• Fisheries and Aquatic Sciences
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• v.21 no.9
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• pp.20.1-20.3
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• 2018

Hypoptychus dybowskii, the Korean sandlance, is widespread in cold areas of the North Pacific. Although H. dybowskii has been considered to occur on the coast of Hamgyeongnam-do in Korea, the species is also distributed along the coast of Goseong-gun, Gangwon-do, south of Hamgyeongnam-do in the eastern part of the Korean Peninsula on the basis of newly collected specimens. In addition, many Koreans confuse H. dybowskii and Ammodytes japonicus (= A. personatus for Korean specimens) because the Korean common name or dialect of both species is "Yang-mi-ri", yet the two species differ in their external morphology. Hypoptychus dybowskii differs from A. japonicus in the location of the origin of the dorsal fin and the number of dorsal and anal fin rays.

• Development and Reproduction
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• v.1 no.1
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• pp.91-97
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• 1997

In order to study the reproductive physiology of Sand ell(Hypoptichus dybowskii) catched at kangwon-do, Wooamjin Bay, spawning and egg development were investigated in April and May, 1996. The observed spawning period was from the middle of April to the end of May with the water temperature above $8^{\circ}$C. Body size and colouration were distinguished between male and female. The type of testicular structure is lobular, and the ovary is a pair of sac-sahaped covering with a fibromuscula capsule and comprising a mature egg of average 86. The unfertilzed egg are demersal and adhesive, and their diameter were 1.65-1.95 mm. the colour of yolk is light yellow and contained a lot of tiny oil globules. The average spawned egg was 62 in sargasso weeds. Hatching was observed in 12 days after fertilization with the water temperature of 14 ${\pm}1^{\circ}$C. The average size of larva after hatching was 6.85${\pm}$0.23mm in total length, and larva were containing yolk including globule.

• Animal cells and systems
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• v.3 no.2
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• pp.199-205
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• 1999

The nucleotide sequences of a 504 bp segment of the mitochondrial cytochrome b gene were analyzed to survey the intraspecific variation of the brown frog, Rana dybowskii, collected from nine populations in South Korea. Comparisons of sequence divergence of the cytochrome b gene suggest that the populations examined are clearly classified into two types (type 1 and type 2), diverged from each other by a high value of 14.3-15.9% sequence divergence. The two types are distributed allopatrically in most populations, but only one population occurs sympatrically. In the Tonghae population, their spawning grounds differ in that type 1 spawns in the puddle and type 2 spawns in the mountain creek. Based on the genetic divergences of the cytochrome b gene sequences, the phylogenetic status of Korean R. dybowskii is elucidated by comparing it with related brown frogs distributed in an area adjacent to the Korean Peninsula. Interspecific sequence divergences among type 1, type 2 and other related brown frog species (Russian R. dybowskii, R. pirica, R. ornativentris, R. chensinensis: 2n=24 chromosomes) used in this study ranged from 11.7 to 16.3%. R. dybowskii in Tsushima is very similar to our type 1 (sequence divergence＝0-1.6%) and R. chensinensis in western China is closest to our type 2 (sequence divergence＝6.8-7.5%).

• The Korean Journal of Zoology
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• v.31 no.2
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• pp.87-94
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• 1988

Korean frogs (R. dybowskii and R. nigromaculara) were collected from chonnam area and their oocyte maturation was induced by using in ultro follicle culture system. Follicles were isolated from the frog ovary and cultured for 24 hr in (amphibian Ringer's soluion AR) at 22 C in the presence or absence of hormones. Follicular cocytes of R. dybowskii were induced to mature (germinal vesicle breakdown, GVBD) by the presence of progesterone, 0.1 $\mu$g/2 ml and that of R. nigromaculata by 1 $\mu$g/2 ml of progesterone. Follicles of the frogs were also responded to (frog pituitary homogenate FPH) in terms of their cocyte maturation. Follicular cocytes of R. dybowskii were induced to mature by FPH at concentration of 0.01 pituitary equivalent/2 ml and that of R.nigromaculata at 0.1 pit equiv./2 ml. The culture time required for the maturation of bath frog follicles was 915 hr. The responsiveness of the follicles of korean frogs to hormones (progesterone or FPH) was nearly the same as that of R. pipiens which are most commonly used amphibians. Particularly, follicular cocytes of R. dybowskii used from February matured spontaneously without stimulation of hormones during in vitro culture. Furthermore, those cocytes were spontaneous- ly ovulted when the ovarian fragments were cultured in a flask.

• Journal of Ecology and Environment
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• v.45 no.1
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• pp.10-16
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• 2021

Background: Ranavirus is an emerging infectious disease which has been linked to mass mortality events in various amphibian species. In this study, we document the first mass mortality event of an adult population of Dybowski's brown frogs (Rana dybowskii), in 2017, within a mountain valley in South Korea. Results: We confirmed the presence of ranavirus from all collected frogs (n = 22) via PCR and obtained the 500 bp major capsid protein (MCP) sequence from 13 individuals. The identified MCP sequence highly resembled Frog virus 3 (FV3) and was the same haplotype of a previously identified viral sequence collected from Huanren brown frog (R. huanrenensis) tadpoles in South Korea. Human habitat alteration, by recent erosion control works, may be partially responsible for this mass mortality event. Conclusion: We document the first mass mortality event in a wild Korean population of R. dybowskii. We also suggest, to determine if ranavirus infection is a threat to amphibians, government officials and researchers should develop continuous, country-wide, ranavirus monitoring programs of Korean amphibian populations.

• The Korean Journal of Ecology
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• v.23 no.4
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• pp.309-313
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• 2000

Since specific types and physical characteristics of anuran calls can represent reproductive qualities of a calling male, anuran calls have been studied in context of mate choice. We in here report call types of Rana dybowskii and their variations from two different recording sites. Calls of R. dybowskii are classified to three types based on their physical characteristics and behavioral observations; 'A-call'functions to advertise locations of a calling male and to attract potential mates. A territorial male emits 'B-call'only during male-male interaction. 'C -call'is released when a male frog was clasped by another male. The A-call from two recording sites, Miwon and Wonju, shows high variations in their call characteristics.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.910-917
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• 2015

A total of 646 strains, including green algae and diatoms, were isolated from 220 samples to screen microalgae with high lipid productivity (LP). The samples were obtained from nine habitats in Northern Xinjiang, China in June 2013. This study initially identified eight lipidrich strains, namely, Desmodesmus intermedius XJ-498, D. intermedius XJ-145, D. intermedius XJ-99, Monoraphidium pusillum XJ-489, M. dybowskii XJ-435, M. dybowskii XJ-151, Mychonastes homosphaera XJ-488, and Podohedriella falcata XJ-176, based on 18S rDNA sequencing. The strains were cultured in a photobioreactor for the same period. Results showed that the specific growth rate (day^-1) of M. pusillum XJ-489 was the highest (1.14 ± 0.06), and the biomass concentration (g/l) of D. intermedius XJ-99 was the highest (2.84 ± 0.3). Futhermore, the lipid content (%) of M. dybowskii XJ-151 was the highest (33.5 ± 4.38), and the lipid productivity (mg l^-1 day^-1) of My. homosphaera XJ-488 was the highest (86.41 ± 9.04). C16 to C18 accounted for 86% to 98% of the total lipid, and the biodiesel qualities of the selected algae corresponded to international standards. This study suggests that My. homosphaera XJ-488, D. intermedius XJ-99, and M. dybowskii XJ-151 are the most potential strains for biodiesel production among all the isolated strains.

• Korean Journal of Veterinary Research
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• v.36 no.1
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• pp.11-21
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• 1996

Comparing hibernation with active periods, the regional distribution and relative frequencies of gastrointestinal endocrine cells were studied immunohist-ochemically in the GITs of the Rana dybowskii. Six kinds of endocrine cells were identified in this study. In this study, several novel findings were emerged: in hibernation period, the perdominant presence of immunoreactive cells; the widely distributional regions of glucagon-, Gas/CCK- and BPP-immunoreactive cells; the intense reaction of immunostaining against the antiserum; and the existence of 5-HT- and somatostat-in-immunoreactive cells in upper regions of the fundic glands. These results suggest that the gastro-entero-endocrine cells in hibernation period synthesize continuously its gut hormones and accumulate in their cytoplasms.

• Korean Journal of Environment and Ecology
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• v.20 no.4
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• pp.400-406
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• 2006

To investigate the incidence of the road-kill of amphibians and reptiles in Songgye valley, Woraksan National Park, a survey of Songgye valley was conducted from January, 2003 to December, 2005. Before the investigation, the survey area was divided into 50 sites at 300m intervals. As a result, road-kill by vehicles were confirmed to affect 40% of the amphibians and 68.3% of the reptiles among the total species in the Woraksan National Park. The most affected species was Rana dybowskii, with a frequency of 94.9% among the total number of road-killed Individuals. The highest road-kill rate occurred between April to May, every year. Therefore, it is necessary to construct an eco-bridge and to perform the continuous ecological monitoring for the conservation of R. dybowskii including other species.

• Animal cells and systems
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• v.2 no.1
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• pp.87-91
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• 1998

The present study investigated the involvement of the phospholipase C (PLC) and protein kinase C (PKC) signaling pathways during progesteroneinduced meiotic maturation in amphibian (Rana dybowskii) oocytes. Prosesterone-induced germinal vesicle breakdown (GVBD) of oocytes was significantly inhibited by a PKC inhibitor, staurosporine and a PLC inhibitor, U73122, in a dose-dependent manner. In contrast, U73343, an inactive analogue of U73122, was ineffective in suppressing GVBD. PKC activity in oocytes reached a maximum level at 30 min after progesterone stimulation and this elevated PKC activity was effectively suppressed by U73122 or staurosporine, suggesting that the activation of PKC enzyme is closely linked to PLC signaling during oocyte maturation. In addition, these inhib itors blocked the maturation promoting factor (MPF) activity which appeared in oocytes in response to progesterone, suggesting that PKC activation is an important signal for MPF activity. Therefore, this study demonstrates that the activation of PKC via PLC signaling is directly linked to an intracellular protein kinase cascade related to the appearance of MPF activity during meiotic maturation in amphibian (Rana dybowskii) oocytes.