• Korean Journal of Veterinary Research
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• v.46 no.1
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• pp.35-41
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• 2006

Vitellogenin (Vtg), a phospholipoglycoprotein precursor of egg yolk is synthesized and secreted from the liver in response to estrogens in female fish. Vtg is normally undetectable in the blood of male fish, but can be induced by exposure to chemicals possessing estrogenic activity. Thus, the presence of Vtg in blood of male fish can serve as a useful biomarker for assessing previous exposure to estrogenic compounds. In the present study, Vtg was abnormally expressed in Rhynchocypris oxycephalus using estradiol benzoate ($E_2$). As the result, it was found that the level of Vtg in blood from R. oxycephalus was increased by treated quantity of $E_2$ with dose-effect manner. Monoclonal antibodies were generated against Vtg of R. oxycephalus. The hybridoma were screened with an enzyme immunoassay for the production of specific anti-Vtg antibodies. Five positive cell lines with a high specificity were selected. Monoclonal antibodies against vtg of R. oxycephalus that was developed in this study, may be a useful bio-indicator for the detection of estrogenic contamination in the aquatic ecosystem.

• Korean Journal of Environment and Ecology
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• v.15 no.4
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• pp.401-407
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• 2002

Fishfauna were investigated in the Taebaeksan area streams. At the upper tributary of the Han River, 8 species of 4 families were collected and the dominant species was Rynchocypris oxycephalus. The two species, Rynchocypris kumgangensis and Silurus microdorsalis were Korean endemic species. Brachymystax lenok tsinlingensis, designated as a natural monument and vulnerable species was confirmed at the Jeongam-sa area streams At the upper streams of the Nakdong River, collected fishes were identified as 14 species of 7 families. The dominant Species was R. oxycephalus and subdominant Zacco temmincki. Korean endemic species were 8species(51.7%), Coreoleuciscus splendidus, Squalidus gracilis majimae, Microphysogobio yaluensis, Niwaella multifasciata, Silurus microdorsalis, Liobagrus mediadiposalis, Coreoperca herzi and Odontobutis platycephala. Brachymystax lenok tsinlingensis were confirmed at the Hyundong-Chon Stream and Baek-chon stream.

• Journal of fish pathology
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• v.13 no.2
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• pp.147-151
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• 2000

Deformed vertebrae by cold shock in Rhynchocypris oxycephalus were discovered. Deformity was externally noticed in the caudal penducle region of R. oxycephalus. Radiographic and histologic investigation confirmed the deformity. Especially, histological investigations provided the fact that extensive fusion between neighbouring vertebrae is caused by removal of endogeneous mineralized tissue. Deformed vertebrae appeared suggesting the direct evidence of vertebral fusion had arisen internally by cold shock in this species.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.52-52
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• 2003

For the evaluation of hormonal control of spermiation in fish, a method to quanify the spermiation response or mature Rhynchocypris oxycephalus (Sauvage and Dabry) to hormonal therapy is described. Spermatocrit was determined after 7 min centrifugation at 18,000 $\times$ｇ and sperm density was estimated by a standard hemocytormer method. Sperm density can be predicted from spermatocrit since their relationship is linear as described by the regression equation, Y=3.68X-27,18 ($R^2$=0.82, N=50), where Y is spermatocrit and X is sperm density. Milt production by mature R. oxycephalus was highest at 24 h after injection of 1,000 IU human chorionic gonadotropin (HCG) and 50 $\mu\textrm{g}$ luteinizing hormone-releasing hormone analogue (LHRHa) per kg body weight. Increased milt production coincided with low spermotocrit and sperm density levels. These results demonstrate that spermition in mature R. oxycephalus can be reliably evaluated by a spermatocrit method and that HCG and LHRHa are effecove in stimulating of spermiation in this species.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.163-172
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• 2007

In this study, fish fauna and stream characteristics were surveyed during October-November 2003 in 31 small streams, which are small sub-tributaries of Geum River. The small streams were classified into 4 types of steep mountainous (SM), mountainous-flatland (MF), flat land (FL), and agricultural watercourse (AW) streams, and their types were categorized by features of stream width, water depth, bottom substrate, riparian vegetation, and landuse patterns. The fishes collected during this survey were identified 4 families and 8 species. Dominant family was Cyprinidae, and the most dominant species was Rhynchocypris oxycephalus with 73% (419 individuals) of the total. Only one species of R. oxycephalus was observed in the all five steep mountainous streams, which was surrounded by 100% forest area and had no point-and non-point pollution sources. The observed frequency of R. oxycephalus (as a relative proportion of species) showed a significant positive correlation (r=0.754, p<0.001, n=31) with the substrate composition of bedrock and boulder, indicating that the species prefer the bedrock and boulder rather than the sand or small pebble. Evidently, all five steep mountainous streams were judged as excellent condition (1st rank) according to the criteria of biological water quality, the Ministry of Environment, Korea. This result was accord with a general tendency of the species in most upper stream of the Koreas streams. One family and one species were found at the steep mountainous types and 4 families 6 species were at the mountainous-flatland. Four families 8 species were found at the flat land, which showed most diverse habitat, and 2 families 2 species were collected agricultural watercourse. These study results of 1st-order streams suggest that R. oxycephalus was considered as one of 1st rank ecological indicator species, and that the dominant area should be protected from various pollutions and disturbances.

• Korean Journal of Environmental Biology
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• v.22 no.3
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• pp.351-368
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• 2004

Following the previous experiments, a starvation experiment was conducted to determine the influence of feeding and starvation on the histological and biochemical changes, the morphormetric changes in the sectioned body and the morphometric changes in Rhynchocypris oxycephalus (Sauvage and Dabry). The influence of starvation on nutritional conditions of the histological changes of hepatocyte and intestinal epithelium as hepatosmatic index (HSI), protein, RNA and DNA concentrations of liver in R. oxycephalus was tested. Although the starved group showed higher concentrations of protein, DNA and RNA than the fed group, food deprivation resulted in a decrease in the HSI, hepatocyte nucleus size and nuclear height of the intestinal epithelium. The RNA - DNA ratio appears to be a useful index of nutritional status in R. oxycephalus and may be useful for determining if R. oxycephalus is in a period of rapid or slow growth at the time of sampling. Additionally, the data have been interpreted in detail and some biologically important relationships discussed. The effects of starvation on the morphometrical changes in sectioned body traits, condition factor, viscera index and dressing percentage were determined for evaluating nutritional conditions of R. oxycephalus. Starvation for nine weeks resulted in a decrease in most sectioned traits as well as in condition factor and viscera index (P<0.05). These findings suggest that nutritional parameters used in this study appear to be a useful index for nutritional status in this species. The data has been interpreted in detail and some important body sectioned values of interest to commercial growers discussed. A 75-day study was conducted to determine the effect of starvation on classical and truss parameters in R. oxycephalus. Truss dimensions of almost the entire head and trunk region as well as the abdomen were increased significantly through feeding or starvation (P<0.05). Truss dimensions of the caudal region generally decreased through feeding or starvation, particularly those dimensions at the hind part of the trunk. There were some significant decreases in classical dimensions of the head region during feeding, in relation to body depth characteristics in the trunk and caudal region during starvation, whereas there was only one decreasing classical dimension in the caudal region during feeding. The results of this study indicate that application of the truss network as a character set enforces classical coverage across the body form, discrimination among experimental groups thus being enhanced. Considering that the dimension of the lower part of the head and some truss and classical dimensions were least affected by feeding and starvation, these dimensions may then be useful as a taxonomical indicator to discriminate the species of Rhynchocypris sp. The value of trunk region dimensions with a large component of body depth in R. oxycephalus is most likely to be compromised by variability related to differences in feeding regimes of fish in different habitats.

• Journal of Aquaculture
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• v.13 no.3
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• pp.193-196
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• 2000

Rhynchocypris oxycephalus and R. steindachneri show very similar karyotypes: 2n=50(EN=90), consisting of 12 metacentics, 28 submetacentrics and 10 acrocentrics with a gradual decrease in chromosome size, but with significant differences in nuclear DNA content of 2.64 and 2.52 pg/nucleus, respectively (P<0.05). Although the erythrocyte measurement and parameters of two species were similar, R. oxycephalus erythrocyte number was lower than that of R. steindachneri. Mode in karyological evolution within the genus Rhychocypris shows an increase of nuclear DNA without apparent changes in karyotype and erhthrocyte size.

• Korean Journal of Ichthyology
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• v.11 no.1
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• pp.33-41
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• 1999

The influence of nutritional conditions on the histological changes of hepatocyte and intestinal epithelium as well as hepatosmatic index (HSI), protein, RNA and DNA concentrations of liver of Rhynchocypris oxycephalus was tested. Although, the starved group showed higher concentrations of protein, DNA and RNA than the fed group, food deprivation resulted in a decrease in the HSI, hepatocyte nucleus size and nuclear height of the intestinal epithelium. The RNA-DNA ratio appears to be a useful index of nutritional status in R. oxycephalus and may be useful for determining if R. oxycephalus is in a period of rapid or slow growth at the time of sampling. Additionally, the data have been interpreted in detail and some biologically important relationships discussed.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.274-281
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• 2000

The dynamic of fish community was investigated in the Wonju stream from March 1998 to February 1999. The collected species during the surveyed period were 24 species belonging to eight families. Eight species (33%) of them were endemic species of Korea. According to relative abundance in the studied areas, Moroco oxycephalus (30.7%), Zacco platypus (29.6%), Carassius auratus (10%), Pseudogobio esocinus (9.4%) and Rhinogobius brunneus (3.6%) dominated. Hemibarbus longirostris, Pungtungia herzi, Squalidus japonicus coreanus, Zacco temmincki, Cobitis rotundicaudata, Silurus asotus, Silurus microdorsalis and Micropterus salmoides were rare to the areas, which occupied less than 0.1% in relative abundance. Dominant species was M. oxycephalus (Kumda-ri, Kwanseol-dong, Hanggu-dong, heongyang-ri), Z. platypus (Gaeun-dong) and C. auratus (Jusan-ri). It was revealed by the analysis of community that St. 3 was the most diverse among all study stations. Coreoleuciscus splendidus and Coreopera herzi have been assumed vanished in the Wonju stream. The species occurring in suddenly decreasing trend were Microphysogobio yaluensis, Liobagrus andersoni, Cottus poecilopus and R. brunneus. The species occurring in representative increasing trend were Cyprinus carpio, C. auratus, P. esocinus, M. oxycephalus, and Z. platypus.

• Korean Journal of Ichthyology
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• v.19 no.1
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• pp.16-23
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• 2007

Oocyte surface in two Korean minnows, Rhynchocypris oxycephalus and R. kumgangensis was examined by light and electron microscope. In two species, the development of the oocyte was similar, but the follicular layer surrounding full-grown oocyte showed an evident difference. In R. oxycephalus, the follicular layer at the yolk vesicle stage became bilaminar with the retention of its outer squamous cell layer and the acquisition of an inner cuboidal or round cell layer just over the zona radiata. As the oocyte grows, the cuboidal cells of the inner follicular layer began to be replaced by columnar cells. At the yolk granule stage, the columnar cells secreted mucin to their cytoplasm (adhesive materials) and then surround the entire oocyte, as bundles of fence-shaped structures. Whereas, although the follicular layer of R. kumgangensis had an outer squamous layer and an inner cuboidal or round cell layer at the yolk vesicles as in R. oxycephalus, no inner cells were more changed with the retention of its cuboidal or round cells. Finally, in R. kumgangensis, the adhesive materials did not occur. In Korean two minnows, the structural difference in the oocyte surface seems to be related to their habitats and spawning characteristics as well as taxonomic characters.