Number 52 December 2002
Holiday Greetings!
Ascidiologists have been busy this year; there are 140 new publications
listed at the end of this newsletter! We worked at the Roscoff laboratory
in Brittany during July and August where Charlie looked into factors leading
to the success of invasive ascidians and Gretchen continued her studies
in ascidian systematics (see Work in Progress). This was our first
visit to the laboratory in 5 years and it was a great pleasure to meet
our long-term friends. Danielle Georges and Marie and Henri Goudeau
are now retired and live elsewhere for most of the year but still spend
their summers in Roscoff. After our stay at the labs we drove through Normandy
and visited Claude and Françoise Monniot in Paris. We spent
most of September at the Friday Harbor Labs giving us ample opportunity
for ascidiological discussions with Dick Whittaker. In late September
we conducted an ascidiological survey of most of the harbors in southern
Vancouver Island with Cathy Carolsfeld from Victoria.
In October we traveled to Nahant Massachusetts where Gretchen presented
a workshop on ascidian identification to 33 participants. The workshop
was organized by Robert Miller and largely funded by Massachusetts MIT
Sea Grant headed by Judy Pederson. We collected ascidians for the workshop
in several Mass. harbors and also got down to Woods Hole with Bob Miller.
While in the Boston area we visited Bob Woollacott in his lab at Harvard.
From Nahant we visted Larry Harris in NH and examined float ascidians with
him. He showed us huge colonies of the cream colored Didemnum
sp. which seems to be present everywhere in the Gulf of Maine. At
the Darling Marine Center in Maine the director Kevin Eckelbarger gave
us a most interesting and informative tour. The laboratory is much
larger than we had envisioned with many new and refurbished buildings and
superb housing. Gretchen identified a troublesome Molgula
species there. From the Darling lab we traveled north to the Huntsman
Marine Science Centre (named in honor of A.G. Huntsman a Canadian ichthyologist
who did very fine work in the systematics of ascidians) in St. Andrews,
New Brunswick, Canada. Gretchen presented a workshop there at the
invitation of Gerhard Pohle. We greatly enjoyed the New England autumn
tree colors which were at their peak. We plan to work at the Friday
Harbor labs next summer and hope to see many of you there.
*Ascidian News is not part of the scientific literature and should not be cited as such.
NEWS AND VIEWS
1. Our congratulations to Dr. Hitoshi Sawada, who recently moved from the Graduate School of Pharmaceutical Sciences, Hokkaido University, to become professor and director of the Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University. Dr. Sawada writes: Sugashima island in Toba-city (http://www.city.toba.mie.jp/eigo/brief/brief.htm) is located in the Ise-Shima National Park in Mie Prefecture, Japan, and it is a very beautiful place. Since the building of Sugashima Marine Biological Laboratory for the visitors was built about six years ago, and also since the old building was renovated at that time, I suppose that visiting investigators and students must be satisfied by nice accommodations and meals (handmade bread and cakes will also be served in the restaurant!). Although it is not so convenient to go shopping because of the isolated location, the accommodations and facilities are excellent. For instance, radioisotope tracer experiments using some marine animals are also permitted in this MBL. Please contact the URL of my laboratory (http://www.bio.nagoya-u.ac.jp:8001/%7Esaraki/MarineE.html). Lastly, I would like to express my hearty welcome to visitors to the Sugashima Marine Biological Laboratory, Nagoya University. Sincerely yours, Hitoshi Sawada, Director
2. Quentin Bone (qb@mail.pml.ac.uk) writes: John Bishop and I are looking at possible sub-micron particle capture by ascidians and its efficiency. No problem with 0.3-0.45 micron particles, but we are at present trying smaller diameter. I would be interested to hear from others looking at ascidian particle capture.
3. From Hervé Bizot, Unité de Physicochimie des Macromolecules, Inst. Nat. Recherche Agronomique, Nantes, France: Our lab, involved in structural studies of plant cell wall polysaccharides, wishes to purchase tunicin or raw ascidian test, which may offer convenient possibilities to extract pure highly crystalline cellulosic microfibrils. We need to reach multiple gram quantities of purified cellulosic microfibrils to make various physical chemistry experiments including adsorption studies. Apprently the usual choice is Halocynthia roretzi but our attention was also drawn by different colleagues (i.e. Dr. Hirose) towards Microcosmus fulcatus (likely difficult to purify) or Oikopleura rufescens (likely with limited yields). If you have suggestions please contact us by e-mail : bizot@nantes.inra.fr .
4. Ascidians of the British Isles--a Colour Guide, by Bernard Picton, published in 1985, is now out of print. But the author has revised the text and species photographs and they are now available online at http://www.ulstermuseum.org.uk/marinelife/ Go to the section on Sea Squirts. There is also a page of literature references.
5. From Dr. Billie Swalla (bjswalla@u.washington.edu)
Dept. of Zool., Univ. of Washington, Seattle WA:
Summer Course Announcement 2003, Friday Harbor Laboratories
(http://depts.washington.edu/fhl/classlist03.html)
Marine Invertebrate Zoology June 9- July 12, Instructors: Drs. Susie
Balser and Bruno Pernet
Comparative Embryology June 9- July 12: Drs. Richard Strathmann
and George von Dassow
Evolution and Development of the Metazoans July 14- August 15:
Drs. Billie J. Swalla and Ken M. Halanych
6. Also from Dr. Swalla: I visited Rosaria de Santis’ lab
and gave a week-long workshop at the Stazione Zoologica Anton Dorhn in
Naples, Italy September 2 - 6, 2002: "Development and Evolution of Animal
Body Plans". The students read papers on the development and evolution
of body plans, then presented a research paper of their choosing on the
final day. The presentations were excellent, and showed the large amount
of work that the students had done. It was a great experience for me, and,
I hope, for the students.
The Italian government recently proposed assimilating
the Stazione into the CNR (National Research Council), thus ending the
130 year independence of the Stazione. [See 16 August issue of Science,
p. 1106-1107.] There was an immediate outcry by the scientific community.
Dr. Giorgio Bernardi, President of the Stazione, writes: “Dear Colleagues
and Friends, I am pleased to inform you that the Italian Ministry of Instruction,
University, and Research has decided to maintain the present statute of
independence and autonomy of the Stazione Zoologica Anton Dohrn. The prompt
response to our circular plea was massive and impressive, and this certainly
played a fundamental role in the final decision of the Ministry. Once more,
the scientific community showed its solidarity when general research policies
are involved. Furthermore, the decision of the Ministry reaches us
at a very appropriate time because, as you may know, we will have our working
space more than doubled in a few months (end of February). This means that
we can now seriously consider our research priorities in view of a further
improvement of our activities. Let me, therefore, express my deepest
gratitude on behalf of the entire staff of the Stazione Zoologica for your
crucial support.”
7. Arjan Gittenberger writes: A new Ascidians webpage is under construction on www.ascidians.com . If anyone has any suggestions (e.g. for better identifications of the species), please let me know. Within a few months photographs of ascidians from Palau and the Red Sea will be added. Ph.D. student, National Museum of Natural History, Naturalis, Leiden The Netherlands (gittenberger@yahoo.com).
8. More information about Dr. R.H. Millar from Tracy-Elizabeth
Price, Secretary to Director Rupert Ormond, University Marine Biological
Station, Millport, Isle of Cumbrae, KA28 0EG. tracy.price@millport.gla.ac.uk.
I knew Dr R H Miller for 42 years. He was known
to his friends as Robin. Born in 1916, he served for a time in the British
Army, presumably during WWII but we have no information on this. He did
his M.A. and Ph.D degrees at Glasgow University and joined the staff of
the Scottish Marine Biological Association at its Millport Marine Station
in 1947. Robin's first interest was ascidians and at first he studied the
morphology and life histories of the local species in the Firth of Clyde.
As you know, he became a leading expert on the group and during his career
and much of his retirement he examined and reported on collections sent
to him from all over the world. What most of his ascidian colleagues may
not know is that when Robin came to Millport he also took on responsibility
for a research programme designed to revive oyster fisheries on the West
Coast of Scotland, which continued into the 1960's. He published a number
of papers on this work. He became a fellow of the Royal Society of
Edinburgh in 1955 and was awarded his D.Sc. from Glasgow University in
1963. In 1964 he was appointed Deputy Director of the Millport Marine Station.
In the late 1960's the Scottish Marine Biological Association transferred
its activities from Millport to Oban, on the mainland west coast of Scotland
and Robin was Deputy Director for the new Dunstaffnage Marine Research
Laboratory until he retired in 1978. Robin was a quiet unassuming
man who was always very interesting to talk to. His friends and colleagues
have many happy memories of him. He leaves a wife, Joan, who has been in
poor health for a number of years.
WORK IN PROGRESS
1. Hemichordates of the Pacific Northwest
This is work Shannon completed as an undergraduate at the University
of Washington. Shannon was a Hughes Undergraduate Researcher and a Mary
Gates Scholar in Billie Swalla's lab. Last spring, she received her B.S.
in Biology and B.A. in Zoology at UW. She also received the John and Dorothy
Franco Award for excellent undergraduate research in the Biological Sciences
for this manuscript. She is currently working on ascidian metamorphosis
in the Swalla Lab.
Morphological and Molecular Identification of Saccoglossus
(Hemichordata: Harrimaniidae) in the Pacific Northwest. Shannon E.
Smith, Rob Douglas, Karen Burke da Silva, and Billie J. Swalla. Canadian
J.of Zool. (in press). Zool. Dept., Univ. of Washington, Seattle, WA 98195.
Hemichordates, especially enteropneust worms, have become
increasingly important in phylogenetic studies to test theories of chordate
evolution. However, there are multiple populations of enteropneusts along
the Pacific Northwest Coast of North America that have not been identified.
Here we show that two common Pacific Northwest enteropneust species, Saccoglossus
pusillus and S. bromophenolosus can be distinguished by both
morphological and molecular characters, and we identify several populations
of both species. We compare them to a closely related species, S. kowalevskii,
from the Atlantic Coast of North America. We compile the morphological
characters used to distinguish harrimaniid enteropneusts, and we describe
a new staining method to examine the gill bars and proboscis skeletons
of enteropneusts to aid in identification. Using 18S and 16S ribosomal
DNA sequences, we determine that the range of Saccoglossus pusillus
extends from Southern California, where the worm was first identified,
to Southern Canada. This previously unknown large range shows a dramatic
geographic cline in adult body size, with the smallest populations found
in the south and the largest adults found near Vancouver Island. In contrast,
S.
bromophenolosus may be a Pacific Northwest species that was relatively
recently introduced from the Atlantic.
2. From Gretchen and Charles Lambert: During our 6 week
stay in France during July and August at the Station Biologique in Roscoff,
Brittany, we found numerous specimens of Corella eumyota at two
marinas: Perros Guirec and Camaret-sur-Mer. This species is abundant
and widespread in the southern hemisphere but to our knowledge this is
the first record of this species in the northern hemisphere. Claude Monniot
at the Paris Museum National d’Histoire Naturelle confirmed the identification,
and GL also confirmed it by comparing them with some samples from New Zealand.
We plan to give a short talk about it at the next bioinvasions symposium,
at Scripps next March.
A second surprising find is that all the subtidal Cionas
collected in the NE Pacific from Alaska and British Columbia are not C.
intestinalis as they were originally identified; but are actually C.
savignyi. Cathy and Yogi Carolsfeld from Victoria, BC recently
collected several hundred Ciona from about 12-18m at several sites
off mainland British Columbia, near Sechelt and Bella Bella, and all are
C.
savignyi. Old museum specimens from Alaska (1913) and BC (1937) were
reexamined by Hoshino and Nishikawa (Hoshino, Z.-I. and Nishikawa, T. 1985.
Taxonomic studies of Ciona intestinalis (L.) and its allies. Publ.
Seto
Mar. Biol. Lab. 30: 61-79) and found to be C. savignyi though they
had originally been identified as C. intestinalis. GL has
just finished examining several Ciona specimens in the Friday Harbor
Laboratories voucher collection, all collected in the 1960’s around southern
Vancouver Island, BC, and all are C. savignyi. Thus we urge
our colleagues to be very careful when identifying Ciona species.
The two characters used by Hoshino and Nishikawa are the presence of an
endostylar appendage in C. intestinalis that is absent in C.
savignyi, and the location of the paired pharyngeo-epicardiac openings.
In addition, there is a difference in the follicle cells which is most
obvious in living animals because the follicle cells fall off the eggs
in preserved animals. See Byrd, J. and Lambert, C. C. 2000. Mechanism of
the block to hybridization and selfing between the sympatric ascidians
Ciona intestinalis and Ciona savignyi. Mol. Repro.
Dev. 55: 109-116. This paper contains a photograph of the egg of
these two species. There is a single large refringent droplet in
each follicle cell in C. intestinalis, and several small droplets
in each follicle cell in C. savignyi. There are often other
differences as well. In many areas (though not all), C. intestinalis
has a large red spot at the end of the sperm duct; this is always absent
in C. savignyi.
3. From Patrick Frank, Dept. of Chemistry, Stanford Univ., Stanford, CA 94305-5080 (Frank@ssrl.slac.stanford.edu): In work that includes Dr. Tony De Tomaso at Hopkins Marine Station, and Keith Hodgson and Britt Hedman at SSRL (Stanford Synchrotron Radiation Laboratory), we recently looked at the x-ray absorption spectra of blood cells and whole bodies of Perophora annectens. These colonials are mentioned in "Intertidal Invertebrates of California" (Robert Morris, Donald Abbott and Eugene Hadlerlie) as being particularly rich in blood cell vanadium.We have already characterized the vanadium in blood cells from Ascidia ceratodes and Phallusia nigra, and wanted to look at an organism that is as different as possible from those solitary species. However, to our surprise, when we did the experiment, the vanadium signal was almost non-existent. What we found instead was a very intense iron signal! This was totally unexpected. There is no doubt that the organism was correctly typed. The iron spectroscopically looks more like Fe(III) than Fe(II), and the same spectrum was observed both in whole blood cells and in the whole animal. We hope to look at a sample of P. annectens taken from another location to check this result. If these indeed contain vanadium, then it may be possible that this organism can switch between metals (or that there is a sub-species).
THESIS ABSTRACTS
1. Molecular embryology of a larvacean urochordate, Oikopleura
dioica, and the origin of chordate innovations. Susie Bassham,
Dept. of Biology, Univ. of Oregon, June 2002. Advisor Dr. John Postlethwait,
Institute of Neuroscience. sbassham@oregon.uoregon.edu
Phyla are recognized by unifying characters, some of which
are unique evolutionary innovations, but how do new structures and body
plans evolve? Defining characters of the phylum Chordata include the notochord,
dorsal hollow nerve cord, and post-anal tail. Despite these commonalities,
the chordate subphyla Vertebrata, Cephalochordata, and Urochordata span
a broad range of morphological diversity. Vertebrates are distinguished
from the other chordates by an elaborated brain, paired sense organs, and
a skeleton. Two embryonic tissues, neural crest and placodes, are essential
for these features. It became widely accepted that crest and placodes are
vertebrate innovations because no clear homologues of these tissues or
their derivatives had been observed in other chordates. Further speculation
suggested that acquisition of neural crest and placodes permitted or propelled
the evolution of raptorial vertebrates from a sessile, filter-feeding ancestor.
By comparing ontogenies of extant chordates and their outgroups, we hope
to reconstruct the timing and mechanism of the origin of chordate novelties.
Within the most basal chordate lineage, Urochordata, larvaceans
uniquely allow us to analyze development of adult characters in a chordate
body plan that does not become reconfigured by sweeping metamorphic events.
This dissertation examines the evolutionary history of two chordate innovations,
notochord and placodes. I present DNA sequences and expression patterns
for larvacean homologues of several vertebrate genes important in notochord
and placode development: T (Brachyury), Pitx, Eya,
and members of the Pax and Six gene families. Larvacean T
is expressed in notochord, but also in posterior endoderm. Because deuterostome
and protostome outgroups display a similar pattern, chordate T may
have a conserved role in endoderm patterning more ancient than its role
in the notochord. I also show that several genes important for the development
of a subset of vertebrate placodes are expressed in the developing ciliary
funnel and ventral organ in larvaceans. Ultrastructure and topography had
previously suggested that these organs are candidate homologues of pituitary
and olfactory placodes. My results are consistent with an origin of these
placodes in the common ancestor of modern chordates, predating the evolution
of vertebrates.
2. Microcosmus squamiger, a solitary ascidian introduced to
southern California harbors and marinas: salinity tolerance and phylogenetic
analysis. Andrew Lowe, M.S. thesis, , Dept. of Biol. Sci., Calif. State
Univ. Fullerton, Fullerton, CA 92834. Advisor Dr. Roger Seapy.
Current address: Dept. of Biol., Calif. State Univ., San Marcos, CA
92096 alowe@csusm.edu
The non-indigenous ascidian Microcosmus squamiger
has become a dominant fouling organism in sheltered portions of southern
California harbors where it appears to be increasing in abundance at the
expense of Molgula manhattensis, a common estuarine ascidian [editors'
comment: also non-indigenous]. I have compared mortality rates of
M.
squamiger and M. manhattensis based on laboratory experiments
that tested the tolerances to salinities ranging from 150/00
to 330/00. Both species survived
at 330/00 and 300/00,
but at 250/00 the average percent survival
of M. squamiger was much higher (80%) than that of M. manhattensis
(50%). This difference was more pronounced at 200/00
(77% and 20%, respectively) and 150/00
(60% and 0%, respectively). These results support the hypothesis
that differential survival allows
M. squamiger to have an advantage
needed to claim limited space over M. manhattensis.
In order to examine patterns of M. squamiger introduction
into southern California and subsequent dispersal among southern California
harbors, mitochondrial DNA sequences were analyzed to assess genetic variation
at a series of sampling locations. The California grouping of sequences
is paraphyletic with the Mediterranean sequences nested within it.
Furthermore, these data suggest that Microcosmus squamiger was introduced
from Australia to southern California, then later introduced from California
to Spain. The average within population genetic diversity (Pi) was
higher (1.28) for southern California populations than either the Spanish
(0.61) or Queensland (0.50) populations, possibly suggesting multiple introductions.
For the southern California sites, diversity between populations (PiT)
was lowest (0.88) for Bahia Point and Mission Bay, suggesting high levels
of gene flow. Within population diversity (Pi) was highest at Oceanside
and Long Beach (1.91).
MEETINGS ABSTRACTS
1. 5th International Larval Biology Meeting, Univ. of Vigo, Spain, Sept. 15-20, 2002
a. Intraspecific variation in larval size affects the length of the
planktonic period in lecithotrophic larvae. Marshall DJ, Keough MJ,
Dept. of Zool., Univ. of Melbourne, Parkville 3052, Australia d.marshall@zoology.unimelb.edu.au
For many species of marine invertebrate, variability in
larval settlement behaviour appears to be the rule rather than the exception.
This variability is important as it has the potential to affect larval
dispersal. Despite the ubiquity and importance of this variability, relatively
few sources of variation in larval settlement behaviour have been identified.
One important factor that can affect larval settlement behaviour is the
nutritional state of larvae. For a number of non-feeding larvae, as energetic
reserves run low, larvae become less discriminating in their "choice" of
settlement substrate, i.e. more desperate to settle. We tested whether
variation in larval size (and presumably nutritional reserves) also affects
the settlement behaviour of three species of colonial marine invertebrate
larvae, the bryozoans Bugula neritina and Watersipora subtorquata
and the ascidian Diplosoma listerianum. For all three species, larger
larvae delayed settlement for longer in the absence of settlement cues,
and settlement of Bugula neritina larvae was accelerated by the
presence of settlement cues, independently of larval size. In the field,
larger Watersipora larvae also took longer to settle than smaller
larvae and were more discriminating towards settlement surfaces. These
differences in settlement time are likely to result in differences the
distance that larvae disperse in the field. We suggest that species that
produce lecithotrophic larvae can indirectly affect the dispersal potential
of their offspring by manipulating larval size and thus larval desperation.
b. Larval activity levels and prolonged swimming affect post-larval
performance in the colonial ascidian Diplosoma listerianum.
Marshall DJ, Pechenik JA, Keough MJ. [also presented at the temperate reef
meeting, New Zealand.
It is becoming widely recognized that extending the larval
period of marine invertebrates, especially of species with non-feeding
larvae, can affect post-larval performance. As these carry-over effects
are presumed to be caused by the depletion of larval energy reserves, we
predicted that the level of larval activity would also affect post-larval
performance. This prediction was tested with the cosmopolitan colonial
ascidian Diplosoma listerianum, in field experiments in southern
Australia. Diplosoma larvae, brooded in the parent colony, are competent
to settle immediately after spawning, and remain competent to metamorphose
for >15 h. Some larvae were induced to metamorphose 0-6 h after release
whilst others were induced to swim actively by alternating light and dark
periods for up to 3 h prior to metamorphosis. Juvenile colonies were then
transplanted to a subtidal field site in Port Phillip Bay and left to grow
for up to 3 weeks. Extending the larval period and increasing the amount
of swimming both produced carryover effects on post-larval performance.
Colonies survived at different rates among experiments, but larval experience
did not affect survival rates. Delays in metamorphosis and increased swimming
activity did, however, reduce colony growth rates dramatically, resulting
in 50% fewer zooids per colony. Moreover, such colonies produced initial
zooids with smaller feeding structures, with the width of branchial baskets
reduced by 10-15%. These differences in branchial basket size persisted
and were still apparent in newly budded zooids 3 weeks after metamorphosis.
Our results suggest that, for Diplosoma, larval maintenance, swimming,
and metamorphosis all use energy from a common pool, and increases in the
allocation to maintenance or swimming come at the expense of post-larval
performance. [Soon to be published in Marine Ecology Progress Series]
c. Relationships of defence mechanisms of larvae and adults of colonial
ascidians: patterns of palatability and toxicity. I. Tarjuelo,
S. Lopez-Legentil, M. Codina and X. Turon, Dept. of Animal Biology (Invertebrates),
Fac. of Biol., Univ. of Barcelona, 645 Diagonal Ave., 08028 Barcelona,
Spain. xaviert@porthos.bio.ub.es
We studied the defence patterns of larvae and adults of
six species of colonial ascidians from the Mediterranean Sea. We tested
palatability with common sympatric predators (fish and crustaceans). The
tests were performed separately for the larvae and for the main compartments
of the adults (zooids and tunic). For the species that proved unpalatable,
tests were repeated with chemical extracts. We also tested toxicity with
the Microtox method. Total energy content, amount of inorganic material
and pH were analysed for all compartments. We looked for patterns of defence
among species, and for relationships of adult/larval palatability, of toxicity/palatability,
pH/palatability and food quality/palatability. Overall, we found a high
variability among species, compartments and predators, but unpalatability
was found in all species in at least one test. Those species with low per
zooid fecundity and large larvae (Cystodytes dellechiajei, Polysysncraton
lacazei, Diplosoma spongiforme and Pseudodistoma crucigaster)
had larvae that were unpalatable to at least two of the predators, while
larvae of the two species with higher fecundity and smaller larvae (Clavelina
lepadiformis and Ecteinascidia herdmanni) were the most palatable.
There was no relationship between adult and larval palatability. Tunic
material was the least palatable in general, and zooid material the most.
Only one of the species studied had acidic tunic. Toxicity was in general
low and not related to palatability, while energy content was positively
related to the latter. Tests with extracts substantiated a chemical basis
for unpalatability in only a few cases, and there was a pattern of increased
palatability of tissues with higher energy content and lower amount of
structural material. We conclude that the defence strategies of colonial
ascidians are highly variable among species (even of the same family),
and that allocation to defence varies between compartments and between
ontogenetic states (larvae or adult). The pattern found indicates a higher
protection against larval predation in species with low fecundity producing
large and costly larvae.
2. Sixth International Conference of Systematic and Evolutionary Biology in Patras, Greece. September 9-16, 2002
Evolution of the chordates: worms or squirts? When, why and how?
Billie J. Swalla, Zool. Dept., Univ. of Washington, Seattle, WA 98195.
Presented in the Symposium "Life, the Universe and Everything" bjswalla@u.washington.edu
The Deuterostomia are a monophyletic group of animals
that diverged from the Ecdysozoa and Lophotrochozoa some time before the
Cambrian period, as all of the four major clades of deuterostomes are present
in the Cambrian fauna. Molecular clocks provide varying estimates of the
period of time in which this radiation occurred, from shortly before the
Cambrian explosion to many millions of years prior to the appearance of
these groups in the fossil record. The problems inherent in molecular clocks
will be discussed and evaluated. One of the most debated questions about
chordate ancestry is whether the ancestral group was sessile or a motile
worm. Neither cladistics nor the fossil record allows unequivocal answers,
so we have turned to developmental gene expression to examine the evolution
of chordates. A strictly cladistic approach will be contrasted with an
analysis that considers evolutionary developmental processes. The importance
of distinguishing solitary and colonial species when examining body plan
evolution will be highlighted. Using developmental characters to compare
the four major deuterostome groups, echinoderms, hemichordates, urochordates
and vertebrates, we will show that echinoderm and urochordate adult body
plans appear to have been highly derived at the time of their divergences
from the other major clades. Using a total data approach, we will show
that the deuterostome ancestor was likely to have been a motile, benthic,
filter-feeding worm with gill slits, an organized skeleton, coelom, and
perhaps even neural crest cells. Ongoing experiments to test these hypotheses
will be presented and critiqued.
3. European Life Scientist Organisation ELSO 2002 meeting, Nice, France, 29 June - 3 July 2002 (previously European Cell Biology Organisation, ECBO).
Cell-mediated immune responses in the colonial ascidian Botryllus
schlosseri: the role of morula cells. Ballarin L., Cima F., Sabbadin
A., Dept. of Biol., Univ. of Padova, Italy. ballarin@civ.bio.unipd.it
The mulberry-shaped vacuolated haemocytes called morula
cells (MC) are a common cell-type in the ascidian blood. In the compound
ascidian Botryllus schlosseri, their number ranging from 20 to 60%
of the total haemocyte number. This fits with the important role of MC
in immunomodulation which results from the observation that they can produce
IL-1-alpha- and TNF-alpha-like molecules when haemocyte cultures are incubated
with the microbial polysaccharide mannan or the protein kinase C activator
phorbol myristate acetate. Besides, MC are the effectors of the rejection
reaction between contacting, genetically incompatible colonies which represents
the typical outcome of colony specificity. In the early stages of this
reaction, MC crowd inside the outgrowths of the marginal vessel known as
ampullae, which contact the opposite colony. Then, they degranulate and
release their vacuolar content (mainly phenoloxidase and its polyphenol
substrata), cross the fenestrated epithelium of the ampullar tips and reach
the tunic where they contribute to the formation of the necrotic masses
which characterise the rejection reaction. Degranulation of MC is preceded
by their acquisition of immunoresponsiveness to anti-human-IL-1-alpha which
indicate a role of this cytokine-like molecule in the rejection reaction.
In addition, previous reports, showing an increase in phagocytosis by ascidian
phagocytes when haemocytes were incubated in the presence of MC extracts,
suggest the involvement of MC in the process through a sort of cell cooperation
mediated by the production of soluble factors. In our opinion these factors
correspond to cytokine-like molecules synthesised and released by MC upon
their recognition of foreign molecules. Our hypothesis is supported by
the observation that anti-human-IL-1-alpha antibodies significantly inhibit
the ACTH-induced ingestion of yeast cells by Botryllus phagocytes.
4. 37th European Marine Biology Symposium, Reykjavik, Iceland, 5-9 August 2002
An Atlantic clade of Clavelina lepadiformis (Ascidiacea) may
have recently colonised Mediterranean marinas by ship transport.
*I. Tarjuelo, 1D. Posada, 1K.
A. Crandall, **M. Pascual, S. Duran & *X. Turon. *Dept. of Animal
Biol. and **Dept. of Genetics, Fac. of Biol., Univ. of Barcelona. 645,
Diagonal Ave. 08028 Barcelona. Spain. 1Dept. of Zool.,
Brigham Young Univ., Provo. UT 84602-5255 xaviert@porthos.bio.ub.es
We studied the genetic structure of populations of the
Atlanto-Mediterranean ascidian Clavelina lepadiformis. A 500 bp
segment of the COI mitochondrial gene was sequenced in Mediterranean and
Atlantic populations from inside and outside harbours and marinas (interior
and exterior form, respectively). We found a marked genetic differentiation
between C. lepadiformis inhabiting the Mediterranean harbours and
those from the Mediterranean rocky littoral, with a genetic divergence
of 5%. Gene flow values among these forms were unappreciable and of the
same order as the values found among both forms and other congeneric species.
The lack of gene flow and the genetic divergence suggests that the interior
and exterior forms of Mediterranean C. lepadiformis are in fact
cryptic species. Levels of gene flow were higher among interior habitats
than among exterior habitats, a pattern likely maintained by genetic exchange
through ships. When compared with four Atlantic populations (one inside
and three outside harbours), we found that these were closely related to
the interior clade in the Mediterranean. We put forward the hypothesis
that both clades evolved separately at both seas, and that a recent colonisation
of Mediterranean marinas from the Atlantic has occurred via ship-hull transport.
5. The 10th Pacific Congress on Marine Science and Technology (PACON2002), July 21-26, 2002, Chiba, Japan.
Accumulation and reduction of vanadium by ascidians. H.
Michibata, Mukaishima Mar. Biol. Sta., Hiroshima Univ., Mukaishima-cho,
Hiroshima 722, Japan (hmichi@sci.hiroshima-u.ac.jp)
Ascidians, so-called seasquirts, are known to accumulate
high levels of vanadium. The highest concentration of vanadium, 350 mM,
was found in the blood cells of Ascidia gemmata belonging to the
suborder Phlebobranchia. This concentration is 107 times higher than that
in seawater. Vanadium accumulated in the blood cells is reduced to V(III)
via V(IV) and stored in vacuoles of vanadocytes (vanadium-containing blood
cells). The contents of vacuoles are maintained in an extremely low pH
of 1.9 by vacuolar-type H+-ATPase. Recently, we have found out at least
two types of vanadium-binding protein, 12.5 kDa and 15 kDa, and cloned
cDNAs encoding them. Both novel proteins, designated as Vanabins, have
been disclosed to consist of about 120 amino acids in which the content
of cysteine residues is very high and occurrence of cysteine residues at
regular intervals is characteristic and common in both novel proteins.
Recombinant Vanabin was found to bind about 10 to 20 atoms of vanadium
and its binding constant is 10-6 to 10-7M, which might have a clue to resolve
the mechanism of vanadium accumulation. Concerning the reduction of vanadium
in vanadocytes, we have localized four enzymes involved in the pentose
phosphate pathway that is known to produce a reducing agent, NADPH. In
fact, NADPH was revealed to conjugate the reduction of V(V) to V(IV) in
vitro. Furthermore, the other types of protein such as a metal-ATPase and
cDNAs involved in the accumulation and reduction of vanadium will be reported.
6. The 73rd annual meeting of the Zool. Soc. of Japan, Kanazawa, Japan, Sept. 24-27, 2002.
The ultrastructure of the sensory cells associated with a branchial
tentacular tunic in the ascidian, Polyandrocarpa misakiensis.
H.Koyama, Coll. Nurs., Yokohama City Univ., Yokohama. hkoyama@med.yokohama-cu.ac.jp
In Polyandrocarpa misakiensis, I studied the ultrastructure
of the ciliated intraepithelial sensory cells in the basal part of branchial
tentacles. The pear-shaped sensory cells form small clusters, and are supported
by thickened epithelial cells of the descending or ascending epithelium
of siphons. The supporting epithelial cells cover the sensory cells except
for their apical part, which has microvilli surrounding a cilium. The basal
cytoplasm of the sensory cells is dense with rough endoplasmic reticulum,
mitochondria, lipid droplets, and dense bodies. The apical cytoplasm, about
1/3 of the entire cell height, is electron-translucent, and has a few organelles.
Since some of the sensory cells have a basal process with the ultrastructural
features of an axon, these cells are regarded as primary sensory neurons,
like many other sensory cells of protochordates. The apicolateral parts
of the sensory cells are joined together by two types of junctions (gap
junctions? and adherent junctions). The supporting cells and sensory cells
are connected by adherent junctions. Certain sensory cells are coupled
to what seem to be neurosecretory cells.
7. American Society for Cell Biology annual meeting, San Francisco CA, Dec. 14-18, 2002.
(a) The role of integrins in sperm activation in the tunicate,
Ascidia ceratodes. Janice Soratorio and Robert A. Koch.
California State University Fullerton, Fullerton, CA rkoch@fullerton.edu
Mitochondrial translocation is an early event during ascidian
fertilization in which the sperm mitochondrion binds to the egg outer surface,
undergoes an actin:myosin-dependent translocation from the head of the
sperm down to the tail. Due to integrin’s known association with actin
filaments, we hypothesize that integrins mediate adhesion of the sperm
cell to the egg outer surface and signal the formation of focal adhesion-like
complexes (FC). Thus, we predict that one or more integrin family members
will span the membrane and interact with FC-specific proteins in the cytosol,
e.g., talin, paxillin and FAK. Using anti-integrin alpha Hr1 and beta Hr
prepared against the ascidian Halocynthia roretzi protein and anti-integrin
beta 1, integrins were detected on the mitochondrial region of ascidian
sperm heads. Integrin beta 2, beta 3 and beta 4 were not detected in the
sperm. The head also labeled positively for the cytoskeletal proteins,
talin, paxillin and FAK, a tyrosine kinase that is known to associate with
integrins in focal adhesion sites. It is known that FC formation
depends on integrin receptor occupancy and clustering. To study the latter,
sperm were exposed to an anti-integrin antibody known to induce integrin
clustering, mAb 12G10. We found that mAb 12G10 triggered sperm activation
in a manner similar to positive controls. To determine integrin’s
function during fertilization, dose-dependent inhibition by echistatin
was tested. In the presence of echistatin (1.5 and 15 µM),
fertilization was inhibited and decreased to 60% and 47%, respectively.
These data demonstrate: (1) the presence of integrins on the ascidian sperm
cell surface, (2) the presence of protein characteristic of focal complexes,
and (3) suggest the importance of integrins as sperm-surface egg receptors
in ascidian fertilization. (Funded by NIH R25GM56820, R25GM56625
and R15HD36500).
(b) Cell polarity and asymmetric divisions in ascidian and
sea urchin embryos. G. Prulière, S. Patalano, C. Sardet,
J. M. Chenevert; Laboratoire de biologie du développement, UMR 7009-CNRS-Université
Paris 6, Villefranche sur Mer, France
The cortical sets of proteins PAR3-PAR6-aPKC-CDC42 and
PAR1 control many events crucial for the establishment of cell polarity
during oogenesis or development. We are exploring the roles of these complexes
in ascidian and sea urchin embryos. In these animals starting at the 8-16
cell stage series of asymmetric cell divisions produce large and small
cells (micromeres) and asymmetrically segregate determinants. At the 16
cell stage, in the sea urchin 4 vegetal blastomeres and in the ascidian
2 posterior blastomeres are generated. We have cloned the cDNAs encoding
cell polarity proteins and find that PAR1, PAR6, CDC42, and aPKC are present
as maternal transcripts in both sea urchins and ascidians remarkable feature
of the ascidian system is the presence of a macroscopic structure responsible
for the asymmetric divisions, the Centrosome Attracting Body ("CAB").
Labellings with heterologous antibodies indicate that PAR-3 protein is
present in the ascidian CAB and also in the vegetal cortex of sea urchin
micromeres. In ascidian embryos, aPKC protein colocalizes with PAR3 enriched
in the CAB and is present on the cortex of all blastomeres. We are generating
antibodies and dominant negative tools to determine the localization and
function of these and other proteins involved in the definition of cell
polarity. In addition we have produced an antibody to a 100kD ascidian
protein which specifically recognizes the CAB and the sea urchin vegetal
cortex. We are currently developing an in vitro assay for cell polarity
using peeled cortices which retain microtubule attachment properties.Our
results suggest that the cell polarity complexes Par-3/Par-1 participate
in the establishment of the embryo polarity in these two experimentally
tractable models and that the sea urchin vegetal cortex contains a structure
similar to the CAB responsible for attraction of a centrosome.
(c) Polarization of the egg cortex and mRNA localization during
early development of ascidians. 1C. Sardet,
1F.
Prodon, 2H. Nishida, 2K. Sawada
; 1Station zoologique, Villefranche sur mer, France;
2TiTech, Tokyo, Japan.
The ascidian egg cortex is involved in calcium signalling,
contractions, translocations subcellular domains, cleavages and the localisation
of maternal determinants. The periphery of the mature oocyte is a polarized
basket made of 2 juxtaposed domains: a mitochondria rich sub-cortical domain
(myoplasm) and an ER rich cortical domain (cER)(1). These two domains are
distributed as a gradient along the animal-vegetal axis (a-v). A class
of cortical maternal mRNAs (postplasmic RNAs) including the muscle determinant
macho1 are initially polarized along the (a-v) axis (2). These move vegetally
and then posteriorly after fertilization to accumulate in the cortex of
the 2 vegetal posterior blastomeres at the 8 cell stage. Postplasmic RNAs
are concentrated in a cortical ER-rich macromolecular structure called
the Centrosome Attracting Body (CAB)(2). The CAB is responsible for three
successive asymmetric cleavages (8-64 cell stages) giving primary muscle
cells and endodermal cells(2). Postplasmic RNAs can be isolated with
the cortex made of the membrane to which a network of microfilaments, a
network of cER and microtubules adhere (3). High resolution fluorescent
in situ hybridization indicates that two postplasmic RNAs, macho-1 and
Hr PEM are associated with the cortical rough ER network before fertilization,
concentrate in the vegetal cortex with the cER after fertilization and
accumulate in the CAB as patches at the 8 cell stage together with the
cortical ER network. In conclusion, the polarized cER network organized
along an (a-v) gradient in the egg is a major precursor of the CAB and
plays an important role in the localization and segregation of maternal
mRNAs determinants (download bioclip “Polarity inside the egg cortex” at
www. bioclips.com) (1) Roegiers et al., 1999, Development, 126:3101-17;
(2) Nishida, 2002, Int Rev Cytol 217:227-76 (3) Sardet, 2002, Dev.Biol.
241:1-23
7. 3rd Intl. Marine Bioinvasions Conference, La Jolla, California March 16-19, 2003.
a) Trans-hemisphere invasion of the south-temperate and subantarctic
ascidian Corella eumyota Traustedt, 1882, into two harbors in Brittany,
France. Lambert, G., Univ. of Washington Friday Harbor Laboratories,
Friday Harbor, WA. Monniot, C. and F., Mus. Nat. d’Hist. Nat., Biologie
des Invertebres marins, 55 rue Buffon, 75005 Paris, France; and Lambert,C.C.,
Univ. of Washington Friday Harbor Laboratories, Friday Harbor, WA.
Corella parallelogramma is the only Corella
species recorded from the English Channel region of France. However, during
July and August 2002 we found numerous large clumps of C. eumyota
on ropes and floats at the marinas at Perros Guirec and Camaret-sur-Mer
in western Brittany on the English Channel. Our identifications are based
on a careful comparison with specimens from southern New Zealand and South
Africa of the adult and egg morphology, and the fact that it is a brooder.
Several thousand embryos are ovulated directly into the peribranchial cavity
where they stick together in a cohesive gelatinous mass. The tadpoles are
retained for several hours after hatching and are not released until they
are competent to settle. Larval life outside the adult is therefore very
short, perhaps only a few minutes; as a result the larvae settle near or
on the adults and large heavy clumps result. The individuals are very tightly
cemented together and often impossible to separate without tearing the
tunics. C. eumyota’s previously known range has been limited to
the southern hemisphere, where it is abundant and widespread in south temperate,
subantarctic, and Antarctic waters: South Africa, S. America, south Australia,
Tasmania, and New Zealand from Aukland to the south tip of the south island.
This species was not present 5 years ago (our last visit to Brittany) at
the 2 marinas where we found it abundantly this year. It has the potential
to become a serious pest for the mussel culture industry in Normandy. We
do not know how widespread it is in Europe but colleagues in the UK have
not seen it. This may be the first record of a southern to northern hemisphere
range extension for an ascidian, although several species are known to
have been transported from Europe to the southern hemisphere.
b) Exotic organisms in southern California bays and harbors.
Cohen, A.N., San Francisco Estuary Institute, Oakland, CA (acohen@sfei.org)
and 11 co-authors.
In recent decades, the world has witnessed an array of
harmful invasions by exotic marine organisms. To provide the public and
policymakers with better information on the status of exotic species in
Southern California waters, the California Department of Fish and Game
and the California State Water Resources Control Board, with supplemental
funding from the National Fish and Wildlife Foundation, commissioned a
Rapid Assessment Survey of selected sheltered waters between San Diego
and Oxnard in the summer of 2000. The primary objective of the survey was
to assess the status of exotic invasions within certain habitat types in
the region. Secondary objectives included obtaining data for comparisons
between habitats and regions and for comparisons with past surveys; obtaining
baseline data for future assessments of changes in invasion status and
the effectiveness of prevention or control efforts; detecting new invasions
and documenting significant range extensions; and identifying new species.
Twenty-two primary sampling sites and three secondary sites were selected
to represent the three major commercial port areas in southern California,
important marina areas and lagoon sites. Sampling was primarily of dock
fouling along with adjacent soft-bottom benthos, nearby intertidal sites,
and selected subtidal lagoon habitats, using a variety of manual techniques.
Sixty-seven of the species collected were identified as exotic, with an
average of 16.7 exotic species collected at each site. These included representatives
from two algal divisions and seven invertebrate phyla. Ascidians were especially
well-represented (15 exotic species) and widely occurring, and certain
polychaetes, bivalves, isopods and amphipods also occurred widely.
c) "Le genie humain reunit les oceans": the movement of species
between the tropical eastern Pacific and western Atlantic via the Panama
Canal. Cohen, A.N., San Francisco Estuary Institute, Oakland,
CA, (acohen@sfei.org) and 10 co-authors.
The Panama Canal was completed in 1914, enabling ships
to pass between the Atlantic and Pacific Oceans with typical transit times
of less than half a day. The Canal may have affected the anthropogenic
dispersal of marine organisms in several ways: by allowing transfers of
organisms between the Eastern Tropical Pacific and Western Tropical Atlantic
regions; by enabling more transfers or more rapid transfers between other
parts of the world; by affecting the size and the operation of ports and
other ship facilities located near either end of the Canal; and by limiting
the size of a substantial part of the world's cargo fleet to "Panamax"
ships. Possible mechanisms for the movement of marine organisms through
the Canal include gradual dispersal through the locks and waters of the
Canal over more than one organism's lifetime; the migration of fish or
other strong swimmers, along with their internal or external parasites,
through the Canal in less than one host organism's lifetime; and the transport
of organisms in external hull fouling, in boreholes or crevices in wooden
hulls, and in the ballast tanks or other components of ships' seawater
systems in under a day. To assess the number of species moved through the
Canal we reviewed records of species in both tropical regions on either
side of the Canal, and conducted a Rapid Assessment Survey of selected
habitats near the Pacific and Atlantic ends of the Canal in the spring
of 2002.
NEW PUBLICATIONS
Akanuma, T., Hori, S., Darras, S. and Nishida, H. 2002. Notch signaling is involved in nervous system formation in ascidian embryos. Dev. Genes Evol. 212: 459-472.
Anand, T. P. and Edward, J. K. P. 2002. Antimicrobial activity in the tissue extracts of five species of cowries Cypraea spp. (Mollusca : Gastropoda) and an ascidian Didemnum psammathodes (Tunicata : Didemnidae). Indian J. Mar. Sci. 31: 239-242.
Appleton, D. R., Page, M. J., Lambert, G., Berridge, M. J. and Copp, B. R. 2002. Kottamides A-D: novel bioactive imidazolone-containing alkaloids from the New Zealand ascidian Pycnoclavella kottae. J. Org. Chem. 67: 5402-5404.
Appleton, D. R., Pearce, A. N., Lambert, G., Babcock, R. C. and Copp, B. R. 2002. Isodiplamine, cystodytin K and lissoclinidine: novel bioactive alkaloids from the New Zealand ascidian Lissoclinum notti. Tetrahedron 58: 9779-9783.
Arai, M. and al., e. 2002. Mutual and directional allogeneic cytotoxic reaction of hemocytes in the solitary ascidian Halocynthia roretzi revealed by one-step quantitative fluorimetric assay. Zool. Sci. 19: 263-270.
Astorga, M., Guinez, R., Ortiz, J. C. and Castilla, J. C. 2002. Phenotypic and genetic variation in tunicate Pyura praeputialis (Heller, 1878) in the northern sac of the Antofagasta Bay. Revista Chilena de Historia Natural 75: 515-526.
Aune, G. J., Furuta, T. and Pommier, Y. 2002. Ecteinascidin 743: a novel anticancer drug with a unique mechanism of action. Anti-cancer Drugs 13: 545-555.
Baldock, J. and Bishop, J. D. D. 2001. Occurrence of the non-native ascidian Perophora japonica in the Fleet, southern England. J. Mar. Biol. Assoc. UK 81: 1067.
Ballarin, L., Cima, F., Floreani, M. and Sabbadin, A. 2002. Oxidative stress induces cytotoxicity during rejection reaction in the compound ascidian Botryllus schlosseri. Comp. Biochem. Physiol. C 133: 411–418.
Ballaro, B. and Reas, P. G. 2002. Rotating spiral waves in fertilized ascidian eggs. Riv. Biol. 95: 101-114.
Bates, W. R. 2002. The phylogenetic significance of maximum direct development in the ascidian, Molgula pacifica. Invert. Repro. & Dev. 41: 185-192.
Boorman, C. J. and Shimeld, S. M. 2002. Pitx homeobox genes in Ciona and amphioxus show left-right asymmetry is a conserved chordate character and define the ascidian adenohypophysis. Evol. Dev. 4: 354-365.
Brookfield, M. E. 1988. Where are all the fossil sea squirts? Micropaleontology 34: 277-283.
Caiqing, M., Douek, J. and Rinkevich, B. 2002. Development of a PCR strategy for thraustochytrid identification on 18s rDNA sequence. Mar. Biol. 140: 883-889.
de Caralt, S., López-Legentil, S., Tarjuelo, I., Uriz, M. J. and Turon, X. 2002. Contrasting biological traits of Clavelina lepadiformis (Ascidiacea) populations from inside and outside harbours in the western Mediterranean. Mar. Ecol. Prog. Ser. 244: 125–137.
Carballo, J. L. and Naranjo, S. 2002. Environmental assessment of a large industrial marine complex based on a community of benthic filter feeders. Mar. Pollution Bull. 44: 605-610.
Castilla, J. C., Collins, A. G., Meyer, C. P., Guinez, R. and Lindberg, D. R. 2002. Recent introduction of the dominant tunicate, Pyura praeputialis (Urochordata, Pyuridae) to Antofagasta, Chile. Mol. Ecol. 11: 1579-1584.
Cavalcante, M. C., de Andrade, L. R., Du Bocage Santos-Pinto, C., Straus, A. H., Takahashi, H. K., Allodi, S. and Pavao, M. S. 2002. Colocalization of heparin and histamine in the intracellular granules of test cells from the invertebrate Styela plicata (Chordata-Tunicata). J. Struct. Biol. 137: 313-321.
Cerda, M. and Castilla, J. C. 2001. Diversity and biomass of macro-invertebrates in intertidal matrices of the tunicate Pyura praeputialis (Heller, 1878) in the Bay of Antofagasta, Chile [in Spanish; English abstract]. Revista Chilena de Historia Natural 74: 841-853.
Chambon, J. P., Soule, J., Pomies, P., Fort, P., Sahuquet, A., Alexandre, D., Mangeat, P. H. and Baghdiguian, S. 2002. Tail regression in Ciona intestinalis (Prochordate) involves a Caspase- dependent apoptosis event associated with ERK activation. Development 129: 3105-3114.
Christiaen, L., Burighel, P., Smith, W. C., Vernier, P., Bourrat, F. and Joly, J.-S. 2002. Pitx genes in tunicates provide new molecular insight into the evolutionary origin of pituitary. Gene 287: 107-113.
Ciancio, A., Scippa, S. and Izzo, C. 1999. Ultrastructure of vegetative and sporulation stages of Haplosporidium ascidiarum from the ascidian Ciona intestinalis L. Europ. J. Protistol. 35: 175-182.
Cima, F., Brena, C. and Burighel, P. 2002. Multifarious activities of gut epithelium in an appendicularian (Tunicata). Mar. Biol. 141: 479-490.
Cima, F., Dominici, D., Ballarin, L. and Burighel, P. 2002. Influence of TBT on activity of detoxifying enzymes from haemocytes of a colonial ascidian. Fresenius Environ. Bull. 11: 573-577.
Davidson, B. and Swalla, B. J. 2002. A molecular analysis of ascidian metamorphosis reveals elements of an innate immune response. Development 129: 4739-4751.
Davis, R. A., Aalbersberg, W., Meo, S., Rocha, R. M. and Ireland, C. M. 2002. The isolation and synthesis of polyandrocarpamines a and b. Two new 2-aminoimidazolone compounds from the Fijian ascidian, Polyandrocarpa sp. Tetrahedron 58: 3263-3269.
Devine, C., Hinman, V. F. and Degnan, B. M. 2002. Evolution and developmental expression of nuclear receptor genes in the ascidian Herdmania. Intl. J. Dev. Biol. 46: 687-692.
Di Gregorio, A. and Levine, M. 2002. Analyzing gene regulation in ascidian embryos: new tools for new perspectives. Differentiation 70: 132-139.
Dumollard, R., Carroll, J., Dupont, G. and Sardet, C. 2002. Calcium wave pacemakers in eggs. J. Cell Sci. 115: 3557-3564.
Erba, E., Bassano, L., Di Liberti, G., Muradore, I., Chiorino, G., Ubezio, P., Vignati, S., Codegoni, A., Desiderio, M. A., Faircloth, G., Jimeno, J. and D'-Incalci, M. 2002. Cell cycle phase perturbations and apoptosis in tumour cells induced by aplidine. British J. Cancer 86: 1510-1517.
Etani, K. and Nishikata, T. 2002. Novel G-protein-coupled receptor gene expressed specifically in the entire neural tube of the ascidian Ciona intestinalis. Dev. Genes Evol. 212: 447-451.
Ferrier, D. E. and Shimeld, S. M. 2002. Evolution of developmental mechanisms. Genome Biol. 3: 4020.
Garrido, L., Zubia, E., Ortega, M. J. and Salva, J. 2002. New meroterpenoids from the ascidian Aplidium conicum. J. Nat. Prod. 65: 1328-1331.
Gibson, D. M. and Paffenhoffer, G. A. 2002. Asexual reproduction of the doliolid, Dolioletta gegenbauri Uljanin (Tunicata, Thaliacea). J. Plankton Res. 24: 703-712.
Goodwin, T. J. and Poulter, R. T. 2002. A group of deuterostome Ty3/ gypsy-like retrotransposons with Ty1/ copia-like pol-domain orders. Mol. Genet. Genomics 267: 481-491.
Green, K. M., Russell, B. D., Clark, R. J., Jones, M. K., Garson, M. J., Skilleter, G. A. and Degnan, B. M. 2002. A sponge allelochemical induces ascidian settlement but inhibits metamorphosis. Mar. Biol. 140: 355-363.
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im Gefolge der Befruchtung. Mikrokosmos 82: 129-135.
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Groepler, W. 2002. Ovulation in Diplosoma (Tunicata, Ascidiacea, Didemnidae): a light microscopical study. Helgoland Mar. Res. 52: 102-111.
Hemmi, H., Yoshida, T., Kumazaki, T., Nemoto, N., Hasegawa, J., Nishioka, F., Kyogoku, Y., Yokosawa, H. and Kobayashi, Y. 2002. Solution structure of ascidian trypsin inhibitor determined by nuclear magnetic resonance spectroscopy. Biochemistry 41: 10657-10664.
Hirose, E., Shirae, M. and Saito, Y. 2002. Colony specificity in the xenogeneic combinations among four Botrylloides species (Urochordata, Ascidiacea). Zool. Sci. 19: 747-753.
Holloway, M. G. and Connell, S. D. 2002. Why do floating structures create novel habitats for subtidal epibiota? Mar. Ecol. Prog. Ser. 235: 43-52.
Hudson, C., Darras, S., Caillol, D., Yasuo, H. and Lemaire, P. 2003. A conserved role for the MEK signalling pathway in neural tissue specification and posteriorisation in the invertebrate chordate, the ascidian Ciona intestinalis. Development 130: 147-159.
Imai, K. S., Satoh, N. and Satou, Y. 2002. An essential role of a FoxD gene in notochord induction in Ciona embryos. Development 129: 3441-3453.
Imai, K. S., Satou, Y. and Satoh, N. 2002. Multiple functions of a Zic-like gene in the differentiation of notochord, central nervous system and muscle in Ciona savignyi embryos. Development 129: 2723-2732.
Inaba, K., Padma, P., Satouh, Y., Shin, I. T., Kohara, Y., Satoh, N. and Satou, Y. 2002. EST analysis of gene expression in testis of the ascidian Ciona intestinalis. Mol. Reprod. Dev. 62: 431-445.
Inoue, I., Tsutsui, I. and Bone, Q. 2002. Excitation-contraction coupling in isolated locomotor muscle fibres from the pelagic tunicate Doliolum which lack both sarcoplasmic reticulum and transverse tubular system. J. Comp. Physiol. B 172: 541-546.
Jackson, D., Leys, S. P., Hinman, V. F., Woods, R., Lavin, M. F. and Degnan, B. M. 2002. Ecological regulation of development: induction of marine invertebrate metamorphosis. Intl. J. Dev. Biol. 46: 679-686.
Jang, W. S., Kim, K. N., Lee, Y. S., Nam, M. H. and Lee, I. H. 2002. Halocidin: a new antimicrobial peptide from hemocytes of the solitary tunicate, Halocynthia aurantium. FEBS Lett. 521: 81-86.
Jeffery, W. R. 2002. Programmed cell death in the ascidian embryo: modulation by FoxA5 and Manx and roles in the evolution of larval development. Mech. Dev. 118: 111-124.
Jeffery, W. R. 2002. Ascidian gene expression profiles. Genome Biol. 3: 10301.1-1030.4.
Jiang, D. and Smith, W. C. 2002. An ascidian engrailed gene. Dev. Genes Evol. 212: 399-402.
Jimeno, J. M. 2002. A clinical armamentarium of marine-derived anti-cancer compounds. Anticancer Drugs 13 Suppl 1: S15-19.
Kamer, I. and Rinkevich, B. 2002. In vitro application of the comet assay for aquatic genotoxicity: considering a primary culture versus a cell line. Toxicol. in Vitro 16: 177-184; 327 (correction).
Kawahara, G., Terakado, K., Sekiguchi, T., Inoue, K. and Kikuyama, S. 2002. Adrenocorticotropin-like immunoreactivity in the granules of neural complex cells of the ascidian Halocynthia roretzi. Zool. Sci. 19: 1061-1065.
Keys and al., e. 2002. Control of intercalation is cell-autonomous in the notochord of Ciona intestinalis. Dev. Biol. 246: 329-340.
Kingsford, M. J., Leis, J. M., Shanks, A., Lindeman, K. C., Morgan, S. G. and Pineda, J. 2002. Sensory environments, larval abilities and local self-recruitment. Bull. Mar. Sci. 70: 309-340.
Kiyota, H., Dixon, D. J., Luscombe, C. K., Hettstedt, S. and Ley, S. V. 2002. Synthesis, structure revision, and absolute configuration of (+)- didemniserinolipid B, a serinol marine natural product from a tunicate Didemnum sp. Org. Lett. 4: 3223-3226.
Kobayashi, M., Matsuda, M., Asakawa, S., Shimizu, N., Nagahama, Y., Satou, Y. and Satoh, N. 2002. Construction of BAC libraries derived from the ascidian Ciona intestinalis. Genes Genet. Syst. 77: 283-285.
Kott, P. 2002. A complex didemnid ascidian from Whangamata, New Zealand. J. Mar. Biol. Assoc. UK 82: 625-628.
Kott, P. 2002. The genus Herdmania Lahille, 1888 (Tunicata, Ascidiacea) in Australian waters. Zool. J. Linn. Soc. 134: 359-374.
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