• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.1
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• pp.1-11
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• 2014

This study was carried out to investigate nutritional and physiologically active characterizations of sikhae and the seasoned products from the sea squirt Halocynthia roretzi. The total taste values of sikhae fermented for 4 and 5 days were 10.9 and 15.4, respectively, which was lower than for commercially seasoned sea squirts. The sikhaes contained mostly glutamic and aspartic acids. The total amino acid contents of sikhaes fermented for 4 and 5 days were 5.5 and 6.0 g/100 g, respectively, which were lower than those of commercial seasoned-sea squirts or similar. An amount of 100 g of sikhae and its seasoned products contained P, K, Mg and Fe, and these minerals, which are deemed good for our health, were at 10% above the recommended daily requirements. The functional properties of sikhae fermented for 4 and 5 days were as follows: for ACE inhibiting activity, 69 and 69.5%, respectively; for antioxidative activity, 28.9 and 29.3%, respectively; for xanthine oxidase inhibitory activity, 52.8 and 53.1%, respectively; and for ${\alpha}$-glucosidase inhibitory activity, 2.4 and 1.4%, respectively. Antimicrobial activity of the 5 day fermented sikhae against Vibrio parahaemolyticus and Staphyloccus aureus was detected in 8 mm and in 7 mm against Escherichia coli.

• Korean Journal of Environmental Biology
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• v.32 no.3
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• pp.225-233
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• 2014

In this study, we investigated the changes in the physiological and histological traits of a sea squirt (Halocynthia roretzi) with the emergence of the soft tunic syndrome induced by the water temperature control (6, 9, 12, 15, 18, 21, 24 and $27^{\circ}C$). It was observed that the induction rate of the soft tunic syndrome was highest at $15^{\circ}C$, but lowest at $24^{\circ}C$. Based on the tunic color condition and contraction strength, the whole process were classified into 4 stages as S0, S1, S2 and S3. Interestingly, there were significant differences in oxygen consumption and filtration rate were observed during S0-S3. The most distinctive aspects were change of blood cell composition at stage S3, whereas multi-vacuole cell ratio was decreased by 1/2 and morula cell ratio expanded about 10 times during S0-S3. Further, change of organ structure started following the syndrome such as degeneration of epithelial cells, microfilaments, increment in hemocytes and damage in muscle fiber have been detected in tunic, siphon, branchial sac, body wall musculature and pyloric gland. Briefly, our study results indicated that the normal physiological functions of the sea squirt can be affected due to the soft tunic syndrome induced by water temperature.

• Development and Reproduction
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• v.5 no.2
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• pp.137-144
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• 2001

Gametogenesis and gonadal development of the sea squirt Halocythia roretzi, which is two years old were investigated by histological study. The specimens were collected in Guryong-po coastal area Kyoungsangbuk-do, Korea from May 1996 to April 1997. The sea squirt is hermaphrodite and oviparous. The ovary is located in the inner wall of the tunic year-round, but the testis can be distinguished from in June. The ovary is composed of 6∼8 gonoducts at the left side and 8∼10 ones at the right side, the testis consists of the complex gonad having irregular sacular structures. Oogonia in the ovarian sac were 11.7∼15.6 ${\mu}m$ in diameter. The early developing oocytes were 39.6∼47.6 ${\mu}m$ and nucleus 10.0∼25.0 ${\mu}m$ in diameter. Oocytes in the ovarian sacs during vitellogenesis were 158.6∼210.0 ${\mu}m$, and fully ripe oocytes which were to 210.0∼230.9 ${\mu}m$ in diameter had several test cells in the cortical parts showing a characteristic of vertebrate. The testis showed a general spermatogenesis as in the marine animals. The three-year old sea squirt occurred the first spawning between January to February under 10$^{\circ}C$

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.248.2-248
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• 1998

No Abstract, See Full Text

• Journal of Microbiology and Biotechnology
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• v.18 no.9
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• pp.1510-1517
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• 2008

Expresssed sequence tag (EST) analysis was developed from three cDNA libraries constructed from cells of the digestive tract, gonad, and liver of sea squirt. Randomly selected cDNA clones were partially sequenced to generate a total of 922 ESTs, in which 687 unique ESTs were identified respectively. Results of BLASTX search showed that 612 ESTs (89%) have homology to genes of known function whereas 75 ESTs (11%) were unidentified or novel. Based on the major function of their encoded proteins, the identified clones were classified into ten broad categories. We also identified several kinds of immune-related genes as identifying novel genes. Sequence analysis of ESTs revealed the presence of microsatellite-containing genes that may be valuable for further gene mapping studies. The accumulation of a large number of identified cDNA clones is invaluable for the study of sea squirt genetics and developmental biology. Further studies using cDNA microarrays are needed to identify the differentially expressed transcripts after disease infection.

• Journal of fish pathology
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• v.7 no.2
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• pp.83-94
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• 1994

Bonnierilla namhaesius n, sp, is described based on the specimens recovered from the ascidians, Halocynthia roretzi Von Drasche in Namhae Islands, Korea, This is distinguished from congeners by having a combination of characters : setal formula 3, 17+1 hook, 9+1 aesthete, 5, 3, 2, 2+1 aesthete, 7+1 aesthete respectively on eight segments of antennule, II, 5 on distal segment of the second leg to fourth leg exopod, and 2, 3, I on distal margin of caudal ramus. This is the second record of the male, and first record of the copepodid in the genus Bonnierilla.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.642-646
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• 2000

Fish paste was prepared to enhance physiological functions by adding 2.5, 5 and 10% dietary fiber isolated from ascidian (halocynthia roretzi) tunic. Hardness, adhesiveness, gumminess, chewiness and shear force of the fish paste were increased with addition of the dietary fiber. Water activity and Hunter's color values of the fish paste were not significantly changed by addition of the dietary fiber. Results of sensory evaluation indicated that no difference was observed in color, texture and overall acceptance (p<0.05). However, the fish paste with 5% dietary fiber scored the highest and was generally preferred by sensory panels.

• Development and Reproduction
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• v.15 no.1
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• pp.1-7
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• 2011

It is suggested that FGF/Ras/MEK/Erk signaling plays crucial roles in specification and cell division of the mesodermal precursor cells in ascidian embryos. To investigate how the number of cell division in tissue precursor cells is determined, we have characterized Wee1 homolog, Hr-Wee1 of the ascidian Halocynthia roretzi. We found that the Hr-Wee1 mRNA is expressed both maternally and zygotically. Maternal transcript is localized to the cytoplasm in the animal cells, while zygotic expression is seen in cells of the endoderm lineage from 32-cell to 110-cell stages. Zygotic in situ signal is detected in the A-line neural plate cells of neurulae, and in epidermal cells of the head region of tailbud embryos. Embryos treated with MEK signaling inhibitor showed a similar pattern to normal embryos in expression of Hr-Wee1. Therefore, it is likely that MEK signaling does not affect the maternal and zygotic expression of Hr-Wee1.

• Development and Reproduction
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• v.21 no.4
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• pp.467-473
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• 2017

Ascidian embryos have become an important model for embryological studies, offering a simple example for mechanisms of cytoplasmic components segregation. It is a well-known example that the asymmetric segregation of mitochondria into muscle lineage cells occurs during ascidian embryogenesis. However, it is still unclear which signaling pathway is involved in this process. To obtain molecular markers for studying mechanisms involved in the asymmetric distribution of mitochondria, we have produced monoclonal antibodies, Mito-1, Mito-2 and Mito-3, that specifically recognize mitochondria-rich cytoplasm in cells of the ascidian Halocynthia roretzi embryos. These antibodies stained cytoplasm like reticular structure in epidermis cells, except for nuclei, at the early tailbud stage. Similar pattern was observed in vital staining of mitochondria with DiOC2, a fluorescent probe of mitochondria. Immunostaining with these antibodies showed that mitochondria are evenly distributed in the animal hemisphere blastomeres at cleavage stages, whereas not in the vegetal hemisphere blastomeres. Mitochondria were transferred to the presumptive muscle and nerve cord lineage cells of the marginal zone in the vegetal hemisphere more than to the presumptive mesenchyme, notochord and endoderm lineage of the central zone. Therefore, it is suggested that these antibodies will be useful markers for studying mechanisms involved in the polarized distribution of mitochondria during ascidian embryogenesis.

• Journal of Life Science
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• v.5 no.4
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• pp.170-180
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• 1995

A carotennnoprotein from the skin of Ascidian(Halocynthia roretzi) was extracted by Triton X-100 and purified by ammonium sulfate fraction, SephadexG-200 charomatography and DEAE-cellulose ion exchange chromatography. The carotenoprotein was redwith broad $\lambda$$_{max}$ between 495, 467 and 318nm. The red carotenoprotein had an approximate molecular weight of 326KDa(gel filtration). SDS-PAGE indicated the presence of two polypeptodes of 84.1KDa and 74.4KDa, with different mobility in polyacrylamide gel electrophoresis. In the presence of denaturing agents such as organic solvent aand extreme pH, the red complex readily disociates to liberate the yellow carotenoid($\lambda$$_{max}$ 452nm) and a colourless apoprotein. The amino acid composition of carotenoprotein were mainly threonine(15.2%), aspartic acid(12.2%), glutamic acid(11.9%) and serine(9.6%), while proline was not found. The carotenoprotein consisted of lipids as structure units. Its major fatty acids composion were C$_{18:1}$, C$_{16:1}$, and C$_{16:0}$. The monounsaturated fatty acids(41.5%) contained abundant content compared to other fatty aacids(polyunsaturated fatty acids 37.4%, saturated fatty acids 20.6%).