Evolutionary implications of two rainbow trout growth hormone genes

Abstract

The primary structures of two rainbow trout growth hormone mRNAs (GH1 and GH2) have been deduced by direct sequencing of their respective cDNA clones and portions of the mRNA. Both GH1 and GH2 mRNA contain open reading frames comprised of 630 nucleotides and encode 210 amino acid residues of which 11 are variant. The translated regions of both mRNA are flanked by a short but rather conserved 5'-end, and a relatively long but highly diverged 3'-end. The differences at translated and 3'-untranslated regions suggest that the GH1 and GH2 mRNA originate from different loci. The GH1 and GH2 mRNA are likely transcribed from two distinct loci which were duplicated during tetraploidization of salmonid genome between 50 to 100 million years ago.The GH2 gene has been isolated and sequenced from a rainbow trout genomic library. This gene spans a region of approximately 4 kilobases. The trout GH gene is comprised of 6 exons and 5 introns, in contrast to 5 exons and 4 introns in mammals. The additional intron in the trout gene interrupts the translated regions that are analogous to the last exon of the mammalian counterpart. The alleged internally repeating sequences in mammalian GH, prolactin (Pr1) and placental lactogen (PL) are not observed in the predicted polypeptide sequence of trout GH. In addition, direct repeats that flank exons I, III and V of mammalian GH, Pr1 and PL genes are absent in trout gene. These findings indicate that the rainbow trout GH gene structure does not support the current hypothesis that internally repeated regions in GH, Pr1 and PL arose from a small primordial gene.

Differential expression of the two GH genes during embryonic development of rainbow trout oncorhynchus mykiss in relation with the IGFs system

“…After appropriate linearisation of the plasmids that contained IGF-1, IGF-2, GH-1, GH-2 (Agellon et al, 1988b;Chen et al, 1989;Gentil et al, 1996), IGFRIa or IGFRIb, sense and anti-sense RNA probes were generated using T3, T6 or SP6 polymerases in the presence of digoxigenin-11UTP (Boehringer, Mannheim) with the Riboprobe 1 Combination System (PROMEGA). The whole-mount in situ hybridisation was performed as described by Delalande and Rescan (1998).…”

ISOLATION AND IDENTIFICATION OF PARTIAL GROWTH HORMONE (GH) mRNA OF TIGER SHOVELNOSE CATFISH Pseudoplatystoma fasciatum (LINNAEUS, 1766)

“…Homology analysis in rainbow trout of the gh1 and gh2 genes had 78.6 % and 89.2 % homology at 32 -and 52 -UTR, respectively, compared to 96.8 % homology in the coding region (Chen et al, 1989). The two genes' non-coding regions were significantly different, which can be explained by the lack of gene Figure 7.…”

CANDIDATE GENES PROMISING FOR MARKER-ASSISTED SELECTION IN AQUACULTURE (review)

“…У многих изученных видов рыб ген гормона роста обладает более высоким уровнем изменчивости в некодирующих областях, чем у других позвоночных, что обусловлено наличием двух функциональных копий гена -GH1 и GH2. Так, два паралога гена гормона роста идентифицированы у Oncorhynch nerka, Tilapia nilotica, Carassius auratus, Oncorhynchus tshawytscha, Cyprinus carpio, Salmo salar, Oncorhynchus mykiss (132,(135)(136)(137)(138)(139)(140). Экспрессия гена гормона обнаружена во многих тканях и органах, включая головной мозг, печень, мышцы, сердце, селезенку, почки и яичники, но самый высокий уровень экспрессии выявлен в гипофизе (91,128,141).…”