Number 45 May 1999
This issue contains a list of the email addresses of many of our Ascidian News subscribers; you will find it near the end of the newsletter, just before the New Publications. If any of you wish to be added, or if you would like to suggest the addition of any other names, please let Gretchen know. We have had a number of requests for such a list, and we hope you will find it useful. If you change your email address, please let us know. There are a large number of meetings abstracts in this AN, especially from the latest meeting of the Zoological Soc. of Japan. The New Publications section at the end of the newsletter includes, as always, a large number of excellent new papers on a wide variety of ascidiological topics. Thank you for the reprints you send us; they are very useful and important to us especially since we have a more limited access to library facilities now. Please send us your new reprints as soon as they appear, and that way you will be assured of being cited in the next AN.
We spent a very enjoyable and productive 6 weeks in Guam this winter. Gretchen worked on the identification of as many local ascidian species as there was time for, and Charley continued his fertilization studies. Please see the Work in Progress section for a more detailed description. This summer Charley will teach the Comparative Invertebrate Embryology course at Friday Harbor with Steve Stricker. Gretchen will continue her identifications of the many ascidians collected in Hawaii and Guam, including a number of problematic forms and probably some undescribed species. From 13 May to 1 September 1999 we will be at the Friday Harbor Laboratories, 620 University Road, Friday Harbor WA 98250 Phone (206) 543-1484 or (360) 378-2165 Fax: (206) 543-1273. We will continue with the same email addresses for the summer. Stop by for a visit if you are in the area.
*Ascidian News is not part of the scientific literature and should not be cited as such.
Ralph Lewin, Scripps Inst. of Oceanography, La Jolla, CA rlewin@ucsd.eduNEWS AND VIEWS
1. Charles and Gretchen Lambert: During late January and all of February we worked at the University of Guam Marine Laboratory in Mangilao. Here Gretchen identified many of the local ascidians as part of an on-going Sea Grant study on introduced species in Guam. Gustav Paulay (the director) and Chris Meyer, his postdoc, were responsible for much of the deeper collecting by snorkel and scuba, while we surveyed the marinas and shallow areas. This was the first inventory of the ascidians of Guam; they are surprisingly different from other areas, not as rich as Palau but quite different from Hawaii except for the ubiquitous Ascidia (=Phallusia) nigra, A. sydneiensis and Herdmania momus. Charley continued his fertilization studies begun in Hawaii last November with Ascidia nigra and A. sydneiensis, and has just submitted a manuscript on this work. Retirement agrees very much with Charley and he is enjoying the opportunity to work on these warm water species while accompanying Gretchen on her taxonomic travels. We were very fortunate to meet our friend Xavier Turon from Barcelona in Guam. He was working mostly with sponges but collected some very interesting deep water ascidians for Gretchen. Near the end of our stay Gretchen presented a taxonomic workshop which included live specimens of many of the species. It was very well received by University of Guam faculty and graduate students. Some of the species are apparently undescribed, including several abundant forms. We hope to make another trip to Guam next winter.
2. Rosaria de Santis desantis@alpha.szn.it We have now cultures of Ciona intestinalis available. A major effort of two technologists of the Cell Biology Laboratory, Drs. Paola Cirino and Alfonso Toscano lead to the design of a set-up (tanks, substrates and feeding systems) for culturing Ciona. The results are quite successful and we can get mature animals in six-eight weeks embryo to embryo. This prompted us to approach the more ambitious project of Ciona mutagenesis that has been developed in our Laboratory in collaboration with Drs. Paolo Sordino and Karl-Philipp Heisenberg, University College, London. At the moment we are performing the conclusive experiments of the screening and we have already the first set of phenotypes. We will keep the Ascidian Community informed of our further results. We presented already the preliminary results at the EMBO workshop "Reproduction and Development" held in Bergen, Norway, last October.
3. Patrick Frank(a) and Keith O. Hodgson(b) a. Dept. of
Chemistry, Stanford Univ., Stanford, CA 94305; b. Stanford Synchrotron
Radiation Lab, SLAC, Stanford Univ, Stanford, CA 94309. frank@SSRL01.slac.stanford.edu
Defining chemical species in complex environments using K-edge X-ray absorption
spectroscopy: vanadium in intact blood cells and Henze solution from the
tunicate Ascidia ceratodes. (The work is still in manuscript form,
and we hope to submit it soon for publication.)
A K-edge x-ray absorption spectral fitting approach has been developed
to explicate the complex environments of vanadium ions within whole blood
cells from the tunicate Ascidia ceratodes. To approach current models
of biological vanadium storage, the response of the K-edge x-ray absorption
spectrum (XAS) of solution-phase vanadium(III) to changes in [sulfate]
and acidity, respectively, was investigated. At constant pH 1.8,
increasing [sulfate] produced systematic effects in the vanadium XAS pre-edge
energy region at 5468.8 eV (pre-edge transitions are: 1s->4A2 at 5464.9
eV; 1s-> 4T2 at 5466.9 eV; and 1s->4T1 at 5468.8 eV for 11 different V(III)/sulfate
solutions). In contrast, variations in acidity (as pH) at constant [sulfate]
produced systematic modification of vanadium pre-edge XAS at 5466.9 eV.
Both sulfate and pH influenced absorption intensity near 5476 eV in the
rising K-edge. The energy position of the V(III) K-edge absorption
maximum also serially shifts 0.33 eV/pH unit, from 5483.7 eV at pH 3.0
to 5484.7 eV at pH 0.3. The K-edge spectra of V(III) in acidic sulfate
solutions along with the vanadium K-edge XAS spectra of other appropriate
V(III) model complexes were then successfully used to fit the vanadium
K-edge XAS spectra of two samples of whole blood cells from the tunicate
Ascidia ceratodes, representing 25 and about 37 animals respectively.
These population-level fits implied storage of blood cell vanadium(III)
ions in four solution regimes: high sulfate/high acid; high sulfate/moderate
(pH 1.8) acid; moderate sulfate/moderate acid, and; moderate sulfate/weak
(pH 3) acid. Evidence was found for small amounts of biological vanadyl
ion and traces (ca. 2%) of possibly tris-chelated V(III). For vanadium
in Henze solution, the best fit implied a predominant (77%) pH 1.6 acid
environment and no detectable V(III)-sulfate interaction, corroborating
previous epr and sulfur K-edge XAS results. Nearly 20% of Henze solution
vanadium(III) appeared tris-chelated. A detailed chemical model of
vanadium within intact whole blood cells of the tunicate Ascidia ceratodes
is calculated using known the known equilibrium behavior of V(III) and
sulfate in acid solution. The fitting approach is suggested to be
generally applicable to elucidating the state of metal ions in a wide variety
of complex environments.
4. Christian Sardet, Station Zoologique, Villefranche sur Mer, 06230 France; sardet@ccrv.obs-vlfr.fr : There will be an EEC sponsored Long term course (1 month) organized in June in Roscoff, France about evolution and development. It will include ascidians and there is a web site. It may be still possible to apply; http://www.bio.uu.nl/~embryo/Meetings/EU99.htm
5. Also from Christian Sardet: POST DOC POSITION: DEVELOPMENTAL BIOLOGY RESEARCH UNIT IN VILLEFRANCHE SUR MER. We are looking for a post doc to join our laboratory in the context of a Human Frontier network that is just starting and will last 3 years. The network's focus is on maternal determinants and their identification and localization in the zygotes of Xenopus and ascidians. The participating laboratories are P. Lemaire (Marseille), M.L. King (Miami), R. Elinson (Toronto) and H. Nishida (Tokyo)and ourselves. As far as our lab is concerned the post doc position will be to work on cortices in Xenopus and ascidians (we have preparation of isolated cortices that have kept some functionality (sliding of microtubules etc.)) and we will also isolate mRNAs from cortices and localize them (low resolution and high resolution in situs with EM). Some of the work will be done with our partners and will require spending periods of time in P. Lemaire and/or ML. King and Nishida's lab. In our laboratory, the post doc will be working directly with Christian Sardet (ascidian) as well as with Evelyn Houliston (Xenopus). Our laboratory is a Molecular and Cell Biology Unit with 30 members situated in an historical building by the Mediterranean in Villefranche (between Nice and Monaco). The post doc position could start any day now and would be paid 10000-12000 FF a month and last from 1-3 years. We will be organizing a workshop gathering the members of the network in May (8-15th) in Villefranche sur mer . For informations/applications contact Christian Sardet at ; sardet@obs-vlf.fr
6. Charles Lambert, Gretchen Lambert and Todd Newberry. Lights Manual, Intertidal Invertebrates of the Central California Coast, 4th Edition: We are working on the revision of Don Abbott’s ascidian chapter and key for the 4th edition of this classic work which is expected to be out in 2000. Jim Carlton is the Editor in Chief. We have finished the new check list and are through a third revision of the keys. We have added several new species because of recent introductions that seem to have naturalized especially in the marinas, and also include some southern California species in the check list, but not the keys, that might be encountered. Eudistoma purpuropunctatum Lambert, 1991. Ciona savignyi Herdman, 1882, Ascidia zara Oka, 1935 Botrylloides diegensis Ritter and Forsyth, 1917, Botrylloides violaceus Oka, 1927, Botryllus schlosseri (Pallas, 1766), and Dendrodoa abbotti Newberry, 1984 have thus far been added to the keys. We would like to hear from any of you if you have found ascidian species that are not in the third (1975) edition or this list of added species. We want to be sure that the keys are truly inclusive of what is out in the real world today.
THE EVOLUTION OF LARVAL MORPHOLOGY IN ASCIDIANS: A PHYLOGENETIC ANALYSIS
OF SPECIATION IN THE MOLGULIDAE. M.S. thesis abstract by Jennifer
Lynn Huber.
The Molgulidae family of ascidians has several species
which have independently evolved anural, or tailless, larvae. This
is in contrast to the typical urodele larva that develops in all other
families, and contains a notochord, muscle cells and a dorsal hollow nerve
cord. Molecular phylogenies using the 18S rRNA gene and the hypervariable
D2 loop of the 28S rRNA gene indicate that species in the family Molgulidae
fall into at least four distinct clades, three of which have multiple anural
members. For at least two of these clades, we present clear evidence
of a circumpolar tailed ancestor whose distribution has subsequently diminished.
Furthermore, we show that complex life history characters such as viviparity,
loss of tail, and ability to self-fertilize are polyphyletic within the
Molgulidae, and appear to have evolved independently. Speciation
of the Molgulidae and evolution of tailless larvae appears to have occurred
primarily at northern latitudes. Our analyses suggest that the evolution
of tailless larvae may be correlated with the biogeography, rather than
the ecology, of adult molgulids.
This work was written as partial fulfillment of
a M.S. degree awarded to Jennifer Huber from Penn State University in the
laboratory of Dr. Billie J. Swalla. A manuscript has been submitted
to Evolution describing in detail the molgulid clades. Meanwhile,
Jenn is planning to continue her education at the University of Hawaii,
pursuing a Ph.D. in the laboratory of Dr. Mark Martindale.
1. Canadian Soc. of Zoologists, Ottawa, May 8, 1999.
EVIDENCE FOR THE EXISTENCE OF A GnRH-LIKE PEPTIDE IN SENSORY CELLS OF
Corella inflata (ASCIDIACEA). Mackie*, G.O. & R.M. Marx,
Biol. Dept, Univ. of Victoria, Victoria, B.C.
Previous studies have demonstrated the existence of two novel
forms of gonadotropin releasing hormone in ascidians, one of which has
been located in a nerve plexus in the dorsal blood sinus and is implicated
in control of reproduction and neural regeneration. We now find immunoreactivity
to Tunicate I GnRH in sensory cells in the body wall of Corella.
The cells appear to derive from neuroblasts produced in the region of the
dorsal strand which migrate through blood spaces to subepithelial locations
in the body wall, where they complete their transformation into sensory
cells.
2. Soc. for Experimental Biology meeting, Edinburgh, Scotland, March 23, 1999.
LONG-TERM SURVIVAL OF NEURAL FUNCTION IN DE-BRAINED ASCIDIANS.
G.O. Mackie and R.C. Wyeth, Biology Dept., Univ. of Victoria,
Victoria, British Columbia.
Ascidians behave as if they had a coelenterate nerve net in
the body wall. Stimulation of one siphon causes contraction of the other
after removal or transection of the brain. Some reflex activity persists
in Chelyosoma for at least four months after brain removal. The
brain does not regenerate and the peripheral innervation does not degenerate.
Contrary to previous claims we find that there is no nerve net in the body
wall in the sense of a plexus of neurons with cell bodies. The only nerve
elements with peripheral cell bodies are scattered sensory elements. The
motor neurons have their cell bodies in the brain. We are trying to sort
out the sensory and motor pathways in normal and debrained animals. Cholinesterase
histochemistry and anti-tubulin immune labeling show a ramifying mass of
nerves running between the siphons, some of which bypass the brain and
could provide coordinating pathways after brain removal. Suction electrode
recordings confirm the propagation of electrical signals between the siphons
in debrained animals.. Surgical experiments suggest multiple pathways.
It is not yet clear if these pathways involve direct connections between
sensory nerves in the periphery, connections between terminal branches
of the motor nerves, or connections between the two.. A recent finding
of GnRH-like immunoreactivity in the sensory nerves offers hope of distinguishing
sensory from motor elements in mixed bundles and thus of determining
how the animal achieves the functional equivalent of a nerve net.
3. American Society of Limnology and Oceanography, Santa Fe, NM, Feb. 3, 1999.
LIGHT, DISTRIBUTION, AND LIFE HISTORY ADAPTATIONS OF THE ASCIDIAN, Corella
inflata. Bingham, B.L., A.M. Reitzel, and N.B. Reyns. Western
Washington Univ., Shannon Pt. Marine Center, 1900 Shannon Pt. Road, Anacortes,
WA. bingham@cc.wwu.edu
The ascidian Corella inflata is a common
fouling organism in the Puget Sound and the San Juan Archipelago, Washington,
USA. Despite its abundance, particularly on floating docks, it is conspicuously
absent from areas that receive direct sunlight. We hypothesized that UV
irradiation damages exposed individuals and creates the observed distribution.
To test this, we exposed C. inflata adults, juveniles, larvae, and
embryos to UV irradiation. In laboratory tests and under natural sunlight
in the field, UV significantly shortened adult life span. Juveniles died
after only 2-3 days in the light. Several hours of exposure were sufficient
to decrease larval settlement and metamorphosis. Abnormalities appeared
in developing embryos after only 30 minutes of exposure. By selectively
filtering natural sunlight, we demonstrated that UV-B wavelengths were
most damaging to C. inflata. However, UV-A and visible light also
produced significant negative effects. We conclude that C. inflata is
sensitive to UV light in all phases of its life history with younger stages
being most vulnerable. We suggest that unique life history traits (i.e.,
time of spawning, brooding behavior, length of larval life) limit exposure
and allow C. inflata to persist in its preferred dock habitat despite
its UV vulnerability.
4. Zool. Soc. of Japan 69th annual meeting, 1998. (Publ. In Zool. Sci. vol. 15, suppl., Dec. 1998)
EXPERIMENTAL ALLOMETRY: HOW DOES METABOLIC RATE CHANGE WITH COLONY SIZE
OF ASCIDIANS? F Nakaya1, Y. Saito2 and T. Motokawa1.
1Basic Biology, Faculty of Bioscience & Biotechnology, Tokyo Inst.
of Technol., 2Shimoda Mar. Research Center, Univ. of Tsukuba.
The allometric relationship between metabolic rate and
body size is well established in individual organisms: the metabolic rate
increases in proportion to the body weight to the power 0.75. The question
why 0.75 is still unanswered. One of the reasons making this problem hard
to solve might lie in the difficulties in experimental manipulation of
the body size. We studied the relationship between metabolic rate and size
of colonial ascidians, because their colony size can be manipulated with
ease. The colonial ascidians Botryllus schlosseri and Botrylloides
simodensis were used. They were chosen because they form a flat single-layered
colony as they grow, thus the effect of three dimensional shape changes
can be neglected. We measured oxygen consumption of colonies of various
sizes (O.03g-5.0g wet weight) by oxygen electrodes. A clear allometric
relationship was found between metabolic rate and colony size: the metabolic
rate increased in proportion to the colony weight to the power 0.788 (B.
schlosseri ) and 0.815 (B. simodensis ), both of which were
statistically not different from 0.75 but different from 1. The effect
of cutting a single colony into smaller colonies was studied. A colony
reared on a polycarbonate sheet was divided into smaller colonies by cutting
it with the polycarbonate sheet attached without tearing the animals from
their substrate. The fragmented colonies were kept in open sea water for
one week for wound healing. The metabolic rate of fragmented colonies tell
just on the regression line of the metabolic fate-size relationship obtained
from intact colonies of various sizes.
A CONVENIENT METHOD OF WHOLE MOUNT IN SITU HYBRIDIZATION (WMISH) FOR
COMPREHENSIVE SURVEY OF MULTIPLE cDNA CLONES. T. Minokawa2, M. Ogasawara1,
Y. Sasakura1, H. Yamamoto2, H. Nishida2, and K. W. Makabe1. 1: Dept.
of Zool., Graduate Sch. of Sci., Kyoto Univ. 2: Dept. of Life Sci.,
Tokyo Inst. of Technology, Yokohama. 1, 2: "Research for the Future"
program
We constructed an arrayed library of cDNAs for maternal
mRNAs in ascidian fertilized eggs. To survey the localization pattern
of each mRNA, the procedure of conventional WMISH protocol is too time-consuming.
To screen a large number of cDNA clones for localized messages in the ascidian
egg, we developed a convenient protocol of WMISH. Digoxigenin (DIG)-labeled
RNA probes simultaneously synthesized directly from PCR products from a
large number of cDNA clones in a relatively short time. Hybridization
and washing were carried out in modified 96-well plates (Silent Screen
Plate, Nunc), in which the bottom is sealed with nylon membranes.
The solution in each well was rapidly drained through the membrane by vacuum.
This WMISH system enabled us to survey a large number of cDNA clones in
a limited time.
ISOLATION OF cDNA CLONES FOR mRNAs TRANSCRIBED ZYGOTICALLY DURING CLEAVAGE
STAGE IN ASCIDIAN EMBRYOS. T. Miya, H. Nishida. Dept. of Life
Sci., Tokyo Inst. of Tech., Yokohama.
The ascidian larva consists of relatively small number
of tissues, and the cell lineage is well described during embryogenesis.
Most of the blastomeres become tissue-restricted by the 110-cell stage
which is just before the onset of gastrulation. During ascidian embryogenesis,
primary muscle, epidermis and endoderm autonomously differentiate, and
the processes are mediated by egg cytoplasmic determinants. We are
trying to isolate cDNAs for genes of which expression is directly triggered
by maternal determinants during early embryogenesis of the ascidian, Halocynthia
roretzi. We constructed cDNA library of 110-cell embryos. By
differential screening using maternal mRNAs and mRNAs from 110-cell embryos,
we isolated several cDNA clones for genes of which transcription starts
during cleavage stage.
CLASSIFICATION OF HEMOCYTES OF THE ASCIDIAN Halocynthia roretzi
by FACS. M. Kumano, N. Tomita, M. Hoshi. Dept. of Life
Sci., Tokyo Institute of Technology.
Hemocytes of the ascidian Halocynthia roretzi are
believed to play an important role in self-defense system and allo-recognition.
Since hemocytes consist of morphologically heterogeneous populations, it
is essential to classify them and clarify the roles of each population
in self-defense and allo-recognition. The hemocytes were classified into
12 groups by FACS using monoclonal antibodies and dyes. Our classification
was compared to the morphological classifications previously reported.
Although tunic cells are thought to be a population of hemocytes that have
migrated into the tunic, a portion of tunic cells show a unique feature,
which has never found in hemocytes, by FACS analysis. The contact reaction
was quantified by the increase in cell number of smaller population (cell
debris) detected by FACS.
THE MECHANISMS RESPONSIBLE FOR THE EXTREMELY LOW PH IN THE VACUOLE OF
VANADOCYTES OF THE ASCIDIAN. T.Ueki1, T.Uyama1, K.Kanamori2 and H.Michibata1.
1Mukaishima Marine Biol. Lab., Fac. Sci. and Lab. Marine Molec. Biol.,
Grad. Sch. Sci., Hiroshima Univ.; 2Dept. Chem., Fac. Sci., Toyama Univ.
Ascidians have long been known to accumulate a transition
metal, vanadium, in their blood cells. The pH within the vacuole is very
low and is correlated with the concentration of vanadium. Vacuoles
of vanadocytes of Ascidia gemmata having the highest level of vanadium
of 350 mM exhibit the lowest pH value of 1.86, those of A. ahodori
containing 60 mM vanadium have pH 2.67, and those of A. sydneiensis
samea containing 13 mM vanadium have pH 4.20. Immunocytological studies
suggested that V-ATPases actually function to accumulate protons in the
vacuoles. Here we propose two possible mechanisms to keep the extremely
low pH. One is the dissociation of the water molecules coordinating
to vanadium(III) ion accumulated. The other is the possibility that
the V-ATPases in the vanadocytes has unusually high activity of proton
pumping. Both mechanisms may function together in the vacuole of
vanadocytes.
cDNA SEQUENCE FOR A 100 kDa ANTIGEN REACTED WITH A MONOCLONAL ANTIBODY
S8E4 IN VANADOCYTES OF THE ASCIDIAN, Ascidia sydneiensis samea.
Y.Suhama, T.Uyama , T.Ueki, H.Michibata. Mukaishima Marine Biol. Lab.,
Fac. Sci. and Lab. Marine Molec. Biol., Graduate Sch. Sci., Hiroshima Univ.
Ascidians have about ten types of blood cells. Among
them, the vanadocyte is a cell characterized by a single, fluid-filled
vacuole and has an unique and unusual functions of containing both extremely
high levels of vanadium ions in the + 3 oxidation state and sulfate ions
under pH 2 in the vacuole. A monoclonal antibody S8E4 specifically
recognizing a 100 kDa protein in the vanadocyte was produced. In
order to characterize the 100kDa antigen, a gene encoding the antigen was
screened using monoclonal antibody S8E4 as a probe from the cDNA library
prepared from the blood cells. A search of sequence databases for
similarities detected that the 100kDa antigen was glycogen phosphorylase.
S8E4 was confirmed to react with the protein translated from the cloned
cDNA in E. coli. Since we have already revealed the existence of enzymes
in the pentose phosphate pathway in vanadocytes, we suppose that this glycogen
phosphorylase functions to provide substrate G1P.
METAL ION AFFINITY WITH A VANADIUM-ASSOCIATED PROTEIN EXTRACTED FROM
THE VANADIUM-RICH ASCIDIAN, Ascidia sydneiensis samea.
Y.Matsumura, T.Uyama, T.Ueki and H.Michibata. Mukaishima Marine Biol. Lab.,
Fac. Sci. and Lab. Marine Molec. Biol., Graduate Sch. Sci., Hiroshima Univ.
Ascidians are known to accumulate vanadium selectively
at extremely high concentration in their blood cells. The highest
level of vanadium ions was reported to be in excess of 350 mM such level
has never reported in living organisms. This phenomenon has attracted
the interest of many investigators between biology and chemistry as a peculiar
mechanism of uptake. We previously identified three kinds of vanadium-associated
proteins (VAPs) which are co-fractionated with vanadium ions using a technique
of anion exchange column. We considered that VAPs are connected with
the peculiar mechanism of vanadium uptake. By equilibrium dialysis
methods, we showed that the VAPs specifically bound to vanadium(V) ions
and the affinity of VAPs to vanadium(V) ions is much higher than that of
BSA or that of proteins at each purification step.
VANADIUM ION AFFINITY OF BLOOD CELL COMPONENTS IN Ascidia sydneiensis
samea.
T.Fukumitsu, T.Uyama, T.Ueki and H.Michibata. Mukaishima Marine Biol.
Lab., Fac. Sci. and Lab. Marine Molec. Biol., Graduate Sch. Sci., Hiroshima
Univ.
Ascidians are known to accumulate vanadium selectively
at extremely high levels in their blood cells. In the process of
the accumulation, vanadium-binding proteins are expected to have important
functions. We previously identified several vanadium-binding proteins
in the soluble fraction of vanadocytes, but no such proteins in the insoluble
fractions have been found. The purpose of the present study is to
examine the affinity of organella and proteins in insoluble fractions to
vanadium ions. After blood cell homogenates were separated by ultracentrifugation,
using equilibrium dialysis methods, we found that the membrane fraction
containing nuclear membranes and plasma membranes, and the vacuolar membrane
fraction had a strong affinity to vanadium ions.
EXPRESSION OF RECOMBINANT VANADIUM-ASSOCIATED PROTEINS (VAPS) IN E.
coli.
S.Kawano, T.Ueki, T.Uyama and H.Michibata. Mukaishima Marine Biol.
Lab., Fac. Sci. and Lab. Marine Molec. Biol., Graduate Sch. Sci., Hiroshima
Univ.
Ascidians, known as sea squirts, accumulate extremely
high levels of vanadium(III) ions in their blood cells. From the blood
cell extracts, we have recently identified several low molecular weight
proteins which are co-purified with vanadium after the anion exchange column
fractionation. We designated them as vanadium-associated proteins
(VAPs). The cDNAs encoding 12.5kDa and 15kDa VAPs have been cloned
and sequenced completely. In this study, we cloned each of them into
an expression vector and transformed into E. coli. Expression
of the fusion protein was induced by the addition of IPTG. The proteins
extracted from the bacteria were analyzed by SDS-PAGE. The fusion
proteins were detected by the polyclonal antibodies against VAPs on the
western blots. Thus, 12.5kDa and 15kDa VAP fusion proteins were successfully
synthesized in the bacteria.
PREPARATION OF MONOCLONAL ANTIBODIES SPECIFIC TO VACUOLAR MEMBRANE PROTEINS
OF ASCIDIAN VANADOCYTES. T.Uyama, S.Nomura, T.Ueki, & H.Michibata.
Mukaishima Mar. Biol. Lab., Fac. Sci. and Marine Molec. Biol., Graduate
Sch. Sci., Hiroshima Univ.
Vanadocyte, vanadium-containing blood cell, is specified
to accumulate and reduce vanadium in ascidian blood cells. Although
vanadium is in the +5 oxidation state in sea water, the accumulated vanadium
is reduced to the +3 oxidation state via the +4 oxidation state and stored
in vacuole of the vanadocyte. However, it is unclear how vanadium
ions are transported into cytoplasm from serum and into vacuole from cytoplasm
in the accumulation and reduction process. In this experiment, therefore,
we tried to raise monoclonal antibodies specific to the vacuolar membrane
proteins of the vanadocyte in vanadium-rich ascidian, Ascidia sydneiensis
samea. As the result, a hybridoma cell line which secretes a monoclonal
antibody, designated V2C3, specific to the vacuolar membrane of the vanadocytes
has been established. Immunoblotting analysis showed that the V2C3
monoclonal antibody was revealed to react with a vacuolar membrane protein
of about 130 kDa.
REDUCTION OF VANADIUM BY NADPH UNDER AEROBIC AND ANAEROBIC CONDITIONS.
T.Kinoshita1,T.Uyama1, K.Kanamori2, T.Ueki1 and H.Michibata1. 1Mukaishima
Marine Biol. Lab., Fac. Sci. and Lab. Marine Molec. Biol., Graduate Sch.
Sci., Hiroshima Univ., Hiroshima. 2Dept. Chem., Fac. Sci., Toyama Univ.
Ascidians are known not only to accumulate high levels
of vanadium in the vacuole of the vanadocytes, vanadium-containing blood
cells, but also to reduce the accumulated vanadium to V(III) via V(IV).
Since vanadium is dissolved in V(V) in seawater, some reducing agents must
participate in the reduction process in the vanadocytes. Recently,
we found that enzymes of the pentose phosphate pathway exist specifically
in the vanadocytes. The finding suggested a possible participation
of NADPH in the reduction of V(V) to V(IV), since enzymes in the pentose
phosphate pathway are known to produce NADPH. The present experiment
is designed to examine whether V(V) is reduced to V(IV) by NADPH in vitro
with the final aim being to prove the intrinsic participation of NADPH
in the reduction of vanadium in the vanadocytes of ascidians. As the result,
it revealed that NADPH can reduce V(V)-EDTA to V(IV)-EDTA but cannot do
V(V) in the form of ortovanadate both under aerobic and anaerobic conditions.
CLONING OF TRANSKETOLASE FROM VANADOCYTES IN THE ASCIDIAN, Ascidia
sydneiensis samea. K.Yamamoto, T.Ueki, T.Uyama, and H.Michibata.
Mukaishima Marine Biol. Lab., Fac. Sci. and Lab. Marine Molec. Biol., Graduate
Sch. Sci., Hiroshima Univ.
Ascidians are known to accumulate extremely high levels
of vanadium(III) ions in the vacuole of their blood cells (vanadocytes).
During the characterization of some antigens recognized by monoclonal antibodies
specific to vanadocytes, we have revealed that glucose-6-phosphate dehydrogenase
(G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) are expressed in the
vanadocytes. Those enzymes belong to the oxydative pathway of the
pentose phosphate pathway, which convert NADP+ to NADPH. In this
study we isolated a cDNA encoding transketolase, one of the enzymes in
the non-oxydative pathway of the pentose phosphate pathway, expressed in
the vanadocytes. Our result strongly supported that pentose phosphate pathway
exists and functions in the vanadocytes.
PREPARATION OF MONOCLONAL ANTIBODY AGAINST GIANT CELLS OF Ascidia
sydneiensis samea. N.Ishimura, T.Uyama, T.Ueki and H.Michibata.
Mukaishima Marine Biol. Lab., Fac. Sci. and Marine Molec. Biol., Graduate
Sch. Sci., Hiroshima Univ.
Ascidians are known to accumulate high levels of vanadium
in the vacuole of one of blood cells, the vanadocytes. Blood cells
are morphologically classified into at least ten types. Among them,
giant cells ranking with vanadocytes are known to have several particular
features. The giant cell is the biggest cell having approx. 80um in diameter
in ascidian blood cells. The large portion of the cell body is occupied
by a vacuole containing a lot of mucopolysaccharides. The vacuole
has extremely low pH as seen in the vanadocytes. In this present
experiment, by immunizing mouse with vacuolar membrane fraction of blood
cells, we successfully obtained several strains of hybridoma cells which
produced antibodies recognizing the vacuolar membrane of both vanadocytes
and giant cells. The size and the localization of the antigens were
determined by western blotting.
EVOLUTIONARY HISTORY OF FREE SWIMMING AND SESSILE LIFESTYLES IN UROCHORDATES
AS DEDUCED FROM ONTOGENY PHYLOGENY. H. Wada. SMBL, Kyoto University,
Shirahama-cho, Wakayama.
Whether the ancestral chordates were free-swimming or
sessile is a longstanding question that still remains to be settled.
Vertebrates and amphioxus are free-swimming, but the most basal chordate
subphylum (the urochordates) includes both sessile and free-swimming species.
Molecular phylogenetic analyses on 18S rDNA of urochordates revealed
a close relationship between salps and doliolids, and paraphyly of the
ascidians. An early divergence of larvaceans, which show a tadpole-like
bodyplan throughout life, is also supported from the analyses. I
also present evidence that the ascidian tadpole larva possesses a highly
organized neural tube, with traces of segmentation, dorsoventral differentiation
and subdivision into regions homologous to fore- and midbrain, anterior
hindbrain and posterior hindbrain and spinal cord, respectively.
Together with the fact that larvacean neural tube is also segmentally organized,
it is likely that the ancestral chordates already possessed a complicatedly
organized neural tube. It is unlikely that such a highly organized
neural tube evolved solely for use during larval stages, especially considering
that the main function of extant ascidian larvae is simply to find a place
to settle and metamorphose. Based on these observations, a free-swimming
ancestor for chordates is more likely and more parsimonious than a sessile
ancestor. The evolutionary history of various lifestyles in chordates
from this ancestral form is proposed.
SURVEY OF GENETIC MOLECULE MARKER OF Ciona intestinalis.
S. Kano1, S. Chiba2, N. Satoh1. 1Dept. of Zool., Graduate Sch. of
Sci., Kyoto Univ.; 2Dept. of Biol., Konan Univ., Okamoto, Hisgashi-Nada-Ku,
Kobe.
Little genomic information about a solitary ascidian,
Ciona intestinalis have stored. To obtain available marker sequences,
RAPD markers which show genetic polymorphisms were surveyed by RAPD-PCR
and AP-PCR method. In the present study, we report that reliable ones were
converted to STS markers and investigated their inheritance between generations.
We also report that some RAPD markers revealed genetic differences between
wild population of both the Ocean side and the Sea of Japan side. These
RAPD markers and STS markers are useful to progress in genetics of this
species.
MUSASHI HOMOLOGUE IN THE ASCIDIAN, H.roretzi, IS EXPRESSED IN
THE NEURAL TISSUE OF THE EMBRYO. T. Kawashima, Y. Sasakura,
M. Ogasawara, and K.W. Makabe. Dept. of Zool., Grad. Sch. of Sci.,
Kyoto Univ.
Musashi gene is required for development of adult external
sensory organs in Drosophila neural development. Mouse-Msi-1, musashi homologue
in mouse, is essential for neural development and differentiation. We have
found Hrmsi-1, a gene homologous to the Drosophila Musashi, from a fertilized
egg - cDNA library of H.roretzi.Hrmsi-1 mRNA is 1.5kb in length
and contains two RNA - binding motifs which are common to musashi family
members. By whole mount in situ hybridization, maternal transcripts were
detected in all blastomeres. Zygotic gene expression was seen predominantly
in the neural tissue of the embryo. The Hrmsi-1 protein may be involved
in neural pattening in ascidian.
A HNF-6 HOMOLOGOUS GENE IS INVOLVED IN NEUROGENESIS IN ASCIDIAN EMBRYOGENESIS.
Y. Sasakura and K. W. Makabe. Dept. of Zool., Grad. Sch. of Sci.,
Kyoto Univ.
HNF-6 is a novel class of transcription factor which contains
single cut domain and homeodomain. To know the function of HNF-6
in ascidian development, we isolated a cDNA of HNF-6 homolog from a gastrula-cDNA
library of the ascidian Halocynthia roretzi. The cDNA is about
3.5kb in length, and the predicted amino-acid sequence contains a cut domain
and a homeodomain. Whole-mount in situ hybridization revealed that
HNF-6 homolog trancripts first appeared at the neural plate stage in the
small regions of neural plate. At the tailbud stage, the transcripts
were detected in some parts of neural tissues including the brain.
The mRNAs of HNF-6 homolog was microinjected in the fertilized eggs of
H. roretzi, and the malformation of the morphology was observed.
In addition, the expression of the neural marker gene HrTBB2 was altered.
Above results suggest that the HNF-6 homolog functions in the development
of neural tissues.
Ciona BRACHYURY GENE TARGETS. K. Hotta1. H. Takahashi1.
N. Satoh1. A. Erives2. M. Levine2. Dept. of Zool., Grad. Sch. of
Sci., Kyoto Univ., Kyoto.1?ADept. of Mol. Cell Biol.,Univ. of California,
Berkeley, USA2
When a fusion gene construct in which the promoter of Cifkh
(Ciona forkhead) was fused with CiBra (Ciona Brachyury) coding
sequence was injected into Ciona eggs by electroporation, CiBra
ectopic expression was induced in the endodermal strand cells of tailbud-stage
embryos. This CiBra ectopic expression was used to isolate candidate CiBra
target genes. Subtractive hybridization method, thus far, yielded about
900 cDNA clones for CiBra downstream gene candidates. Sequencing of both
3'and 5' regions and dot blot hybridization demonstrated that, among them,
528 clones are independent and activated by CiBra overexpression. In situ
hybridization revealed that several genes are expressed specifically in
notochord cells of the embryo.
ISOLATION AND ANALYSIS OF AN ASCIDIAN MATERNAL T-BOX GENE, AS-MT
N. Takada1 , K.Tagawa2+ , H. Takahashi2 , N. Satoh2. 1 Dept.
of Biol., Fac. of Edu., Mie Univ., 2 Dept. of Zool., Grad. Sch. of Sci.,
Kyoto Univ.; + Present address: Dept. of Biochem. and Mol. Biol., Univ.
of Texas MD Anderson Cancer Center, Texas, USA
The T-box genes encode transcriptional factors that contain
DNA binding region called T-domain. An ascidian egg is a typical mosaic
egg, and cell differentiation and morphogenesis are determined dependent
on prelocalized egg cytoplasmic factors. In this study, taking note
of T-box gene, we characterized maternally expressed T-box gene ( As-mT
). As-mT cDNA consisted of 3819bp and encoded a polypeptide consisting
of 891 amino acids with T-domain. Its transcript was distributed
almost evenly within the embryo until about 110-cell stage. Zygotic
expression was not detected. Furthermore, the injection of As-mT mRNA resulted
in delay of gastrulation and tissue differentiation. This result suggests
that As-mT is involved in temporal control of the early development.
ORIGIN AND EVOLUTION OF THE PHARYNGEAL GILL AND Pax1/9 RELATED GENES
M. Ogasawara, N. Satoh. Dept. of Zool., Grad. Sch. of Sci., Kyoto
Univ., Kyoto.
The pharyngeal gill is an organ key to an understanding of the
molecularmechanism underlying the origin and evolution of chordates.
We focused onthe Pax1/9 related genes (Pax1 and Pax9) that encode transcription
factors and are expressed in the pharyngeal pouch of higher vertebrates.
In this study, we isolated cDNA clones of Pax1/9 related genes from urochordates
(HrPax1/9 and CiPax1/9) and hemichordate(PfPax1/9). These Pax1/9
related genes are expressed only in the adult pharyngeal gills in these
species, suggesting its function in the formation of this organ.
Therefore, these Pax1/9 related genes may serve as probes for further analysis
of molecular mechanisms involved in the formation and evolution of the
pharyngeal gill.
INDUCTION OF SPAWNING BY INJECTION OF GONADOTROPIN-RELEASING HORMONE
(GNRH) INTO COELOM OF AN ASCIDIAN Halocynthia roretzi.
K. Terakado. Dept. of Regul. Biol., Fac. of Sci., Saitama Univ.,
Urawa.
Recently, two new froms of GnRH were identified in a tunicate
by Powell et al. (1996). They speculated that GnRH ppeptides may
be released into the bloodstream to act directly on the gonads for gonadal
development and spawning. We injected GnRHs into the body cavity
of the ascidian Halocynthia roretzi to examine the ability to spawn
during the breeding season. Several types of GnRHs were used, and
each given at dose of 1ng, 10 ng and 100ng/gr of body weight. It
is known that, in "day-type" of H. roretzi, spawning naturally occurrs
when individuals are maintained under light condition for 4-5 hrs following
maintenance in dark condition, but not under continuous light. The
injected animals were all placed under illumination by fluorescence lights.
The injected animals significantly spawned sperm initially and then eggs.
Control animals also began to spawn after 4-5 hrs of light exposure.
In excised and GnRH-treated gonads, no spawning was observed. These
observations suggest that GnRH may induce spawning in the ascidian, but
not directly.
LYSIS OF TUNIC LUMINOCYTES IS ESSENTIAL FOR LUMINESCENCE IN A LUMINESCENT
ASCIDIAN? Euichi Hirose1 and Kazuyoshi Chiba2. 1Dept.
Chem. Biol. & Mar. Sci., Fac. Sci., Univ. of the Ryukyus, Nishihara,
and 2Dept. Biol. Col. Sci., Ochanomizu Univ., Tokyo.
One type of tunic cell (free cells distributed in the
tunic) is the light source in the luminescence of Clavelina miniata.
Strong luminescence occurs in the tunic, when the tunic or tunic cells
treated with cell-lytic condition (picking the tunic or hypertonic/hypotonic
treatment). High concentration of potassium ion is known to induce
luminescence, but the amount is about one 80th of that induced with hypotonic
treatment. Ionophores, A23187 and valinomycin, also induce luminescemce
at very high concentration (0.2Ð0.01 mM), but the light amount is only
one half to one eighth of that induced with potassium ion treatment.
These low amounts of luminescence may indicate that luminescence is produced
from spontaneous cell lysis but not the ionic effects in these treatments.
Tunic luminocytes contain acidic vesicles that may be concerned with luminescence.
However, since luminescence was not induced with anmonium ion treatment,
neutralization of the vesicles is not sufficient for the luminescence induction.
In C. miniata, cell lysis may be essential for luminescence even
in natural conditions.
EXPRESSION AND FUNCTION OF A RETINOIC ACID RECEPTOR HOMOLOG IN BUDDING
TUNICATES. Y. Tsuchida, S. Fujiwara, K. Kawamura and T. Yubisui.
Dept. of Biol., Fac. of Sci., Kochi Univ., Kochi.
Retinoic acid (RA) is an endogenous regulator of cell
differentiation and morphogenesis in developing buds of the tunicate Polyandrocarpa
misakiensis. We examined the localization of a tunicate homolog of
retinoic acid receptor (PmRAR) by whole mount in situ hybridization. The
signal was first detected in the epidermis at the proximal-most area of
developing buds soon after isolated from the parent. Then, the atrial epithelium
and mesenchymal cells including the glomerulocyte of epidermal origin were
stained weakly. By the stage where the gut rudiment formed, the PmRAR signal
disappeared from any tissue of developing buds, but it reappeared on the
pharynx of adult animals. Recombinant PmRAR protein was bound in vitro
to affinity-purified PmRXR protein. This binding was enhanced by 13-cis-RA
that has been shown to have the highest activity to induce the secondary
bud axis. Our results suggest strongly that, like vertebrate RARs, PmRAR
acts as a heterodimer together with PmRXR, while it binds 13-cis-RA rather
than all-trans-RA. We suggest that one of functions of PmRAR in the epidermis
is to regulate gene expression of aldehyde dehydrogenase, a potent RA synthase.
G-PROTEIN FAMILY IN ASCIDIAN, Halocynthia roretzi.
T.Iwasa, K.Kanehara, A.Watari, N.Ohkuma, M.Tsuda. Dept. of Life Sci.,
Fac. of Sci. Himeji Inst. of Technology, Hyogo.
Heterotrimeric G proteins form a family of signal transducing
molecule from cell surface receptor to cytoplasmic effector. The
family was divided several class according to their amino acid sequence
identity, and also to their effector. Recently, it became evident
that G proteins occupy a large part of an interconnecting signaling pathways
in living cells. In order to investigate how such signaling networks
are formed during the developmental stages and how it works in an organism,
we studied the G protein family of an ascidian larva. A well
characterized cell lineage of the ascidan larvae makes it a simple model
system for studying the differentiation and organization of a signaling
network of an organism. As an first step, we tried to characterize
all G proteins participating in a signaling network of the ascidian larvae.
We isolated five different clones of G protein a subunit (Ga) from
a cDNA library (kindly provided from Y. Okamura) of an ascidian larva,
Halocynthia roretzi. One was a Gn, a novel Ga previously reported
by us. The other three classes were found to be Gi, Gq, and Gs class based
on their amino acid identity. Comparing the full length predicted
amino acid sequence, the remaining one showed a low degree of identity
with any Ga class. We tentatively termed this as G?. Two distinct
cDNA clones of Gi and G? were isolated. They were identical in a
coding sequences, but different in 3' non-coding region. Northern
blot analysis of these Ga message revealed that these Ga subunit genes,
although they were obtained from cDNA library of larva, were found
in all adult tissues studied. In situ hybridization of these Ga messages
in the tadpole larva shows the spatial distribution of these messages in
different tissues.
GROWTH OF THE LARVAE OF THE SOLITARY ASCIDIAN Ciona IMPLANTED
IN THE TUNIC OF THE ADULT. T. Numajiri, T. A. Nomaguchi*, and
H. Fujisawa. Fac. Educ., Saitama Univ. and *Tokyo Metropol. Inst.
Gerontol.
Growth of an ascidian larva implanted in the tunic of
the adult was investigated in vivo and in vitro. The materials used
were the ascidian Ciona intestinalis and C. savignyi obtained
at Kiba, Yokohama and Futtsu around Tokyo Bay. The implanted larvae
produced by self-fertilization were able to metamorphose into juveniles
in the tunic of their parents, whereas their metamorphosis was blocked
at the caudal or acaudal stage in the tunic of non-parental adults.
The growth of larvae produced by cross-fertilization was almost suppressed
at the caudal or acaudal stage in the tunic of both parental and non-parental
adults. The implanted larvae were enveloped in a capsule formed in
the tunic by the recipient (larva implanted adult). The capsules
enclosing the dead larvae became shrunken or the larvae was ejected from
the body of the adult. Growth of the larvae was also arrested in
vitro within the larval stage by blood cells from the non-parental adults.
These results indicate that blocking of the growth of implanted larvae
is dependent on an immunogenetic interaction between the donor (larva)
and the recipient.
THE RELATION BETWEEN PROTOCHORDATE ABD VERTEBRATE TROPONIN CS
H. J. Yuasa and T. Takagi. Biol. Inst., Grad. Sch. Science, Tohoku
Univ.
The troponin C (TnC) gene of the ascidian and amphioxus,
both belong to Protochordata, is a single copy gene. On the other
hand, mammal and birds possess two TnC genes, fast skeletal and slow/cardiac
TCs. In this study, we determined the cDNA of two TnC isoforms from
the frog and the lamprey. Thus it is supposed that the presence of
two TnC isoforms is unversal among vertebrate species, and that the gene
duplication might have occurred at a vertebrate ancestor after the protochordate/vertebrate
divergence. The distribution of introns in the TnC genes of protochordate
and vertebrate are identical, except 4th intron. One possibility
is to assume that the 4th intron sliding had occurred prior to the gene
duplication. Another possibility is that the difference of 4th intron
positions arised from the evolutionary independent gain of the intron.
If so, there might have been two lineages of the TnC, the protochordate-type
and the vertebrate-type.
IDENTIFICATION OF THE MYOPLASMIC COMPONENTS WHICH INTERACT WITH MYOPLASMIN-C1.
Y. Shibata and T. Nishikata. Fac. of Sci., Konan Univ., Kobe.
In the ascidian embryo, the myoplasm, which is thought
to contain muscle determinants, has a critical role in larval muscle
formation. Myoplasmin-C1 is a component of the myoplasm and is thought
to be important for the muscle cell differentiation. It is firmly associated
with the egg cytoskeleton. The sequence analysis revealed that the
myoplasmin-C1 could form coiled-coil structures on both ends and might
be a tethering molecule. In this study, using 6xHis-myoplasmin-C1
fusion proteins synthesized with pET-28(+) vector, we searched for the
molecules which can bind to the myoplasmin-C1. This in vitro binding assay
revealed that one of the myoplasmic component, p58, could interact with
myoplasmin-C1.
MTR1; A NOVEL PROTEIN WHICH RELATED TO THE OOPLASMIC SEGREGATION OF
THE ASCIDIAN Ciona intestinalis. R. Nakamori, A. R.
Murakami and T. Nishikata. Fac. of Sci., Konan Univ., Kobe.
In the fertilized ascidian egg, cytoplasmic domain called
myoplasm is thought to contain cytoplasmic determinants for the larval
muscle cell differentiation. The myoplasm is segregated into the appropriate
region of the egg by the movement of microtubules during ooplasmic segregation.
MTR1(microtubule related antigen 1), which is recognized by a monoclonal
antibody, shows a similar localization pattern to that of microtubules.
But, these two localization patterns are not identical. Moreover, MTR1
and microtubule have different relative molecular mass. During ooplasmic
segregation, MTR1 localized between the myoplasm and the egg cortex. This
result suggested that the MTR1 related to the segregation movement of the
myoplasm.
VIRIFORM CELL SEEN AS A NATIVE TUNIC CELL OF Halocynthia roretzi
THROUGH ANALYSIS OF GENOMIC DNA. T. Abe, S. Ohtake, F. Shishikura,
and K. Tanaka. Dept. of Biol., Nihon Univ. Sch. of Med., Tokyo.
Viriform cells crowd close to the epidermis and move freely
in the tunic matrix. There has been an argument on whether viriform
cells are natural or parasites. In order to find out, we examined
their genomic DNA fingerprints by RAPD. Tunic pieces of H. roretzi
were placed in a culture dish containing artificial sea water. Viriform
cells migrated from the cut surface and formed clusters exclusive of other
cell types on the substratum. The cells were collected from the clusters
in high purity of more than 95%. The genomic DNA was isolated from
mantle cells, hemocytes and viriform cells by proteinase K/phenol method.
When the genomic DNA was used as templates for polymerase chain reaction
(PCR) with 10-mer oligonucleotide primers (OPA-9 and OPA-18), fingerprints
similar to those of mantle cells, hemocytes and viriform cells from an
individual used. It is known that viriform cells constituted
the major population in the tunic matrix but are rare in the hemolymph
and not found in other tissues. It is concluded that
the viriform cell is a native cell and not a parasite of H. roretzi and
that it is a kind of tunic cell.
THE STRUCTURE OF "WHITE ROOTS" AND THE DISTRIBUTION OF VIRIFORM CELLS
IN THE ROOTS OF Halocynthia roretzi. Shin-Ichi Ohtake1,
Teruhisa Ishii2, and Kunio Tanaka1. 1Dept. of Biol., Nihon Univ.
Sch. of Med., Tokyo. 2Dept. of Natural & Envl. Sci., Fac. of Educ.
& Human Studies, Akita University, Akita.
Halocynthia roretzi is a sessile marine animal.
Animals reared in laboratory aquaria send out some new "white roots" (attachment
villi) from the tunic surface around the marginal zone of the animals within
a month. We observed new white and old roots by light microscopy
and electron microscopy. The new roots consist of the tunic cuticle,
tunic matrix and some tunic vessels. In the tunic matrix, viriform
cells are prominent. Many viriform cells distributed around the tunic
vessels (epidermis) were especially distinct. These findings are
basically the same in the old roots. The density of viriform cells
is, however, higher in the new roots. The cells crowded at an area
just under the cuticle where subcuticle is formed later. But the
cells were absent from the developed subcuticle layer of the old roots.
We find that the viriform cell is a native cell and not a parasite of H.
roretzi and believe it is a kind of tunic cell. This suggests
that viriform cells may play an important role in tunic formation and the
new root development of this ascidian.
IDENTIFICATION OF GELSOLIN-POSITIVE CELLS IN ASCIDIAN TADPOLE LARVA
AS EPIDERMAL NEURONS. Y. Ohtsuka1, Y. Okamura1 and T. Obinata2.
1Natl Inst. of Biosci. and Human Technology Agency of Industrial Sci. and
Technology M.I.T.I., Tsukuba; 2Dept. of Biol., Fac. of Sci., Chiba Univ.
We previously reported that gelsolin, an actin filament
severing and capping protein, was detectable in the cells within epidermis
during early embryogenesis. These cells possessed cilia which extended
into larval tunic. We assumed that they are epidermal sensory neurons
as judged by morphological characteristics TuNaI is neuron-specific
voltage-gated sodium channel, and its expression in tadpole was very similar
to that of gelsolin. In this study, to confirm that the gelsolin-positive
cells are epidermal sensory neurons, we performed two-color in situ hybridization
using both gelsolin- and TuNaI-specific riboprobes. Both signals
were detected in the same cells withinepidermis, whereas the signal of
troponin T, a marker for larval tail muscle, was detected in a pattern
distinct from the gelsolin-signal under the same condition. These
results indicate that the gelsolin-positive cells in epidermis are epidermal
neurons, and that transcription of gelsolin gene scarcely occurs in the
larval muscle, although gelsolin was abundant in the adult body wall muscle.
IDENTIFICATION OF THE INDIVIDUAL MOTOR NEURONS IN ASCIDIAN LARVAE
T. Okada1, Y. Katsuyama1, F.Ono, Y. Okamura 1,2,3.
1Lab of Cell Biochem., NIBH.,Tsukuba, 2Univ.of Tokyo; 3PRESTO., Japan Sci.
and Technology Corp., "Intelligence and Synthesis".
We previously showed that the motor neurons of ascidian
larvae originate from the A-line. However, the exact number and position
of motor neurons remains unknown. In this study, we identified motor neurons
in larvae of Halocynthia roretzi by expressing GFP protein under
control of a neuron-specific promoter. We microinjected the plasmid,
containing GFP gene linked to the native synaptotagmin promoter, into a
blastomere at the 8 and 16 cell stage. We observedGFP signals at the larval
stage with epifluorescense microscope. Wefound three motor neurons consecutively
lined up in the caudal neural tube. Judging from the distribution
of co-injected lineage tracer, these were the most three anterior cells
of the neural tube derived from A5.2. We called these neurons moto-A, -B,
and -C in order from anterior to posterior. Moto-A extends the axon onto
the ventral muscle cells. On the other hand, moto-B and C innervate the
dorsal muscle cells. Electronmicroscopic observation was also performed
on these neurons. We also found that some neurons originate from
A5.1 in the region just posterior to the sensory vesicle. These neurons
extend their axons toward motor neurons, suggesting that they are interneurons.
THE MOLECULAR PHYLOGENY OF THE GENUS Halocynthia Verrill.
T. Kakuda. Reseach Inst. for Integrated Sci., Kanagawa Univ.
On the coast of Japan, five species of the genus Halocynthia
Verrill are found. The phylogenetic relationships among three species
of the genus Halocynthia was inferred by the amino acid sequences
in the mitochondrial cytochrome b gene. In this study, 120 amino
acids of pertical cytochrome b gene were sequenced from five individuals
in each species, and a phylogenetic tree was constructed using Styela
clava Herdman as an outgroup. The phylogenetic tree revealed
H. roretzi (Drasche) and Halocynthia aurantium (Pallas) are
more closely related than the synonym of H. hispida (Herdman).
This shape of tree constructed from sequence data was much like the one
constructed from the data of restriction fragment length polymorphism (RFLP)
(Kakuda '97). However, proportion of base-pair substitution of sequence
data was far larger than the rate of RFLP data.
THE ROLE OF A VITELLINE COAT COMPONENT, HrVC70, IN FERTILIZATION OF
THE ASCIDIAN, Halocynthia roretzi. E. Tanaka, T. Abe,
H. Yokosawa and H. Sawada. Dept. Biochem., Grad. Sch. of Pharm. Sci.,
Hokkaido Univ.
Although mature eggs of several ascidians including Halocynthia
roretzi and Ciona intestinalis, which are hermaphroditic animals,
are self-sterile, immature oocytes and acidic seawater-pretreated mature
oocytes of these animals are self-fertile. We previously reported
that a 70-kDA component of the vitelline coat of H. roretzi (HrVC70) appears
to be specifically attached to the vitelline coat during oocyte maturation
and this molecule is released from the isolated vitelline coat by treat
ment with 1mM HCl. In the present study, we investigated the binding
ability of self- or non-self-sperm to the Affi-Gel 10 agarose beads that
were coupled with components released from the vitelline coat under acidic
conditions. We found that the number of nonself-sperm bound to the
beads is significantly larger than that in the case of self-sperm, suggesting
that HrVC70 is a candidate for a self-nonself recognition molecule in the
fertilization of H. roretzi. cDNA cloning of HrVC70 revealed
that it is made up of 12 EGF-like repeats, which are similar but not identical
to one another.
LOCALIZATION AND VITELLINE COAT-DEGRADING ACTIVITY OF SPERM PROTEASOMES
IN FERTILIZATION OF THE ASCIDIAN Halocynthia roretzi.
H. Sawada, Y. Takahashi, T. Abe, E. Tanaka, and H. Yokosawa.
Dept. Biochem., Grad. Sch. of Pharm. Sci., Hokkaido Univ.
We previous ly reported that the sperm 20S proteasome
and 26S-like high molecular mass proteasome are involved in sperm binding
to and penetration through the vitelline coat, respectively, of the eggs
of the ascidian, Halocynthia roretzi. Here, we investigated
the localization and vitelline coat-degrading activity of the proteasomes
during fertilization. Ascidian sperm were treated with NHS-LC-biotin
and extracted with CHAPS. Avidin-agarose chromatography of the extract
showed that about 40% of the total activity was adsorbed to the column,
suggesting that a part of the proteasome is exposed to the sperm cell surface.
About 70% of the total sperm proteasome activity was detected in the hydrophobic
fraction by fractionation with Triton X-114. In addition, Suc-Leu-Leu-Val-Tyr-MCA-hydrolyzing
activity, which is inhibited by MG115, was localized in the sperm head
and was activated by alkaline treatment, which can induce the ascidian
sperm reaction. It was found that the purified 26S-like proteasome
digested the vitelline coat 70kDa component (VC70) via the ubiquitin pathway.
Immunocytochemistry using anti-multi-ubiquitin antibody revealed that the
vitelline coat was ubiquitinated during fertilization.
CIS-REGURATORY ELEMENTS SPECIFICALLY CONSERVED IN THE VERTEBRATE TYROSINASE
GENE AFFECT EXPRESSION OF ASCIDIAN TYROSINASE FAMILY GENES OF A PROTOCHORDATE
Halocynthia roretzi. R. Toyoda1, S. Sato1, T.
Numakunai2, T. Gojobori3, K. Ikeo3 and H. Yamamoto1. 1Biol. Inst.
Yohoku Univ.; 2Marine Biol. Stn. Tohoku Univ., Asamushi; 3Natl. Inst. Genet.,
Mishima.
Tyrosinase family genes are expressed in pigment cells
and determine the vertebrate coloration. In tadople larvae of a Japanese
ascidian, Halocynthia roretzi, the tyrosinase gene is also expressed
specifically in pigment cells. To carry out a phylogenetic study
on the regulation of tyrosinase gene expression, we cloned a putative tyrosinase
gene and a gene encoding tyrosinase-related protein (TRP) from H. roretzi.
A deletion series of the 5' region of these genes were fused to a lacZ
reporter gene and microinjected into fertilized eggs of H. roretzi.
Pigment cell specific expression was obtained with as little as 250 base
pairs of 5' flanking sequence of the tyrosinase gene. In vertebrates,
there are several cis-elements playing important roles in expression of
tyrosinase family genes. Surprisingly, none of those vertebrate cis-elements
were found in the corresponding ascidian upstream region. Nonetheless,
we found that cis-elements are active if introduced into the ascidian fertilized
eggs. These results suggest a functional conservation of developmental
mechanism of pigment cells.
PHOTO-SENSITIVE NEURON IN THE CEREBRAL GANGLION OF ASCIDIAN, Ciona
savignyi.
H. Tsutsui and Y. Oka. Misaki Marine Biol. Station, Univ. Tokyo.
Biochemical and histochemical evidence has implicated
that the cerebral ganglion of adult ascidian may be a light-sensitive organ.
However, there has been no direct electrophysiological evidence to prove
this possibility. Here, we recorded membrane potentials from neurons
on the ventral side of the 'isolated neural complex preparation' of adult
ascidian, Ciona savignyi using intracellular microelectrodes.
Resting potentials of the neurons were -30~-60mV, and some of the neurons
showed various types of voltage responses to light stimuli. The voltage
responses could be categorized as follows: 1) transient hyperpolarization,
2) transient depolarization, 3) high frequency discharges, 4) off-responses
with discharges and sustained depolarization, and combinations of these.
Among these types, type (1) was the majority. Voltage responses of
neurons of type (1) showed all-or-none properties to different stimulus
duration, and response amplitude decreased during hyperpolarizing DC current
injections.
A MUSCLE-LIKE STRUCTURE OF Amphioxus NOTOCHORD. K.
Kubokawa1, K. Terakado2, and S. Kimura3. 1Ocean Research Inst., Univ.
Tokyo; 2Dept. Regul. Biol., Fac. Sci., Saitama Univ.; 3 Dept. Biol., Fac.
Sci., Chiba Univ.
The notochord of Amphioxus has been shown to be
derived from striated muscle cells by electron microscopy (Flood 1968;
Welsch 1968). The present detailed observations revealed that the
striation of Amphioxus notochord differs from that of muscle. An
SDS PAGE examination showed the presence of muscle myosin heavy chains
and of actin. An actin antibody cross-reacted with the actin band.
It is to be mentioned that pieces of glycerinated notochord did not contract
at all on addition of MgATP and Ca 2+. The unique striated structure
of Amphioxus notochord will be discussed in detail.
5. Amer. Soc. for Cell Biol. meeting (San Francisco Dec12-16, 1998)
LOCALIZATIONS AND MYOGENIC DETERMINANTS IN THE ASCIDIAN EGG. J Chenevert,F Roegiers, C Sardet. Station Zoologique, Villefranche sur Mer, 06230 France. Molec Biol of the Cell(1998) Vol 9 supplement,abst 354.
PHASES OF CORTICAL AND CYTOPLASMIC REORGANIZATIONS IN THE ASCIDIAN ZYGOTE. Sardet, C., F Roegiers, C Djediat, R Dumollard, C Rouviere, P Dru, & J Chenevert. Abstract L12 late abstracts poster session
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Bak, R.P.M. 1998. Bacterial suspension feeding by coral reef benthic organisms. Mar. Ecol. Prog. Ser. 175:285-288.
Bingham, B.L. & N.B. Reyns 1999. Ultraviolet radiation and distribution of the solitary ascidian Corella inflata (Huntsman). Biol. Bull. 196:94-104.
Birkeland, C., L. Cheng & R. Lewin 1981. Motility of didemnid ascidian colonies. Bull. Mar. Sci. 31:170-173.
Bishop, J.D.D. & A.D. Sommerfeldt 1999. Not like Botryllus: indiscriminate post-metamorphic fusion in a compound ascidian. Proc. R. Soc. Lond. B 266:241-248.
Bochdansky, A.B. & D. Deibel 1999a. Functional feeding response and behavioral ecology of Oikopleura vanhoeffeni (Appendicularia, Tunicata). J. Exp. Mar. Biol. Ecol. 231:181-211.
Bochdansky, A.B. & D. Deibel 1999b. Measurement of in situ clearance rates of Oikopleura vanhoeffeni (Appendicularia: Tunicata) from tail beat frequency, time spent feeding and individual body size. Mar. Biol. 133:37-44.
Cohen, A.N. & J.T. Carlton 1998. Accelerating invasion rate in a highly invaded estuary. Science 279:555-558.
Cole, L. & M. Vorontsova 1998. Species of Pyuridae (Ascidiacea) from South Vietnam. Bull. Mar. Sci. 62:1-6.
Corbo, J.E., S. Fujiwara, M. Levine & A. Di Gregorio 1998. Suppressor of hairless activates Brachyury expression in the Ciona embryo. Dev. Biol. 203:358-368.
D'Aniello 1999. Localization of hatching enzyme in embryos and larvae of Ciona intestinalis. Molec. Repro. & Develop. 34:247-252.
D'Aniello, A., F. De Bernardi, M. De Vincentiis, U. Fascio, S. Groppelli, S. Scippa, et al. 1998. Localization of hatching enzyme in embryos and larvae of the sea-squirt Ciona intestinalis. Invert. Repro. & Develop. 34:247-252.
D'Aniello, A., M.J. Denuce, M. de Vincentiis, M.M. Di Fiore & S. Scippa 1997. Hatching enzyme from the sea-squirt Ciona intestinalis: purification and property. Biochim. Biophys. Acta 1339:101-112.
Di Bella, M.A., G. Cassara, D. Russo & G. De Leo 1998. Cellular components and tunic architecture of the solitary ascidian Styela canopus (Stolidobranchiata, Styelidae). Tiss. & Cell 30:352-359.
Di Fiore, M.M., L. Perrone & A. D'Aniello 1997. Presence of a human-like thyroid stimulating hormone (TSH) in Ciona intestinalis. Life Sci. 61:623-629.
Di Gregorio, A., M.G. Villani, A. Locascio, F. Ristoratore, F. Aniello & M. Branno 1998. Developmental regulation and tissue-specific localization of calmodulin mRNA in the protochordate Ciona intestinalis. Develop. Growth Differ. 40:387-394.
Fernandez, J., F. Roegiers, V. Cantillana & C. Sardet 1998. Formation and localization of cytoplasmic domains in leech and ascidian eggs. Int. J. Dev. Biol. 42:1075-1084.
Frank, P., B. Hedman & K.O. Hodgson 1999. Sulfur allocation and vanadium-sulfur interactions in whole blood cells from the tunicate Ascidia ceratodes, investigated using X-ray absorption spectroscopy. Inorg. Chem. 38:260-270.
Fuke, M. & T. Numakunai 1999. Self-sterility of eggs induced by exogenous and endogenous protease in the solitary ascidian, Halocynthia roretzi. Molec. Repro. & Develop. 52:99-106.
Garrett, F.E., S. Goel, J. Yasul & R.A. Koch 1999. Liposomes fuse with sperm cells and induce activation by delivery of impermeant agents. Biochim. Biophys. Acta 1417:77-88.
Gionti, M., F. Ristoratore, A. Di Gregorio, F. Aniello, M. Branno & R. Di Lauro 1997. Cihox 5, a new Ciona intestinalis Hox-related gene, is involved in regionalization of the spinal chord. Dev. Genes & Evol. :.
Giuliano, P., R. Marino, M.R. Pinto & R. De Santis 1998. Identification and developmental expression of Ci-isl, a homologue of vertebrate islet genes, in the ascidian Ciona intestinalis. Mechanisms of Development 78:199-202.
Godeaux, J.E.A. 1999. The Thaliaceans, a group of animals refractory to Lessepsian migration: an updated survey of their populations in the Levantine Basin and the Red Sea. Israel J. Zool. 45:91-100.
Hirose, E., S. Kimura, T. Itoh & J. Nishikawa 1999. Tunic morphology and cellulosic components of pyrosomes, doliolids, and salps (Thaliacea, Urochordata). Biol. Bull. 196:113-120.
Jeffery, W.R., N. Ewing, J. Machula, C.L. Olsen & B.J. Swalla 1998. Cytoskeletal actin genes function downstream of HNF-3beta in ascidian notochord development. Int. J. Dev. Biol. 42:1085-1092.
Johnson, S. & E.A. Widder 1998. Transparency and visibility of gelatinous zooplankton from the northwest Atlantic--Gulf of Mexico. Biol. Bull. 195:337-348.
Kajihara, T., R. Hirano & K. Chiba 1975. Marine fouling animals in the Bay of Hamana-ko, Japan. The Veliger 18:361-366.
Knight, J., G.W. Taylor, P. Wright, A.S. Clare & A.F. Rowley 1999. Eicosanoid biosynthesis in an advanced deuterostomate invertebrate, the sea squirt (Ciona intestinalis). Biochim. Biophys. Acta 1436:467-478.
Kott, P. 1998. Hemichordata, Tunicata, Cephalochordata. pp. 51-252, 259-261 in Zoological Catalogue of Australia, ed. vol. 34, ed. by Wells, A. & W.W.K. Houston.
McDougall, A. & M. Levasseur 1998. Sperm-triggered calcium oscillations during meiosis in ascidian oocytes first pause, restart, then stop: correlations with cell cycle kinase activity. Development 125: 4451-4459.
McRory, J.E. & N.M. Sherwood 1997a. Ancient divergence of insulin and insulin-like growth factor. DNA and Cell Biol. 16: 939-949.
McRory, J. & N.M. Sherwood 1997b. Two protochordate genes encode pituitary adenylate cyclase-activating polypeptide and related family members. Endocrinology 138: 2380-2390.
Michibata, H. & K. Kanamori 1998. Selective accumulation of vanadium by ascidians from sea water. pp. 217-249 in Vanadium in the Environment. Part I: Chemistry and Biochemistry, ed. vol., ed. by Nriagu, J.O.
Naranjo, S.A. et al. 1998. Towards a knowledge of marine boundaries using ascidians as indicators. Biol. J. Linn. Soc. 64: 151-177.
Nette, G.W., S. Scippa & M. de Vincentiis 1998. Cytochemical localisation of vanadium(III) in the ascidian Phallusia mammillata Cuvier during development. Invert. Repro. & Develop. 34: 195-196.
Nielsen, C. 1998. Morphological approaches to phylogeny. Amer. Zool. 38: 942-952.
Nielsen, C. 1999. Origin of the chordate central nervous system - and the origin of chordates. Dev. Genes & Evol. 209: 198-205.
Nishikawa, T. 1998a. Morphology, taxonomy, natural history [in Japanese]. pp. 3-21 in Biology of Ascidians [in Japanese], ed. vol., ed. by Satoh, N.
Nishikawa, T. 1998b. Notes on recent occurrences of an ascidian, Halocynthia roretzi (Drasche), along the coast of Mie and Aichi Prefectures, central Japan [in Japanese; English abstract]. Studies in Informatics and Sciences No.8: 79-89.
Nishino, A. & M. Morisawa 1998. Rapid oocyte growth and artificial fertilization of the larvaceans Oikopleura dioica and Oikopleura longicauda. Zool. Sci. 15: 723-727.
Norley, M.C. & G. Pattenden 1998. Total synthesis and revision of stereochemistry of cyclodidemnamide, a novel cyclopeptide from the marine ascidian Didemnum molle. Tetrahed. Lett. 39: 3087-3090.
Patricolo, E., L. Villa & P. D'Agati 1998. Polar body formation in Ascidia malaca eggs: a SEM and Nomarski optics study. Anim. Biol. 7:71-78.
Petersen, J.K., S. Mayer & M.A. Knudsen 1999. Beat frequency of cilia in the branchial basket of the ascidian Ciona intestinalis in relation to temperature and algal cell concentration. Mar. Biol. 133:185-192.
Ribes, M., R. Coma & J.M. Gili 1998. Seasonal variation of in situ feeding rates by the temperate ascidian Halocynthia papillosa. Mar. Ecol. Prog. Ser. 175:201-213.
Ricciardi, A. & E. Bouget 1998. Weight-to-weight conversion factors for marine benthic macroinvertebrates. Mar. Ecol. Prog. Ser. 163: 245-251.
Rinkevich, B. 1998. Transplantation of Fu/HC-incompatible zooids in Botryllus schlosseri results in chimerism. Biol. Bull. 195: 98-106.
Rinkevich, B., Porat & Goren 1999. Development and reproduction of Botryllus schlosseri from the eastern Mediterranean. Molec. Repro. & Develop. 34:207-218.
Sanamyan, K. 1998. Ascidians from the North-western Pacific region. 5. Phlebobranchia. Ophelia 49:97-116.
Sanamyan, K.E. & N.P. Sanamyan 1998. Some deep-water ascidians from the NW Pacific (Tunicata: Ascidiacea). Zoosystematica Rossica 7:209-214.
Sardet, C., F. Roegiers, R. Dumollard, C. Rouviere & A. McDougall 1998. Calcium waves and oscillations in eggs. J. Biophys. Chem. 72:131-140.
Sardet, C., C. Rouviere, B. Flannery & J. Davoust 1991. Time lapse confocal microscopy of mitochondrial movements in ascidian embryos. Amer. Inst. of Physics 226:77-82.
Sardet, C., J. Speksnidjer, S. Inoue & L. Jaffe 1989. Fertilization and ooplasmic movements in the ascidian egg. Development 105:237-249.
Satoh, N. 1998. Mechanisms of specification in ascidian embryos. Biol. Bull. 195:381-383.
Stewart-Savage, J., B.J. Wagstaff & P.O. Yund 1999. Developmental basis of phenotypic variation in egg production in a colonial ascidian: primary oocyte production versus oocyte development. Biol. Bull. 196:63-69.
Stoecker, D. 1980. Distribution of acid and vanadium in Rhopalaea birkelandi Tokioka. J. Exp. Mar. Biol. Ecol. 48:277-281.
Uyama, T., K. Yamamoto, K. Kanamon & H. Michibata 1998. Glucose-6-phosphate dehydrogenase in the pentose phosphate pathway is localized in vanadocytes of the vanadium-rich ascidian, Ascidia sydneiensis samea. Zool. Sci. 15:441-446.
Wilding, M., K. Kyozuka & B. Dale 1997. Multiple pathways to calcium release in unfertilized ascidian oocytes stimulated by ascidian sperm extract. Zygote :.
Wilding, M., G.L. Russo, B. Dale, M. Marino & A. Galione 1997.
A major role for ADPr in ascidian oocyte activation. Development
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