Preliminary Studies Of Turbot(Scophthalmus Maximus) White Spotted Body Color Formation Physiological Mechanism

In this paper, Shandong Province varieties breeding project of three generations of turbot for the study, found that one of the series fish eye side table has a clear white spotted turbot in the selective breeding process, the general gray-black turbot seems pretty brilliant, to be its breeding and promotion. But this white piebald coloration turbot surface color is not stable, the rear surface stress by quickly dispersed black with white markings. So Based on turbot skin pigment cells morphology and histology observation; melanin-concentrating hormone regulating body color measuring hormone and catecholamine levels; skin tissue and brain melanin-concentrating hormone receptor mch-r and melanocortin receptor expression mclr to conduct a preliminary inquiry on the causes and mechanism of this turbot white piebald coloration formed to provide reference and basis for turbot body color studies to help breeding superior varieties farmed turbot. The main contents are as follows:1. Take two body color turbot have eyes on the back and side of the body skin side making temporary loading and paraffin on the surface of the pigment cells in the skin and skin structure was observed by optical microscope. The results show turbot skin pigment cells mainly in melanoma cells, melanocytes and iridescent yellow pigment cells based. Wherein the number of melanoma cells significantly more than the other two types of pigment cells. There are two forms of melanoma cells:one whole cell small and spherical, no star-branched or obvious; another individual cells generally larger and more prominent and distinct branches, the whole cell is rendered as a snowflake. Melanoma cells and melanocytes located in the top of the yellow iris pigment cells. Piebald white body color yellow pigment cell number compared with lower than normal body color turbot, the number of melanoma cells was significantly lower than the normal number of melanocytes body color turbot, and the degree of aggregation of pigment granules in the pigment cells was significantly higher than normal body color. But observation of paraffin tissue sections found turbot two body color no significant difference in the color and thickness of pigment cell layer, so presumably resulting in two body color turbot color differences may be the main reason for melanocytes less melanin pigment granules within the content within the aggregate and melanocytes.2. By enzyme-linked immunosorbent assay for induction of skin melanin aggregation turbot two main hormones were determined. Melanin concentrating hormone (MCH) is a peptide neurotransmitter, white spotted body color turbot in MCH average content 46.9pg/ml, the average content of normal body color turbot MCH is 44pg/ml. Two kinds of body color turbot in MCH content was not significantly different. Catecholamines also induced aggregation of fish flounder melanocytes. White body color spotted turbot average content of CA was 318.35ng/ ml, normal body color turbot average content of CA was 244.65ng/ml. Two kinds of body color turbot in CA content were significantly different. The formation of white spotted turbot may be due to adrenergic receptors by catecholamines and adrenergic receptor causes aggregation α2-melanin granules or weaken cAMP-PKA signal leads melanoma cell apoptosis, and thus make the fish body color appear white markings.3. By real-time quantitative PCR techniques on two body color turbot in the regulation of gene melanin melanin-concentrating hormone receptor gene aggregation (MCHR) and melanin synthesis pathway key genes melanocortin receptor gene (MC1R) in two body color expression turbot skin and brain were detected. The results show that gene expression in white piebald MCHR1 body color turbot skin was significantly higher than normal body color, while MCHR2 gene expression levels in two body color skin there is no significant difference. The circulatory system in the MCH fish showed no significant difference, and therefore affects the aggregation speculate MCHR1 melanocytes, causing the formation of white spotted body color. White body color spotted turbot flounder gene expression in the skin MC1R unexpectedly higher than normal body color, this table understand piebald coloration turbot skin melanin synthesis pathway genes switch normal fish also show variation in color the regulators suffered many differences more complex and require further study.