광량에 따른 붉바리(Epinephelus akaara)의 멜라닌 관련유전자 발현 특성

Abstract

The present study was investigated the expression of melanin related factors on the developmental stage and light intensity in red spotted grouper, Epinephelus akaara. The expression of melanin related factors on the developmental stage of red spotted grouper was conducted from 1 DAH (Day after hatching) to 50 DAH. At 5 DAH, the expression level of melanin concentrating hormone (mch) mRNA, pro-opiomelanocortin (pomc) mRNA and melanocortin 1 receptor (mc1r) mRNA were significantly higher than the other stage. And also at 10 DAH, the expression level of agouti signalling peptide (asip) mRNA was significantly higher than the other stage. The light intensity experiment was examined by expression of the melanin related genes and RGB cod value. Experiment performed from July 2017 to October 2017. Fish (n=200, body weight 0.5 ± 0.1 g, total length 3.2 ± 0.9 cm) was reared under different light intensity (i.e., 0 lux, 200 lux, 1,000 lux and 2,000 lux) for 9 week under 12 hour light and 12 hour dark photoperiod and natural water temperature (20.1 ~ 28.9 ˚C). After exposure of four different light intensity for 3, 6 and 9 weeks, the mch mRNA, pomc mRNAs, mc1r mRNA and asip mRNA, were analyzed in the brain with pituitary and skin. At 6 weeks, the expression level of mch mRNA in the 2,000 lux treatment group were significantly higher than the other light intensity exposed groups (P˂ 0.05). At 9 weeks, the expression level of pomc mRNA and mc1r mRNA in the 1,000 lux treatment group were significantly lower than the other light intensity exposed groups (P˂ 0.05). The expression level of asip mRNA showed no significant difference between treatment groups. The highest expression level of asip mRNA was at the initial state, and after 3 weeks it decreased rapidly and stayed low until 9 weeks. The results of the RGB (Red, Green, Blue) code values in 0 lux, 200 lux, 1000 lux and 2000 lux under different light intensity treatment groups were the brightest at 1000 lux and the darkest at 0 lux. The pomc mRNA and mc1r mRNA might play an important melanin synthesis parameters role. In this study, these genes were affected by the light intensity, and the expression level were varied according to the light intensity. To understand the molecular mechanism of the coloration better in red spotted grouper, further studies are needed to clarify the relationship between melanophores development and its related genes (e.g., pomc mRNA, mc1r mRNA and mch mRNA).