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Malintoi, Adrianus, Inneke F. M. Rumengan, Kakaskasen A. Roeroe, Veibe Warouw, Ari B. Rondonuwu i Medy Ompi. "KOMUNITAS ASCIDIA DI PESISIR MALALAYANG DUA, TELUK MANADO, SULAWESI UTARA". JURNAL PESISIR DAN LAUT TROPIS 8, nr 1 (15.01.2020): 39. http://dx.doi.org/10.35800/jplt.8.1.2020.27403.
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Field survey on ascidian community was conducted along the coastal area of Malalayang Dua in order to find out species of ascidia, species abundance, and ascidian substrates. A survey method and quadrant transects were applied. Pictures were taken, while species and their substrates were sampled. Species identification was based on morphological characteristics, while substrate type identification was based on ascidian species attachment. The results shows that 21 ascidian species were found in the the coastal of Malalayang Dua. Didemnum molle was the highest abundant species in the area, followed by Polycarpa aurata, Polycarpa sp.4. and Polycarpa sp.2.. Dead coral algaes (DCA) were found to be the most preferred substrates by ascidians in the area. Keywords : ascidia, species, substrate, distribution, and abundance Survei lapangan terhadap komunitas ascidia dilakukan di pesisir Malalayang Dua untuk mendapatkan data jenis, kelimpahan, dan substrat ascidia. Metode yang digunakan yaitu metode survei jelajah dan transek kuadran. Identifikasi jenis ascidia dilakukan berdasarkan karakteristik morfologi. Hasil penelitian ditemukan ada 21 jenis ascidia. Substrat jenis death coral algae (DCA) merupakan substrat yang paling banyak ditempati ascidia. Kelimpahan ascidia tertinggi adalah Didemnum molle di pesisir Malalayang Dua, diikuti oleh Polycarpa aurata, Polycarpa sp.4. dan Polycarpa sp.2. Death coral alga (DCA) ditemukan sebagai substrat yang paling disukai oleh ascidia di daerah itu. Kata Kunci : ascidia, spesies, substrat, distribusi, dan kelimpahan
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KNEER, DOMINIK, FRANCOISE MONNIOT, THOMAS STACH i MARJOLIJN J. A. CHRISTIANEN. "Ascidia subterranea sp. nov. (Phlebobranchia: Ascidiidae), a new tunicate belonging to the A. sydneiensis Stimpson, 1855 group, found as burrow associate of Axiopsis serratifrons A. Milne-Edwards, 1873 (Decapoda: Axiidae) on Derawan Island, Indonesia". Zootaxa 3616, nr 5 (22.02.2013): 485–94. http://dx.doi.org/10.11646/zootaxa.3616.5.5.
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A new tunicate, Ascidia subterranea sp. nov., was found in burrows of the axiid crustacean Axiopsis serratifrons on De-rawan Island, Indonesia. It differs from other ascidians in its habitat as well as numerous morphological peculiarities which are described in detail. The shrimp Rostronia stylirostris Holthuis, 1952 was found inside A. subterranea sp. nov., and 4 species of bivalves, 3 species of polychaetes, 1 gastropod, 1 polyplacophoran and 1 sponge species were found as burrow associates besides the ascidian.
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Leleran, Andreas J. P. L., Silvester B. Pratasik, Meiske S. Salaki, Lawrence J. L. Lumingas, Alex D. Kambey i Suzanne L. Undap. "Distribution and Diversity of Ascidian in Manado Bay, North Sulawesi". Jurnal Ilmiah PLATAX 10, nr 1 (14.04.2022): 124. http://dx.doi.org/10.35800/jip.v10i1.38842.
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The purpose of this study was to determine the distribution and the diversity of ascidians in Manado Bay including species composition, density, diversity, and dominance. This study used the quadrat transect method. This study found differences in the number of ascidian species with water depth, 11 species of 5 families at 15 M depth, and 8 species of 3 families at 7 M depth. The diversity index ranged from 0.868 to 1.844 at 15 M depth and 0.965 to 1.864 at 7 M depth, the evenness index was 0.533 – 0.839 at 15 M depth and 0.600 – 0.897 at 7 M depth, the dominance index was 0.254 – 0.745 at 15 M depth and 0.254 – 0.708 at 7 M depth. Ascidian in Manado Bay had two distribution patterns, a uniform distribution pattern and a clustered distribution pattern. Environmental parameters had a water temperature of 27 oC – 31 oC, the salinity of 30 0/00 – 32 0/00, the brightness of 12 m – 14 m, and pH of 8 – 10.*Keywords: Ascidian; diversity; ecological index; distribution patternAbstrakTujuan dari penelitian ini adalah untuk mengetahui distribusi dan keanekaragaman jenis ascidia di perairan Teluk Manado meliputi: komposisi jenis, kepadatan individu, keanekaragaman, dan dominansi. Serta mengetahui pola distribusi ascidia. Penelitian ini menggunakan metode transek kuadran. Pada penelitian ini ditemukan perbedaan jumlah spesies ascidia menurut kedalaman, 11 spesies dari 5 family pada 15 M dan 8 spesies dari 3 famili pada kedalaman 7 m. Nilai indeks keanekaragaman ascidia di kedalaman 15 m = 0.868 – 1.844 dan 7 m = 0.965 - 1.864, indeks keseragaman 15 m = 0.533 – 0.839 dan 7 m = 0.600 – 0.897, indeks Dominasi15 m = 0.254 – 0.745 dan 7 m = 0.254 – 0.708. Ascdia di perairan Teluk Manado memiliki dua pola distribusi yaitu pola distribusi seragam dan pola distribusi mengelopok. Parameter lingkungan memiliki suhu air 27 oC – 31 oC, salinitas 30 0/00 – 32 0/00, kecerahan 12 m – 14 m, dan pH 8 – 10.*Kata kunci : Ascidia; keanekaragaman; indeks ekologi; pola distribusi
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Musak, Putra, Christian Palit, Mutiara Ratih i Deiske A. Sumilat. "KOMPOSISI JENIS DAN KEPADATAN ASCIDIA Rhopalaea sp. DI PESISIR PANTAI KINAMANG, MALALAYANG DUA, TELUK MANADO". JURNAL PESISIR DAN LAUT TROPIS 10, nr 3 (2.10.2022): 240–45. http://dx.doi.org/10.35800/jplt.10.3.2022.55008.
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Ascidian is one of the marine biotas with considerable potential in Indonesian waters but has not received serious attention. Therefore, a little research on this species is good to do with the aim of knowing the species composition and density of Rhopalaea sp. in Manado Bay waters with different depths. The purpose of this study was to analyze the Ascidian index to determine the species composition and density of Ascidian Rhopalaea sp. at different depths in Manado Bay waters, in this case the Kinamang coastal waters, Malalayang Dua. This research was carried out for 5 (five) months starting from April to August 2022. The tools and materials used in this study were: Global Positioning System (GPS), SCUBA set, roll meter, waterproof paper, writing utensils, camera, identification books, Horiba, laptop, Microsoft excel software and Ascidian. Data analysis was conducted to determine the composition and density of Ascidia Rhopalaea sp. The results obtained are Ascidia Rhopalaea sp. found there are 2 types, namely Rhopalaea and Rhopalaea crassa. After analyzing the data, Ascidian species R. crassa had higher composition and density values than Rhopalaea species.
Keywords: Ascidian, Species Composition, Density, Manado Bay
ABSTRAK
Ascidia merupakan salah satu biota laut dengan potensi yang cukup besar di Perairan Indonesia akan tetapi belum mendapatkan perhatian yang serius. Oleh karena masih sedikit penelitian mengenai jenis ini sehingga penelitian ini baik untuk dilakukan dengan tujuan untuk mengetahui komposisi jenis dan kepadatan jenis Rhopalaea di Perairan Teluk Manado dengan kedalaman berbeda. Tujuan penelitian ini yaitu menganalisis indeks ascidia untuk mengetahui komposisi jenis dan kepadatan Ascidia Rhopalaea sp. pada kedalaman yang berbeda di Perairan Teluk Manado dalam hal ini perairan pesisir Kinamang, Malalayang Dua. Penelitian ini dilaksanakan selama 5 (lima) bulan dimulai pada bulan April sampai dengan Agustus tahun 2022. Alat dan bahan yang digunakan dalam penelitian ini yaitu : Global positioning system (GPS), Set SCUBA, roll meter, kertas anti air, alat tulis menulis, kamera, buku identifikasi, Horiba, laptop, software microsoft excel dan ascidia. Analisis data dilakukan untuk mengetahui komposisi jenis dan kepadatan Ascidia Rhopalaea sp. Hasil yang didapat yaitu Ascidia Rhopalaea sp. yang ditemukan berjumlah 2 jenis yaitu Rhopalaea dan Rhopalaea crassa. Setelah dilakukan Analisa data, Ascidia jenis R. crassa memiliki nilai komposisi jenis dan kepadatan yang lebih tinggi dari jenis Rhopalaea.
Kata Kunci: Ascidia, Komposisi Jenis, kepadatan, Teluk Manado
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Macpal, Yuliana, Veibe Warouw, Deiske A. Sumilat, James J. H. Paulus, Natalie D. C. Rumampuk i Reni L. Kreckhoff. "AKTIVITAS ANTIBAKTERI DAN ANTI-UV BEBERAPA ASCIDIAN DARI PERAIRAN PANGALISANG BUNAKEN". JURNAL PESISIR DAN LAUT TROPIS 7, nr 3 (23.07.2019): 271. http://dx.doi.org/10.35800/jplt.7.3.2019.26019.
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Ascidians are sesile marine invertebrates that have bioactive compounds such as antibacterial and anti-UV. The purpose of this study is to determine the antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria and to test the anti-UV activity of the ascidian water fraction. Antibacterial activity test was carried out using the diffusion method (disc diffusion Kirby & Bauer) and the water fraction of ascidian that showing antibacterial activity tested in a UV spectrophotometer to see the anti-UV activity. Results of the study were obtained 4 types of ascidians extracted from partitioned into water fraction, n-hexane fraction, methanol fraction. All three fractions were tested for antibacterial activity and the result showed that there were antibacterial activities of ascidian extract Clavelina sp. against both test bacteria with inhibition of S. aureus and E. coli with strong categories. Ascidian Phlebobranch sp. showed the presence of antibacterial activity with inhibition of S. aureus and E. coli with very strong categories (16,6 mm). extract Eudistoma sp. showed the presence of antibacterial activity with inhibition S. aureus and E. coli in the medium category (9 mm). The water fraction found active in antibacterial testing is then tested using a UV spectrophotometer for anti UV testing, the result show that water fraction of the four ascidians can absorb UV-B (290-320nm) and UV-A ( 320-400nm).Keywords : Ascidian, Antibacterial, Partition, Anti- UV.
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Tatian, M., R. J. Sahade, M. E. Doucet i G. B. Esnal. "Ascidians (Tunicata, Ascidiacea) of Potter Cove, South Shetland Islands, Antarctica". Antarctic Science 10, nr 2 (czerwiec 1998): 147–52. http://dx.doi.org/10.1017/s0954102098000194.
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Certain physical factors, substrate type and ice action appear to be important determinants for ascidian distribution. Three different substrate types were sampled at depths between 0–30 m by SCUBA diving: soft bottoms, hard bottoms and moraine deposits. The species found were Aplidium radiatum, Synoicum adareanum, Distaplia cylindrica, Sycozoa gaimardi, Sycozoa sigillinoides, Tylobranchion speciosum, Corella eumyota, Ascidia challengeri, Cnemidocarpa verrucosa, Styela wandeli, Dicarpa insinuosa, Pyura bouvetensis, Pyura discoveryi, Pyura obesa, Pyura setosa, Molgula enodis and Molgula pedunculata. Highest diversity and patchy distribution was found in less stringent environments, where epibiosis is a commmon phenomenon on stolidobranch ascidians. Differences in stalk development were found in the most abundant species Molgula pedunculata and Cnemidocarpa verrucosa. Ice action may be the main factor that determines the absence of ascidians above 15 m in all the stations sampled.
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Hasegawa, Naohiro, Natsumi Hookabe, Yoshihiro Fujiwara, Naoto Jimi i Hiroshi Kajihara. "Supplemental re-description of a deep-sea ascidian, Fimbrora calsubia (Ascidiacea, Enterogona), with an inference of its phylogenetic position". Zoosystematics and Evolution 100, nr 1 (26.01.2024): 129–40. http://dx.doi.org/10.3897/zse.100.113132.
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Fimbrora Monniot & Monniot, 1991, a macrophagous ascidian genus within the family Ascidiidae Adams & Adams, 1858, is currently monotypic, represented by F. calsubia Monniot & Monniot, 1991, a species previously recorded from the bottom of the South Pacific at depths of 1000–1860 m. The taxonomic status of Fimbrora has remained ambiguous because characteristics in its branchial papillae and neural-gland opening are incompletely known in previous studies, while these traits are essential for distinguishing other ascidiid genera. So far, no nucleotide sequence representing F. calsubia is available. In this study, we collected a single specimen of F. calsubia at a depth of 2027 m, about 400 km off the Pacific coast of Honshu, Japan. This is the deepest record, as well as the first report from the North Pacific, for the species. Our examination indicates that Fimbrora is morphologically similar to another ascidiid genus, Psammascidia Monniot, 1962, by having only secondary branchial papillae in the pharynx. Our phylogenetic analysis, based on the 18S ribosomal RNA and cytochrome c oxidase subunit I genes, along with those of 27 ascidian species available in public databases, showed that F. calsubia was more closely related to Ascidia zara Oka, 1935, Phallusia fumigata (Grube, 1864) and Phallusia mammilata (Cuvier, 1815) than to Ascidia ceratodes (Huntsman, 1912), Ascidiella aspersa (Müller, 1776) and Ascidiella scabra (Müller, 1776). Our results also indicated that acquisitions of macrophagous feeding by deep-sea members happened independently at least three times in the evolutionary history of the entire Ascidiacea.
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Koike, I., M. Yamamuro i PC Pollard. "Carbon and nitrogen budgets of two Ascidians and their symbiont, Prochloron, in a tropical seagrass meadow". Marine and Freshwater Research 44, nr 1 (1993): 173. http://dx.doi.org/10.1071/mf9930173.
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Two species of ascidian, Didemnum molle Herdman and Lissoclinum voeltzkowi Michaelsen, were collected from a Fijian seagrass meadow. The primary production of their symbiont (Prochloron), the inorganic nitrogen metabolism and the filtration rate were measured to assess the nutritional coupling between the symbiont and the host animal. The loss of organic carbon due to the respiration of D. molle (1.1 �g at. C (mg dry wt)-1 day-1) was greater than that supplied through photosynthesis of the Prochloron (0.69 �g at. C (mg dry wt)-1 day,-1). The carbon supplied through filter-feeding appeared to supplement the ascidian's carbon budget. In contrast, organic carbon from the Prochloron of L. voeltzkowi appeared to meet the colony's respiration needs. The nitrogen budgets of both ascidian colonies were estimated from their respiration rates, the nitrogen requirement of the Prochloron, and the uptake of inorganic nitrogen and particulate organic nitrogen uptake from the water column. The nitrogen incorporated from the surrounding environment could contribute to the net nitrogen gain of the colony. However, our estimate of the nitrogen needed by the Prochloron was much greater than that which could be supplied externally. The amount of nitrogen released by the ascidians was also greater than that which could be supplied externally. This suggests that nitrogen is efficiently recycled within the symbiotic Prochloron-ascidian relationship.
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Hirose, Euichi, Kaori Ohtsuka, Masaharu Ishikura i Tadashi Maruyama. "Ultraviolet absorption in ascidian tunic and ascidian-Prochloron symbiosis". Journal of the Marine Biological Association of the United Kingdom 84, nr 4 (sierpień 2004): 789–94. http://dx.doi.org/10.1017/s0025315404009956h.
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To characterize the ultraviolet (UV) light-absorbing function of the ascidian tunic, the light absorption spectrum was compared in 22 ascidian species collected from tropical and temperate waters. Non-photosymbiotic ascidians (17 species) had transparent tunics transmitting both visible and UV light, or pigmented or opaque tunics equally absorb both UV and visible light. However, a prominent absorption peak around 320 nm was exclusively found in the colonial ascidians hosting the algal symbiont Prochloron sp., and this absorption peak corresponded to absorption of UV-A (320–400 nm) and UV-B (280–320 nm). The UV-absorbing substances were extracted with methanol. They were mycosporine-like amino acids (MAAs): mycosporine-glycine, palythine, shinorine, and porphyra-334. The MAAs are thought to be synthesized by the shikimic acid pathway that does not occur in animals. Since the isolated Prochloron cells contain MAAs, the symbionts are the most possible candidates as the source of the MAAs in the tunic. In Diplosoma virens, the composition of MAAs was different between isolated Prochloron cells and colony residue from which Prochloron cells were extracted.
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Cone, Angela C., i Robert W. Zeller. "Using ascidian embryos to study the evolution of developmental gene regulatory networks". Canadian Journal of Zoology 83, nr 1 (1.01.2005): 75–89. http://dx.doi.org/10.1139/z04-165.
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Ascidians are ideally positioned taxonomically at the base of the chordate tree to provide a point of comparison for developmental regulatory mechanisms that operate among protostomes, non-chordate deuterostomes, invertebrate chordates, and vertebrates. In this review, we propose a model for the gene regulatory network that gives rise to the ascidian notochord. The purpose of this model is not to clarify all of the interactions between molecules of this network, but to provide a working schematic of the regulatory architecture that leads to the specification of endoderm and the patterning of mesoderm in ascidian embryos. We describe a series of approaches, both computational and biological, that are currently being used, or are in development, for the study of ascidian embryo gene regulatory networks. It is our belief that the tools now available to ascidian biologists, in combination with a streamlined mode of development and small genome size, will allow for more rapid dissection of developmental gene regulatory networks than in more complex organisms such as vertebrates. It is our hope that the analysis of gene regulatory networks in ascidians can provide a basic template which will allow developmental biologists to superimpose the modifications and novelties that have arisen during deuterostome evolution.
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Rocha, Rosana Moreira, Edlin Guerra-Castro, Carlos Lira, Sheila Marquez Pauls, Ivan Hernández, Adriana Pérez, Adriana Sardi i in. "Inventory of ascidians (Tunicata, Ascidiacea) from the National Park La Restinga, Isla Margarita, Venezuela". Biota Neotropica 10, nr 1 (marzec 2010): 209–18. http://dx.doi.org/10.1590/s1676-06032010000100021.
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Although ascidians form a conspicuous part of sessile assemblages in the Caribbean, no specialized inventories have been developed in Venezuela, except for a list of 15 species reported from Margarita Island (1984). Here we present the results of a taxonomic workshop held in the Universidad de Oriente, Boca del Rio, Margarita Island during April 20-25 of 2009, sponsored by the NaGISA-Caribbean Sea program. La Restinga National park was surveyed and we found 29 species belonging to 19 genera and 10 families. The most abundant colonial species were Clavelina oblonga, Aplidium accarense, Polyclinum constellatum, Distaplia bermudensis, Symplegma rubra, S. brakenhielmi, Botrylloides nigrum and Ecteinascidia turbinata. Among the solitary ascidians Phallusia nigra, Ascidia curvata, Microcosmus exasperatus, Styela canopus, Styela sp.1 and Styela sp. 2 were the most abundant. The ascidian diversity in this lagoon is one of the highest for similar habitats in the Caribbean and seven species are new registers for Venezuela (Ascidia curvata, Ecteinascidia styeloides, Aplidium accarense, Distaplia stylifera, Trididemnum orbiculatum, Symplegma rubra, and S. brakenhielmi). One point of concern for the conservation of la Restinga National Park is the presence of possible introduced species, and some management procedures are suggested.
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Kawada, Tsuyoshi, Michio Ogasawara, Toshio Sekiguchi, Masato Aoyama, Kohji Hotta, Kotaro Oka i Honoo Satake. "Peptidomic Analysis of the Central Nervous System of the Protochordate, Ciona intestinalis: Homologs and Prototypes of Vertebrate Peptides and Novel Peptides". Endocrinology 152, nr 6 (5.04.2011): 2416–27. http://dx.doi.org/10.1210/en.2010-1348.
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The phylogenetic position of ascidians as the chordate invertebrates closest to vertebrates suggests that they might possess homologs and/or prototypes of vertebrate peptide hormones and neuropeptides as well as ascidian-specific peptides. However, only a small number of peptides have so far been identified in ascidians. In the present study, we have identified various peptides in the ascidian, Ciona intestinalis. Mass spectrometry-based peptidomic analysis detected 33 peptides, including 26 novel peptides, from C. intestinalis. The ascidian peptides are largely classified into three categories: 1) prototypes and homologs of vertebrate peptides, such as galanin/galanin-like peptide, which have never been identified in any invertebrates; 2) peptides partially homologous with vertebrate peptides, including novel neurotesin-like peptides; 3) novel peptides. These results not only provide evidence that C. intestinalis possesses various homologs and prototypes of vertebrate neuropeptides and peptide hormones but also suggest that several of these peptides might have diverged in the ascidian-specific evolutionary lineage. All Ciona peptide genes were expressed in the neural complex, whereas several peptide gene transcripts were also distributed in peripheral tissues, including the ovary. Furthermore, a Ciona neurotensin-like peptide, C. intestinalis neurotensin-like peptide 6, was shown to down-regulate growth of Ciona vitellogenic oocytes. These results suggest that the Ciona peptides act not only as neuropeptides in the neural tissue but also as hormones in nonneuronal tissues and that ascidians, unlike other invertebrates, such as nematodes, insects, and sea urchins, established an evolutionary origin of the peptidergic neuroendocrine, endocrine, and nervous systems of vertebrates with certain specific molecular diversity.
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Wada, H., H. Saiga, N. Satoh i P. W. Holland. "Tripartite organization of the ancestral chordate brain and the antiquity of placodes: insights from ascidian Pax-2/5/8, Hox and Otx genes". Development 125, nr 6 (15.03.1998): 1113–22. http://dx.doi.org/10.1242/dev.125.6.1113.
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Ascidians and vertebrates belong to the Phylum Chordata and both have dorsal tubular central nervous systems. The structure of the ascidian neural tube is extremely simple, containing less than 400 cells, among which less than 100 cells are neurons. Recent studies suggest that, despite its simple organization, the mechanisms patterning the ascidian neural tube are similar to those of the more complex vertebrate brain. Identification of homologous regions between vertebrate and ascidian nervous systems, however, remains to be resolved. Here we report the expression of HrPax-258 gene: an ascidian homologue of vertebrate Pax-2, Pax-5 and Pax-8 genes. Molecular phylogenetic analyses indicate that HrPax-258 is descendant from a single precursor gene that gave rise to the three vertebrate genes. The expression pattern of HrPax-258 suggests that this subfamily of Pax genes has conserved roles in regional specification of the brain. Comparison with expression of ascidian Otx (Hroth) and a Hox gene (HrHox1) by double-staining in situ hybridizations indicate that the ascidian brain region can be subdivided into three regions; the anterior region marked by Hroth probably homologous to the vertebrate forebrain and midbrain, the middle region marked by HrPax-258 probably homologous to the vertebrate anterior hindbrain (and maybe also midbrain) and the posterior region marked by Hox genes which is homologous to the vertebrate hindbrain and spinal cord. Later expression of HrPax-258 in atrial primordia implies that basal chordates such as ascidians have already acquired a sensory organ that develops from epidermal thickenings (placodes) and expresses HrPax-258; we suggest it is homologous to the vertebrate ear. Therefore, placodes are not likely to be a newly acquired feature in vertebrates, but may have already been possessed by the earliest chordates.
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Casertano, Marcello, Marialuisa Menna i Concetta Imperatore. "The Ascidian-Derived Metabolites with Antimicrobial Properties". Antibiotics 9, nr 8 (13.08.2020): 510. http://dx.doi.org/10.3390/antibiotics9080510.
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Among the sub-phylum of Tunicate, ascidians represent the most abundant class of marine invertebrates, with 3000 species by heterogeneous habitat, that is, from shallow water to deep sea, already reported. The chemistry of these sessile filter-feeding organisms is an attractive reservoir of varied and peculiar bioactive compounds. Most secondary metabolites isolated from ascidians stand out for their potential as putative therapeutic agents in the treatment of several illnesses like microbial infections. In this review, we present and discuss the antibacterial activity shown by the main groups of ascidian-derived products, such as sulfur-containing compounds, meroterpenes, alkaloids, peptides, furanones, and their derivatives. Moreover, the direct evidence of a symbiotic association between marine ascidians and microorganisms shed light on the real producers of many extremely potent marine natural compounds. Hence, we also report the antibacterial potential, joined to antifungal and antiviral activity, of metabolites isolated from ascidian-associate microorganisms by culture-dependent methods.
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Koyongian, Silvia E., Deiske A. Sumilat, Rosita A. J. Lintang, Stenly Wullur, Sandra O. Tilaar i Henneke Pangkey. "ISOLASI BAKTERI YANG BERSIMBION DENGAN ASCIDIAN Herdmania momus YANG MEMILIKI AKTIVITAS ANTIBAKTERI". JURNAL PESISIR DAN LAUT TROPIS 8, nr 2 (30.05.2020): 20. http://dx.doi.org/10.35800/jplt.8.2.2020.28766.
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Ascidian is marine invertebrates in coral reef ecosystems that produce many bioactive compounds for pharmacology. The presence of symbiotic bacteria with marine organisms is protected the host biota by producing secondary metabolites. The purpose of this study is to obtain symbiotic bacterial isolates with Herdmania momus ascidian, then to observe the antibacterial activity of these bacterial isolates against Escherichia coli, and Staphylococcus aureus. Isolation and culture of the symbiotic bacteria were made on Nutrient Agar and Zobell Marine Broth media. The antibacterial screening showed that the Herdmania momus symbiotic bacteria were able to inhibit the growth of Staphylococcus aureus and Escherichia coli.Keywords: ascidians, Herdmania momus, bacteria, isolation, antibacterialAbstak Ascidian adalah avetebrata laut di ekosistem terumbu karang yang banyak menghasilkan senyawa bioaktif untuk bidang farmakologi. Keberadaan bakteri yang bersimbion dengan organisme laut pada umumnya untuk melindungi biota yang ditumpanginya dan dirinya dengan cara menghasilkan senyawa metabolit sekunder. Tujuan dari penelitian ini yaitu untuk mendapatkan isolat bakteri yang bersimbion dengan ascidian Herdmania momus, kemudian mengamati aktivitas antibakteri dari isolat bakteri tersebut terhadap Escherichia coli, dan Staphylococcus aureus. Isolasi dan kultur bakteri yang bersimbion dengan ascidian dibuat pada media Nutrient Agar dan Zobell Marine Broth. Skrining aktivitas antibakteri menunjukkan isolat bakteri yang bersimbion dengan ascidian Herdmania momus mampu menghambat pertumbuhan organisme uji Staphylococcus aureus dan Escherichia coli.Kata kunci: ascidian, Herdmania momus, bakteri, isolasi, antibakteri
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McDougall, A., M. Levasseur, A. J. O'Sullivan i K. T. Jones. "Cell cycle-dependent repetitive Ca(2+)waves induced by a cytosolic sperm extract in mature ascidian eggs mimic those observed at fertilization". Journal of Cell Science 113, nr 19 (1.10.2000): 3453–62. http://dx.doi.org/10.1242/jcs.113.19.3453.
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Sperm-triggered Ca(2+) oscillations occur throughout the animal kingdom. The mechanism sperm use to trigger Ca(2+) oscillations at fertilization has not been resolved in any egg. The temporal, spatial and regulatory characteristics of the Ca(2+) oscillations during fertilization in ascidians offer a unique advantage over other systems for determining the mechanism of fertilization. For example, sperm trigger two phases of Ca(2+) oscillations that are all waves in ascidians. The first of these Ca(2+) waves begins at the point of sperm-egg fusion while a second phase of Ca(2+) waves originates at a vegetal protrusion termed the contraction pole. In addition, cyclin B1-dependent kinase activity provides a form of positive feedback, maintaining the second phase of Ca(2+) waves during meiosis and thereby ensuring meiotic exit. We therefore prepared cytosolic ascidian sperm extracts or MonoQ-fractionated ascidian sperm extracts from this urochordate to investigate if a Ca(2+)-releasing sperm-borne factor was responsible for egg activation. Spatially, ascidian sperm extract induced repetitive Ca(2+) waves that mimicked the spatial pattern displayed during fertilization: all the second-phase Ca(2+) waves originated at a vegetal protrusion termed the contraction pole (thus mimicking fertilisation). We also demonstrated that ascidian sperm extract-induced Ca(2+) oscillations were maintained when CDK activity was elevated and MAP kinase activity was low, as found previously for sperm-triggered Ca(2+) oscillations. As would be predicted, large doses of ascidian sperm extract injected into prophase-stage oocytes, lacking CDK activity, failed to induce any Ca(2+) release even though they responded to microinjection of the Ca(2+)-releasing second messenger inositol 1,4,5-trisphosphate. Finally, since the Ca(2+)-releasing activity from Mono-Q fractionated ascidian sperm extract eluted predominantly as one fraction, this may imply that one factor is responsible for the Ca(2+)-releasing activity. These data support a model of egg activation whereby the sperm introduces a Ca(2+)-releasing cytosolic factor into the egg. We demonstrated that ascidian sperm contain a protein factor(s) that is regulated by the egg CDK activity and can trigger all the Ca(2+)waves observed at fertilization with a spatial pattern that mimics those initiated by sperm.
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Swalla, B. J., M. R. Badgett i W. R. Jeffery. "Identification of a cytoskeletal protein localized in the myoplasm of ascidian eggs: localization is modified during anural development". Development 111, nr 2 (1.02.1991): 425–36. http://dx.doi.org/10.1242/dev.111.2.425.
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The myoplasm of ascidian eggs is a localized cytoskeletal domain that is segregated to presumptive larval tail muscle cells during embryonic development. We have identified a cytoskeletal protein recognized by a vertebrate neurofilament monoclonal antibody (NN18) which is concentrated in the myoplasm in eggs and embryos of a variety of ascidian species. The NN18 antigen is localized in the periphery of unfertilized eggs, segregates with the myoplasm after fertilization, and enters the larval tail muscle cells during embryonic development. Western blots of one-dimensional and two-dimensional gels showed that the major component recognized by NN18 antibody is a 58 × 10(3) Mr protein (p58), which exists in at least three different isoforms. The enrichment of p58 in the Triton X-100-insoluble fraction of eggs and its reticular staining pattern in eggs and embryos suggests that it is a cytoskeletal protein. In subsequent experiments, p58 was used as a marker to determine whether changes in the myoplasm occur in eggs of anural ascidian species, i.e. those exhibiting a life cycle lacking tadpole larvae with differentiated muscle cells. Although p58 was localized in the myoplasm in eggs of four urodele ascidian species that develop into swimming tadpole larvae, this protein was distributed uniformly in eggs of three anural ascidian species. The eggs of two of these anural species contained the actin lamina, another component of the myoplasm, whereas the third anural species lacked the actin lamina. There was no detectible localization of p58 after fertilization or segregation into muscle lineage cells during cleavage of anural eggs. NN18 antigen was uniformly distributed in pre-vitellogenic oocytes and then localized in the perinuclear zone during vitellogenesis of urodele and anural ascidians. Subsequently, NN18 antigen was concentrated in the peripheral cytoplasm of post-vitellogenic oocytes and mature eggs of urodele, but not anural, ascidians. It is concluded that the myoplasm of ascidian eggs contains an intermediate filament-like cytoskeletal network which is missing in anural species that have modified or eliminated the tadpole larva.
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Wilding, Martin, i Brian Dale. "Soluble extracts from ascidian spermatozoa trigger intracellular calcium release independently of the activation of the ADP ribose channel". Zygote 6, nr 2 (maj 1998): 149–54. http://dx.doi.org/10.1017/s0967199498000070.
Pełny tekst źródłaStreszczenie:
We have injected soluble extracts of sperm from the ascidian Ciona intestinalis into oocytes of the same species to test whether these extracts can mimic the events of fertilisation. Injection of ascidian sperm extracts leads, after a delay of approximately 60 s, to a large calcium transient and repetitive pattern of calcium oscillations, mimicking the normal fertilisation response. The response was concentration-independent, suggesting a stimulatory mechanism in triggering the fertilisation response. We tested the pathway of calcium release in ascidian oocytes after injection of sperm extracts by preinjection of calcium release inhibitors. The data demonstrate that dual pathways to calcium release act at fertilisation in ascidians, as in other species. C. intestinalis oocytes are characterised by a nion channel in the plasma membrane that is gated uniquely by ADP ribose. We show that this channel is not gated by the injection of ascidian sperm extracts. Our data suggest that one metabolic pathway triggered by sperm, the release of nitric oxide, is not stimulated by sperm extracts and that several metabolic pathways are stimulated at fertilisation by more than one factor within sperm.
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Mohsin A. Al-Sofyani, Abdul, i Sathianeson Satheesh. "Recruitment patterns of the solitary ascidian Phallusia nigra Savigny, 1816 on artificial substrates submerged in the central Red Sea, Saudi Arabia". Oceanological and Hydrobiological Studies 48, nr 3 (25.09.2019): 262–69. http://dx.doi.org/10.2478/ohs-2019-0023.
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Abstract The solitary ascidian Phallusia nigra is commonly found on hard substrates along the Jeddah coastal waters of the central Red Sea. In this study, the recruitment pattern of P. nigra on artificial substrates was assessed in relation to their type, surface color and orientation. The results showed a higher recruitment rate of the ascidian species on concrete and dark panels. The abundance of the ascidian on test panels varied between the four seasons. The orientation (vertical or horizontal) of the panels did not show any major difference in the recruitment. Significant effects of light intensityon the recruitment of P. nigra were observed on test panels, with higher abundance on panels submerged in the shade. In conclusion, this study clearly indicates the importance of the type and color of substrates in the recruitment of ascidians on artificial materials.
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Opa, Samuel L., Deiske A. Sumilat, Silvester B. Pratasik, Billy Th Wagey, Gustaf F. Mamangkey, Elvy L. Ginting i Medy Ompi. "Community Structure of Ascidian in Mike’s Point Bunaken Waters, Manado City, North Sulawesi Province". JURNAL ILMIAH PLATAX 8, nr 1 (31.01.2020): 61. http://dx.doi.org/10.35800/jip.8.1.2020.27827.
Pełny tekst źródłaStreszczenie:
Ascidians are marine invertebrates that have been classified with the subphylum Urochordata (Tunicata). These organisms are very important because they contribute a lot to the stability of the marine ecosystem. This study aims to determine the species composition, density, ecological index (diversity, uniformity, dominance), distribution patterns, and substrate occupied by Ascidian. Data were collected at Mike’s Point Bunaken waters at two depths 7 m and 14 m. The method used a direct observation along the 50 m and 2 m width belt transect. In this study, the transect was applied parallel to the coastline at each depth, where 3 replications were performed. The results show 26 species consisting of 13 species at a depth of 7 m and 22 species at a depth of 14 m were identified. The average density of each species was 0.05 ind/m2 at both depths. Diversity Index of 1.76 at 7 m depth and 2.24 at 14 m depth was determined. Uniformity Index was 0.68 at 7 m depth and 0.73 at 14 m depth. Dominant Index of 0.67 at 7 m depth and 0.88 at 14 m depth was also determined. The distribution pattern of species was dominated by uniform distribution, and the substrate most commonly occupied by Ascidianns was dead coral overgrown with algae.Keywords: Ascidian, composition and density, ecological index, distribution pattern, substrate AbstrakAscidian adalah Avertebrata laut yang termasuk dalam subfilum Urochordata (Tunicata). Organisme ini sangat penting karena mereka banyak berkontribusi pada stabilitas ekosistem laut. Penelitian ini bertujuan untuk menentukan komposisi spesies, kepadatan, indeks ekologi (keanekaragaman, keseragaman, dominasi), pola distribusi, dan substrat yang ditempati oleh Ascidian. Data dikumpulkan di Perairan Mike's Point Bunaken pada dua kedalaman 7 m dan 14 m. Metode yang digunakan adalah pengamatan langsung sepanjang transek sabuk 50 m dan lebar 2 m. Transek dipasang sejajar dengan garis pantai dan pada setiap kedalaman. Pengambilan data dilakukan 3 ulangan. Hasil dari penelitian ini adalah ditemukan 26 spesies yang terdiri dari 13 spesies pada kedalaman 7 m dan 22 spesies pada kedalaman 14 m. Kepadatan total Ascidian pada kedalaman 7 m (0,67 ind/m2) dan pada kedalaman 14 m (1.11 ind/m2). Indeks Keanekaragaman adalah 1,76 pada kedalaman 7 m dan 2,24 pada kedalaman 14 m. Indeks Keseragaman adalah 0,68 pada kedalaman 7 m dan 0,73 pada kedalaman 14 m. Indeks Dominansi 0,67 pada kedalaman 7 m dan 0,88 pada kedalaman 14 m. Pola distribusi spesies didominasi oleh pola distribusi yang seragam, dan substrat yang paling umum ditempati oleh Ascidian adalah karang mati yang ditumbuhi alga.Kata Kunci: Ascidian, komposisi dan kepadatan, indeks ekologi, pola sebaran, substrat
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Pichon, Julien, Nicholas M. Luscombe i Charles Plessy. "Widespread use of the “ascidian” mitochondrial genetic code in tunicates". F1000Research 8 (10.12.2019): 2072. http://dx.doi.org/10.12688/f1000research.21551.1.
Pełny tekst źródłaStreszczenie:
Background: Ascidians, a tunicate class, use a mitochondrial genetic code that is distinct from vertebrates and other invertebrates. Though it has been used to translate the coding sequences from other tunicate species on a case-by-case basis, it is has not been investigated whether this can be done systematically. This is an important because a) some tunicate mitochondrial sequences are currently translated with the invertebrate code by repositories such as NCBI GenBank, and b) uncertainties about the genetic code to use can complicate or introduce errors in phylogenetic studies based on translated mitochondrial protein sequences. Methods: We collected publicly available nucleotide sequences for non-ascidian tunicates including appendicularians such as Oikopleura dioica, translated them using the ascidian mitochondrial code, and built multiple sequence alignments covering all tunicate classes. Results: All tunicates studied here appear to translate AGR codons to glycine instead of serine (invertebrates) or as a stop codon (vertebrates), as initially described in ascidians. Among Oikopleuridae, we suggest further possible changes in the use of the ATA (Ile → Met) and TGA (Trp → Arg) codons. Conclusions: We recommend using the ascidian mitochondrial code in automatic translation pipelines of mitochondrial sequences for all tunicates. Further investigation is required for additional species-specific differences.
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Pichon, Julien, Nicholas M. Luscombe i Charles Plessy. "Widespread use of the “ascidian” mitochondrial genetic code in tunicates". F1000Research 8 (14.04.2020): 2072. http://dx.doi.org/10.12688/f1000research.21551.2.
Pełny tekst źródłaStreszczenie:
Background: Ascidians, a tunicate class, use a mitochondrial genetic code that is distinct from vertebrates and other invertebrates. Though it has been used to translate the coding sequences from other tunicate species on a case-by-case basis, it is has not been investigated whether this can be done systematically. This is an important because a) some tunicate mitochondrial sequences are currently translated with the invertebrate code by repositories such as NCBI GenBank, and b) uncertainties about the genetic code to use can complicate or introduce errors in phylogenetic studies based on translated mitochondrial protein sequences. Methods: We collected publicly available nucleotide sequences for non-ascidian tunicates including appendicularians such as Oikopleura dioica, translated them using the ascidian mitochondrial code, and built multiple sequence alignments covering all tunicate classes. Results: All tunicates studied here appear to translate AGR codons to glycine instead of serine (invertebrates) or as a stop codon (vertebrates), as initially described in ascidians. Among Oikopleuridae, we suggest further possible changes in the use of the ATA (Ile → Met) and TGA (Trp → Arg) codons. Conclusions: We recommend using the ascidian mitochondrial code in automatic translation pipelines of mitochondrial sequences for all tunicates. Further investigation is required for additional species-specific differences.
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Dias, G. M., R. M. Rocha, T. M. C. Lotufo i L. P. Kremer. "Fifty years of ascidian biodiversity research in São Sebastião, Brazil". Journal of the Marine Biological Association of the United Kingdom 93, nr 1 (7.06.2012): 273–82. http://dx.doi.org/10.1017/s002531541200063x.
Pełny tekst źródłaStreszczenie:
The city of São Sebastião (SS), in south-eastern Brazil, is one of the hotspots for marine research since the establishment of the Centre of Marine Biology of the University of São Paulo in the 1960s. The SS region experienced intense transformation during the past 50 years, including increasing urbanization and construction of maritime facilities. Ascidian surveys during the past 50 years have found 62 species, eight of which were described as new and 12 are introduced. Didemnidae and Styelidae are the most speciose families in São Sebastião Channel, with 20 and 15 species respectively. Phallusia nigra, Didemnum psammatodes, Trididemnum orbiculatum, Botrylloides nigrum and Symplegma rubra are the most common ascidians. Most of the species are of tropical origin and São Paulo is their southern geographical limit. Comparisons of reports of the ascidians from different time periods allowed detection of species introductions and shifts in assemblage structure in terms of both species composition and abundance. Additionally, we discuss the main taxonomic issues regarding ascidians from south-eastern Brazil and identify profitable areas for future research. We believe that the temporal data compiled here will serve as a baseline for monitoring and management of ascidians in SS. Additionally, this study provides one of the most detailed datasets of ascidian diversity from the south-western Atlantic Ocean.
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Nichols, Claire L., Gretchen Lambert i Marie L. Nydam. "Continued persistence of non-native ascidians in Southern California harbors and marinas". Aquatic Invasions 18, nr 1 (18.04.2023): 1–22. http://dx.doi.org/10.3391/ai.2023.18.1.101962.
Pełny tekst źródłaStreszczenie:
Non-native ascidians have long dominated the artificial structures in southern California’s (United States) marinas and harbors. To determine the change in ascidian abundance and community composition over the last several decades, in 2019–2020 we replicated surveys from 1994–2000. We then created nMDS plots using the abundance data collected in the 1994–2000 and 2019–2020 surveys to compare the two groups. Range and average abundance per species were analyzed to determine trends and changes in ascidian community composition. Of the species used for comparison, four are native, three are cryptogenic, and 12 are non-native. As predicted by Lambert and Lambert, non-native species have persisted in southern California; however, ranges and abundances have changed. The only native species found consistently in both sets of surveys, Ascidia ceratodes, remained rare in 2019–2020, with an unchanged average abundance. Several non-native species increased in abundance or remained common. The non-native colonial species Polyandrocarpa zorritensis had the greatest influence on the dissimilarity between the surveys, increasing from rare in 1994–2000 to more common in 2019–2020, and spreading north to Santa Barbara. Several non-native species confined to San Diego in the 1994–2000 surveys have also spread north, such as Botrylloides giganteus and Styela canopus which were found in Santa Barbara in 2019–2020. A formerly unidentified Aplidium sp. has now been identified as the non-native Aplidium accarense. There have also been additional introductions since 2000, including Ascidia cf. virginea and the first report of Ascidiella aspersa in the NE Pacific. The overwhelming trends of the surveys indicate that we will continue to see an increase and persistence of newly introduced non-natives in Southern California marinas, with possible continued northward expansion.
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Sargent, P. S., J. F. Hamel i A. Mercier. "The life history and feeding ecology of velvet shell, Velutina velutina (Gastropoda: Velutinidae), a specialist predator of ascidians". Canadian Journal of Zoology 97, nr 12 (grudzień 2019): 1164–76. http://dx.doi.org/10.1139/cjz-2018-0327.
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Velvet shell, Velutina velutina (Müller, 1776), is a specialist predator of ascidians, like other members of the gastropod family Velutinidae. Globally, invasive ascidians have become problematic, ecologically and economically, yet ecological knowledge of velutinids remains limited. This study outlines the life history and feeding ecology of V. velutina in eastern Canada based on laboratory work complemented by field observations. The life history of V. velutina is closely linked with ascidians, which serve as prey and protection for their egg capsules. Egg capsules were embedded within tunics of Aplidium glabrum (Verrill, 1871) and Ascidia callosa Stimpson, 1852, with a preference for the latter. Seasonal behavioural shifts were consistent annually and corresponded with seawater temperature cycles. Feeding dominated during the coldest months (January–May), growth occurred as water temperature increased to the annual maximum (June and July), transitioning to mating during the warmest period (July–August), and egg capsule deposition dominated as water temperature declined (November–January). Larvae hatched between January and July after 2–4 months of development. Velutina velutina preyed on all ascidian species presented during this study, including golden star tunicate, Botryllus schlosseri (Pallas, 1766), and vase tunicate, Ciona intestinalis (Linnaeus, 1767), two non-indigenous species, although solitary species were preferred.
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Palit, Christian, Deiske A. Sumilat, Antonius P. Rumengan Rumengan, Farnis B. Boneka, Chatrien A. L. Sinjal i Jans Lalita. "KOMUNITAS DAN KEANEKARAGAMAN ASCIDIA DI PESISIR MINANGA, MALALAYANG SATU, KOTA MANADO". JURNAL PESISIR DAN LAUT TROPIS 10, nr 2 (5.06.2022): 219–25. http://dx.doi.org/10.35800/jplt.10.2.2022.54995.
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Ascidian is one of the biota components that make up coral reefs, which has many biological, ecological and pharmaceutical benefits. This makes Ascidian a very attractive target due to its high and unique diversity among marine invertebrates. The purpose of this study is to provide information about the Ascidia community and diversity in the Minanga Coast, Malalayang Satu, Manado City. This research was conducted for 3 (three) months from April to June 2022 with the location of data collection is Minanga Divers Coast. Data were collected using the visual census method at a depth of 7 and 14 m with a transect length of 50 m and a width of 5 m. Data analysis was carried out to obtain the value of species composition and density and ecological index. The results obtained: 1). Ascidia found were 14 species consisting of 12 species at a depth of 7 m and 10 species at a depth of 14 m. 2). The highest species composition and density values were Ascidia P. aurata, and then D. molle 3). The Ascidia diversity index at the study site was was 2.00 at a depth of 7 m and 1.84 at a depth of 14 m.
Keyword : Ascidian, species composition, density, diversity.
ABSTRAK
Ascidia merupakan salah satu komponen biota penyusun terumbu karang yang mempunyai banyak manfaat baik biologi, ekologi dan farmasitika. Sehingga menjadikan Ascidia target yang sangat menarik karena keanekaragamannya yang tinggi dan unik di antara avertebrata laut. Tujuan penelitian ini yaitu memberikan informasi mengenai komunitas Ascidia di Pesisir Minanga, Malalayang Satu, Kota Manado. Penelitian ini dilakukan selama 3 (tiga) bulan April – Juni 2022 dengan lokasi pengambilan data yaitu Pesisir Minanga Divers. Pengambilan data dilakukan dengan menggunakan metode sensus visual pada kedalaman 7 dan 14 m dengan panjang transek 50 m dan lebar 5m. Analisis data dilakukan untuk mendapatkan nilai komposisi jenis dan kepadatan, indeks ekologi dan pola sebaran. Hasil yang didapatkan : 1). Ascidia yang ditemukan berjumlah 14 spesies yang terdiri dari 12 spesies pada kedalaman 7 m dan 10 spesies pada kedalaman 14 m, 2). Nilai komposisi jenis dan kepadatan tertinggi yaitu Ascidia P. aurata pada D. molle da 3). Indekskeanekaragaman Ascidia pada lokasi penelitian yaitu dengan nilai 2,00 pada kedalaman 7 m dan 1,84 padakedalaman 14 m.
Kata Kunci : Ascidia. komposisi spesies, kepadatan, keanekaragaman.
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Łukowiak, Magdalena. "First record of late Eocene ascidians (Ascidiacea, Tunicata) from southeastern Australia". Journal of Paleontology 86, nr 3 (maj 2012): 521–26. http://dx.doi.org/10.1666/11-112.1.
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Ascidian spicules are reported for the first time from the upper Eocene (Paleogene) biosiliceous marls and mudstones of the Blanche Point Formation in the St. Vincent Basin, southeastern Australia. The spicules that belong to the family Polycitoridae are identified as a Recent species Cystodytes cf. dellechiajei, and Cystodytes sp. and spicules of the family Didemnidae are indentified as representing genera Lissoclinum, Didemnum, and Polysyncraton. Five other different morphological spicule types which can be classified only at the family level also belong to the Didemnidae. This study demonstrates that ascidians had a very wide distribution by the late Eocene and that ascidian fauna was already of a modern character.
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Morton, Brian, i Grete E. Dinesen. "The biology and functional morphology of Modiolarca subpicta (Bivalvia: Mytilidae: Musculinae), epizoically symbiotic with Ascidiella aspersa (Urochordata: Ascidiacea), from the Kattegat, northern Jutland, Denmark". Journal of the Marine Biological Association of the United Kingdom 91, nr 8 (15.12.2010): 1637–49. http://dx.doi.org/10.1017/s0025315410001980.
Pełny tekst źródłaStreszczenie:
This study of the little known north-eastern Atlantic mytilid Modiolarca subpicta suggests a more intimate relationship with ascidians and, especially, Ascidiella aspersa, than has hitherto been appreciated. Both live for ~18 months and the reproductive cycle of both is approximately co-ordinated so that juvenile ascidians become available as hosts to the settling spat of the symbiotically epizoic M. subpicta each summer. Settling spat of M. subpicta are thought to be attracted to the exhalant flow from the ascidian's anal siphon. After the ascidian's death, the liberated mussels may adopt a wandering, free-living, lifestyle they have occasionally been reported to pursue. Anatomically, M. subpicta is of the typical mytilid plan, albeit simplified commensurate upon its normal lifestyle of protective envelopment within the host's tunic. The foot, however, is highly mobile and in addition to being used for locomotion, especially in juveniles, is responsible for the planting of byssal threads, typically dorsally above the shell, so that each individual stimulates the ascidian to produce an epidermal pocket into which it manœuvres itself and reposes, securely attached, but dorsal side down Modiolarca subpicta, epizoic in the tests of ascidians, could have evolved from a more isomyarian, equivalve, ancestor via a nestling, epibyssate, Trichomusculus-like shaped intermediary with ventral flattening and, hence, stability characteristic of the more familiar heteromyarian mytilids of rocky shores and lotic freshwaters being achieved through living dorsal side down.
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White, Kristine, Louis Ambrosio i Christa Edwards. "Anthropogenic Sound in the Sea: Are Ascidians Affected?" Gulf and Caribbean Research 32 (2021): 1–7. http://dx.doi.org/10.18785/gcr.3201.02.
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Sound pollution in the marine environment has been increasing largely due to anthropogenic sources such as vessel traffic, coastal development, fossil fuel extraction, and military exercises. Studies determining the effects of anthropogenic sound on marine organisms have mostly focused on vertebrates, namely fish and marine mammals; however, less research has been done to study the effects of sound on marine invertebrates. The goal of this research is to examine the effect of anthropogenic sound on the ascidian Styela plicata (Lesueur, 1823) in Tampa Bay, FL. A total of 48 ascidians were collected from 2 sites with differing amounts of boat traffic and thus different anthropogenic soundscapes. Ascidians were individually exposed to 3 separate stimuli: a recording of a boat motor, a song recording, and a water current to simulate turbulence. Ascidian reactions were recorded as the frequency of siphon closing events and the length of time the siphons remained closed after disturbance. Ascidians from both sites increased the frequency and longevity of siphon closure events in response to anthropogenic stimuli but showed only a minor difference in response between sample sites. Research into the effect of anthropogenic sound on invertebrates such as ascidians and their symbionts may provide a better understanding of larger scale ecological impacts from such disturbances.
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Wilding, Martin, Marcella Marino i Daniela Dale. "Nicotinamide alters the calcium release pattern and the degradation of MPF activity after fertilisation in ascidian oocytes". Zygote 7, nr 3 (sierpień 1999): 255–60. http://dx.doi.org/10.1017/s0967199499000647.
Pełny tekst źródłaStreszczenie:
Fertilisation in ascidian oocytes triggers a plasma membrane current, the release of intracellular calcium and the degradation of Maturation Promoting Factor (MPF) activity leading to the completion of meiosis and the initiation of embryo development. We have previously shown that the fertilisation current in ascidians is produced through the metabolism of nicotinamide nucleotide (NN) metabolites to ADP ribose. In this study we have used nicotinamide to test whether NN metabolism plays additional roles in fertilisation in ascidians. Nicotinamide treatment blocked calcium-induced calcium release (CICR) and arrested the cell cycle prior to the completion of meiosis I. Nicotinamide further prevented the abolition of MPF activity after fertilisation. Interestingly, nicotinamide treatment caused ascidian oocytes to form interphase-like pronuclei after fertilisation, despite the high MPF activity. The data demonstrate that NN metabolism is involved in calcium signalling through CICR and further suggest that a NN metabolite acts as a messenger connecting MPF activity to the formation of the meiotic apparatus.
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Ma, Kevin C. K., Don Deibel, Kenneth K. M. Law, Mai Aoki, Cynthia H. McKenzie i Maria L. D. Palomares. "Richness and zoogeography of ascidians (Tunicata: Ascidiacea) in eastern Canada". Canadian Journal of Zoology 95, nr 1 (styczeń 2017): 51–59. http://dx.doi.org/10.1139/cjz-2016-0087.
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Managers and policymakers in eastern Canada embrace science-based management of nonindigenous species and may benefit from having comprehensive regional species checklists at subnational jurisdictional levels. In this paper, regional checklists provide an account of the richness of ascidians in eastern Canada. Records of 58 ascidians resulted from reviewing 108 published sources, accessing data from two online databases, and collecting some common indigenous ascidian specimens. Analysis comparing the similarity of species among nine regions indicates that there is greater similarity in species composition between contiguous regions than between noncontiguous regions and suggests that there are four zoogeographic clusters in eastern Canada. Our checklists can inform managers and policymakers of the diversity of the ascidian taxa and can minimize taxonomic uncertainties of established nonindigenous and prospective invading species, for example, by identifying indigenous species that are congeners of nonindigenous species. The maintenance of checklists can be a valuable tool for the management of nonindigenous species as baselines to estimate changes in richness and to document the invasion status of nonindigenous species over time. For example, more importance can be placed on the spread of nonindigenous ascidians from one zoogeographic cluster to another than spread within the same cluster.
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Fodor, Alexander C. A., Megan M. Powers, Kristin Andrykovich, Jiatai Liu, Elijah K. Lowe, C. Titus Brown, Anna Di Gregorio, Alberto Stolfi i Billie J. Swalla. "The Degenerate Tale of Ascidian Tails". Integrative and Comparative Biology 61, nr 2 (28.06.2021): 358–69. http://dx.doi.org/10.1093/icb/icab022.
Pełny tekst źródłaStreszczenie:
Abstract Ascidians are invertebrate chordates, with swimming chordate tadpole larvae that have distinct heads and tails. The head contains the small brain, sensory organs, including the ocellus (light) and otolith (gravity) and the presumptive endoderm, while the tail has a notochord surrounded by muscle cells and a dorsal nerve cord. One of the chordate features is a post-anal tail. Ascidian tadpoles are nonfeeding, and their tails are critical for larval locomotion. After hatching the larvae swim up toward light and are carried by the tide and ocean currents. When competent to settle, ascidian tadpole larvae swim down, away from light, to settle and metamorphose into a sessile adult. Tunicates are classified as chordates because of their chordate tadpole larvae; in contrast, the sessile adult has a U-shaped gut and very derived body plan, looking nothing like a chordate. There is one group of ascidians, the Molgulidae, where many species are known to have tailless larvae. The Swalla Lab has been studying the evolution of tailless ascidian larvae in this clade for over 30 years and has shown that tailless larvae have evolved independently several times in this clade. Comparison of the genomes of two closely related species, the tailed Molgula oculata and tailless Molgula occulta reveals much synteny, but there have been multiple insertions and deletions that have disrupted larval genes in the tailless species. Genomics and transcriptomics have previously shown that there are pseudogenes expressed in the tailless embryos, suggesting that the partial rescue of tailed features in their hybrid larvae is due to the expression of intact genes from the tailed parent. Yet surprisingly, we find that the notochord gene regulatory network is mostly intact in the tailless M. occulta, although the notochord does not converge and extend and remains as an aggregate of cells we call the “notoball.” We expect that eventually many of the larval gene networks will become evolutionarily lost in tailless ascidians and the larval body plan abandoned, with eggs developing directly into an adult. Here we review the current evolutionary and developmental evidence on how the molgulids lost their tails.
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Jain, Seema Sachin, i Darshan Sunil Marjadi. "First record of Five Species of Ascidians (Tunicata: Ascidiacea) from Okha, Gujarat". ECOLOGY, ENVIRONMENT AND CONSERVATION 29, suppl (2023): 272–75. http://dx.doi.org/10.53550/eec.2023.v29i06s.039.
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Ascidians are filter-feeding organisms that are sedentary and hermaphrodite in nature. In India we have 263 ascidian species coming under 41 genera, 12 families, 3 suborders, and 2 orders of the class Ascidiacea. In this study, specimens of ascidians were collected in the intertidal zones of Okha, Gujarat for the very first time. Five solitary ascidians are recorded in this region, adding to the biodiversity of Gujarat. Also, a literature review on the distribution of ascidians revealed that this is the first report of these ascidians from Okha, Gujarat. A note on the taxonomic features of these specimens is discussed in the present study.
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Miya, T., K. Morita, A. Suzuki, N. Ueno i N. Satoh. "Functional analysis of an ascidian homologue of vertebrate Bmp-2/Bmp-4 suggests its role in the inhibition of neural fate specification". Development 124, nr 24 (15.12.1997): 5149–59. http://dx.doi.org/10.1242/dev.124.24.5149.
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The ascidian tadpole larva is thought to be close to a prototype of the ancestral chordate. The vertebrate body plan is established by a series of inductive cellular interactions, whereas ascidians show a highly determinate mode of development. Recent studies however, suggest some roles of cell-cell interaction during ascidian embryogenesis. To elucidate the signaling molecules responsible for the cellular interaction, we isolated HrBMPb, an ascidian homologue of the vertebrate bone morphogenetic protein (BMP) gene, from Halocynthia roretzi. The amino acid sequence of HrBMPb closely resembled those of vertebrate BMP-2 and BMP-4 and of Drosophila Decapentaplegic (DPP). In addition to the sequence similarity, HrBMPb overexpression induced the ventralization of Xenopus embryos, suggesting functional conservation. The zygotic expression of HrBMPb was first detected around gastrulation. HrBMPb expression was maintained in some cells at the lateral edges of the neural plate through gastrulation to neurulation, although that in the presumptive muscle cells was downregulated. HrBMPb was not expressed in the presumptive epidermis during gastrulation. When HrBMPb mRNA was injected into fertilized Halocynthia eggs, cells that normally give rise to the neural tissue differentiated into epidermis, causing a loss of anterior neural tissue in the larva. In addition, HrBMPb might function synergistically with HrBMPa, an ascidian homologue of BMPs-5 to 8. However, HrBMPb overexpression did not affect differentiation of the notochord and muscle cells. These results suggest that HrBMPb functions as a neural inhibitor and as an epidermal inducer but not as a ventralizing agent in ascidian development.
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Possner, Sven T., Frank C. Schroeder, Hans Tore Rapp, Volker Sinnwell, Stefan Franke i Wittko Francke. "3,7-Isoquinoline quinones from the ascidian tunicate Ascidia virginea". Zeitschrift für Naturforschung C 72, nr 7-8 (14.07.2017): 259–64. http://dx.doi.org/10.1515/znc-2017-0012.
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AbstractA new isoquinoline quinone system and its iodinated derivatives were isolated from the ascidian tunicateAscidia virgineaMüller 1776 (Phlebobranchia: Ascidiidae). Structures were elucidated by spectroscopic methods and derivatization reactions. Ascidine A (3,7-dihydro-1,8-dihydroxy-4-(4′-hydroxyphenyl)isoquinoline-3,7-dione (1), ascidine B (3,7-dihydro-1,8-dihydroxy-4-(4′-hydroxy-3′-iodophenyl)isoquinoline-3,7-dione (2), and ascidine C (3,7-dihydro-1,8-dihydroxy-4-(4′-hydroxy-3′,5′-diiodophenyl)isoquinoline-3,7-dione (3) represent a novel type of tyrosine-derived alkaloids.
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Demers, Marie-Claire A., Nathan A. Knott i Andrew R. Davis. "Under the radar: Sessile epifaunal invertebrates in the seagrassPosidonia australis". Journal of the Marine Biological Association of the United Kingdom 96, nr 2 (13.08.2015): 363–77. http://dx.doi.org/10.1017/s0025315415000612.
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Despite the current global decline in seagrass, sessile epifaunal invertebrates inhabiting seagrass ecosystems, particularly sponges and ascidians, have been poorly studied due to their taxonomic complexity. Understanding patterns of distribution of sessile epifaunal communities in seagrass meadows is an important precursor to determining the processes driving their distribution and species interactions. This study (1) identified the sponge and ascidian assemblage associated withPosidonia australismeadows and (2) determined distributional patterns of these invertebrates at a hierarchy of spatial scales in Jervis Bay, Australia. We used a fully nested design with transects distributed in the seagrass (10s m apart), two sites (100s m apart), and six locations (km apart). Within these transects, we recorded the abundance, volume, diversity and substratum used for attachment by sponges and ascidians. We encountered 20 sponge species and eight ascidian species; they were sporadically distributed in the seagrass meadows with high variability among the transects, sites and locations. A few sponge and ascidian species dominated the assemblage and were widespread across the largest spatial scale sampled. The remaining species were mostly rare and sparsely distributed. Sponges attached to a variety of substrata but most notably shells,P. australisand polychaete tubes. No obligate seagrass species were recorded although three species predominantly usedP. australisas a substratum. These sponge species relying heavily on seagrass for their attachment are likely prone to disturbances impacting their host habitat. Examining the response of sessile epifauna to the degradation of their seagrass habitat remains a key challenge for the future.
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Ristoratore, F., A. Spagnuolo, F. Aniello, M. Branno, F. Fabbrini i R. Di Lauro. "Expression and functional analysis of Cititf1, an ascidian NK-2 class gene, suggest its role in endoderm development". Development 126, nr 22 (15.11.1999): 5149–59. http://dx.doi.org/10.1242/dev.126.22.5149.
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In solitary ascidians the fate of endoderm is determined at a very early stage of development and depends on cytoplasmic factors whose nature has not been determined. We have isolated a member of the NK-2 gene family, Cititf1, from the ascidian Ciona intestinalis, showing high sequence homology to mammalian TITF1. The Cititf1 gene was expressed in all endodermal precursors at the pregastrula and gastrula stages, and is thus the first specific regulatory endodermal marker to be isolated from an ascidian. Cititf1 expression was downregulated at the end of gastrulation to reappear at middle tailbud and larval stages in the most anterior and ventral parts of head endoderm, regions which give rise, after metamorphosis, to the adult endostyle, where Cititf1 mRNA was still present. Microinjection of Cititf1 mRNA into fertilized eggs resulted in tadpole larvae with abnormalities in head-trunk development consequent to the formation of excess endoderm, perhaps due to recruitment of notochord precursors to an endodermal fate. These data suggest that Cititf1 plays an important role in normal endoderm differentiation during ascidian embryogenesis.
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Hirose, Euichi, i Noburu Sensui. "Substrate Selection of Ascidian Larva: Wettability and Nano-Structures". Journal of Marine Science and Engineering 9, nr 6 (7.06.2021): 634. http://dx.doi.org/10.3390/jmse9060634.
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Ascidians are marine sessile chordates that comprise one of the major benthic animal groups in marine ecosystems. They sometimes cause biofouling problems on artificial structures underwater, and non-indigenous, invasive ascidian species can potentially and seriously alter native faunal communities. Ascidian larvae are usually tadpole-shaped, negatively phototactic, and adhere on substrates by secreting a glue from their adhesive organs. Although larvae often prefer hydrophobic surfaces, such as a silicone rubber, for settlement, hydrophobic materials are often used to reduce occurrence of fouling organisms on artificial structures. This inconsistency may indicate that an attractive surface for larvae is not always suitable for settlement. Micro-scale structures or roughness may enhance the settlement of ascidian larvae, but settlement is significantly reduced by a nano-scale nipple array (or moth-eye structure), suggesting functional properties of similar structures found on the body surfaces of various invertebrates. The substrate preferences of larvae should be one of the important bases in considering measures against biofouling, and this review also discusses the potential uses of materials to safely reduce the impacts of invasive species.
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Tsotsios, Dimitrios, Dimitrios K. Papadopoulos, Maria V. Alvanou, Ioannis Georgoulis, Athanasios Lattos, Basile Michaelidis, Konstantinos Feidantsis, Ioannis A. Giantsis i John A. Theodorou. "Environmentally Friendly and Efficient Methods for Mitigating the Density of Ascidian Fouling in Mediterranean Mussel Farming". Fishes 9, nr 4 (14.04.2024): 135. http://dx.doi.org/10.3390/fishes9040135.
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Ascidian biofouling generates significant challenges to bivalve aquaculture. Their rapid spread across almost every available surface leads to increased maintenance costs and reduced yields in shellfish farming. In addition, ascidians may introduce pathogens or toxins, further compromising the health and marketability of bivalve stocks and thereby necessitating strict management strategies to manage these impacts. The aim of this study was the evaluation of different management practices for eliminating ascidian fouling and the identification of the best method for Mytilus galloprovincialis (Lamarck, 1819) aquaculture farms. The effects of different anti-fouling treatments as well as their interactive outcomes were examined by conducting two experiments. Various experimental procedures were applied, including the temporally differential washing of mussels, air exposure and immersion in 50 ppt and 70 ppt salinity solutions, as well as the combination of these applications. All treatments reduced the number of ascidian colonies on mussel socks but at varying proportions. Immersing mussel socks in a 70 ppt salinity solution followed by air exposure for 1 day was the most efficient method and led to a 93% eradication.
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Nakatani, Y., R. Moody i W. C. Smith. "Mutations affecting tail and notochord development in the ascidian Ciona savignyi". Development 126, nr 15 (1.08.1999): 3293–301. http://dx.doi.org/10.1242/dev.126.15.3293.
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Ascidians are among the most distant chordate relatives of the vertebrates. However, ascidians share many features with vertebrates including a notochord and hollow dorsal nerve cord. A screen for N-ethyl-N-nitrosourea (ENU)-induced mutations affecting early development in the ascidian Ciona savignyi resulted in the isolation of a number of mutants including the complementing notochord mutants chongmague and chobi. In chongmague embryos the notochord fails to develop, and the notochord cells instead adopt a mesenchyme-like fate. The failure of notochord development in chongmague embryos results in a severe truncation of tail, although development of the tail muscles and caudal nerve tracts appears largely normal. Chobi embryos also have a truncation of the tail stemming from a disruption of the notochord. However, in chobi embryos the early development of the notochord appears normal and defects occur later as the notochord attempts to extend and direct elongation of the tail. We find in chobi tailbud embryos that the notochord is often bent, with cells clumped together, rather than extended as a column. These results provide new information on the function and development of the ascidian notochord. In addition, the results demonstrate how the unique features of ascidians can be used in genetic analysis of morphogenesis.
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Murugan, Rajaram, i Gnanakkan Ananthan. "Ascidian diversity (Chordata: Tunicata) from Andaman and Nicobar Islands, India". Oceanological and Hydrobiological Studies 47, nr 2 (26.06.2018): 107–17. http://dx.doi.org/10.1515/ohs-2018-0012.
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Abstract Ascidians are filter-feeding sac-like marine urochordates of great evolutionary, ecological and economic importance. Andaman and Nicobar Islands are one of the most important hot spots of biodiversity in India, while the ascidian diversity of this region is very scanty. Ascidians belonging to 29 species were identified at the Andaman and Nicobar Islands during the field research carried out from March 2014 to April 2015. Eight species (Didemnum granulatum, Didemnum molle, Didemnum psammatodes, Diplosoma listerianum, Lissoclinum fragile, Lissoclinum levitum, Lissoclinum patella, Trididemnum Cyclops) from the Didemnidae family were found and identified. Various diversity indices, such as the Shannon -Wiener index (H’), Margalef’s index (D), Pielou’s index (J’), K-dominance curves, Cluster Analysis and Multidimensional Scaling, were used to analyze the diversity, richness and evenness of species, and to compare the diversity between samples and their resemblance in terms of species composition. The maximum species richness was observed in Campbell Bay (2.424) and the minimum in Haddo Wharf (0.910). This finding shows the rich species diversity of ascidian fauna at Andaman and Nicobar Islands.
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Katsuyama, Y., S. Wada, S. Yasugi i H. Saiga. "Expression of the labial group Hox gene HrHox-1 and its alteration induced by retinoic acid in development of the ascidian Halocynthia roretzi". Development 121, nr 10 (1.10.1995): 3197–205. http://dx.doi.org/10.1242/dev.121.10.3197.
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Ascidian embryogenesis shares several developmental features with vertebrates. Thus, it is presumed that some molecular mechanisms that are critical for vertebrate development may also act in the early development of ascidians. Here, we investigated expression of the ascidian labial group Hox gene HrHox-1 in the development of Halocynthia roretzi. HrHox-1 showed a spatially restricted expression pattern along the anterior-posterior axis, which is remarkably similar to that of the vertebrate gene, Hoxb-1. The expression of HrHox-1, however, was exclusively in tissues of ectoderm origin unlike its vertebrate counterpart. Exposure of the embryos to 10(−6) M all-trans retinoic acid induced a larval phenotype with elimination of the anteriormost structures, the papillae. In this phenotype, the level of HrHox-1 expression was enhanced and ectopic expression was observed at the anterior terminal epidermis where the papillae are otherwise formed. These observations suggest that there are some conserved mechanisms in the spatial regulation of expression of labial group genes in embryogenesis of ascidians and vertebrates.
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Mercurio, Silvia, Matteo Bozzo, Alessandro Pennati, Simona Candiani i Roberta Pennati. "Serotonin Receptors and Their Involvement in Melanization of Sensory Cells in Ciona intestinalis". Cells 12, nr 8 (13.04.2023): 1150. http://dx.doi.org/10.3390/cells12081150.
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Serotonin (5-hydroxytryptamine (5-HT)) is a biogenic monoamine with pleiotropic functions. It exerts its roles by binding to specific 5-HT receptors (5HTRs) classified into different families and subtypes. Homologs of 5HTRs are widely present in invertebrates, but their expression and pharmacological characterization have been scarcely investigated. In particular, 5-HT has been localized in many tunicate species but only a few studies have investigated its physiological functions. Tunicates, including ascidians, are the sister group of vertebrates, and data about the role of 5-HTRs in these organisms are thus important for understanding 5-HT evolution among animals. In the present study, we identified and described 5HTRs in the ascidian Ciona intestinalis. During development, they showed broad expression patterns that appeared consistent with those reported in other species. Then, we investigated 5-HT roles in ascidian embryogenesis exposing C. intestinalis embryos to WAY-100635, an antagonist of the 5HT1A receptor, and explored the affected pathways in neural development and melanogenesis. Our results contribute to unraveling the multifaceted functions of 5-HT, revealing its involvement in sensory cell differentiation in ascidians.
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MONNIOT, F., i C. MONNIOT. "A deep water Ascidia (Ascidiidae, Tunicata) from the tropical western Pacific". Zootaxa 1168, nr 1 (6.04.2006): 43. http://dx.doi.org/10.11646/zootaxa.1168.1.4.
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A single, solitary, free living ascidian, Ascidia alisea sp.nov., collected from a sandy substrate on the Austral Ridge (Polynesia) between 120 and 203 meters depth, is ovoid with a layer of sandy debris adhering to the tunic and has distinctive body muscles and neural area and an unusual course of its vas deferens.
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Chen, Lei, Xue-Ning Wang, Chang-Ming Fu i Guang-Yu Wang. "Phylogenetic Analysis and Screening of Antimicrobial and Antiproliferative Activities of Culturable Bacteria Associated with the Ascidian Styela clava from the Yellow Sea, China". BioMed Research International 2019 (28.08.2019): 1–14. http://dx.doi.org/10.1155/2019/7851251.
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Over 1,000 compounds, including ecteinascidin-743 and didemnin B, have been isolated from ascidians, with most having bioactive properties such as antimicrobial, antitumor, and enzyme-inhibiting activities. In recent years, direct and indirect evidence has shown that some bioactive compounds isolated from ascidians are not produced by ascidians themselves but by their symbiotic microorganisms. Isolated culturable bacteria associated with ascidians and investigating their potential bioactivity are an important approach for discovering novel compounds. In this study, a total of 269 bacteria were isolated from the ascidian Styela clava collected from the coast of Weihai in the north of the Yellow Sea, China. Phylogenetic relationships among 183 isolates were determined using their 16S rRNA gene sequences. Isolates were tested for antimicrobial activity against seven indicator strains, and an antiproliferative activity assay was performed to test for inhibition of human hepatocellular carcinoma Bel 7402 and human cervical carcinoma HeLa cell proliferation. Our results showed that the isolates belonged to 26 genera from 18 families in four phyla (Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes). Bacillus and Streptomyces were the most dominant genera; 146 strains had potent antimicrobial activities and inhibited at least one of the indicator strains. Crude extracts from 29 strains showed antiproliferative activity against Bel 7402 cells with IC50 values below 500 μg·mL−1, and 53 strains showed antiproliferative activity against HeLa cells, with IC50 values less than 500 μg·mL−1. Our results suggest that culturable bacteria associated with the ascidian Styela clava may be a promising source of novel bioactive compounds.
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Anderson, Daniel H., John R. Berg i James H. Swinehart. "Uptake of vanadium by the ascidian Ascidia ceratodes". Comparative Biochemistry and Physiology Part A: Physiology 99, nr 1-2 (styczeń 1991): 151–58. http://dx.doi.org/10.1016/0300-9629(91)90250-g.
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Baur, Philipp, Michael Kühl, Peter Comba i Lars Behrendt. "Possible Functional Roles of Patellamides in the Ascidian-Prochloron Symbiosis". Marine Drugs 20, nr 2 (2.02.2022): 119. http://dx.doi.org/10.3390/md20020119.
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Patellamides are highly bioactive compounds found along with other cyanobactins in the symbiosis between didemnid ascidians and the enigmatic cyanobacterium Prochloron. The biosynthetic pathway of patellamide synthesis is well understood, the relevant operons have been identified in the Prochloron genome and genes involved in patellamide synthesis are among the most highly transcribed cyanobacterial genes in hospite. However, a more detailed study of the in vivo dynamics of patellamides and their function in the ascidian-Prochloron symbiosis is complicated by the fact that Prochloron remains uncultivated despite numerous attempts since its discovery in 1975. A major challenge is to account for the highly dynamic microenvironmental conditions experienced by Prochloron in hospite, where light-dark cycles drive rapid shifts between hyperoxia and anoxia as well as pH variations from pH ~6 to ~10. Recently, work on patellamide analogues has pointed out a range of different catalytic functions of patellamide that could prove essential for the ascidian-Prochloron symbiosis and could be modulated by the strong microenvironmental dynamics. Here, we review fundamental properties of patellamides and their occurrence and dynamics in vitro and in vivo. We discuss possible functions of patellamides in the ascidian-Prochloron symbiosis and identify important knowledge gaps and needs for further experimental studies.
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Dalby, JE. "Consequences of aggregated living in the ascidian Pyura stolonifera: Evidence for non-contact intraspecific competition". Marine and Freshwater Research 46, nr 8 (1995): 1195. http://dx.doi.org/10.1071/mf9951195.
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Non-contact intraspecific competition was examined as a possible consequence of the aggregated distribution of the ascidian Pyura stolonifera near Melbourne, Australia. In a field experiment designed so that experimental individuals did not touch surrounding conspecific individuals, ascidians inside aggregations grew significantly more slowly than those outside aggregations: at the end of the 24-month experiment, the former animals had shorter body lengths, lighter bodies, lighter tunics, and lighter gonads. This is one of few conclusive demonstrations of the existence of this type of intraspecific competition in sessile marine invertebrates occupying hard substrata, and the only demonstration for ascidians.
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Degnan, BM, PR Rohde i MF Lavin. "Normal development and embryonic gene activity of the ascidian Herdmania momus". Marine and Freshwater Research 47, nr 3 (1996): 543. http://dx.doi.org/10.1071/mf9960543.
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Embryonic and post-larval development of the tropical solitary ascidian Herdmania momus is shown to be similar to that of extensively studied ascidian model systems. H. momus development is rapid and temperature-dependent, with hatching occurring 8.5 h after fertilization at 28�C. An increase in total embryonic gene transcription is detected at the 110-cell stage or the onset of gastrulation. Treatment of early embryos with actinomycin D inhibits transcription and curtails morphogenetic cell movement in the early gastrula without immediately inhibiting cell division. The prevalence of homeobox-containing transcripts increases around the 110-cell stage and later in development. Isolated H. momus homeobox genes, expressed at the tailbud stage, have greatest sequence identity to members of Hox, otd/Otx, eve/Evx and cad/Cdx homeobox classes. Evidence from H. momus and other ascidians suggests that urochordates possess most of the homeobox genes of the chordate HOX cluster.
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Jeffery, William R., i Billie J. Swalla. "An ankryin-like protein in ascidian eggs and its role in the evolution of direct development". Zygote 1, nr 3 (sierpień 1993): 197–208. http://dx.doi.org/10.1017/s0967199400001477.
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SummaryAn erythrochyte anti-ankryin antibody was used to investigate the presence and distribution of ankryin in eggs and embryos of ascidian species with different modes of development. In eggs of the indirect developer Ascidia ceratodes anti-ankryin reacted with a 210 kDa polypeptide which has an electrophoretic mobility similar to the vertebrate ankryins. Immunofluorescence microscopy showed that the ankryin-like protein is co-distributed with the myoplasm throughout development. It is restricted to a thin layer under the plasma membrane in unfertilised eggs, undergoes ooplasmic segregation to the posterior pole of the zygote after fertilisation, and is distributed to the tail muscle cells during cleavage and embryogenesis. After gastrulation and neurulation, lower levels of the ankryin-like protein, presumably of zygotic origin, were observed in brain cells and in the apical margin of epidermal cells. The ankryin-like protein was also localised in the myoplasm in eggs and embryos of another indirect developing species, Halocynthia roretzi. The ankryin-like protein may link the cytoskeleton with the plasma membrane in ascidian eggs, as it does in vertebrate erythrocytes. In contrast to A. ceratodes and H. rorefzi, which are members of the families Ascidiidae and Pyuridae respectively, the pattern of ankryin-like protein expression was changed in five species in the family Molgulidae. These molgulid ascidians exhibit either indirect or direct development, and eggs of the direct developing species have lost or modified the myoplasm. The ankryir like protein was present in young oocytes but failed to persist during oogenesis and disappeared in mature eggs and embryos of these molgulid species. The change in ankryin-like protein expression may be a preadaptation for loss of the myoplasm and the evolution of direct development.