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1
Morton, Brian, and 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, no. 8 (December 15, 2010): 1637–49. http://dx.doi.org/10.1017/s0025315410001980.
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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.
2
Palomino-Alvarez, Lilian A., Rosana Moreira Rocha, and Nuno Simões. "Checklist of ascidians (Chordata, Tunicata) from the southern Gulf of Mexico." ZooKeys 832 (March 19, 2019): 1–33. https://doi.org/10.3897/zookeys.832.31712.
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This study is the first inventory of ascidians from shallow waters (0–25 m) of coastal and reef habitats in the southern Gulf of Mexico where ascidian diversity is poorly known. Sampled environments in 14 locations (38 sites) with 134 samples collected from 2015 to 2017 included coral reefs, coastal lagoons, mangroves, seagrass, ports, and artificial platforms. The 31 identified species comprise 19 genera and 13 families. Ten species are newly reported in the Gulf of Mexico: Ascidia panamensis Bonnet & Rocha, 2011; Ecteinascidia styeloides (Traustedt, 1882); Cystodytes roseolus Hartmeyer, 1912; Eudistoma aff. amanitum Paiva & Rocha, 2018; Eudistoma recifense Millar, 1977; Euherdmania fasciculata Monniot, 1983; Euherdmania aff. vitrea Millar, 1961; Polycarpa cartilaginea (Sluiter, 1885); Botrylloides magnicoecum (Hartmeyer, 1912) and Didemnum granulatum Tokioka, 1954. Two new species will be described separately (Clavelina sp. and Pyura sp.). This study provides the first records for 26 species ascidians for the region as well as describes increased distributions of ten Atlantic species. Thus, our data provide a starting point for future ecological, experimental and taxonomic studies of ascidians of the Gulf of Mexico.
3
Jain, Seema Sachin, and 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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Tatian, M., R. J. Sahade, M. E. Doucet, and G. B. Esnal. "Ascidians (Tunicata, Ascidiacea) of Potter Cove, South Shetland Islands, Antarctica." Antarctic Science 10, no. 2 (June 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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Eckhardt, Shannon, Tracy D. Ainsworth, William Leggat, and Charlotte E. Page. "Colonial Ascidian Populations at Inshore Coral Reefs of Norfolk Island, South Pacific." Diversity 16, no. 7 (June 30, 2024): 384. http://dx.doi.org/10.3390/d16070384.
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Subtropical coral reefs such as the lagoonal reefs of Norfolk Island in the remote South Pacific are vastly understudied, with many benthic species unrecorded in the scientific literature. Here we report on ascidian populations from 2021 to 2023 at Norfolk Islands inshore reefs. Quantitative assessments spanning that period were conducted to assess ascidian presence, cover, and benthic interactions. We show ascidian cover remained persistently low and stable across the lagoonal reefs during the study period. We find adjacent reef site, Cemetery Bay showed variation in ascidian cover over time, where we measure a 3.2-fold increase in cover over 2 years. Ascidians were associated primarily with sand and sediment substrates at all reef locations. Recorded interactions between hard corals and ascidians were low. This study provides valuable insights into the population dynamics of ascidians within subtropical reef ecosystems. Ongoing ascidian population monitoring can provide a comprehensive understanding of ascidian dynamics whilst also providing insight of theimpact of anthropogenic stressors on benthic communities. Together, this can aid in informing management and conservation strategies for subtropical reefs.
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KNEER, DOMINIK, FRANCOISE MONNIOT, THOMAS STACH, and 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, no. 5 (February 22, 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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Malintoi, Adrianus, Inneke F. M. Rumengan, Kakaskasen A. Roeroe, Veibe Warouw, Ari B. Rondonuwu, and Medy Ompi. "KOMUNITAS ASCIDIA DI PESISIR MALALAYANG DUA, TELUK MANADO, SULAWESI UTARA." JURNAL PESISIR DAN LAUT TROPIS 8, no. 1 (January 15, 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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Sargent, P. S., J. F. Hamel, and 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, no. 12 (December 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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Rocha, Rosana Moreira, Edlin Guerra-Castro, Carlos Lira, Sheila Marquez Pauls, Ivan Hernández, Adriana Pérez, Adriana Sardi, et al. "Inventory of ascidians (Tunicata, Ascidiacea) from the National Park La Restinga, Isla Margarita, Venezuela." Biota Neotropica 10, no. 1 (March 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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Dou, Xiaoju, and Bo Dong. "Origins and Bioactivities of Natural Compounds Derived from Marine Ascidians and Their Symbionts." Marine Drugs 17, no. 12 (November 28, 2019): 670. http://dx.doi.org/10.3390/md17120670.
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Marine ascidians are becoming important drug sources that provide abundant secondary metabolites with novel structures and high bioactivities. As one of the most chemically prolific marine animals, more than 1200 inspirational natural products, such as alkaloids, peptides, and polyketides, with intricate and novel chemical structures have been identified from ascidians. Some of them have been successfully developed as lead compounds or highly efficient drugs. Although numerous compounds that exist in ascidians have been structurally and functionally identified, their origins are not clear. Interestingly, growing evidence has shown that these natural products not only come from ascidians, but they also originate from symbiotic microbes. This review classifies the identified natural products from ascidians and the associated symbionts. Then, we discuss the diversity of ascidian symbiotic microbe communities, which synthesize diverse natural products that are beneficial for the hosts. Identification of the complex interactions between the symbiont and the host is a useful approach to discovering ways that direct the biosynthesis of novel bioactive compounds with pharmaceutical potentials.
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Macpal, Yuliana, Veibe Warouw, Deiske A. Sumilat, James J. H. Paulus, Natalie D. C. Rumampuk, and Reni L. Kreckhoff. "AKTIVITAS ANTIBAKTERI DAN ANTI-UV BEBERAPA ASCIDIAN DARI PERAIRAN PANGALISANG BUNAKEN." JURNAL PESISIR DAN LAUT TROPIS 7, no. 3 (July 23, 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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Casertano, Marcello, Marialuisa Menna, and Concetta Imperatore. "The Ascidian-Derived Metabolites with Antimicrobial Properties." Antibiotics 9, no. 8 (August 13, 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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White, Kristine, Louis Ambrosio, and 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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Dias, G. M., R. M. Rocha, T. M. C. Lotufo, and L. P. Kremer. "Fifty years of ascidian biodiversity research in São Sebastião, Brazil." Journal of the Marine Biological Association of the United Kingdom 93, no. 1 (June 7, 2012): 273–82. http://dx.doi.org/10.1017/s002531541200063x.
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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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Tsotsios, Dimitrios, Maria V. Alvanou, Dimitrios K. Papadopoulos, Vlasoula Bekiari, Konstantinos Feidantsis, Ioannis A. Giantsis, and John A. Theodorou. "Influence of Key Physicochemical Factors on the Temporal Dynamics of Invasive and Native Ascidian Settlement." Water 17, no. 8 (April 9, 2025): 1122. https://doi.org/10.3390/w17081122.
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In an effort to monitor ascidian recruitment in mussel aquaculture facilities, a series of settlement plates (20 × 20 cm) were placed in a mussel farm located in the Amvrakikos Gulf (Ionian Sea). The plates were vertically deployed on floating facilities in the water column at regular intervals (depths of 0.2 m, 1.5 m, and 3 m) to monitor the settlement and proliferation of ascidians. Furthermore, measurements of seawater physicochemical parameters such as temperature, salinity, dissolved oxygen, and chlorophyll-a concentration were conducted together with the record of ascidian species in each sampling from January 2021 to November 2021. The correlation of these parameters with ascidian species provides information on their effect on the periodicity of ascidians’ recruitment. The results demonstrated a significant correlation between ascidian presence and water temperature. The potential influence of other important environmental parameters such as chlorophyll-a was not revealed, likely due to the limited number of values and samples included in the analyses. While increased chlorophyll levels, reflecting increased primary productivity or nutrient availability, are associated with increased growth and reproduction of all ascidian species, the effect of temperature was more potent and species-specific. Ciona robusta, Styela plicata, Microcosmus squamiger, and Phallusia mammillata were mainly detected at temperatures below 25 °C, whereas Clavelina oblonga was prevalent at temperatures above 25 °C. The absence of most ascidians at temperatures above 25 °C was possibly attributed to decreased settlement success and to the increased competition from C. oblonga at higher temperatures. The deployment of settlement plates in correlation with seawater physiochemical parameters can provide valuable data on ascidian settlement dynamics and support the development of targeted management practices for biofouling control.
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Ma, Kevin C. K., Don Deibel, Kenneth K. M. Law, Mai Aoki, Cynthia H. McKenzie, and Maria L. D. Palomares. "Richness and zoogeography of ascidians (Tunicata: Ascidiacea) in eastern Canada." Canadian Journal of Zoology 95, no. 1 (January 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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Bates, William R. "Environmental factors affecting reproduction and development in ascidians and other protochordates." Canadian Journal of Zoology 83, no. 1 (January 1, 2005): 51–61. http://dx.doi.org/10.1139/z04-164.
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Protochordate reproduction and development are influenced by many kinds of environmental factors. For example, spawning, sexual and asexual reproduction, larval behaviour, and life-cycle transitions (metamorphosis) are key processes known to be affected by environmental factors. This review must be restricted primarily to only one group of protochordates, the ascidians or "sea squirts", because information on the reproductive ecology of hemichordates and cephalochordates is limited to only a few studies. Topics discussed in the present review include (i) environmental factors that regulate larval settlement, (ii) how pelagic embryos avoid damage to DNA caused by UV radiation, (iii) the effect of water temperature and food availability on sexual reproduction in colonial ascidians, (iv) environmental regulation of asexual budding, (v) environmental regulation of metamorphosis, and (vi) the possible role of the environment in the evolution of direct-developing ascidians. A novel role for HSP90 and nitric oxide signaling in the integration of environmental factors with cell signaling pathways in ascidians is discussed near the end of this review. Throughout this review, the multiple roles of environmental stress on ascidian reproduction and development are emphasized.
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Kawada, Tsuyoshi, Michio Ogasawara, Toshio Sekiguchi, Masato Aoyama, Kohji Hotta, Kotaro Oka, and 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, no. 6 (April 5, 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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Chen, Lei, Xue-Ning Wang, Chang-Ming Fu, and 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 (August 28, 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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Dalby, JE. "Consequences of aggregated living in the ascidian Pyura stolonifera: Evidence for non-contact intraspecific competition." Marine and Freshwater Research 46, no. 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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Sanamyan, K. E., N. P. Sanamyan, and O. L. Zimina. "New records of deep-water ascidians (Ascidiacea: Stolidobranchia) from the Arctic Ocean, with comments on nomenclature and taxonomy." Zoosystematica Rossica 34, no. 1 (April 11, 2025): 118–27. https://doi.org/10.31610/zsr/2025.34.1.118.
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Three species of stolidobranch ascidians, Asajirus arcticus (Hartmeyer, 1923), Eugyrioides pedunculatus (Traustedt, 1886), comb. nov., and Kukenthalia borealis Hartmeyer, 1903 are recorded from the deep waters of the Arctic Ocean for the first time and are briefly described based on new material. The nomenclature of the involved ascidian taxa is discussed. It is shown that Eugyra Hancock, 1870 (Ascidiacea) is preoccupied by Eugyra Fromentel, 1857 (Anthozoa) and that the valid generic name for ascidians currently assigned to Eugyra is Eugyrioides Seeliger, 1907. The currently accepted subfamily name Polyzoinae Michaelsen, 1900 is invalid, as it is a junior synonym of Polystyelinae Herdman, 1886.
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Nakatani, Y., R. Moody, and W. C. Smith. "Mutations affecting tail and notochord development in the ascidian Ciona savignyi." Development 126, no. 15 (August 1, 1999): 3293–301. http://dx.doi.org/10.1242/dev.126.15.3293.
Full textAbstract:
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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Koike, I., M. Yamamuro, and PC Pollard. "Carbon and nitrogen budgets of two Ascidians and their symbiont, Prochloron, in a tropical seagrass meadow." Marine and Freshwater Research 44, no. 1 (1993): 173. http://dx.doi.org/10.1071/mf9930173.
Full textAbstract:
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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Huang, Qiuyang, Xiaoling Zang, Xinyu Jin, Qian Liu, Xin Zhang, Xinyu Li, Lizhen Zhao, and Zhihua Lv. "Discovery of PD-L1 Peptide Inhibitors from Ascidian Enzymatic Hydrolysates by Affinity Ultrafiltration Coupled to NanoLC-MS/MS." Marine Drugs 23, no. 4 (March 21, 2025): 137. https://doi.org/10.3390/md23040137.
Full textAbstract:
Anti-PD-1 and anti-PD-L1 antibodies have achieved great clinical success in cancer immunotherapy, and peptide and small molecule inhibitors of PD-1/PD-L1 binding also attract much attention. Ascidians are not only seafood, but are also an important source of bioactive substances, including anti-tumor components. In this study, ascidian enzymatic hydrolysates were found to contain PD-1/PD-L1 inhibitory components. Affinity ultrafiltration (AUF) coupled with the nanoLC-MS/MS method was first applied in screening for PD-L1 peptide inhibitors from ascidian enzymatic hydrolysates. Two anti-PD-L1 ascidian peptides, C5 (LDVVIHTVTYGDR) and S2 (VLRDNIQGITKPAIR), were filtered out from the ascidians Ciona intestinalis and Styela clava, respectively. C5 and S2 showed moderate anti-PD-1/PD-L1 effects with the IC50 values of 33.9 µM (C5) and 112.8 μM (S2), respectively, by homogenous time-resolved fluorescence (HTRF) binding assay, and the KD values of 22.9 µM (C5) and 29.1 µM (S2), respectively, by surface plasmon resonance (SPR) assay. The results of this study suggest that ascidian enzymatic hydrolysates may be a potential source of bioactive peptides with anti-PD-1/PD-L1 activity.
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Palomino-Alvarez, Lilian A., Rosana Moreira Rocha, and Nuno Simões. "Checklist of ascidians (Chordata, Tunicata) from the southern Gulf of Mexico." ZooKeys 832 (March 19, 2019): 1–33. http://dx.doi.org/10.3897/zookeys.832.31712.
Full textAbstract:
This study is the first inventory of ascidians from shallow waters (0–25 m) of coastal and reef habitats in the southern Gulf of Mexico where ascidian diversity is poorly known. Sampled environments in 14 locations (38 sites) with 134 samples collected from 2015 to 2017 included coral reefs, coastal lagoons, mangroves, seagrass, ports, and artificial platforms. The 31 identified species comprise 19 genera and 13 families. Ten species are newly reported in the Gulf of Mexico:AscidiapanamensisBonnet & Rocha, 2011;Ecteinascidiastyeloides(Traustedt, 1882);CystodytesroseolusHartmeyer, 1912; Eudistomaaff.amanitum Paiva & Rocha, 2018;EudistomarecifenseMillar, 1977;EuherdmaniafasciculataMonniot, 1983; Euherdmaniaaff.vitrea Millar, 1961;Polycarpacartilaginea(Sluiter, 1885);Botrylloidesmagnicoecum(Hartmeyer, 1912) andDidemnumgranulatumTokioka, 1954. Two new species will be described separately (Clavelinasp. andPyurasp.). This study provides the first records for 26 species ascidians for the region as well as describes increased distributions of ten Atlantic species. Thus, our data provide a starting point for future ecological, experimental and taxonomic studies of ascidians of the Gulf of Mexico.
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Su, Shih-Wei, Euichi Hirose, Serina Lee Siew Chen, and Michael Hin-Kiu Mok. "Photosymbiotic ascidians in Singapore: turbid waters may reduce living space." ZooKeys 305 (May 30, 2013): 55–65. https://doi.org/10.3897/zookeys.305.4893.
Full textAbstract:
The photosymbiotic ascidian fauna at Changi Beach, Pulau Semakau, Sentosa and St. John’s Island, Singapore were surveyed. A total of five species,<i> Diplosoma simile, Lissoclinum bistratum, L. punctatum,</i> <i>L. timorense </i>and <i>Trididemnum cyclops,</i> were recorded, with <i>L. timorense</i> and <i>T</i>.<i> cyclops</i> being newly recorded in Singapore. However, no photosymbiotic species were found at Changi Beach probably due to the polluted waters in the region. Coastal development has caused Singapore waters to become turbid, leading to decrease in suitable habitats for photosymbiotic ascidians. Clean waters in Pulau Semakau probably provide a better environment for the growth of photosymbiotic ascidians and this area has a greater variety of these ascidians than the other areas in Singapore. Each of the five species has also been recorded in the Ryukyu Archipelago (Japan) and three species (<i>Diplosoma simile</i>, <i>Lissoclinum bistratum</i> and <i>Trididemnum cyclops</i>) have also been recorded in Taiwan.
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Hirose, Euichi, Ryuma Adachi, and Koji Kuze. "Sexual reproduction of the Prochloron-bearing ascidians, Trididemnum cyclops and Lissoclinum bistratum, in subtropical waters: seasonality and vertical transmission of photosymbionts." Journal of the Marine Biological Association of the United Kingdom 86, no. 1 (January 12, 2006): 175–79. http://dx.doi.org/10.1017/s0025315406013002.
Full textAbstract:
The seasonality of sexual reproduction was studied in two Prochloron-bearing ascidians, Trididemnum cyclops and Lissoclinum bistratum, on a subtropical coral reef off Okinawajima Island, Japan. These colonial ascidians had testes and/or eggs/embryos from spring to summer. Embryos with tails occurred in summer. Whereas many photosymbiotic didemnids are thought to be sexually mature throughout the year in the tropics, sexual reproduction of the same species in subtropical waters may be limited to spring and summer. The subtropical winter may be too cold for gonad formation. A histological study of sexually mature colonies showed no Prochloron cells attached to ascidian larvae in the pre-hatch stage.
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Wilding, Martin, Marcella Marino, and Daniela Dale. "Nicotinamide alters the calcium release pattern and the degradation of MPF activity after fertilisation in ascidian oocytes." Zygote 7, no. 3 (August 1999): 255–60. http://dx.doi.org/10.1017/s0967199499000647.
Full textAbstract:
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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Cone, Angela C., and Robert W. Zeller. "Using ascidian embryos to study the evolution of developmental gene regulatory networks." Canadian Journal of Zoology 83, no. 1 (January 1, 2005): 75–89. http://dx.doi.org/10.1139/z04-165.
Full textAbstract:
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 M. da, and Laura P. Kremer. "Introduced ascidians in Paranaguá Bay, Paraná, southern Brazil." Revista Brasileira de Zoologia 22, no. 4 (December 2005): 1170–84. http://dx.doi.org/10.1590/s0101-81752005000400052.
Full textAbstract:
Exotic (introduced) species are a growing problem in ports worldwide and comprise the most important impacts in marine ecosystems. Periodic monitoring to detect introduced species is extremely important for effective population control. Here we sampled ascidian species near the port of Paranaguá for a taxonomic study of this fauna to attempt to detect introduced species. Larval stages in ascidians are short-lived, and dispersal is restricted to small distances, and so ascidians are very good bioindicators for exotic introductions due to ship transport. Four locations were sampled within Paranaguá Bay (Ilha das Cobras, Pier Tenenge, Ilha do Mel and Ilha da Galheta) and one location outside of the bay (Parque dos Meros). Information for the nearby fauna and for geographic distributions of the species involved was obtained from the literature. Eighteen species were found: Perophora multiclathrata (Sluiter, 1904), Ascidia curvata (Traustedt,1882), A. sydneiensis Stimpson, 1855, Clavelina oblonga Herdman, 1880, Cystodytes dellechiajei (Della Valle, 1877), Eudistoma carolinense van Name, 1945, Distaplia bermudensis van Name, 1902, Didemnum granulatum Tokioka, 1954, Diplosoma listerianum (Milne-Edwards, 1841), Lissoclinum fragile (van Name, 1902), Botryllus planus (van Name, 1902), B. tuberatus Ritter & Forsyth 1917, Botrylloides nigrum Herdman, 1886, Symplegma rubra Monniot, 1972, Styela canopus (Savigny, 1816), S. plicata (Lesueur, 1823), Microcosmus exasperatus Heller, 1878 and Molgula phytophila Monniot, 1970. The known geographic distributions based on the literature and collections suggest that three species are native, one is a inter-regional introduction, two are introduced from the Pacific and the remaining 12 are cryptogenic.
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López-Legentil, Susanna, Xavier Turon, and Patrick M. Erwin. "Feeding cessation alters host morphology and bacterial communities in the ascidian Pseudodistoma crucigaster." Frontiers in Zoology 13, no. 1 (January 14, 2016): 2. https://doi.org/10.1186/s12983-016-0134-4.
Full textAbstract:
<strong>Background: </strong>Ascidians can associate with abundant and diverse consortia of microbial symbionts, yet these communities remain unexamined for the majority of host ascidians and little is known about host-symbiont interactions.<strong>Methods: </strong>We coupled electron microscopy and 16S rRNA gene tag pyrosequencing to investigate the bacterial communities associated with the colonial ascidian <i>Pseudodistoma crucigaster</i>, a species endemic to the Mediterranean Sea that has a life cycle with two phases: actively-filtering (active) and non-filtering (resting) forms.<strong>Results: </strong>Resting colonies exhibited a reduced branchial sac (feeding apparatus) and a thickened cuticle. Electron microscope images also suggested higher abundance of colonizing microorganisms on surfaces of resting colonies. Accordingly, bacterial sequences associated with environmental sources (sediment and biofilms, >99 % similarity) were detected exclusively in resting colonies. Bacterial communities of <i>P. crucigaster</i> colonies (active and resting) were dominated by 3 core taxa affiliated (>94 % similarity) with previously described symbiotic Alphaproteobacteria in marine invertebrates. Shifts in rare bacteria were detected when ascidians entered the resting phase, including the appearance of strictly anaerobic lineages and nitrifying bacterial guilds.<strong>Conclusions: </strong>These findings suggest that physical (thickened cuticle) and metabolic (feeding cessation) changes in host ascidians have cascading effects on associated bacteria, where modified oxygen concentrations and chemical substrates for microbial metabolism may create anaerobic microhabitats and promote colonization by environmental microorganisms.
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Katsuyama, Y., S. Wada, S. Yasugi, and 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, no. 10 (October 1, 1995): 3197–205. http://dx.doi.org/10.1242/dev.121.10.3197.
Full textAbstract:
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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Murugan, Rajaram, and Gnanakkan Ananthan. "Ascidian diversity (Chordata: Tunicata) from Andaman and Nicobar Islands, India." Oceanological and Hydrobiological Studies 47, no. 2 (June 26, 2018): 107–17. http://dx.doi.org/10.1515/ohs-2018-0012.
Full textAbstract:
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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Hirose, Euichi, Kaori Ohtsuka, Masaharu Ishikura, and Tadashi Maruyama. "Ultraviolet absorption in ascidian tunic and ascidian-Prochloron symbiosis." Journal of the Marine Biological Association of the United Kingdom 84, no. 4 (August 2004): 789–94. http://dx.doi.org/10.1017/s0025315404009956h.
Full textAbstract:
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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Mercurio, Silvia, Matteo Bozzo, Alessandro Pennati, Simona Candiani, and Roberta Pennati. "Serotonin Receptors and Their Involvement in Melanization of Sensory Cells in Ciona intestinalis." Cells 12, no. 8 (April 13, 2023): 1150. http://dx.doi.org/10.3390/cells12081150.
Full textAbstract:
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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Lambert, Gretchen, and Karen Sanamyan. "Distaplia alaskensis sp.nov. (Ascidiacea, Aplousobranchia) and other new ascidian records from south-central Alaska, with a redescription of Ascidia columbiana (Huntsman, 1912)." Canadian Journal of Zoology 79, no. 10 (October 1, 2001): 1766–81. http://dx.doi.org/10.1139/z01-141.
Full textAbstract:
Alaskan ascidians are incompletely known and rarely sampled. The Smithsonian Environmental Research Center recently conducted an extensive survey of harbors and marinas for nonindigenous species at major marine traffic sites on the Kenai Peninsula and Prince William Sound in Alaska. Collections made during summer 1998 and 1999 included 12 species of ascidians, one of which is a new species of Distaplia, D. alaskensis. We consider it indigenous, though it could be cryptogenic because it was collected only from marina floats and no neighboring natural subtidal areas have ever been sampled. All the other species are natives except Botrylloides violaceus. This aggressive invader from Japan has recently spread rapidly along both coasts of the U.S.A. and Canada as well as in many other parts of the world, and is here reported from Alaska for the first time. Ascidia columbiana (Huntsman, 1912), synonymized in 1924 by Hartmeyer under Ascidia callosa, has now been shown to be a valid species, based on differences in morphology and reproductive mode; a redescription of A. columbiana is included here. Several species collected in 2000 at the Sitka Sea Farm mariculture facility near Sitka are also included. Because all these collections are from areas never before sampled for ascidians, all are new records for these species.
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Pichon, Julien, Nicholas M. Luscombe, and Charles Plessy. "Widespread use of the “ascidian” mitochondrial genetic code in tunicates." F1000Research 8 (December 10, 2019): 2072. http://dx.doi.org/10.12688/f1000research.21551.1.
Full textAbstract:
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, and Charles Plessy. "Widespread use of the “ascidian” mitochondrial genetic code in tunicates." F1000Research 8 (April 14, 2020): 2072. http://dx.doi.org/10.12688/f1000research.21551.2.
Full textAbstract:
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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Nichols, Claire L., Gretchen Lambert, and Marie L. Nydam. "Continued persistence of non-native ascidians in Southern California harbors and marinas." Aquatic Invasions 18, no. 1 (April 18, 2023): 1–22. http://dx.doi.org/10.3391/ai.2023.18.1.101962.
Full textAbstract:
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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Nichols, Claire L., Gretchen Lambert, and Marie L. Nydam. "Continued persistence of non-native ascidians in Southern California harbors and marinas." Aquatic Invasions 18, no. (1) (April 18, 2023): 1–22. https://doi.org/10.3391/ai.2023.18.1.101962.
Full textAbstract:
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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Van Volkom, Kaitlin S., Larry G. Harris, and Jennifer A. Dijkstra. "The influence of invasive ascidian diets on the growth of the sea star Henricia sanguinolenta." Journal of the Marine Biological Association of the United Kingdom 101, no. 1 (February 2021): 151–57. http://dx.doi.org/10.1017/s0025315420001228.
Full textAbstract:
AbstractInvasive species can disrupt food webs by altering the abundance of prey species or integrating into the food web themselves. In the Gulf of Maine, there have been a suite of invasions that have altered the composition of the benthic ecosystem. These novel prey species can potentially benefit native predators depending on their nutritional value and relative abundance. We measured feeding instances of the native blood star, Henricia sanguinolenta, and changes in the seasonal abundances of invasive ascidian prey species. Results indicate that H. sanguinolenta forages optimally, as the blood star will prey on invasive ascidians when in high abundance, but feed on other species during periods of scarcity. Further, our study shows that blood stars prey on a wider variety of species than was previously known, such as small bivalves and barnacles. Additionally, we compared growth and reproduction of sea stars fed different combinations of invasive ascidians (Diplosoma listerianum or Botrylloides violaceus) or a native sponge (Haliclona oculata). Sea stars grew more on the native diet when compared with the invasive ascidian species, and D. listerianum appeared to be a superior quality food source when compared with B. violaceus. By comparing our data with historical data, we determined that there was a dramatic increase in sea star populations between 1980 and 2011, but then populations decreased by almost half from 2011 to 2016–2017. These data suggest that while invasive ascidians may have helped sea star populations at one point, sea stars are declining without their native food source.
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Mastrototaro, F., G. D'Onghia, and A. Tursi. "Spatial and seasonal distribution of ascidians in a semi-enclosed basin of the Mediterranean Sea." Journal of the Marine Biological Association of the United Kingdom 88, no. 5 (July 25, 2008): 1053–61. http://dx.doi.org/10.1017/s0025315408001392.
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A total of 25 species of ascidians were collected in the Mar Piccolo of Taranto, a semi-enclosed Mediterranean basin. Three are non-indigenous for the Mediterranean Sea: Microcosmus squamiger, Polyandrocarpa zorritensis and Distaplia bermudensis. The substrate features, season and depth affect the distribution of ascidians in the study area. Some species, such as Pyura dura and Pyura microcosmus, were found only on artificial substrates, while Ascidiella aspersa was almost exclusively recovered on natural bottoms. Seasonal variation in the ascidian distribution and abundance seems to be due mainly to their biological cycles, larval recruitment and adaptation. During the autumn and winter the most abundant species were Clavelina phlegraea and Ciona intestinalis, while A.aspersa was particularly abundant during spring. Depth and more directly light intensity play an important role in ascidian distribution. In the upper few metres the shallow-water species Polyandrocarpa zorritensis was abundant due to its photopositive larvae. Even though the distribution and abundance changed significantly between substrates, seasons and depths, the most abundant species in the Mar Piccolo of Taranto were Clavelina phlegraea, Ciona intestinalis and Styela plicata all of which are able to tolerate the variations in environmental conditions, low rate of water renewal and continuous silting of this semi-enclosed sea. Assuming the role that the above mentioned species have as marine pollution indicators and the abundance recorded for some of them, a high degree of environmental stress can be confirmed for the Mar Piccolo of Taranto. A comparative list of the ascidians recorded in this and previous studies is also reported.
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Rosner, Amalia, and Baruch Rinkevich. "Harnessing Ascidians as Model Organisms for Environmental Risk Assessment." Environments 11, no. 11 (October 23, 2024): 232. http://dx.doi.org/10.3390/environments11110232.
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Environmental Risk Assessment (ERA) often relies on a restricted set of species as bio-indicators, introducing uncertainty when modeling complex environmental variables. This may lead to oversimplified or erroneous risk assessments. Ascidians, marine filter-feeding sessile chordates, are valuable models for scientific research in various biological fields such as stem cell biology, embryogenesis, regeneration, innate immunity, and developmental biology. Their global distribution, sensitivity to pollutants, high abundance, mass sexual reproduction, and habitation in coastal areas impacted by anthropogenic pollution make them excellent indicators for monitoring marine pollution and global environmental changes, including biological invasions and species diversity diminution cases. Despite their potential as environmental bioindicators, ascidians remain underutilized in ERAs (≤0.13% of ERA studies), particularly in the field of chemical pollution impact assessment, primarily due to a lack of standardization. This underrepresentation poses a challenge for accurate modeling, especially in models relying on a broad range of species (e.g., Species Sensitivity Distributions). Given these constraints, expanding the use of ascidians in ERAs could improve the comprehension and precision of environmental changes and their assessments. This underscores the necessity for future research to establish standardized testing protocols and choose the most suitable ascidian species for inclusion in ERAs.
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Sanamyan, Karen E., Nadya P. Sanamyan, and Olga L. Zimina. "New records of deep-water ascidians (Ascidiacea: Stolidobranchia) from the Arctic Ocean, with comments on nomenclature and taxonomy." Zoosystematica Rossica 34, no. 1 (April 11, 2025): 118–27. https://doi.org/10.31610/zsr/2025.34.1.118.
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Three species of stolidobranch ascidians, <em>Asajirus arcticus</em> (Hartmeyer, 1923), <em>Eugyrioides pedunculatus</em> (Traustedt, 1886), <strong>comb. nov.</strong>, and <em>Kukenthalia borealis</em> Hartmeyer, 1903 are recorded from the deep waters of the Arctic Ocean for the first time and are briefly described based on new material. The nomenclature of the involved ascidian taxa is discussed. It is shown that <em>Eugyra</em> Hancock, 1870 (Ascidiacea) is preoccupied by <em>Eugyra</em> Fromentel, 1857 (Anthozoa) and that the valid generic name for ascidians currently assigned to <em>Eugyra</em> is <em>Eugyrioides</em> Seeliger, 1907. The currently accepted subfamily name Polyzoinae Michaelsen, 1900 is invalid, as it is a junior synonym of Polystyelinae Herdman, 1886.
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Leleran, Andreas J. P. L., Silvester B. Pratasik, Meiske S. Salaki, Lawrence J. L. Lumingas, Alex D. Kambey, and Suzanne L. Undap. "Distribution and Diversity of Ascidian in Manado Bay, North Sulawesi." Jurnal Ilmiah PLATAX 10, no. 1 (April 14, 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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Łukowiak, Magdalena. "First record of late Eocene ascidians (Ascidiacea, Tunicata) from southeastern Australia." Journal of Paleontology 86, no. 3 (May 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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Wada, H., H. Saiga, N. Satoh, and 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, no. 6 (March 15, 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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MONNIOT, FRANÇOISE. "Some new data on tropical western Pacific Ascidians." Zootaxa 2561, no. 1 (August 9, 2010): 1. http://dx.doi.org/10.11646/zootaxa.2561.1.1.
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Numerous collections of ascidians have been made in the Pacific and Indian Oceans but the inventory is far from complete. Each sampling provides new species. Two new didemnids are described here from Palau and Vanuatu. New records are given for 22 additional species with complementary descriptions and underwater photographs. The tropical ascidian fauna is highly diverse and successive new collections show that many of the species are not only widely distributed from the central to western Pacific but also common to the Indian Ocean.
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Demers, Marie-Claire A., Nathan A. Knott, and Andrew R. Davis. "Under the radar: Sessile epifaunal invertebrates in the seagrassPosidonia australis." Journal of the Marine Biological Association of the United Kingdom 96, no. 2 (August 13, 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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Manni, Lucia, Federico Caicci, Chiara Anselmi, Virginia Vanni, Silvia Mercurio, and Roberta Pennati. "Morphological Study and 3D Reconstruction of the Larva of the Ascidian Halocynthia roretzi." Journal of Marine Science and Engineering 10, no. 1 (December 24, 2021): 11. http://dx.doi.org/10.3390/jmse10010011.
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The swimming larva represents the dispersal phase of ascidians, marine invertebrates belonging to tunicates. Due to its adhesive papillae, the larva searches the substrate, adheres to it, and undergoes metamorphosis, thereby becoming a sessile filter feeding animal. The larva anatomy has been described in detail in a few species, revealing a different degree of adult structure differentiation, called adultation. In the solitary ascidian Halocynthia roretzi, a species reared for commercial purposes, embryogenesis has been described in detail, but information on the larval anatomy is still lacking. Here, we describe it using a comparative approach, utilizing 3D reconstruction, as well as histological/TEM observations, with attention to its papillae. The larva is comparable to those of other solitary ascidians, such as Ciona intestinalis. However, it displays a higher level of adultation for the presence of the atrium, opened outside by means of the atrial siphon, and the peribranchial chambers. It does not reach the level of complexity of the larva of Botryllus schlosseri, a phylogenetically close colonial ascidian. Our study reveals that the papillae of H. roretzi, previously described as simple and conform, exhibit dynamic changes during settlement. This opens up new considerations on papillae morphology and evolution and deserves to be further investigated.