of Biology, Univ. of Victoria, British Columbia, Canada
simkanin@uvic.ca
Biotic
resistance to the infiltration of natural habitats by an invasive ascidian:
examining the role of predation in the distribution of Botrylloides violaceus.
Anthropogenic marine habitats, such as
marinas and breakwaters, are frequently colonized by non-indigenous species
(NIS). Comparative studies show that few sessile
6. From V.K.
Meenakshi:
D.Shanmugapriya, Assistant Prof. of
Chemistry, is doing her Ph.D, entitled “Studies on some ascidians of Tuticorin coast” under the guidance
of Dr. Dr.S.Gopalakrishnan, Dept. of
Pharmaceutical Chemistry, Manonmanium Sundaranar University, Tirunelveli and
coguidance of Dr. V.K. Meenakshi, Dept. of Zoology, A.P.C.Mahalaxmi College for
Women, Tuticorin, Tamilnadu, India.
GC-MS analysis, HPTLC technique and pharmacological studies are in progress in the simple ascidian Phallusia nigra. GC-MS analysis of the methanolic extract of the animal revealed the presence of eleven components. Methyl 3-bromo-1-adamantaneacetate (24.65%), n-Hexadecanoic acid (24.45%), 11-Hexadecen-1-ol,(Z)-(17.64%) and 2,6-Dimethyl-6-trifluoroacetoxyoctane (9.82%) are some of the components found to have antimicrobial, antifungal, antioxidant, hypocholesterolemic and hemolytic properties. These chemical components have not been reported elsewhere from ascidians especially Phallusia nigra and hence can be considered as a first report. HPTLC analysis of the flavonoids present in the simple ascidian Phallusia nigra showed the presence of five flavonoids such as Gallic acid, Ferulic acid, Caffeic acid, Isoquercitrin and quercetin. Pharmacological properties like anti pyretic and analgesic activity of the methanolic extract of Phallusia nigra indicates the presence of biomedical components.
7.
From Gretchen Lambert: In
July I participated in a Navy 5 day biological survey of San Diego Bay with
several other taxonomists; we sampled a number of marina floating docks and
examined many settlement panels both wood and plastic that had been in place
for a year and were thus heavily fouled. The emphasis was on documentation of
invasive species; with Charley’s and my long familiarity with the ascidians of
southern California we were looking forward to resurveying many of our sites
after an absence of 11 years or more, and therefore I wanted to honor this
commitment. I invited a colleague and 2 graduate students working on southern
Calif. ascidians to participate in the survey, and at its completion the 4 of
us surveyed a number of marinas in nearby Mission Bay.
Of the 17 non-native ascidian species we
originally documented, all but one are still present and thriving. Very
surprisingly, we did not find any new ascidian introductions.
[Lambert, C. C. and Lambert, G. 1998.
Non-indigenous ascidians in southern California harbors and marinas. Mar. Biol.
130: 675-688.
Lambert, C.
C. and Lambert, G. 2003. Persistence and differential distribution of
nonindigenous ascidians in harbors of the Southern California Bight. Mar. Ecol.
Prog. Ser. 259: 145-161.
Cohen, A. N.,
Harris, L. H., Bingham, B. L., Carlton, J. T., Chapman, J. W., Lambert, C. C., Lambert,
G., Ljubenkov, J. C., Murray, S. N., Rao, L. C., Reardon, K. and Schwindt, E.
2005. Rapid Assessment Survey for exotic organisms in southern California bays
and harbors, and abundance in port and non-port areas. Biol. Invasions 7:
995-1002.
Lambert, G.
2007. The nonindigenous ascidian Molgula
ficus in California. Cah. Biol. Mar. 48: 95-102.]
1.Society for Integrative &
Comparative Biology (SICB) Annual Meeting, January 3-7, 2012, Charleston, SC.
Experimental whole body regeneration
among botryllid ascidian species in San Francisco Bay. Chow, B., Wray, M., Villines, B.,
Pinnick, G., Sheets, E., Spaulding, J., Cohen, C. S. San Francisco State
Univ. sarahcoh@rtc.sfsu.edu
Regeneration processes show a broad phyletic distribution and dramatic
variation in potential across diverse organisms. Colonial ascidians in the
family Botryllidae are the only chordates known to be capable of whole body
regeneration (WBR). WBR may occur following the artificial removal of zooids
and buds, leaving behind ampullar fragments that may ultimately lead to
production of new functional zooids. Prior work on botryllid WBR has relied on
laboratory assays, primed by application of retinoic acid, and aimed at
elucidating intrinsic differences in mechanism through morphological
observations. We compared the regenerative abilities of three botryllid species
(Botryllus schlosseri, Botrylloides violaceus, and Botrylloides
sp.) at three separate locations in San Francisco Bay. All three species were
successful in regenerating complete zooids from ampullar fragments in the field
without exogenous application of retinoic acid; however, success rate varied
among sites and species. B. violaceus had significantly lower success
overall with complete regeneration occurring at only one site. Conversely, B.
schlosseri and Botrylloides sp. showed success at both early and later
stages at all three sites. Mean time to regeneration for successful individuals
was significantly longer between B. violaceus and the other two species
and field regeneration times were longer than published laboratory studies with
RA. This study shows that WBR occurs in the field and varies among species and
populations, thus potentially affecting population viability following
disruptive processes such as predation, senescence, or intentional human
removal.
2. 35th Scientific
Meeting of the Assoc. of Marine Laboratories of the Caribbean, May 23-27, 2011,
Univ. of Costa Rica, San Jose, Costa Rica.
Diversity and Distribution of Tunicata
(Urochordata) of Tobago.
Linda Cole, Smithsonian Institution National Museum of Natural History, Dept.
of Invertebrate Zoology, Wash., D.C. colel@si.edu
The beautiful island of Tobago is the southernmost
Caribbean island. The sister island of Trinidad, it belongs to the Republic of
Trinidad and Tobago. Thirty two species of tunicates were collected from Tobago
from depths of 40 meters or less and they are listed. Tunicates listed in this
work are from collections made in 1956, 1991, 1993, 2002 and 2006 and although
specimens were collected from the Atlantic Ocean side of the island as well as
the Caribbean Sea side, all species turned out to be typical Caribbean species.
[poster]
3.
ColEvol
(Colombian Evolutionary Biology) Meeting, 28- 29 July 2011, Medellín, Colombia.
Identificación y
caracterización de la gemación en ascidias de Colombia y Panamá.
Pilar Andrea
Endara Pinillos, Federico D. Brown. Laboratorio
de Biología del Desarrollo Evolutiva (EvoDevo), Depto. de Ciencias Biológicas, Univ. de los Andes, Bogotá
D.C., Colombia. fd.brown46@uniandes.edu.co
El presente
estudio hace un registro de especies de la clase Ascidiacea por primera vez en
Colombia. El muestreo, se realizó en sitios de manglares a no más de dos metros
de profundidad, en tres diferentes localidades de la costa Caribe colombiana:
la isla Barú en el Archipiélago Corales del Rosario, la isla Titipán que hace
parte del Archipiélago de San Bernardo e Inca Inca en las cercanías de Santa
Marta. Se identificó mediante claves taxonómicas y se encontraron siete
especies ya registradas en Venezuela y Panamá y una posible especie nueva. Las
especies compartidas en los tres países de referencia en el Caribe fueron
Rhopalaea abdominalis, Botrylloides nigrum, Pyura vittata y Symplegma
brakenhielmi. Esta última, al parecer es
ubicua, pues se encontró en las tres localidades colombianas y también está en Bocas del Toro, Panamá y La Restinga,
Venezuela. Adicionalmente se hicieron observaciones de la gemación de las
ascidias se mapeó este carácter en la filogenia de estos organismos para
analizar la relación con la evolución de su colonialidad. Se colectaron
ascidias con gemación por estrobilación y paleal, pero no se colectó ninguna
ascidia con gemación estolonial. La estrobilación abdominal es un rasgo
característico de la familia Didemnidae, y la gemación paleal ocurre en las
Botryllidae. La colonialidad está relacionada a cambios en rasgos del
desarrollo y reproductivos, como la viviparidad, la miniaturización del cuerpo,
diferencia en la diferenciación de los órganos adultos en las larvas de
ascidias solitarias y coloniales y mayor potencial de regeneración. Estos
cambios modulares en el desarrollo, podrían generar también diferencias en los
mecanismos de gemación en cada grupo de ascidias coloniales. De este modo, se
relacionó la agregación de los individuos de una colonia con el desarrollo los
diferentes tipos de gemación. Se encontró que el índice de agregación, i.e. la
relación entre el área que ocupan los zooides adultos en la colonia y la
distancia entre estos, es mayor en aquellas especies en que se ha registrado
dos tipos de gemación, paleal y vascular, es decir, en miembros de la familia
Botryllidae.
4. 6th International Tunicate Meeting, Montreal (Canada), July 3-7, 2011.
a) Determining
the native region of the putatively invasive ascidian Didemnum vexillum.
Lauren Stefaniak, Huan Zhang, Adriaan Gittenberger, Kirsty Smith, Kent
Holsinger, Senjie Lin, Robert Whitlatch. lauren.stefaniak@uconn.edu
Over the past thirty years, many new
populations of a colonial ascidian, recently identified as Didemnum vexillum, have been recorded in most temperate coastal
regions of the world. These newly established populations affect aquaculture
operations and infest both natural rocky habitats and cobble/gravel substrates.
The earliest sample thought to be D.
vexillum was collected in Mutsu Bay, Japan in 1926, although it was not
described as a species at the time. Because D.
vexillum was not described until 2002, populations discovered before that
time were misidentified, often as species native to the region of discovery.
The combination of incomplete historical records and misidentification means
that the native range of D. vexillum
is not conclusively known. To determine which portion of the current known
range of D. vexillum is within its
native region, we sequenced two genes, co1 (mitochondrial) and tho2 (nuclear),
from 353 samples of D. vexillum from
around the world. Both population genetics (co1 only) and phylogenetics (co1 and
tho2) were used to identify a potential native region based on comparisons of
the amount and type of variation present in each region where D. vexillum is currently found (Eastern
North America, Japan, New Zealand, Western Europe, and Western North America).
b) Mitogenomics reveals a
remarkably high intra-specie substitution rate in the ascidian Botryllus
schlosseri. Francesca Griggio (1),
Ayelet Voskoboynik (2), Fabio Iannelli (1), Dmitry Pushkarev (2), Carmela Gissi
(1)* (1) Dip. Scienze Biomolecolari e Biotecnologie, Università degli Studi di
Milano, Milano, Italy (2) Institute of Stem Cell Biology and Regenerative
Medicine, Stanford Univ. School of Medicine, Stanford, USA.
The leitmotiv of mitochondrial genome
(mtDNA) evolution in ascidians is the hypervariability of many genomic features
(such as gene order, nucleotide substitution rate and tRNA gene content) even
at short phylogenetic distances. As consequence, the ascidian mtDNA has been
proved to unambiguously discriminate between two cryptic species of Ciona
intestinalis. Here, we describe the mtDNA of a model species, the colonial
ascidian Botryllus schlosseri. Two specimens, one from California and
one from Italy, have been sequenced. We found that the mtDNA of B.
schlosseri has a novel gene order, completely different from other
ascidians, and encodes for peculiar tRNA-like structures. Surprisingly, the
sequence divergence between the two specimens is up to one order of magnitude
higher (depending on the functional mt region) than the one measured in other
ascidian intra-species comparisons. However, this value is lower than the one
measured within genera, and between the two cryptic C. intestinalis
species. Thus, based on mtDNA, the Californian and Italian B. schlosseri
specimens appear to belong to a single species that is characterized by a
remarkably high nucleotide substitution rate.
c) Comparative analysis of neural related microRNA during the
development of Amphioxus and ascidians. Roberta Pennati (1)*,
Roberta De Santis (1), Mario Pestarino (2), Carmela Gissi (3), David S.
Horner (3), Fiorenza De Bernardi (1), Simona Candiani (2).
(1)
Dept. of Biology, Univ. of Milano; (2) Dept of Biology, Univ. of Genova; (3)
Dept of Biotechnology, Univ. of Milano, Italy.
MicroRNAs (miRNAs) are small non-coding RNAs
that act as posttranscriptional and translational regulators of gene
expression. Recent studies suggested that increased morphological complexity in
metazoans is correlated with the number and function of miRNAs. We analyzed and
compared the spatio-temporal expression of miRNA in the amphioxus
Branchiostoma floridae and in two ascidian species, Phallusia mammillata
and Ciona intestinalis. We focused our attention on 6 conserved miRNA
families known to be expressed exclusively or preferentially in the nervous
system of invertebrates and vertebrates. Interestingly, some of the analyzed
miRNA showed a conserved pattern of expression among the analyzed species,
while others differ regarding the spatial (CNS vs. PNS) or the temporal (early vs.
late) expression pattern. These data can help to elucidate the evolution of
nervous system among chordates.
d) A
collaborative study of non-indigenous ascidians on the south coast of
Newfoundland. Don Deibel (ddeibel@mun.ca), J. Ben Lowen,
Kevin C. K. Ma, Cynthia H. McKenzie, Matthew L. Rise, Gavin Applin, Jennifer
Hall and Ray Thompson. Ocean Sciences Centre, Mem.
Univ. of Newfoundland, St. John's, Canada.
In
2007, a harbour monitoring program was established linking researchers from
Memorial University, the federal Department of Fisheries and Oceans (DFO) and
the provincial Department of Fisheries and Aquaculture. Shortly thereafter, two
non-indigenous ascidian species, Botryllus schlosseri and Botrylloides
violaceus, were discovered in several harbours on the south coast of
insular Newfoundland. Although B. schlosseri had been known in
Newfoundland since 1975, this was the first report of B. violaceus. Since
both of these species are well known pests of aquaculture operations elsewhere,
we designed an interdisciplinary research program focused on factors predicting
invasion fitness and future spread in the cold coastal waters of Newfoundland.
Our results are intended to inform the early warning, zonal closure, and
mitigation decisions of government. The seasonal life cycle of B. schlosseri
is being determined in Arnold's Cove, including somatic growth and
the rates and timing of asexual and sexual reproduction (poster of Lowen et
al.) and larval recruitment (poster of Ma et al.). Diver surveys are being
conducted in Belleoram harbour to assess the effectiveness of trial efforts by
DFO to remove B. violaceus. Since mitigation efforts are more effective
if applied at an early stage of invasion, an early warning tool kit is being
developed consisting of TaqMan molecular gene probes sufficiently sensitive to
detect a single egg or larva (poster by Applin et al.). B. schlosseri
has been found in several harbours, with high colour morphotype and genetic
diversity, while B. violaceus has been found only in a single harbour,
with much less colour and genetic diversity.
e) Seasonal
variability in larval recruitment of the non-indigenous ascidian Botryllus schlosseri in
Arnold’s Cove, Newfoundland. Kevin C. K. Ma (kevin.ma@mun.ca), J. Ben
Lowen, Don Deibel, and Cynthia H. McKenzie. Ocean Sciences Centre, Mem. Univ. of Newfoundland, St. John's, Canada.
Viable populations
of Botryllus schlosseri, a potentially invasive species that
has been disrupting shellfish aquaculture in Atlantic Canada, are fouling
wharf structures and boat hulls in the subarctic waters of insular
Newfoundland. At monthly intervals from March to December, settlement
plates (aluminum, PVC, and wood) were moored at 3 subtidal depths (1, 2.5,
and 4 m from the surface) at 3 floating docks in Arnold’s Cove. 12
megapixel images of settlement plates were analysed for the presence
of larvae and juvenile colonies using “ImageJ.” Environmental data (in
situ fluorescence, salinity, and temperature) were also collected 4 times
per day using a moored YSI sonde. Larval settlement occurred from late
August to October, coincident with maximum seasonal temperatures. Larval
recruitment rates were highest at 1 m depth and at the most sheltered
mooring site (from 11-31 larvae m-2d‑1).
Unexpectedly, larvae readily settled on PVC at higher rates than on
aluminum and wood substrates. Thus, the continued use of PVC plates to
track recruitment of invasive ascidians within the Atlantic Zone
Monitoring Program is recommended. Future management of B. schlosseri can
target mitigation efforts before peak recruitment in September. Also,
risk of regional spread can be minimised by identifying sheltered harbours
and boat hulls that are susceptible to settlement and fouling.
f) Life-history constraints affecting
invasion success in the ascidian Botryllus
schlosseri. J.
Ben Lowen (jlowen@mun.ca ), Don Deibel,
Kevin Ma, Cynthia H. McKenzie, Ray Thompson. Ocean Sci. Centre, Mem. Univ. of
Newfoundland, St. John’s,
Canada.
Temperature limits for somatic growth and
sexual reproduction may strongly influence the invasive ability of Botryllus schlosseri. However, somatic
growth and sexual reproduction rates of B.
schlosseri have yet to be determined in a sub-arctic environment with an
extended 'over wintering' period. To address this lack of information, we
analyzed the life-history strategies of B.
schlosseri in
g) Ascidian photosymbionts: Do we know who’s hiding in the
tunic? López-Legentil
S, Turon X, Song B. slopez@ub.edu
Symbiotic interactions between ascidians and
microbes are only beginning to be explored. We reviewed the existing literature
on ascidian-cyanobacteria symbiosis and added our own research to the field by
characterizing the cyanobacterial populations of some didemnid species from the
Bahamas. So far, 91 species have been shown to contain photosymbionts, mostly
from the genera Prochloron (Prochlorales) and Synechocystis
(Chroococcales). To identify the photosymbionts present in Trididemnum
solidum, T. cyanophorum, Lissoclinum fragile, and L. aff. fragile,
we sequenced a fragment of the cyanobacterial 16S rRNA gene and the entire
16S-23S rRNA internal transcribed spacer region (ITS), and observed symbiont
morphology by transmission electron (TEM) and confocal microscopy (CM). Similar
to previous results for other ascidians, Trididemnum spp. mostly
contained symbionts from the Prochloron-Synechocystis group.
However, sequence analysis of the symbionts in Lissoclinum revealed two
major clades. The first clade could not be associated with any known cyanobacterium
(<93% max. identity), while the second clade matched closest to Acaryochloris
marina (95% max. identity). Further observations using CM revealed the
presence of both chl d and phycobiliproteins within these symbiont
cells, which are characteristic of Acaryochloris species. Moreover,
these symbionts were also observed by TEM in both the adult and larvae of L.
fragile, indicating vertical transmission to the progeny. ITS gene
sequences displayed much higher variability than 16S rRNA sequences, allowing a
precise determination of the genetic diversity and host specificity of symbiont
populations among ascidian species. Our results demonstrate that there is still
much to learn on ascidian symbiosis, and that further work is necessary to
assess the diversity, dynamics and significance of the microbial symbionts
hiding in ascidian tunics.
h) Protochordate
VCBPs are involved in the host-microbial dialogue of the gut.
Larry
J. Dishaw, Stefano Giacomellid, Daniela Melillod, Ivana Zucchetti, Robert N.
Haire, Lenina Natale, Nicola A. Russo, Rosaria De Santis, Gary W. Litman, Maria
Rosaria Pinto.
Statione
Zoologica Anton Dohrn, Naples, Italy. ldishaw@gmail.com
In all metazoans, despite an enormous
variation in developmental morphology, an endodermally derived gut plays a
central role not only in host metabolism but in the molecular dialogue between
host and microbes. The typical gut consists of an outer epidermal case and an
inner epithelial layer separated by a thin tissue space, which in many cases is
populated by immunocytes. Innate immunity provides immediate and, in many
animals, the exclusive form of recognition and defense within the gut.
Throughout phylogeny, a variety of protein structures have been recruited by
innate immunity to facilitate host discrimination of dietary antigens, and
transient or symbiotic microbes. Variable region-containing chitin-binding
proteins (VCBPs) of protochordates have been described in amphioxus and
proposed to function in gut immunity. Here we describe VCBPs in Ciona intestinalis, a urochodate model
of development and immunity. In Ciona,
VCBPs are expressed exclusively by distinct cells of the gut epithelium and
both expressed and recognized by specific amoebocytes. Using native and
recombinant forms of VCBPs, as well as immunogold histochemistry, we show that
secretory VCBPs bind bacteria in the gut lumen and enhance phagocytosis in
amoebocytes opposite the epithelium. This is the first demonstation of an
immunoglobulin-type molecule functioning in the molecular dialogue between host
and gut microflora in non-vertebrate species.
i) Crossing
the thin line between introduced and invasive species: factors shaping the
distribution and invasive potential of the solitary ascidian Styela plicata. M.C.
Pineda*1, S. Lopez-Legentil1, M. Rius2, C.
McQuaid3, X. Turon4.
1Animal Biology
Dept., Univ. of Barcelona, Spain; 2Dept. of Evolution & Ecol., Univ. of CA, Davis, CA; 3Dept. of Zool. & Entomology, Rhodes Univ., Grahamstown, S. Africa; 4Centre for Advanced Studies of Blanes (CEAB,
CSIC), Blanes, Spain.
There is a thin line between
introduced and invasive species. However, since their invasive potential is
uncertain, introduced species commonly receive less attention. The aim of this
study was to use an integrative approach to assess the invasive potential of
the solitary ascidian Styela plicata.
Demographic and biological parameters were studied using four different
approaches: 1) A global phylogeography using two genetic markers; 2) An
assessment of the S. plicata
reproductive cycle in two Mediterranean populations over a 2-year period; 3) An
assessment of the susceptibility of S. plicata to changes in salinity, pollutant concentration, and temperature; and
4) An assessment of the stress response of S.
plicata to natural environmental fluctuations over time, through
quantification of hsp70 gene
expression. Taken together, our results showed that S. plicata has been present in all studied oceans for a long time,
and that the present distribution of
this species appears to be regulated by high tolerance to pollution, and high
sensitivity to low salinity and high temperature events. Proliferation and
survival of S. plicata over time is
ensured by a protracted reproductive period and rapid growth. This study
highlights the importance of multidisciplinary approaches for understanding the
interaction among the many factors shaping the invasive potential of introduced
species.
j) Wild
and cultured edible tunicates: a review. Mary R. Carman1 and Gretchen Lambert2.
1Biology Dept., Woods Hole Oceanog.
Instit., Woods Hole, MA mcarman@whoi.edu
2Univ. of Washington Friday Harbor
Labs, Friday Harbor, WA 98250 glambert@fullerton.edu
Most tunicate species are not edible but some solitary stolidobranchs in
the Styelidae and
Pyuridae families are harvested wild
or cultured. The main species are Halocynthia aurantium, H. roretzi,
Microcosmus hartmeyeri, M. sabatieri, M. sulcatus, M. vulgaris, Polycarpa
pomaria, Pyura chilensis, Styela clava, and S. plicata, and they may
be eaten raw, cooked, dried or pickled. Historically the Maoris ate Pyura
pachydermatina in New Zealand and aboriginal people ate P. praeputialis in
Australia, though it is now only used for fishing bait. There is a large market
for cultured tunicates, especially among Asian populations. S. clava and
S. plicata have become extremely abundant in many countries as
non-native introductions; they could easily be harvested and sold as seafood,
as could common species that have not previously been consumed such as Herdmania
pallida. Disease and overexploitation can reduce cultured product and wild
populations. Recently, the disease ‘soft tunic syndrome’ caused up to a 70%
loss of H. roretzi crop in Korea, while harvesting wild P. chilensis reduced
their richness three fold in some parts of Chile. Most aquaculture operations
are located in bays with urban runoff where pollutants including heavy metals
and toxic substances could accumulate in tunicates. Natural disasters like
tsunamis will also negatively impact aquaculture. Nevertheless, with proper
controls and monitoring, certain edible tunicate species that are currently an
underutilized food in many parts of the world could be easily cultivated or the
huge numbers of invaders could be harvested and marketed.
k) Overwintering
of the tunicate Didemnum vexillum in coastal New England. Page C. Valentine1, Mary R.
Carman2, and Dann S. Blackwood1. 1US Geological Survey, Woods Hole, MA 02543;
2Woods Hole Oceanog. Instit., Woods Hole, MA 02543. pvalentine@usgs.gov
The
invasive colonial tunicate Didemnum vexillum flourishes in the coastal
waters of New England. Colonies regress in winter when water temperatures can
reach 0 oC and lower. To document this process, in May 2008 we set
out 6 vertically-oriented, dark gray PVC settlement plates (12 x 12 cm) at 3 m water
depth in Woods Hole, MA as substrates for D. vexillum. The plates were
naturally covered with D. vexillum by the start of observations on
November 3, 2008 (11.7 °C), by which time cloacal canals and apertures were
clogged with fecal pellets indicating that feeding by the colonies had ceased.
Plates were inspected at 8-9 day intervals until April 28, 2009. By December 9
(5.5 °C), zooid thoraces were tightly contracted. By December 29 (4.9 °C), the
outer surfaces of cloacal canals had fallen off, exposing pockets of loose
fecal pellets. From January 19 (0.4 °C) to April 8 (5.9 °C), colony tissues
were either patches of white, spicule-laden, intact surface tissue or patches
of disintegrating tissue, where the orange internal abdominal organs of the
zooids were exposed. By April 14 (6.6 °C), the white tissue began to enlarge
and oral siphons with tentacles were visible. Tissue regeneration signaled the
end of the overwintering stage. By then, 91 to 100 % of the original colonies
had disintegrated and fallen off the plates. By April 28 (9.8 °C), oral siphons
were open, cloacal apertures had formed and were expelling fecal material, and
the zooids were feeding. The response of D. vexillum to falling
temperatures can result in a significant loss in areal coverage, but the effect
is temporary, as we observed the colonies grow and spread as waters warmed.
l) Didemnum vexillum in
eelgrass habitat. MR
Carman1 mcarman@whoi.edu;
DW Grunden2; P Colarusso3; MM Chintala4; DS Blackwood5; BH Becker6; K
Smith7. 1Biol. Dept., Woods Hole
Oceanog. Inst., Woods Hole, MA; 2Oak Bluffs Shellfish Dept., Oak Bluffs, MA;
3US Envl. Protection Agency, Boston, MA; 4US Envl. Protection Agency, Atlantic
Ecology Division, Narragansett, RI; 5US Geol. Survey, Woods Hole, MA; 6Point
Reyes Natl. Seashore, Point Reyes Station, CA; 7Cawthron Institute, Nelson, New
Zealand.
Seagrasses may be facilitating the spread of invasive tunicates by
providing substrate and a dispersal mechanism (rafting). During the past 3
years, we observed D. vexillum in the
northwest Atlantic (Massachusetts) and
eastern Pacific (California) utilizing eelgrass
(Zostera marina) as substrate
for the first time ever. In some cases D. vexillum encapsulated plants to such an
extent that they could no longer naturally defoliate or release seed, and
upright shoots collapsed from the weight of the tunicates. Genetic analysis of D.
vexillum specimens indicated that there is no genetic difference between
colonies on eelgrass versus other substrate. Eelgrass that has been colonized
by tunicates had fewer leaves, grew at a slower rate and had higher
concentrations of sugar in its leaves. We speculate that the plants are
reacting to loss of light by producing less new tissue and stockpiling the
carbon it does produce. Tunicate growth affects the ability of eelgrass to
function as a complex habitat. The presence of tunicates on eelgrass inhibits
its use by bay scallops (Argopecten irradians) and herbivorous grazers
such as snails.
m) Evidence for positive selection on
an allorecognition locus in Botryllus
schlosseri.
Nydam, M.K. (mln32@cornell.edu), Taylor,
A.A., and De Tomaso, A.W.
5. 82th Annual Meeting of the
Zoological Society of Japan, Asahikawa, Japan, 21-23 September 2011.
Organization of the neural complex of Symplegma viride. Hiromichi Koyama1 and Shigeki
Fujiwara2, 1College of Nursing, School of Medicine, Yokohama City Univ.; 2Dept.
of Applied Science, Kochi Univ.
We examined the ultrastructure of the
cerebral ganglion of Symplegma viride
with a transmission electron microscope. The cerebral ganglion is enveloped by
a fibrous sheath about 3 microns thick. This sheath covers the nerve fiber
bundles emanating from the cerebral ganglion. Each nerve fiber is also covered
by thin fibrous mesh. The nucleus of the large somata contains chromatin
clusters, some of which demarcate the internal nuclear membrane. There are
mitochondria, Golgi complex, centriole, and many vesicles in the cytoplasm. The
rough ER in large neuronal somata is less extensive than that of Polyandrocarpa misakiensis. The vesicles
with electron-dense content vary in size, 100 - 300 nm in diameter. There is a
hithero undescribed organelle in ascidian neurons, and we named it
multigranular body. The multigranular body is irregular in shape and occupied
by electron-transparent matrix, which contains several electron dense granules.
6. Western Soc. of Naturalists' 2011
Annual Meeting, Vancouver, WA, Nov. 10-13, 2011.
a)
Contrasting effects of flow on adult and juvenile ascidian life history stages,
including the global invasive Didemnum vexillum. Tren Kauzer1,2, Joseph D. Spaulding2,
C. Sarah Cohen2. Calif. State Univ., San Luis Obispo1;
Biology Dept and Romberg Tiburon Center for Environmental Studies, San
Francisco State Univ.2
The colonial ascidian Didemnum vexillum
has shown an incredible propensity to invade marine ecosystems and poses a
threat to both native species and the aquaculture industry. For sessile filter
feeders, flow is a critical element influencing survival and growth,
determining success across life history stages.
However, few studies have quantified the relationship between flow and
the recruitment, growth and survival of colonial filter feeders. In this study
we evaluated the growth of D. vexillum and larval recruitment under
different local flow conditions in Half Moon Bay, California, USA. D.
vexillum colonies were subjected to four different manipulated flow
conditions over the course of three weeks, and growth and recruitment were
measured. A direct relationship was seen
between inferred increases in flow and adult growth, and an inverse
relationship was seen between inferred increases in flow and recruitment. These trends suggest that optimal flow
conditions differ for juveniles and adults. Significant differences in
growth were seen between colonies subjected to almost no flow and the other
three conditions. The adults' ability to
grow over a range of flow conditions adds to its danger as a biological
invader. Understanding how adult and
juvenile ascidians behave under different flow conditions could be used to
determine which marine environments are most vulnerable to invasion and could help
those who wish to eradicate or control its spread. [poster presentation]
b) The importance of early
life-history stages in ecological succession. Rius M, Potter E, Aguirre JD, Stachowicz JJ. Dept. of Evolution and Ecology, Univ. of
Calif., Davis CA
mrius@ucdavis.edu
Ecological succession is a crucial process
for understanding the spatial distribution of species and the maintenance of
species diversity. In marine systems, succession has long been studied in
fouling communities, but the focus has been on understanding interactions
between adults or effects of adults on new recruits. Despite considerable
advances, it is still not clear, for example, how competitively inferior
species persist in places with low disturbance intensity and frequency. Here,
we studied ecological interactions during early life-history stages to assess
their influence on successional dynamics of the fouling community in Spud Point
(Bodega Bay, California), a sheltered marina where population and reproductive
phenologies have been studied over 10 years. During the period when community
development and breeding thrived, we conducted additive and replacement design
experiments in the laboratory covering interactions from gamete release to
post-metamorphic stages. We also placed new metamorphs in the field in various
combinations to examine effects of early life-history neighbors on longer-term
success. The solitary ascidian Ascidia ceratodes is the clear competitive
dominant in this system, yet it does not monopolize the space and coexists with
other competitively inferior species. Similarly, the non-indigenous Ciona
intestinalis has been slow to invade the system and has not established
monocultures as it has elsewhere, despite the fact that it is likely to be
competitively dominant. This study seeks to answer whether solitary ascidians
are not more dominant because their early life-history stages are susceptible
to predation and competition, even though as adults they are generally
resistant to both.
7. 7th
Intl. Conference on Marine Bioinvasions, Barcelona, Spain, 23-25 August 2011.
a) Coming and going: Temporal genetic variability of the introduced sea
squirt Styela plicata. Valero, C., Pérez-Portela, R., López-Legentil, S. slopez@ub.edu
Introduced species may have an important
impact on the natural ecosystem, disrupting ecological processes such as
succession and species composition. Styela plicata is a solitary
ascidian commonly found in harbors and marinas from tropical and temperate
waters. This species is believed to have spread worldwide travelling on ship
hulls. In this study, we determined the temporal genetic structure between and
within cohorts of S. plicata. Samples were collected from the decks of
the Center for Marine Science (UNC Wilmington, USA) between February 2007 and
July 2009. We used the 454 Genome Sequencer GS-FLX next-generation sequencing
platform to obtain 159,832 genomic reads averaging 278 bp. These sequences were
then analyzed for repeat motives using Phobos v 3.3.12. We obtained over 100
potential microsatellite regions and from these, we isolated 8 polymorphic
microsatellites. Our results showed that there were genetic differences among
cohorts during the 2.5 years of study. In addition, there was a clear shift in
the genetic structure of the population between May and July. This shift may be
due to the high mortality event recorded every June, followed by the arrival of
new recruits in July. Our results suggest that the dispersion and
re-colonization of Styela plicata in coastal waters of North Carolina is
an ongoing process. The most parsimonious explanation is an arrival of new
recruits carried by the many ships that cross the Intracostal Waterway, which
runs parallel to the coast from New Jersey to Texas.
b) A
threat around the corner? Assessing the invasive potential and biogeographic
boundaries of an introduced ascidian. M.C. Pineda*, Animal Biology Dept., Univ. of Barcelona, Spain;
S. Lopez-Legentil, Animal Biol. Dept.,
Univ. of Barcelona, Spain; M Rius,
Dept. of Evolution & Ecol., Univ. of Calif., Davis, CA; C.D. McQuaid, Dept.
of Zool. & Entomology, Rhodes Univ., Grahamstown, S. Africa; X. Turon,
Centre for Advanced Studies of Blanes (CEAB, CSIC), Spain.
There is a thin line between introduced and invasive species. However,
since their invasive potential is uncertain, introduced species commonly
receive less attention. The aim of this study was to use an integrative
approach to assess the invasive potential and biogeography of marine introduced
species. For this, we used as a model organism the solitary ascidian Styela plicata (Lesueur, 1823), a
species that is present in harbours and on submerged structures around the
world. Nevertheless, this species is not considered invasive, as there are few demonstrations
of introduced populations outcompeting native species. Demographic and
biological parameters were studied using four different approaches: 1) A global
phylogeography using two genetic markers; 2) An assessment of the S. plicata reproductive cycle in two
Mediterranean populations over a 2-year period; 3) An assessment of the susceptibility of S. plicata to changes in
salinity, pollutant concentration, and temperature; and 4) An assessment of the
stress response of S. plicata to
natural environmental fluctuations over time, through quantification of hsp70 gene expression. The results of
the phylogeographic study showed that S.
plicata has been present in all the studied oceans for a long time, and
that its populations have been shaped by recurrent and ongoing colonization
events through ship traffic. The study assessing the
reproductive cycle of this species showed that S. plicata has a protracted reproductive period and rapid growth.
Experiments using embryos and larvae showed that early life-history stages of
this species were highly tolerant to a common pollutant (copper), while low
salinities (as found in estuarine conditions) and high temperatures seriously
impaired larval development. Finally, low salinities and high temperatures in
the field significantly increased hsp70 gene expression in this species. Taken
together, our results indicate that the
present distribution of this species appears to be regulated by low salinity
and high temperature events in estuaries, while it shows high tolerance of
pollution in harbours and marinas. Considering that many potentially suitable
coastal areas remain to be colonized, our
results suggest that S. plicata has
the potential to proliferate and extend beyond its current boundaries. This
study highlights the importance of multidisciplinary approaches for
understanding the interaction among the many factors shaping the invasive
potential of introduced species.
8. International Human Microbiome Congress, Vancouver,
March 2011
A protochordate model of gut
microbial-immune dynamics. Larry J. Dishaw, M. Gail Mueller, Jaime Flores-Torres, Daniela
Melillo, Ivana Zucchetti, Rosaria De Santis, Maria Rosaria Pinto, and Gary W.
Litman. Statione Zoologica Anton Dohrn, Naples, Italy. ldishaw@gmail.com
Most encounters between host and microbe
involve complex symbiotic relationships, of which many are governed at the
surface of gut epithelium. This single cell layer of gut epithelium is
phylogenetically ancient and is thought to possess fully developed
immunological capabilities. Ciona
intestinalis, which is a descendant of the last common ancestor of all
vertebrates and lacks adaptive immunity, is a potentially valuable new model
for studying gut microbial-immune dynamics (GMID) and barrier defenses. A
variety of immunological phenomena are well characterized in Ciona, including the expression of
relevant innate immune molecules such as toll-like receptors, complement C3,
and variable domain-containing chitin- binding proteins. We find that the Ciona
gut is populated with diverse microbial communities and is predominated by
gamma-proteobacteria. As with vertebrate models, the Ciona diet plays a significant role in microbial composition;
presumably relevant dysbiosis is induced via starvation. The Ciona gut epithelium is responsive to
microbial associated molecular patterns (MAMPs), and a distinct, hemocyte-
rich, gut-associated tissue actively engages the microbiata. GMID can be
investigated in Ciona against the background of a competent innate immune
system and in the absence of central components of vertebrate adaptive
immunity.
9. 9th
Congress of the Southern African Society for Systematic Biology, Grahamstown,
South Africa, 19-21 January 2011.
Detecting taxonomic boundaries of a
species complex: the case of a widespread marine invertebrate. Rius M, Teske PR. mrius@ucdavis.edu
Coastal environments are among the most
heavily invaded ecosystems in the world. A large proportion of the coastal
invertebrate fauna has poorly resolved taxonomic status and unknown historical
distributions, which makes it difficult to distinguish between invasive species
and long-established, but previously overlooked, cryptic species. We address
this dilemma by studying the widespread marine ecosystem engineer Pyura stolonifera, a large solitary
ascidian found in Africa, Australasia and South America. The taxonomic status
of different populations of this species is disputed, especially since there is
evidence for several distinct morphological and genetic units that point
towards the existence of multiple cryptic species. While some researchers still
recognize P. stolonifera as a single
species, others treat the different populations as distinct species. Here, we
present a revision of the P. stolonifera
species complex based on a morphological examination and a phylogenetic study
of samples from all regions where there are reliable reports of this taxon. We
recognize four species that are morphologically distinct, one of which is new
to science. In addition, at least five cryptic species can be further
subdivided into regional genetic lineages. Strong evidence for both cryptic
native diversity and the existence of invasive populations allows us to
considerably refine our view of its native versus introduced status within the
different coastal communities it dominates. Cryptic diversity in widespread
species, and the taxonomic confusion arising from it, represents a major
challenge for managing biodiversity.
THESIS ABSTRACTS
1. Examination of secondary
metabolites and inorganic acids as chemical defenses against predation and
fouling in Antarctic and sub-tropical ascidians. Gil Koplovitz, Dept. of Biology,
Univ. of Alabama at Birmingham. Ph.D. dissertation; advisor Dr. J.B.
McClintock. gilkop@gmail.com
Palatability of fresh outer tissues of 12
species of ascidians from the Western Antarctic Peninsula was evaluated using
the sympatric, omnivorous fish Notothenia coriiceps and sea star Odontaster
validus as model predators. All ascidians were unpalatable to fish,
while 58% were unpalatable to sea stars. Lipophilic and hydrophilic
extracts of 11 ascidian species were incorporated into food pellets and tested
in fish and sea star bioassays. Only the lipophilic extract from Distaplia
colligans caused feeding deterrence in either predator. Organic
extracts were also examined in food pellets using the sympatric, omnivorous
amphipod Gondogeneia antarctica. Only the lipophilic extract of Distaplia
cylindrica was deterrent. Five species of ascidians had acidic
tunics. Acidified food pellets were deterrent against sea stars but not
fish.
The secondary metabolites from a similar
suite of Antarctic ascidian species were tested against sympatric marine
bacteria and diatoms from the Western Antarctic Peninsula. All ascidians had
lipophilic and hydrophilic extracts assayed against twenty bacterial strains
and against a sympatric diatom (Syndroposis sp.). Only the lipophilic
extract of D. colligans showed broad-spectrum antimicrobial activity. At
least one extract from all but one ascidian taxa caused significant diatom
mortality.
The palatability of five species
of ascidians commonly found in sub-tropical seagrass habitats were evaluated
using the sympatric, omnivorous pinfish Lagodon rhomboides as a model
predator. Fresh outer tissues of three of the ascidian species were unpalatable
to fish. Food pellets containing organic extracts of these species did not
deter feeding by the fish. The toughness of the tunic of all five
ascidian species was evaluated using a penetrometer. Tunic toughness is
likely to explain the lack of palatability of two of the three species.
Acidity is unlikely to explain deterrence in the third species as
fish consumed acidified food pellets.
Despite their lack of
palatability to sea stars and fish, organic chemical defenses against predation
are uncommon in both Antarctic and Sub-tropical ascidians. Toughness and
inorganic chemicals appear more important. Despite the lack of antibacterial defenses in
Antarctic ascidians, secondary metabolites appear to play a potential role in
preventing fouling by diatoms.
2. Chemical
screening and pharmacological evaluation of ascidians. S. Gomathy, Dept. of
Zoology, A.P.C.Mahalaxmi College for Women, Tuticorin, Tamilnadu, India. gmathyramesh@gmail.com. Ph.D. dissertation; advisor Dr.V.K.
Meenakshi.
The
simple ascidian Microcosmus exasperatus
was subjected to qualitative chemical screening, HPTLC and GC - MS analysis.
This screening revealed the presence of various chemical constituents like
alkaloids, terpenoids, steroids, tannins, saponins, flavonoids, quinones,
anthraquinones, proteins, carbohydrates and lipids. HPTLC profile for flavonoids showed the
presence of gallic acid, ferulic acid, caffeic acid, isoquercitrin and
quercetin which are being reported for the first time from the whole body extract
of Microcosmus
exasperatus. Twenty biologically active constituents were identified in the
ethanolic extract by GC-MS analysis. Of these 20 constituents, the following
seven constituents: n-hexadecanoic acid, tetradecanoic acid, trichloroacetic
acid, hexadecyl ester, 26-Nor-5-cholesten-3á-ol-25-one, 6,9,12-Octadecatrienoic
acid, phenylmethyl ester, (Z,Z,Z)- ), Cholestan-3-ol and 2-piperidinone, showed biological
activities such as antioxidant, antimicrobial, anti-nflammatory,
hepatoprotective, hypoglycemic, antiasthmatic, anticancer, antipyretic and
antiandrogenic.
3. Identificación
taxonómica y caracterización de la gemación en ascidias de Colombia y
Panamá. Pilar Andrea
Endara Pinillos. Laboratorio de Biología del Desarrollo Evolutiva
(EvoDevo), Depto. de Ciencias Biológicas, Univ. de los Andes, Bogotá
D.C., Colombia. Undergraduate thesis; advisor Dr. Federico Brown. fd.brown46@uniandes.edu.co
Este estudio
presenta el primer registro para Colombia de las especies de tunicados de la
clase Ascidiacea. El muestreo se realizó en tres diferentes ubicaciones o
estaciones de la costa Caribe colombiana: la playa de Cholón en la isla de
Barú, la isla Titipán que hace parte del Archipiélago de San Bernardo e Inca
Inca en la bahía de Gaira en Santa Marta. De las siete especies encontradas,
seis ya han sido registradas en Venezuela o Panamá y un organismo colectado en
Colombia no ha sido descrito una posible nueva especie. Observaciones
detalladas de la gemación y la agregación de las colonias de ascidias fueron
registradas fotográficamente. Mediante el cálculo de un índice de agregación
simple (IA) se discute su relación con la gemación y la evolución de los
estilos de vida solitario y colonial en el grupo.
4. Determination of genetic
differences between cohorts of the introduced ascidian Styela plicata. Claudio Valero, Master in Biodiversity,
University of Barcelona. Advisers: Rocío Pérez-Portela and Susanna López-Legentil
Introduced species may have an important
impact on the natural ecosystem, disrupting ecological processes such as
succession and species composition. Styela plicata is a solitary
ascidian commonly found in harbors and marinas from tropical and temperate waters.
This species is believed to have spread worldwide travelling on ship hulls. In
this study, we isolated microsatellite loci from shotgun DNA genome
pyrosequencing and performed a preliminary study of the temporal genetic
structure between and within cohorts of S. plicata. Samples were
collected from the Center for Marine Science docks (UNC Wilmington, USA)
between February 2007 and July 2009. We used the 454 Genome Sequencer GS-FLX
platform (Roche) to obtain 159,832 genomic reads averaging 278 bp. The
resulting sequences were analyzed for repeat motives using Phobos v 3.3.12.
Over a hundred potential microsatellite regions were detected, and from these,
we selected and tested 18 primer pairs. Eight polymorphic microsatellites were
finally isolated and optimized for further analyses. Preliminary analyses of S.
plicata’s cohort structure showed that there were few genetic differences
during the 2.5 years of study. However, a clear shift in the genetic structure
of the population was detected between May 07 and July 07, which could be
attributed a mass mortality event recorded in June. New recruits appeared to
re-colonize the area in July, carried by the many ships that cross the
Intracostal Waterway, where the Center for Marine Science docks are located. Our
results indicated that the genetic structure of the analyzed population was
quite constant over time, with occasional re-colonization events in summer.
|
5. Diversity,
invasibility, and resource use in marine fouling communities of San Francisco
Bay.
Safra Altman, Univ. of
Georgia Odum Sch. of Ecology & UGA Marine Institute. Ph.D. dissertation, Univ. of Maryland. safraaltman@gmail.com
|
Invasive species threaten the biodiversity
of estuaries worldwide. To examine the relationships between biodiversity,
invasibility, and invasion success, I conducted field surveys and experiments
in San Francisco Bay marine fouling communities, including 1) surveys to
estimate alpha, gamma, and beta diversity of native, non-native and cryptogenic
components of the community; 2) experiments to assess the influence of
diversity and resource availability on short-term recruitment of novel
non-indigenous species (NIS) into test communities and subsequent community
development over time; and 3) an experiment to explore the role of facilitative
interactions of NIS in the diversity-invasibility relationship. Surveys (10-24
sites) showed that non-native alpha diversity was significantly greater than
native or cryptogenic alpha diversity, beta diversity was significantly greater
for native and cryptogenic species than for NIS, and gamma diversity was
similar for NIS and native species. These results indicate that native species
had high turn over from site to site while NIS were spread throughout the Bay.
Experiments showed that on short time scales (2-4 weeks), the effect of initial
diversity on the density of recruitment of NIS was significant and negative,
with no effect of resource level (increased open space). Changes in community
composition over time (2-24 weeks) also indicated significant inverse
relationships between percent cover of NIS and diversity of the initial
community with no evidence of a resource effect. Abundant NIS occupied less
space in communities with higher initial diversity. However, the same NIS
occupied (i.e., had invaded) all experimental communities regardless of
starting diversity. Additional experiments revealed that recruitment to
secondary substrates did not vary significantly with invasive species diversity
or resource availability. When total recruitment to primary and secondary
substrates were combined, there was no longer a significant relationship
between diversity and recruitment. Analysis of secondary settlement patterns
revealed that some NIS, such as Bugula neritina, were facilitating recruitment
and settlement of additional NIS. In contrast, other species, such as Clathria
prolifera and Botryllus schlosseri, inhibited secondary settlement of NIS. The
influence of diversity and primary resource availability on secondary
settlement did not appear to affect settlement on facilitative species, but
reduced settlement on inhibitive species.
NEW PUBLICATIONS
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C. L., Ebert, D., Tabata, A. and Therriault, T. W. 2011. Twelve microsatellite
markers in the invasive tunicate, Didemnum vexillum, isolated from low
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