Candidate gene analysis of GH1 for effects on growth and carcass composition of cattle

Abstract

We present an approach to evaluate the support for candidate genes as quantitative trait loci (QTLs) within the context of genome-wide map-based cloning strategies. To establish candidacy, a bacterial artificial chromosome (BAC) clone containing a putative candidate gene is physically assigned to an anchored linkage map to localise the gene relative to an identified QTL effect. Microsatellite loci derived from BAC clones containing an established candidate gene are integrated into the linkage map facilitating the evaluation by interval analysis of the statistical support for QTL identity. Permutation analysis is employed to determine experiment-wise statistical support. The approach is illustrated for the growth hormone 1 (GH1) gene and growth and carcass phenotypes in cattle. Polymerase chain reaction (PCR) primers which amplify a 441 bp fragment of GH1 were used to systematically screen a bovine BAC library comprising 60,000 clones and with a 95% probability of containing a single copy sequence. The presence of GH1 in BAC-110R2C3 was confirmed by sequence analysis of the PCR product from this clone and by the physical assignment of BAC110R2C3 to bovine chromosome 19 (BTA19) band 22 by fluorescence in situ hybridisation (FISH). Microsatellite KHGH1 was isolated from BAC110R2C3 and scored in 529 reciprocal backcross and F2 fullsib progeny from 41 resource families derived from Angus (Bos taurus) and Brahman (Bos indicus). The microsatellite KHGH1 was incorporated into a framework genetic map of BTA19 comprising 12 microsatellite loci, the erythrocyte antigen T and a GH1-TaqI restriction fragment length polymorphism (RFLP). Interval analysis localised effects of taurus vs. indicus alleles on subcutaneous fat and the percentage of either extractable fat from the Iongissimus dorsi muscle to the region of BTA19 harbouring GH1.

Association of GH and IGF-1 polymorphisms with growth traits in a synthetic beef cattle breed

“…The hypothesis of a segregating QTL close to the bovine GH is not supported by the results reported in the literature, since the QTLs for growth or meat production traits where mapped to intervals that do not include bGH, as discussed in Casas et al (2003). The hypothesis that the effects of GH observed in the present study might result from a different polymorphism in this gene appears to be more acceptable, since other polymorphisms of this gene have been associated to growth traits in cattle (Taylor et al, 1998).…”

Associação do polimorfismo do gene do hormônio de crescimento com a caraterística peso em bovinos da raça Nelore

“…Este polimorfismo tem sido associado, por TAYLOR et al (1998), à qualidade de carcaça (porcentagem de ácidos graxos), característica não estimada neste trabalho. A falta de associação, provavelmente, ocorreu em função do tamanho da amostra.…”

“…Os estudos sobre a estrutura do bGH foram seguidos de pesquisas que procuraram relacionar os polimorfismos encontrados à produção (HOJ et al, 1993) e quantidade de gordura do leite (YAO et al, 1996), ao peso ao nascimento (ROCHA et al, 1992) e, ainda, à composição e qualidade de carcaça (TAYLOR et al, 1998).…”

Strategies for the genetic improvement of South African Angora goats

“…The growth hormone gene (GH1) has been mapped to BTA 19 (corresponding to CHI 19, on which a putative QTL for WW was identified), indicating that this chromosome should be associated with growth traits (Hediger et al, 1990;Taylor et al, 1998).…”