Gene expression profiles of growth and reproduction related genes during the early development of common carp (Cyprinus carpio L.)
鲤鱼发育早期HPG轴和GH/IGF轴相关因子的转录起始分析

As many researches revealed some relations between HPG and GH/IGF axis in teleost, we detected gene expression profiles of growth- and reproduction-related genes from HPG or GH/IGF axis in common carp ( Cyprinus carpio) embryos and early larval stages, in order to find some regulatory relations between HPG and GH/IGF axis in the early development stages of common carp. The genes under detection were sGnRH, cGnRH, GtH α subunit and β subunit from HPG axis and GH, IGF, growth hormone receptor (GHR) from GH/IGF axis, with β-actin gene as the internal control. Samples were collected from embryos and larvae of unfertilized eggs, 64-cell stage, 32-cell stage, 256-cell stage, 50%-epiboly, 20-, 23-, 26-, 32-, 40-, 46- and 58- hours post fertilization ( hpf) , and 1-, 2-, 3-, 5-, 7- and 9- days post hatching (dph) reared at 23℃, and then RNA extracted from the samples was used in RT-PCR. sGnRH, cGnRH, GtH α subunit, GtH-I β subunit, GtH-II β subunit, GH, GHR and IGF-1 showed different expression patterns in carp embryos and larvae. Development around 20h post fertilization ( hpf) and 23hpf was critical for carp embryos, as sGnRH, cGnRH, GtH-1β subunit and GHR were first detectable at 20hpf, IGF-1 at 23hpf and GtH-II β at 26hpf. Meanwhile, embryos in 20hpf and 23hpf stages showed apparent development in brain region, indicating a regulatory function of GnRH and GtH in the development of brain. GtH α subunit was first detectable at 46hpf while GH was first detectable at 1 d post hatching (dph). The difference in the timing of the expression of GH and IGF mRNA may suggest that IGF gene expression is not GH-dependent. Additionally, the timing of the expression of GtH α subunit, GtH-I β subunit, GtH-II β subunit were unsyn-chronized in embryos, suggesting a regulatory function of GtH α subunit in GtH expression.