• 한국발생생물학회지:발생과생식
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• 제18권2호
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• pp.79-87
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• 2014

In Pleuronectiformes, blind-side malpigmentation (hypermelanosis) is common in cultured flatfishes, and is economically important. To understand the mechanism of blind-side hypermelanosis in flatfishes, we examined when the malpigmentation initially occurred, and studied how the symptoms proceeded during early development of the starry flounder, Platichthys stellatus. To assess quantitative pattern changes of blind-side skin, we observed morphological development of the whole body from 22 (total length [TL] $10.0{\pm}0.2$ mm and body weight [BW] $8.8{\pm}0.57$ mg) to 110 days (TL $23.4{\pm}0.7$ mm, BW $193.6{\pm}23.3$ mg) after hatching (DAH), and also examined the malpigmented area rate of blind-side skin and the malpigmented fish ratios. The experimental animals were reared in fiberglass-reinforced plastic (FRP) tanks in water at a temperature of $18.9{\pm}1.9^{\circ}C$ and salinity of $32.6{\pm}0.6$ psu and were fed with rotifer and Artemia nauplii from 22 to 48 DAH, and with A. nauplii and commercial feed from 49 to 110 DAH. As results, the first staining patch seen by the naked eye was observed around the area between the anus and pelvic fin or caudal edge of the trunk at 80 DAH (TL $20.6{\pm}0.5$ mm, BW $112.5{\pm}8.8$ mg). The pigmented area and the pigmented fish ratios were significantly increased from 80 to 110 DAH. These results indicated that malpigmentation on the blind side of starry flounder was initially observed at about 2 cm in length and 100 mg in weight, and the pigmented domain on the blind-side skin was continually broadened by the differentiation of pigmented cells (melanophores and xanthophores) with growth.

• Fisheries and Aquatic Sciences
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• 제17권3호
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• pp.325-337
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• 2014

To assess the functional structure of prepro-melanin-concentrating hormone (pMCH), we isolated and cloned pMCH (of-pMCH) mRNA from the brain of the olive flounder, Paralichthys olivaceus, and compared its amino acid sequence with those from other animals. In addition, to examine whether activation of the brain of-pMCH gene is influenced by background color, density, and feeding, we compared pMCH mRNA activities against different background colors (bright and dark) and at different densities (100% PCA and 200% PCA). To examine whether the pMCH gene is related with malpigmentation of blind-side skin and appetite, we compared pMCH gene expression between ordinary and hypermelanic flounders, and between feeding and fasting flounders. The of-pMCH cDNA was 405 bp in the open reading frame [ORF] and encoded a protein of 135 amino acids; MCH was 51 bp in length and encoded a protein of 17 amino acids. An obvious single band of the expected size was obtained from the brain and pituitary by RT-PCR. In addition, of-pMCH gene activity was significantly higher in the bright background only at low density (< 100% PCA) making the ocular skin of fish whitening, and in ordinary fish. However, the gene activity was significantly decreased in dark background, at high density (>200% PCA), and in hypermelano fish. These results suggest that skin whitening camouflage of the flounder is induced by high MCH gene activity, and the density disturbs the function of background color in the physiological color change. Moreover, our data suggest that a low level of MCH gene activity may be related to malpigmentation of the blind-side skin. In feeding, although pMCH gene activity was significantly increased by feeding in the white background, the pMCH gene activity in the dark background was not influenced by feeding, indicating that the MCH gene activity increased by feeding can be offset by dark background color, or is unaffected by appetite. In conclusion, this study showed that MCH gene expression is related to ocular-skin whitening camouflage and blind-skin hypermelanosis, and is influenced by background color and density.

• 한국수산과학회지
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• 제47권5호
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• pp.588-596
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• 2014

To examine the influences of water temperature and stocking density on feeding, growth and blind-side hypermelanosis of the starry flounder Platichthys stellatus, we performed an experiment with fry at two densities: 2 and 8 fish/L. The fry had a total length of $3.2{\pm}0.1cm$, body weight $0.6{\pm}0.1g$, and pigmented patches (pigmented ratio $2.6{\pm}0.4%$) on the blind side. Duplicate experiments were conducted in 93.7 L glass tanks for 120 days, from July to November. We determined daily food intake (DFI), food efficiency (FE), growth, survival rate, ratio of hypermelanic fish, and pigmented area rate on the blind side at 60-day intervals. The DFI was less than 50 mg/fish/day, and growth was delayed from July to September (water temperature [WT]> $20^{\circ}C$). After October, when WT < $20^{\circ}C$, the DFI increased significantly and the growth was accelerated, suggesting that the rearing temperature of starry flounder in artificial facilities should be < $20^{\circ}C$. While the FE, and survival did no differ between the two density groups, DFI and growth were significantly higher at 2 fish/L than at 8 fish/L. There was no difference in the pigmented area ratio between the two density groups. Although the hypermelanosis was not correlated with body size, the malpigmentation increased with growth. These results suggest that a high stocking density is not the main cause of blind-side hypermelanosis, although it can accelerate hypermelanosis in the starry flounder.

• 한국해양생명과학회지
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• 제1권1호
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• pp.56-62
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• 2016

본 연구는 넙치를 인공사육 시설에서 육성할 때 나타나는 무안측 흑화(착색증)의 스트레스 관련성을 확인하기 위해, 무안측에 체색이 없는 것(정상 그룹)와 체색이 있는 것(흑화 그룹)들 사이 스트레스 인자 비교 실험을 실시하였다. 본 실험에 사용된 실험어는 평균 전장 21.5±0.42 cm, 평균 무게 87.5±6.1 g였으며, 실험어의 무안측 착색면적률은 정상 그룹 0.63±0.12%, 착색증 그룹 16.7±4.7%였다. 분석한 스트레스 관련 인자는 혈중 GLU 및 TP, 코티졸 및 갑상선호르몬(FT₃ & FT₄) 농도 및 어체 성분(수분, 조단백, 조지방, 조회분)이었다. 실험 결과, 정상과 무안측 착색 넙치에 있어 혈중 GLU 및 TP의 농도는 정상 형질보다 착색증 형질에서 유의하게 높게 나타났다. 혈중 호르몬 농도에 있어 갑상선호르몬의 경우 정상과 착색증 그룹 사이에는 유의차를 찾아볼 수 없지만, 코티졸은 착색증 그룹이 정상 그룹에 비해 유의하게 높게 나타났다. 어체 중 영양 성분의 경우, 수분과 회분은 그룹 간 유의차가 없었지만, 조단백은 착색증 그룹이 정상보다 다소 낮으며, 조지방은 정상보다 유의하게 높았다. 이상의 스트레스 인자를 통한 정상과 착색증 그룹 간 비교를 통해 알 수 있듯, 양식산 넙치의 착색증은 만성적이 약한 스트레스에 관련되어 있을 가능성이 높은 것으로 확인되었다.