远缘杂交是获得具有生长优势子代重要途径之一。然而，杂交子代中生长优势的分子机理尚未彻底阐明。在我们首先发现快速生长的杂交鱼中GH/IGF生长轴相关基因表达上调的基础上，本课题拟针对奥尼杂交罗非鱼的生长优势，从GH/IGF生长轴入手，探讨杂交后代较亲本生产快的原因。本项目拟分三个层次展开：1.运用Realtime PCR、Western blot以及免疫荧光技术探讨GH/IGF生长轴在奥尼罗非鱼和亲本中的表达差异；2.采用高分辨率融解曲线、Taqman探针法和焦磷酸测序技术研究奥尼罗非鱼对父母本基因的选择性表达；3.结合CpG甲基化分析、重亚硫酸盐测序和荧光素酶报告分析父母本基因组选择性表达的产生机制。从mRNA和蛋白质表达层次、基因组选择表达层次以及表观遗传学层次，为揭示杂交奥尼罗非鱼生长优势的分子生物学机制提供线索。本课题将为鱼类内分泌调控提供新思路，为罗非鱼杂交育种技术提供理论支持。

The distance hybridization is an important method for obtaining growth advantage and breeding new varieties. However, the mechinism of the growth advantage in these descendants is still now compeletly unveiled. Base on our initial findings that the fast growth hybrids with higher expression of GH/IGF genes, the focus of present project is on growth advantage in Oreochromis niloticus (♀) × O. aureus (♂) and their parents. It was showed that elevated expressions of GH/IGF genes has correlated with fast growth in hybrids. This project will spread with three levels: 1. using Realtime PCR, Western blot and immunofluorescence technique to discuss the expression differentation of GH/IGF axis genes between Oreochromis niloticus (♀) × O. aureus (♂) and parents; 2. by employing high-resolution melting curve, Taqman probe method and pyrosequencing technique to investigate parental genome selected expression in the hybrids; 3. we would use CpG methylation analysis, bisulfite sequencing and luciferase reporter system to study the mechanism of parental genome selected expression in the hybrids. From mRNA and protein expression levels, parental genome selected expression levels and epigenetic level, the project would offer clues of molecular mechanism of advanced growth phenotype in the hybrids. The study could provide new thinking for endocrine regulation and theoretical support of hybrid breeding technology in tilapia.