ISOLATION, TRANSCRIPTS POLYMORPHISM AND TISSUES EXPRESSION OF|GROWTH HORMONE RECEPTOR GENES IN CYPRINUS CARPIO VAR. JIAN

Four jlGHRs (jlGHR1a, jlGHR1b; jlGHR2a, jlGHR2b) were cloned by using PCR, RT-PCR and RACEmethods in Cyprinus carpio var. jian. Homology analysis and phylogenetic tree showed that jlGHR1a,-1b andjLGHR2a,-2b belonged to fish GHR1 and GHR2, respectively. The differences of amino acid sequence were 5% and11% between the two paralogs, but the functional conversation regions, such as extracellular motif FGVFS, Box1 andBox2 were mostly identical. The difference between jlGHR1s with jlGHR2s amino acid sequence was 41%. jlGHRs hadthe same genetic structure as zebrafish. There were 7 introns in the open reading frame. The lengths of specific intronsbetween paralogs were obvious different. The comparability between jlGHR1, jlGHR2 and other GHR1, GHR2 wasconsisted with traditional staple. In this study, different jlGHR transcripts were found in the liver of Cyprinus carpio var.jian, including jlGHR 1b' (lost exon 4), jlGHR2a' (containing intron 3) and jlGHR 2as (lost partial exon 8). Realtime-PCR results indicated that despite quite different quantity, 4 genes expressed in all the 8 tissues, such as brain, liver,heart, head kidney, kidney, intestines, spleen and muscle. Expression levels of 4 jlGHRs were the highest in muscle.Except brain, jlGHR2b expression was higher than other 3 genes in tissues. It was conferred that jlGHR2a was underlower selection stress than jlGHR 2b from the several transcripts and lower expression. The two paralogs jlGHR1s and-2s isolated from C. carpio approved that two sets of gene existed in Cyprinus carpio var. jian, which indicated that C.carpio var. jian was good material for homeotic genes differentiation researching. The two sets of gene existed in Cyprinuscarpio var. jian also laid foundation for finding SNP loci in the GHR correctly.