Evolution of duplicated growth hormone genes in autotetraploid salmonid fishes

Abstract

A defining character of the piscine family Salmonidae is autotetraploidy resulting from a genome-doubling event some 25-100 million years ago. Initially, duplicated genes may have undergone concerted evolution and tetrasomic inheritance. Homeologous chromosomes eventually diverged and the resulting reduction in recombination and gene conversion between paralogous genes allowed the re-establishment of disomic inheritance. Among extant salmonine fishes (e.g. salmon, trout, char) the growth hormone (GH) gene is generally represented by two functional paralogs, GH1 and GH2. Sequence analyses of salmonid GH genes from species of subfamilies Coregoninae (whitefish, ciscos) and Salmoninae were used to examine the evolutionary history of the duplicated GH genes. Two divergent GH gene paralogs were also identified in Coregoninae, but they were not assignable to the GH1 and GH2 categories. The average sequence divergence between the coregonine GH genes was more than twofold lower than the corresponding divergence between the salmonine GH1 and GH2. Phylogenetic analysis of the coregonine GH paralogs did not resolve their relationship to the salmonine paralogs. These findings suggest that disomic inheritance of two GH genes was established by different mechanisms in these two subfamilies.

Major Quantitative Trait Loci Affect Resistance to Infectious Pancreatic Necrosis in Atlantic Salmon (Salmo salar)

“…This strongly suggests that parts of these two linkage groups are ancestrally homeologous and raises the possibility that the two QTL detected may represent two functional paralogs of the same gene(s). For example, the growth hormone gene has two functional paralogs (GH1 and GH2) in salmonids that are both inherited in a diploid fashion (McKay et al 2004), although the locations of these genes on the salmon linkage map are unknown.…”

Phylogenetic analysis of the insulin-like growth factor binding protein (IGFBP) and IGFBP-related protein gene families

“…Duplicate genes are common in the bony fishes due to a genome wide duplication event that occurred early in their evolution ). An additional genome duplication event specifically within the salmonids (Hordvik, 1998) is responsible for up to four unique copies of some genes in some species including the rainbow trout (Brunelli et al, 2001;Garikipati et al, 2006;Kavsan et al, 1993;McKay et al, 2004). Thus, the existence of two IGFBP-2 paralogs in rainbow trout is not necessarily surprising.…”

Genomic structure, polymorphism and expression analysis of the growth hormone (GH) gene in female and male Half-smooth tongue sole (Cynoglossus semilaevis)

“…Previous reports demonstrated that the GH genes of some teleost like the catostomid and salminid fishes have two categories (GH1 and GH2) which are normally caused by a genome duplication events (Bart et al, 2010;McKay et al, 2004). As shown in Fig.…”