• Animal cells and systems
• /
• v.10 no.3
• /
• pp.169-173
• /
• 2006

Zygomolgus dentatus n. sp. is described based on specimens from washings of compound ascidians from intertidal shores of Korea. It possesses the long caudal rami which are 5.6 times as long as their width, four scales on the convex side of mandible, and three setal elements and a large process on maxillule. Lichomolgides cuanensis Gotto, the only representative of the genus Lichomolgides, is transferred to the genus Zygomolgus.

• Development and Reproduction
• /
• v.6 no.2
• /
• pp.77-82
• /
• 2002

In ascidians, a primitive chordate, maternal cytoplasmic factors and inductive interactions are involved in the specification of cell fates in early embryos. The larval structure of ascidians is relatively simple, and the major mesodermal tissues of the tadpole larva are notochord, muscle, and mesenchyme. Formation of muscle cells is a cell-autonomous process, and localized maternal macho-l mRNA specify muscle fate in the posterior marginal zone of the early embryo. In contrast, inductive influence from endoderm precursors plays important roles in the specification of notochord and mesenchyme fates. FGF-Ras-MAPK signaling is involved In the induction of both tissues. The difference in responsiveness of the posterior mesenchyme and anterior notochord precursors to FGF signaling is caused by the presence or absence of intrinsic factors that inherited from the posterior-vegetal egg cytoplasm, respectively. In these inductions, directed signal polarizes the induced cells and promotes asymmetric cell divisions to produce two daughter cells with distinct fates.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.2
• /
• pp.68-72
• /
• 2007

The flow properties of sulfated polysaccharides purified from the ascidian Halocynthia roretzi tunic were investigated. The sulfated polysaccfarides produced aqueous solutions of low apparent viscosity with pseudoplastic flow behavior. The respective activation energies of TCA-treated and TCA-nontreated solutions were $2.2248{\times}10^4\;and\;1.442{\times}10^4J/kg{\cdot}mol$ at a 150L/s shear rate. The viscosity of the sulfated polysaccharides solution was increased by the addition of sugar, while it was not changed by the addition of NaCl.

• YAKHAK HOEJI
• /
• v.37 no.5
• /
• pp.527-531
• /
• 1993

As a part of chemical study on the bioactive metabolites from marine organisms, we have investigated cytotoxicity using brine shrimp bioassay for each solvent fractions of the marine algae(12 species), marine sponges(3 species), coelenterates(2 species), echinoderms(4 species), marine molluscs(17 species), and ascidians(2 species), respectively. As the results, chloroform extract of Stichopus japonicus (LC$_{50}$ : 274 $\mu\textrm{g}$/ml), ethyl acetate extract of Anthocidaris crassispina(LC$_{50}$ : 121 $\mu\textrm{g}$/ml), n-butanol extract of Unda), ia Pinnatifida (LC$_{50}$ : 178 $\mu\textrm{g}$/ml), and water extract of Thais clavigera (LC$_{50}$ : 61 $\mu\textrm{g}$/ml) displayed the most significant cytotoxic activity against brine shrimp. Among the marine organisms tested, echinoderms and marine molluscs were thought to be the most active Phylums on screening of new bioactive compounds.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.6
• /
• pp.761-769
• /
• 1995

About 2.1g of pale yellow flavor concentrate was obtained from 10kg of chopped fresh ascidians through a Likens-Nickerson steam distilllation/solvent extraction. These concentrates could be fractionated to neutral $(91.5\%),\;basic\;(1.0\%),\;phenolic\;(3.2\%),\;and\;acidic\;(4.3\%)$ fractions. Total 65 volatile compounds were identified from those concentrates. The neutral fraction was representative flavor fraction which showed a similar flavor of total steam distillates of ascidian. The major compounds $(38.2\%\;of\;neutral\;fraction)$ were identified as carbon atoms 8 to 10 of alcohols. Among these volatile alcohols, 1-octanol, 2,7-decadien-1-o1, 3-octen-l-01, 7-decen-l-ol, and l-decanol were the dominent compounds found in neutral fraction. But the basic, phenolic, and acidic fractions differs from ascidian steam distillates flavor.

• Animal Systematics, Evolution and Diversity
• /
• v.31 no.1
• /
• pp.1-7
• /
• 2015

Colonial ascidians, Clavelina elegans (Oka, 1927) and Clavelina miniata Watanabe & Tokioka, 1973 are reported for the first time in Korean waters. As a result of this study, three species of the genus Clavelina are now recorded in Korean fauna. Clavelina elegans and C. miniata have been reported only from Japan. We expanded the distribution range of these species to Korea. The specimens of C. elegans and C. miniata were collected from the subtidal zone of Beomseom and Chagwido in Jeju-do by SCUBA diving. Detailed descriptions, illustrations and photographs of these species are provided in this paper.

• Animal Systematics, Evolution and Diversity
• /
• v.37 no.1
• /
• pp.26-30
• /
• 2021

Botrylloides violaceus is native to the Northwest Pacific, including Korea. This species has many color variations in alive condition and a variety of zooid compound forms, and therefore difficult to identification in the field survey. This is the first report of COI DNA barcodes of B. violaceus from Korea. The intra-specific pairwise distance between Korean and UK populations had ranged from 1.4% to 2.6%. The inter-specific variations between B. violaceus and other Botrylloides species were 21.0-36.8%. The new DNA barcodes for Korean B. violaceus may be helpful in the identification of colonial ascidians, which is a difficult task when based on morphological identification.

• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.37-40
• /
• 2002

Ascidians are lower chordates, and their tadpole-like larvae share a basic body plan with vertebrates. To study photoreceptive systems in ascidians, we have isolated and characterized cDNA clones for three opsins, five G protein ${\alpha}$ subunits (G${\alpha}$), catalytic and regulatory subunits of cGMP phosphodiesterase (PDE), and arrestin from the ascidian Ciona intestinalis tadpole larva. Ci-opsin1 and Ci-opsin2 are vertebrate-type opsins, while Ci-opsin3 is a retinal photoisomerase similar to retinochrome and mammalian RGR. Both Ci-opsin1 and arrestin are specifically localized in the photoreceptor cells of the ocellus, whereas Ci -opsin2 is not expressed in the photoreceptors, but is co-localized in another population of neurons in the brain with PDE (Ci-PDE9 and Ci-PDE$\delta$). Ci-opsin3 is present in the entire region of the brain. Though five different cDNAs encoding Ga have been cloned, no transducin-type G protein has been found yet. Interestingly, one of G${\alpha}$i isoform is conspicuously expressed in the entire region of the brain. The Ci-opsin3 gene expression was observed in a broad area of the brain vesicle as well as in the visceral ganglion. Genes encoding ascidian homologs of CRALBP and ${\beta}$-CD, whose function is required for the mammalian visual cycle, are co-expressed with Ci-opsin3 in the brain vesicle and visceral ganglion. Localization of Ci-opsin3, CRALBP, and ${\beta}$-CD in a broad area of the brain suggests that the brain of the ascidian larva has a visual cycle system similar to that of the vertebrate RPE. Based on these data, we discuss the evolution of vertebrate visual systems.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.31 no.5
• /
• pp.440-453
• /
• 2005

Objectives : To develop a bioactive membrane for guided bone regeneration (GBR), the biocompatibility and bone regenerating capacity of the cellulose membrane obtained from the Ascidians squirt skin were evaluated. Materials and methods : After processing the pure cellulose membrane from the squirt skin, the morphological study, amino acid analysis and the immunoreactivity of the cellulose membrane were tested. Total eighteen male Spraque-Dawley rats (12 weeks, weighing 250 to 300g) were divided into two control (n=8) and another two experimental groups (n=10). In the first experimental group (n=5), the cellulose membrane was applicated to the 8.0 mm sized calvarial bone defect and the same sized defect was left without cellulose membrane in the first control group (n=4). In the another experimental group (n=5), the cellulose membrane was applicated to the same sized calvarial bone defect after femoral bone graft and the same sized defect with bone graft was left without cellulose membrane in the another control group (n=4). Each group was sacrificed after 6 weeks, the histological study with H&E and Masson trichrome stain was done, and immunohistochemical stainings of angiogenin and VEGF were also carried out. Results : The squirt skin cellulose showed the bio-inductive effect on the bone and mesenchymal tissues in the periosteum of rat calvarial bone. This phenomenon was found only in the inner surface of the cellulose membrane after 6 weeks contrast to the outer surface. Bone defect covered with the bioactive cellulose membrane showed significantly greater bone formation compared with control groups. Mesenchymal cells beneath the inner surface of the bioactive cellulose membrane were positive to the angiogenin and VEGF antibodies. Conclusion : We suppose that there still remains extremely little amount of peptide fragment derived from the basement membrane matrix proteins of squirt skin, which is a kind of anchoring protein composed of glycocalyx. This composition could prevent the adverse immunological hypersensitivity and also induce bioactive properties of cellulose membrane. These properties induced the effective angiogenesis with rapid osteogenesis beneath the inner surface of cellulose membrane, and so the possibilities of clinical application in dental field as a GBR material will be able to be suggested.

• Parasites, Hosts and Diseases
• /
• v.52 no.3
• /
• pp.305-310
• /
• 2014

Ascidian soft tunic syndrome (AsSTS) caused by Azumiobodo hoyamushi (A. hoyamushi) is a serious aquaculture problem that results in mass mortality of ascidians. Accordingly, the early and accurate detection of A. hoyamushi would contribute substantially to disease management and prevention of transmission. Recently, the loop-mediated isothermal amplification (LAMP) method was adopted for clinical diagnosis of a range of infectious diseases. Here, the authors describe a rapid and efficient LAMP-based method targeting the 18S rDNA gene for detection of A. hoyamushi using ascidian DNA for the diagnosis of AsSTS. A. hoyamushi LAMP assay amplified the DNA of 0.01 parasites per reaction and detected A. hoyamushi in 10 ng of ascidian DNA. To validate A. hoyamushi 18S rDNA LAMP assays, AsSTS-suspected and non-diseased ascidians were examined by microscopy, PCR, and by using the LAMP assay. When PCR was used as a gold standard, the LAMP assay showed good agreement in terms of sensitivity, positive predictive value (PPV), and negative predictive value (NPV). In the present study, a LAMP assay based on directly heat-treated samples was found to be as efficient as DNA extraction using a commercial kit for detecting A. hoyamushi. Taken together, this study shows the devised A. hoyamushi LAMP assay could be used to diagnose AsSTS in a straightforward, sensitive, and specific manner, that it could be used for forecasting, surveillance, and quarantine of AsSTS.