• Development and Reproduction
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• v.4 no.1
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• pp.19-28
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• 2000

Diploid and triploid hybrid between female mud loach Misgurnus mizolepis and male cyprinid loach, M. andguillicaudatus were produced, using artificial propagation. The influence of hybridization and triploidization on characteristics of the some tissues of retina optic tectum and trunk kidney in loach was determined histologically. Diploid hybrid have almost size similarities in nucleus and the cell size of some tissues to both parents. In the triploid hybrid the nucleus and／or the cell size in erythrocyte, horizontal cell in inner nuclear layer of retina ganglion cell in ganglion cell layer of retina, neuronal cell in granular layer of optic tectum, and secondary proximal tubule cell of trunk kidney, are much larger than those of the corresponding cells in the diploid hybrid individuals. However, triploid hybrid showed fewer number of cells in outer nuclear layer in retina and nuclei in secondary proximal tubule of trunk kidney than in diploid hybrid. Results of this study suggest that some characteristics in the triploid hybrid exhibiting larger cell and nucleus size with fewer number of cell than diploid hybrid can be useful criteria for the distinction between diploid hybrid and triploid hybrid, and the ploidy level in loach.

• Fisheries and Aquatic Sciences
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• v.17 no.4
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• pp.471-478
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• 2014

Genomic organization, including the structural characteristics of 5'-flanking regions of two 65-kDa protein (WAP65) isoform genes associated with warm temperature acclimation, were characterized and their transcriptional responses to immune challenges were examined in the intestine, kidney and spleen of the mud loach (Misgurnus mizolepis; Cypriniformes). Both mud loach Wap65 isoform genes displayed a 10-exon structure that is common to most teleostean Wap65 genes. The two mud loach Wap65 isoforms were predicted to possess various stress- and immune-related transcription factor binding sites in their regulatory regions; however, the predicted motif profiles differed between the two isoforms, and the inflammation-related transcription factor binding motifs, such as NF-${\kappa}B$ and CREBP sites, were more highlighted in the Wap65-2 isoform than the Wap65-1 isoform. The results of qRT-PCR indicated that experimental immune challenges using Edwardsiella tarda, lipopolysaccharide or polyI:C induced the Wap65-2 isoform more than Wap65-1 isoform, although modulation patterns in response to these challenges were tissue- and stimulant-dependent. This study confirms that functional diversification between the two mud loach Wap65 isoforms (i.e., closer involvement of Wap65-2 in the acute phase of inflammation and innate immunity) occurs at the mRNA level in multiple tissues, and suggests that such differential modulation patterns between the two isoforms are related to the different transcription factor binding profiles in their regulatory regions.

• Development and Reproduction
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• v.19 no.4
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• pp.181-187
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• 2015

Early life stage mortality in fish is one of the problems faced by loach aquaculture. However, our understanding of immune system in early life stage fish is still incomplete, and the information available is restricted to a few fish species. In the present work, we investigated the expression of immune-related transcripts in loach during early development. In fishes, recombination-activating gene 1 (RAG-1) and sacsin (SACS) have been considered as immunological function. In this study, the expression of the both genes was assessed throughout the early developmental stages of loach using real-time PCR method. maRAG-1 mRNA was first detected in 0 dph, observed the increased mostly until 40 dph. Significant expression of maRAG-1 was detected in 0 to 40 dph. These patterns of expression may suggest that the loach start to develop its function after hatching. On the other hand, maSACS was detected in unfertilized oocyte to molura stages and 0 to 40 dph. maSACS mRNA transcripts were detected in unfertilized oocytes, suggesting that they are maternally transferred.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.446-451
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• 2017

The length frequency and weight-length relationships within the loach population of Misgurnus anguillicaudatus were investigated in environment-friendly (EFP) and conventional paddy fields (CP) in South Korea, in order to identify the influences of farming practices to the loach population living in paddy ecosystem. The size-frequency of distribution of M. anguillicaudatus populations noted to differ significantly when the loach populations of the EFP and the CP were compared. The mean weight and length of the loach population in EFP was greater than those of the loaches in CP. The equations based on weight and total length relationship in EFP and CP were $W=0.000004L^{3.0747}$ and $W=0.000002L^{3.2106}$, respectively. The condition factor (K) against total length of loaches at two paddy field types with different farming practices indicates that the loach population in EFP(mean K=0.95) had access to better nutritional conditions than those in CP (mean K=0.67). It therefore appears that the size and structure of loach populations in rice paddy fields might be affected by farming practices.

• Korean Journal of Animal Reproduction
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• v.18 no.3
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• pp.183-189
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• 1994

We examined early development in loach(Misgurnus mizolepis) embryos with parthenogenetic agents well-known in mammals. Female loach was superovulated with an intraperitoneal injection of 15 IU human chorionic gonadotrophin (hCG) per gram body weight. After 13 h of hCG injection, the oocytes were obtained from the abdomen. The oocytes were activated with 10% ethanol in tap water or fish Ringer's solution for 5, 10 and 15 minutes(eTW5, 10, 15 and eFRS5, 10, 15), respectively. The activation rates were 29% and 10% in eFRS10 and eFRS15, 5% and 6% in eTW10 and eTW15 by judging the cleaved blastomeres. Whereas, no parthenogenetic embryo was produced by tap water or fish Ringer's solution alone. The activation rate with the fish Ringer's solution was higher than that of tap water. No embryonic development was observed by calcium ionophore, A23187, at concentrations of 10, 20, 40 and 100$\mu$M when treated for 1, 2.5 and 5 minutes, respectively. The activation agents did not cause early development as in mammalian eggs. Therefore, the results suggest that fresh water fish may have a different egg activation pathway from that of mammals.

• Journal of fish pathology
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• v.21 no.3
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• pp.201-208
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• 2008

We compared the pathogenicity and antigenicity of two different Edwardsiella tarda (E. tarda) strains KFE and Edk-2 isolated in Korea and Japan respectively. In the pathogenicity analysis with challenge test against loach, E. tarda KFE isolate showed stronger pathogenicity compared to that of E. tarda Edk-2 isolate. The differences were also confirmed by the comparison of OMP (outer membrane protein) in SDSPAGE which showed three major bands, 41kDa, 37kDa and 30kDa, for E. tarda KFE isolates and two major bands, 41kDa and 30kDa, for E. tarda Edk-2 isolates. On the base of these results, we tried to determine the differences of antigenicities of these two isolates in loach which is one of the important species in freshwater aquaculture in Korea. Numbers of specific antibody secreting cells (SASC), appeared to be higher in loach immunized with FKC of E. tarda Edk-2 than loach immunized with FKC of E. tarda KFE. ELISPOT-assay for the comparison of antigenicity showed relatively high percentage of cross-reaction and implied the presence of some common epitopes in the antigens of these two E. tarda isolates.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.3
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• pp.265-271
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• 1994

Differences in carotenoid composition in the integuments of wild and cultured chinese muddy loach Misgurnus mizolepis and muddy loach Misgurnus anguillicaudatus were compared. Total carotenoid contents in the integuments of the wild and cultured chinese muddy loach were $4.76mg\%\;and\;3.43mg\%$, respectively. The important carotenoids in the integuments of the wild chinese muddy loach were lutein($30.5\%$), ${\beta}$-cryptoxanthin($24.6\%$), ${\beta}$-carotene($20.6\%$) and cynthiaxanthin($11.7\%$). In addition, zeaxanthin($4.7\%$), tunaxanthin ($4.5\%$), and a-cryptoxanthin($1.0\%$) were present in small amounts. In the integuments of the cultured chinese muddy loach, lutein($35.4\%$), ${\beta}$-cryptoxanthin($17.9\%$), cynthiaxanthin($16.0\%$) and ${\beta}$-carotene($12.7\%$) were present as important carotenoids. In addition, zeaxanthin($8.1\%$), tunaxanthin($5.0\%$), a-cryptoxanthin($0.9\%$) were found in small amounts. Total carotenoid contents in the integuments of the wild and cultured muddy loach were $4.00mg\%\;and\;2.99mg\%$, respectively. The important carotenoids in the integuments of the wild muddy loach were lutein($32.9\%$), ${\beta}$-cryptoxanthin($18.8\%$), cynthiaxanthin($17.0\%$) and ${\beta}$-carotene($15.1\%$). In addition, zeaxanthin($6.5\%$), tunaxanthin($6.0\%$) and a-cryptoxanthin($1.5\%$) were found in small amounts. In the integuments of the cultured muddy loach, lutein($51.8\%$), cynthiaxanthin($19.9\%$) and ${\beta}$-cryptoxanthin($10.8\%$) were observed as important carotenoids. In addition, ${\beta}$-carotene($5.0\%$), zeaxanthin($4.8\%$), tunaxanthin($4.5\%$) and a-cryptoxanthin($0.2\%$) were found in small amounts.

• Journal of fish pathology
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• v.15 no.2
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• pp.83-92
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• 2002

EST analysis was performed to identify stress-responsive and immune-related genes from mud loach (Misgurnus mizolepis), cDNA libraries were constructed with liver, intestine and kidney tissues and randomly chosen clones (216 for liver, 198 for intestine and 224 for kidney) were subjected to automated sequence analysis. Of 638 clones sequenced in totlal, approximalely 25% of ESTs was novel sequences (no match to GenBank) or sequences with high homology to hypothrtical/unknown genes. Several potential stress-responsive biomarker and/or immure-related genes were identified in all the tissues examined. It included lectin, MHC class I/II proteins, proteinase inhibitors, superoxide dismulase, catalase, glutathionc-S. transferase, heat-shock protein, warm temperature acclimation protein, complements, methylrransferasc, zinc finger proteins, macrophage maturation associated protein, and others. This information will offer new possibilities as fundamental baseline data for the molecular genetics and breeding of this species with an emphasis on the development of stress. (and disease)-resistsnt fish.

• Journal of Aquaculture
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• v.21 no.4
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• pp.325-330
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• 2008

Two different Eelwardsiella tarda isolates, KFE and Edk-2, were obtained from Korea and Japan respectively. On the base of the previous results showing higher pathogenicity of E. tarda KFE compared to that of E. tarda Edk-2 isolate, we tried to determine the differences of antigenicities of these two isolates in loach which is one of the important species in freshwater aquaculture in Korea. Concentration of specific antibody in the serum appeared to be much higher in loach immunized with FKC of E. tarda Edk-2 than those found in loach immunized with FKC of E. tarda KFE. Cross-reaction analysis using agglutination test with normal and antigen-absorbed antisera implied the differences epitopes in the antigens of these E. tarda isolates. For the comparison of bactericidal activity of the produced antibody with different antigens, absorption analysis was performed and confirmed the presence of critical epitopes in the FKC of E. tarda KFE strain. The prophylactic agent, polysaccharide-bound protein (PS-K) injected 1 week before the artificial infection with E. tarda KFE isolates decreased the cumulative mortality in loach and would be on effective method to prevent the occurrence of bacterial infection including E. tarda.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.25-25
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• 2001

Generation of transgenic fish acquiring the ability to express desirable phenotypes offers new possibilities for addressing fundamental biological questions, and can also attribute to enhanced aquaculture productivity. I describe here the recent research progress in my laboratory with particular emphasis on the development of fast-growing autotransgenic fish and its chromosome-set manipulation using our experimental organism, the mud loach, Misgurnus mizolepis. (omitted)