• Animal cells and systems
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• v.5 no.1
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• pp.45-50
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• 2001

Rana ovarian follicles consist of oocyte, vitelline envelope, granulosa cells, and theca/epithelial layer. Using scanning electron microscopy, the surface structure of each follicular component was investigated. Changes in oocyte surface during oocyte maturation were also examined. Theca/epithelial layer was almost transparent and some blood vessels and granulosa cells were observed underneath in intact follicle. The number of granulosa cells was estimated to be 6700-7200 per oocyte. The granulosa cells partially overlapped each other and their microvilli penetrated the vitelline membrane via holes present in the vitelline envelope and seemed to be linked to oocyte microvilli. After removal of the vitelline envelope by microforcep, oocyte microvilli were observed on the surface of the devitellined oocyte. The oocyte microvilli formed partial clusters on the surface of white spot area which appears iust before germinal vesicle breakdown (GVBD), whereas they were evenly distributed in other areas. The microvilli became shorter and less dense with oocyte maturation. The lengths of oocyte microvilli in the immature and mature oocyte were 1.5 $\mu$m and 0.6 $\mu$m, respectively. The present study suggests a fundamental structural change occurring on the oocyte surface during maturation.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.537-540
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• 2015

Social parasitism is occasionally found in some Polistes and Vespa species, such as Vespa dybowskii. We report a discovey of interspecific facultative social parasitism by Polistes sp. (possibly P. mandarinus) on Polistes djakonovi Kostylev in two rural areas of South Korea. P. djakonovi is very similar to Polistes sp. in its body color patterns except that the mark on the clypeus is different. In nest 1 (65 cells), we found 5 females of P. djakonovi and 4 females of Polistes sp. on 30 July 2014, whereas nest 2 (102 cells) contained 12 females and 16 males of P. djakonovi, and 3 females of Polistes sp. on 28 August 2013. Although we found the two nests in July and August, P. djakonovi seems to have been exploited by Polistes sp. at the end of the preemergence period (early to mid-June). The two nests found in this study had mainly white cocoon caps of P. djakonovi with several yellow ones of Polistes sp. In most cases of social parasitism, intruders have a larger size of the body or some body parts than the host in order to usurp the host; in contrast, this study showed that the hosts had lager bodies than the intruders.

• Korean Journal of Environment and Ecology
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• v.12 no.4
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• pp.381-388
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• 1999

Herpetofauna of Kojedo was surveyed in both May 3, 1998~May 5, 1998 and Nov. 7, 1998~Nov. 8, 1998. 9 species of 6 families in Amphibia and 9 species of 3 families in Reptile were observed by survey and heard the evidence in this study. It was observed relatively rich biota to the Kayasan, Sokrisan, Soraksan and Chirisan National Park in Korea. There were Specific Endangered Animal assigned by Minister of Environment such as Hynobius leechii, Bufo bufo gargarizans, Rana dybowskii, Elaphe rufodorsata, Zamenis spinalis, Dinodon rufo-zonatum rufozonatum, Agkistrodon blomhoffii bevicaudus and Agkistrodon saxatilis. Especially Rana catesbeiana which was originated from North America was very abundantly distributed at one pond. So Rana catesbeiana should be controlled for stable environmental condition of endemic Amphibia distribution.

• Korean Journal of Veterinary Service
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• v.37 no.3
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• pp.203-212
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• 2014

Frog culture industry is not yet familiar but has much potential. Generally, in farm, the population density is higher than that of in nature and frog farm is not the exception. But when population density is high, it can easily leads to stressful condition, poor sanitation. When a disease occur, it is a primary factor that makes the population more susceptible and the results more grave. Because of severe Rhabditoidea- helminth infection and subsequent bacterial septicemia, 50~70% of the total population had been died in a farm in Jeong-sun in Gangwon-do and Chungju in Chungcheongbuk-do from late June, 2012 to September, 2012. Diseased frogs showed ruptured lung, bloody ascites, liver discoloration, myocardium weakness, congested kidney, microcytic anemia and so on. Enterobacteriacea, Citrobacter.sp, Cupriavidus metallidurans, Acinetobacter.sp were isolated as major bacterium that had caused septicemia in frogs. Among isolated bacterium, Cupriavidus metallidurans, Ewingella americana, Shewanella aquimarina and Pseudoalteromonas sp. have not reported as potential pathogens in frogs before. It is a good example that severe helminth infection in frogs can lead to secondary infection of bacteria.

• The Korean Journal of Zoology
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• v.35 no.4
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• pp.518-525
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• 1992

본 연구에서는 horizontal clinostat과 원심분리 방법의 이용으로 각각 저중력 상태($\mu$G)와 고중력 상태(3G)를 유도하여, 중력장의 변화가 양서류 수정란의 초기 형태 형성에 미치는 영향을 북방산개구리(Rano dybows비름를 대상으로 조사하였다. 중력장의 변화는 첫번째 수평 분열인 제3분열면의 위치에 영향을 미쳤다. 즉 저중력 상태에서는 분열면이 적도면 근처에서, 또 고중력 상태에서는 분열면이 동물극 근처에서 형성되었다. 이와 같은 변화는 포배기로 이어져 할강의 위치와 동물극 정단 세포층 수에 영향을 미쳤다. 즉 저중력에 노출된 포배는 정상배(1G)에 비해 할강이 중앙에 위치했으며 동물극 정단의 세포층 수가 증가하는 반면 고중력에 노출된 포배는 할강이 보다 동물극 폭에 위치했으며 동물극 정단의 세포층 수도 감소하였다. 그러나 낭배기에 도달하면 동물극 정단 세포층 수의 차이는 정상 상태로 조절되었다. 한편 중력장의 변화는 낭배기에 이르는 발생 속도와 원구상순부의 위치를 변경시켰다. 낭배기 이후의 발생 단계에서 중력에 의한 변화로는 tail fin circulation(stage 22)시기의 머리크기의 변화를 들 수 있다. 이상의 결과로 무미 양서류의 초기 형태 형성은 중력장에 의해 변형될 수 있으며 이러한 변화는 발생이 진행됨에 따라 조절되는 것으로 보인다.

• The Korean Journal of Zoology
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• v.37 no.3
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• pp.304-310
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• 1994

Using in situ hybridization, we have mapped the anatomical localization of perikarya containing myNA that codes for sonadotropin releasing hormone (GnRH) in the brains of female frogs, R. dybowskii. DNA olisomers, with sequences complementary to the GnRH portion of pro-GnRH myNA sequence, were synthesized and hybridized to paraformaldehvde-fixed, sagittal sections of the whole brain stem. The distribution of the GnRH mRNA containing cell bodies was similar to that described for GnRH peptide by immunohistochemistrv. That is, cells containing GnRH mRNA were observed in the medial septal area, anterior preoptic area, ventromedial hvpothalamus and infundibular regions. However, another cell groups which contains GnRH mRNAs were also detected by in situ hybridization in the bed nucleus of hippocampal commissure, preoptic area, nucleus infundibularis dorsalis, mesencephalic nuclei and intermediolateral cell column of spinal cord areas. These results demonstrate the feasibility of using in situ hybridization as a strategy to study the distribution of GnRH neurons and the detection of GnRH gene expression in the vertebrates.

• Animal cells and systems
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• v.3 no.3
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• pp.303-309
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• 1999

Inter- and intraspecific genetic relationships between Rana amurensis from Korea and Russia and other brown frogs were investigated by nucleotide sequence of a 504 base pair (bp) fragment of the mitochondrial cytochrome b gene. Nucleotide sequence similarities among Korean populations of R. amurensis ranged from 99.6% to 97.6% and 98.8% within Russian populations. The nucleotide sequence similarity between Korean and Russian R. amurensis ranged from 86.9% to 85.5%. Based on Kimura-2-parameter distance, the sequence divergence between R. amurensis from Korea and Russia was 16.18% and 18.04% among other related brown frogs. interspecific sequence divergences among R. amurensis and other related brown frogs diverged by 20.3%. Using an estimate of 2-4% mitochondrial DNA sequence divergence per million years, Korean and Russian R. amurensis diverged about 8 to 4 million years ago (Mya) and other brown frogs diverged about 9 to 5 Mya from ancestral frogs and distributed from North Asia to Sakhalin in a short time. In the neighbor-joining and UPGMA tree R. amurensis was clustered into two groups with Korean and Russian populations and the other brown frogs were grouped separately with diverged trichotomous clusters (R. dybowskii and R. pirica, R. okinavana and R. tsushimensis, and R. japonica and R. longicrus).

• Animal cells and systems
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• v.5 no.1
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• pp.51-57
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• 2001

We have previously shown that oocyte maturation is induced by an immobilized progesterone, progesterone-3-carboxymethyloxime - bovine serum albumin conjugate (P-BSA) in Rana dybowskii. In this study, we confirmed the maturation inducing activity of P-BSA on Xenopus oocyte and examined the binding character of the immobilized progesterone on the surface of Xenopus oocytes after removal of the vitelline layer. P-BSA induced maturation of Xenopus oocytes but E-BSA failed to do so as observed in Rana. Binding of the immobilized progesterone, fluorescein isothiocyanate-labeled progesterone-3-0-carboxymethyloxime-BSA (P-BSA-FITC) on the devitellined oocytes surface was examined by fluorescence confocal microscopy. The binding affinity of P-BSA-FITC to the devitellined oocyte was higher than that of estrogen-BSA-FITC (E-BSA-FITC) or testosterone-BSA-FITC (T-BSA-FITC). The binding disappeared in the presence of excess free progesterone but not in the presence of free estrogen. Maximum binding occurred after two-hours of incubation with P-BSA-FITC at pH 7.5. Stronger binding occurred in oocytes at stage Vl than stage IV, and in vitro treatment of hCG enhanced the binding. Taken together, these results suggest that a specific receptor for progesterone exists on the plasma membrane of Xenopus oocytes and that progesterone acts initially on this putative receptors and triggers generation of membrane-mediated second messengers during the early stage of oocyte maturation In amphibians.

• Korean Journal of Environment and Ecology
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• v.17 no.1
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• pp.18-25
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• 2003

In order to know the effects of PCB(Arochlor 1248) on the oocyte maturation and proges-terone(P$_4$) production by FPH(Frog pituitary homogenate: 0.01 p.e/$m\ell$) of frog in vitro, the oocytes were cultured for 20 hours in presence of the PCB at various concentrations and exam-ined their maturation(germinal vesicle breakdown: GVBD) rates and P$_4$ levels secreted by the oocyte in the culture medium. The results show that PCB concentration of 10 ppb suppressed the maturation of the oocytes and secretion of P$_4$. To examine the reversibility of the inhibitory effects, the oocytes were exposed to the PCB only for 3 hours, and then transferred to plain medium and cultured further for 17 hours. The oocytes were recovered from the toxic effect of the PCB when they were exposed to 2.5 ppb, but not to 5 ppb of the PCB. These results indi-cate that PCB suppress the maturation of oocytes and secretion of p, at low concentration, sug-gesting that the frog oocyte culture system can be used as a useful tool to evaluate the toxicity of the pollutants in the environment.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.2
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• pp.421-429
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• 2014

We investigated the feeding ecology of juvenile chum salmon (Oncorhynchus keta) during the critical early life stage prey selectivity of juvenile chum salmon during early marine migration in Korean waters at spring 2011. Salmon juveniles and zooplanktons were collected to draw with $20m{\times}5m$ gill net and $300{\mu}m$ mesh zooplankton net at each station on 11th-13th April n 2011. Collected zooplanktons were classified to 5 Phylum, 6 Class, 9 Order 17 Species in this study. Almost 76.4-100% species were classified to Phylum Arthropoda, dominant species was a species out of Hyperia galba of Order Amphipoda, Acartia spp and Paracalanus parvus of Order Calanoida. Collected salmon juveniles were grew up to average 4.7-5.4 cm fork length and average 1.0-1.5 g wet weight in whole station. Fish stomach content (mg/salmon) was heaver to 97.4, 82.4 and 63.2 mg wet weight/salmon in ST 2, 3, 4 than 20.4, 18.9 mg/salmon of ST 1, 5, because there are fish (sand eel, Hypoptychus dybowskii) and Krill (Euphausia) as prey in salmon stomach in ST 2, 3, 4. And ST 2, 3, 4 and 5 were dominated by Amphipoda as Hyperia galba, Themisto japonica and Gammarus sp., but ST 1 was dominated by copepod, because of absence of Amphipoda in the station. Therefore small Amphipoda as Hyperia galba was good prey for just released salmon juvenile in nature.