Association between a polymorphism in the IGF2 gene and finishing weight in a commercial rabbit population

Influence of polymorphisms in candidate genes on carcass and meat quality traits in rabbits

Candidate gene is a powerful approach to study gene-trait association and offers valuable information for genetic improvement using marker-assisted selection. The current work aimed to study the polymorphisms of four single nucleotide polymorphism (SNPs) at located growth hormone (GH), insulin-like growth factor-II (IGF-II), fat mass and obesity-associated (FTO), and insulin receptor substrate-1 (IRS-1) genes, and their association with the carcass, and meat quality traits in rabbits. The SNPs were genotyped using RFLP-PCR in New Zealand White and local Baladi rabbits. The results revealed that the heterozygous genotype was the most frequent in all cases, except for the FTO SNP in LB rabbits. There was a significant effect for GH genotypes on meat lightness after slaughter and hind-part weight. While, IGF-II mutation significantly affected slaughter, hot carcass, commercial carcass, and hind-part weights. The FTO SNP was associated with cooking loss and intramuscular fat weight, and the IRS-1 SNP was significantly associated with drip loss and intramuscular fat. Specific-breed effects were obtained for IGF-II SNP on cooking loss, and for the intramuscular fat. Although the results suggested that these mutations are useful candidate genes for selection, more research for detecting more variants associated with carcass and meat quality traits in rabbits are recommended.

Candidate genes for marker-assisted selection for growth, carcass and meat quality traits in rabbits

Growth and meat production are the most relevant targets for animal breeders, there are strong relationships between animal growth regulation, body composition and meat quality. Therefore, it is essential to identify the genetic factors that are controlling growth, carcass, and meat quality traits and to explore the correlations between identified genes of those traits. Identification of candidate genes may shift rabbit breeding from classical to modern approaches, which offer great potential to accelerate genetic improvement plans, especially in developing countries. The current work reviews several genes and mutations affecting growth, carcass and meat quality traits. These candidate genes and mutations can be incorporated into MAS programs to improve rabbit breeds especially local breeds, provided that a reasonable proportion of trait additive genetic variance is explained by the significant marker. Furthermore, we highlighted the indispensable need for more researches investigating candidate genes for different traits.

Association of growth hormone (GH), insulin-like growth factor 2 (IGF2) and progesterone receptor (PGR) genes with some productive traits in Gabali rabbits

<p>The objectives of the present study were 1) to evaluate the polymorphism of growth hormone(GH), insulin-like growth factor 2 (IGF2) and progesterone receptor (PGR) genes in Sinai Gabali rabbits, and 2) to assess their associations with growth, litter size and milk production traits in Sinai Gabali rabbits. The C&gt;T, A&gt;Del and A&gt;G single nucleotide polymorphisms of GH, IGF2 and PGR genes were genotyped by polymerase chain reaction-restriction fragment length polymorphism using BstUI, HpyF31 and BsaI restriction enzymes, respectively. The C/T genotype of GH gene recorded the heaviest body weights for body weight (BW) at 8 wk (1190.22±19.29 g) and 12 wk of age (1842.46±30.19 g) and recorded the largest litter size at birth (LSB: 7.37±0.12 kits) traits. The Del/Del genotype of IGF2 gene showed the superiority over the other genotypes for BW at 4 wk (507.17±8.87 g), 8 wk (1239.39±14.0 g), and 12 wk of age (1950.15±18.1 g), as well as for daily weight gain from 4 to 8 wk (26.05±0.37 g/d), and from 8 to 12 wk of age (25.48±0.56 g/d) traits. The G/G genotype of the PGR gene showed superiority for LSB (7.51±0.13 kits) and litter size at weaning (6.53±0.14 kits) traits over the other genotypes. Regarding milk yield traits; the C/C, A/A and A/A genotypes of GH, IGF2 and PGR genes yielded more milk compared to the other genotypes. The means of total milk yield in 28 d for these genotypes were 2936±29 g, 2921±43 g and 2930±35 g, respectively. Thus, GH, IGF2 and PGR genes might be useful for marker-assisted selection programmes for improvement of rabbit growth, litter size and milk yield traits.</p>

Adaptive potential of genomic structural variation in human and mammalian evolution

Because phenotypic innovations must be genetically heritable for biological evolution to proceed, it is natural to consider new mutation events as well as standing genetic variation as sources for their birth. Previous research has identified a number of single-nucleotide polymorphisms that underlie a subset of adaptive traits in organisms. However, another well-known class of variation, genomic structural variation, could have even greater potential to produce adaptive phenotypes, due to the variety of possible types of alterations (deletions, insertions, duplications, among others) at different genomic positions and with variable lengths. It is from these dramatic genomic alterations, and selection on their phenotypic consequences, that adaptations leading to biological diversification could be derived. In this review, using studies in humans and other mammals, we highlight examples of how phenotypic variation from structural variants might become adaptive in populations and potentially enable biological diversification. Phenotypic change arising from structural variants will be described according to their immediate effect on organismal metabolic processes, immunological response and physical features. Study of population dynamics of segregating structural variation can therefore provide a window into understanding current and historical biological diversification.