• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.28-28
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• 2003

Viable interspecific hybrids between yellowtail flounder (Pleuronectes ferrugineus, Store.) and winter flounder (Pleuronectes americanus, Walbaum) were produced by artificial insemination of yellowtail flounder eggs with winter flounder sperm. However, mean fertilization rate, hatching success and early survival up to 3 weeks post hatch were significantly lower than those of parental pure cross controls (P<0.01). Overall, cytogenetic traits (karyological analysis and estimation of cellular DNA contents using flow cytometry) of hybrid flounder were intermediate between the two parental species. Microsatellite assay was used to distinguish the parental genomes in the hybrids; in most cases, one allele was specific to each of the parents. Morphometrics assessed by body proportions indicated that hybrids generally displayed a morphology intermediate between the maternal and paternal species. Interspecific hybrids exhibited abnormal and retarded gonad development in both sexes based on histological analysis of gonads from adult fish. The sterility of the hybrids presents a significant advantage for their use in aquaculture, as potential escapees would not be capable of reproducing in the wild and contaminating natural stocks.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.65.2-65.2
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• 2008

• Ocean and Polar Research
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• v.26 no.3
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• pp.475-480
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• 2004

Recently, less toxic and more effective anaesthetics are essential for marine fishes. Lidocaine belongs to a group of anaesthetics which are used as local anaesthetic in human medicine. This chemical was tested fer winter flounder, Pleunnectes americanus. Anaesthetic effect of lidocaine hydrochloride-sodium bicarbonate mixture (lidocaine $HCl/NaHCO_3$) was tested for the winter flounder at five different temperature regimes: $3^{\circ}C,\;7^{\circ}C,\;11^{\circ}C,\;15^{\circ}C\;and\;19^{\circ}C$ Anaesthetic dose and temperature-dependent relationship in exposure and recovery time were observed for the winter flounder of $17.2{\pm}0.1cm$ mean total length. Based on the results, anaesthetic lidocaine $HCl/NaHCO_3$ showed rapid exposure time and rapid recovery time for winter flounder. The results indicate that lidocaine $HCl/NaHCO_3$ can be used as suitable anaesthetic for this species.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.304-305
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• 2006

• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1386-1394
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• 2013

In our previous study, the 25-mer antimicrobial peptide pleurocidin (Ple) had been thought to induce apoptosis in Candida albicans. This study demonstrated that reactive oxygen species (ROS) production was a major cause of Ple-induced apoptosis. Four truncated analogs were synthesized to understand the functional roles in the N- and C-terminal regions of Ple on the apoptosis. Ple, Ple (4-25), Ple (1-22), and Ple (1-19) produced ROS, including hydroxyl radicals, on the order of [Ple > Ple (1-22) > Ple (4-25) > Ple (1-19)], whereas Ple (7-25) did not induce any ROS production. The results suggested that the N-terminal deletion affected the ROS-inducing activities much more than that of the C-terminal deletion, and net hydrophobicity [Ple > Ple (1-22) > Ple (4-25) > Ple (1-19) > Ple (7-25)] was related to ROS generation rather than other primary factors like net charge. Hence, we focused on the N-terminal-truncated peptides, Ple (4-25) and Ple (7-25), and examined other apoptotic features, including mitochondrial membrane depolarization, caspase activation, phosphatidylserine externalization, and DNA and nuclear fragmentation. The results also confirmed the disappearance of apoptotic activity of Ple (7-25) by the truncation of the N-terminal region (1-6) and the specific activity patterns between Ple and analogs. In conclusion, the N-terminal region of Ple played an important role in apoptosis.

• Journal of Microbiology and Biotechnology
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• v.22 no.10
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• pp.1367-1374
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• 2012

Pleurocidin, a 25-mer antimicrobial peptide, has been known to exhibit potent antibacterial activity. To investigate the functional roles in N- and C-terminal regions of pleurocidin on the antibacterial activity, we designed four truncated analogs. The antibacterial susceptibility testing showed that pleurocidin and its analogs exerted antibacterial effect against various bacterial strains and further possessed specific activity patterns corresponding with their hydrophobic scale [pleurocidin > Anal 3 (1-22) > Anal 1 (4-25) > Anal 4 (1-19) > Anal 2 (7-25)]. Fluorescence experiments using 1,6-diphenyl-1,3,5-hexatriene (DPH) and 3,3'-dipropylthiadicarbocyanine iodide [$diSC_3(5)$] indicated that the differences in antibacterial activity of the peptides were caused by its membrane-active mechanisms including membrane disruption and depolarization. Blue shift in tryptophan fluorescence demonstrated that the decrease in net hydrophobicity attenuates the binding affinity of pleurocidin to interact with plasma membrane. Therefore, the present study suggests that hydrophobicity in the N- and C-terminal regions of pleurocidin plays a key role in its antibacterial activity.

• Ocean and Polar Research
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• v.25 no.4
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• pp.607-615
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• 2003

Many organisms are known to survive in icy environments. These include both over wintering terrestrial insects and plants as well the marine fish inhabiting high latitudes. The adaptation of these organisms is both a fascinating and important topic in biology. Marine teleosts in particular, can encounter ice-laden seawater that is approximately $1^{\circ}C$ colder than the colligative freezing point of their body fluids. These animals produce a unique group of proteins, the antifreeze proteins (AFPs) or antifreeze glycoproteins (AFGPs) that absorb the ice nuclei and prevent ice crystal growth. Presently, there are at least four different AFP types and one AFGP type that are isolated from a wide variety of fish. Despite their functional similarity, there is no apparent common protein homology or ice-binding motifs among these proteins, except that the surface-surface complementarity between the protein and ice are important for binding. The remarkable diversity of these proteins and their odd phylogenetic distribution would suggest that these proteins might have evolved recently in response to sea level glaciations just 1-2 million years ago in the northern hemisphere and 10-30 million years ago around Antarctica. Winter flounder, Pleuronectes americanus, has been used as a popular model to study the regulation of AFP gene expression. It has a built-in annual cycle of AFP expression controlled negatively by the growth hormone. The signal transduction pathways, transcription factors and promoter elements involved in this process have been studied in our laboratory and these studies will be presented.