The Study On The Different Expression Of GH/IGF-1Axis Related Factors In Different Ploidy Cyprinids

The growth of fish is controlled by GH/IGF axis. GH/IGF axis which contains of growth hormone (GH), growth hormone receptor (GHR), insulin-like growth factor-1(IGF-1) and insulin-like growth factor binding protein (IGFBP), plays a crucial role in regulating growth in teleost. In the vertebrate growth, different hormones and factors regulate the body’s growth process together. The secretion of growth hormone plays a crucial role in the GH/IGF axis. So it is necessary to study on GH/IGF axis.Our laboratory gains a bisexual fertile allotetraploid. The triploid crucian carp was produced by mating the males of allotetraploids with the females of japanese crucian carp (Carassius auratus cuvieri), which have shown several enhanced performances such as sterility, faster growth rate, good flesh quality and higher anti-disease ability. Triploids provided a biological material for the comparative studies of different ploidy level fishes. Our study focus on regulation of fish, which combine GH/IGF axis related factors with polyploidy crucian carp.The main topics in this paper are present as follows:1) In present study, to elucidate the effect of E2on genes of GH/IGF-1expression in different ploidy fishes, the E2injection was performed in diploids and triploids. Our results suggest that E2reduce expression of GHR and IGF-1in diploids, and no effect of E2on these genes expression in triploids. Meanwhile, ER expression is deficient in triploids, which results in lacking of suppression effect due to the action of E2and ER binding. These results mean that the dysfunction of ER may contribute to the fast growth in female triploids during ovulation seasons.2) By PCR, we obtain the cDNA sequences of IGFBP-1of diploids, triploids and tetraploids, and analysis the homology of sequences. By comparison, a length of570bp’IGFBP-1in liver, we find out two subtype fragment of IGFBP-1gene, we named IGFBP1a and IGFBP1b. The IGFBP1a of triploids and tetraploids has high homology with diploids, compare with common carp, the same result exist in IGFBP1b. We can conclude that liver of triploids and tetraploids expression IGFBP1gene come from diploids and common carp.3) By RT-PCR, we detect the expression of IBFBPs in different ploidy crucian carp and different period of development. To explore the rapid growth of triploid and provides a theoretical basis. The results show, IGFBP-1、-2and-3had expression in heart, liver, spleen, kidney, muscle, gonad, brain, pituitary and gill. The expression of IGFBP-1mRNA has low expression levels in early gastrulation, we detect IGFBP-1mRNA while sarcomere period, and expression of IGFBP-3turn out in middle gastrulation. So we conclude that IGFBP-1、-2、and-3synthesize by local organizations and acting on IGFs to regulate the growth and development of fish. Meanwhile, IGFBP-1、-2and-3have high tissue-specific, and have high expression in liver.