NPY和POMC基因在生长差异与饥饿再摄食鳙个体中的表达分析

为研究摄食促进基因和摄食抑制基因对鱼类生长调控和饥饿再摄食过程的影响,研究克隆了鳙神经肽Y(HynNPY)基因和前阿黑皮素原(HynPOMC)基因cDNA序列,采用qRT-PCR技术分析它们在生长显著差异鳙个体下丘脑、肠中的基因表达变化;设置对照组(连续投喂4周)、饥饿组、饥饿再摄食组,分析NPY和POMC在不同处理组鳙的下丘脑、肠中的基因表达变化。鳙NPY和POMC基因cDNA全长分别为839和799 bp,开放阅读框有291和657 bp,分别编码96和218个氨基酸。系统进化分析结果表明,鳙NPY和POCM基因具有高度保守性。鳙NPY在下丘脑的表达量最高,其次为肠和脑; POMC在肠道中的表达量最高,其次为下丘脑和肝脏。在相同环境下生长差异鳙个体的下丘脑和肠中, NPY在极大个体的表达量高于极小组个体, POMC在极小个体中的表达量高于极大个体。饥饿导致NPY在下丘脑表达上升,在肠表达量显著上升,恢复摄食后, NPY在下丘脑和肠中表达量下降; POMC在饥饿组下丘脑和肠中都表现为表达量呈显著上升,复投喂后POMC表达量逐步下降至接近对照组水平。肠组织学观察显示,极大个体的肠腔直径...

EXPRESSION ANALYSES OF NPY AND POMC GENES IN EXTREME GROWTH AND STARVATION-REFEEDING BIGHEAD CARP (HYPOPHTHALMICHTHYS NOBILIS)

Fish growth is one of the most complex traits that may be influenced by many physiological processes. Among them, feeding is a necessary prerequisite to ensure the growth, development and survival of fish. In order to study the effects of feeding promoting and feeding inhibiting genes on genetic regulation of growth and starvation-refeeding, cDNA sequences of neuropeptide Y (HynNPY) and pro-opiomelanocortin (HynPOMC) genes were cloned in bighead carp (Hypophthalmichthys nobilis) in this study. By using qRT-PCR, expression levels of NPY and POMC genes were studied in hypothalamus and intestine of extreme growth and starvation-refeeding of bighead carp by setting control (feeding), starvation, and starvation-refeeding group, respectively. The full-length cDNA of NPY and POMC genes were 839 and 799 bp, encoding 96 and 218 amino acids, respectively. Phylogenetic analysis showed that NPY and POCM are highly conserved in teleosts. The expression of NPY in hypothalamus was the highest, followed by intestine and brain. The expression of POMC in intestine was the highest, followed by hypothalamus and liver. In the hypothalamus and intestine of extreme large (mean 42.4 g) and extreme small (mean 18.8 g) individuals cultured in the same pond, the expression of NPY in extremely large group was higher than that of extremely small group, while the expression of POMC in extreme small group was significantly higher than that of extreme small group. Starvation increased the expression ofNPY in hypothalamus and intestine. After starvation, the expression of NPY increased in the hypothalamus and increased significantly in the intestine. After refeeding, the expression of NPY decreased in the hypothalamus and intestine. The expression of POMC in hypothalamus and intestine of starvation group increased significantly, and decreased to the level of control group after refeeding. Histological observations showed that structure of intestine in extremely large group is better than that of extremely small group, meanwhile, broken intestinal villi and leukocyte infiltration in starvation group tend to recover gradually after refeeding. In short, NPY promotes the intake of more food and POMC supresses appetite, and both of them are involved in feeding mediation of central and peripheral nerve systems of bighead carp. NPY and POMC may directly or indirectly affect the growth of bighead carp by controlling feeding behavior, intake of feed nutrition and GH secretion. These results would provide insights into further understanding of molecular mechanisms for differential growth in bighead carp and gene resources for genetic improvement.