TAILIEUCHUNG - Báo cáo khoa hoc:"Association of a missense mutation in the bovine leptin gene with carcass fat content and leptin mRNA levels"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: Association of a missense mutation in the bovine leptin gene with carcass fat content and leptin mRNA levels | 105 Genet Sei. Evol. 34 2002 105-116 INRA EDP Sciences 2002 DOI gse 2001006 Original article Association of a missense mutation in the bovine leptin gene with carcass fat content and leptin mRNA levels Fiona C. Buchanana CarolYn J. Fitzsimmonsb Andrew G. Van Kessela TraceY D. Thuea Dianne c. Winkelman-Sima Sheila M. Schmutza a Department of Animal and PoultrY Science 51 Campus Drive UniversitY of Saskatchewan Saskatoon S7N 5A8 Canada b Department of Animal Science 2255 Kildee Hall Iowa State UniversitY Ames 50011 USA Received 16 MaY 2001 accepted 24 September 2001 Abstract - Previously we have shown that alleles of the BM1500 microsatellite located kb downstream of the leptin gene in cattle were associated with carcass fat measures in a population of 154 unrelated beef bulls. Subsequently a cytosine C to thymine T transition that encoded an amino acid change of an arginine to a cysteine was identified in exon 2 of the leptin gene. A PCR-RFLP was designed and allele frequencies in four beef breeds were correlated with levels of carcass fat. The T allele was associated with fatter carcasses and the C allele with leaner carcasses. The frequencies of the SNP alleles among breeds indicated that British breeds have a higher frequency of the T allele whereas the continental breeds have a higher occurrence of the c allele. A ribonuclease protection assay was developed to quantify leptin mRNA in a separate group of animals selected by genotype. Animals homozygous for thymine expressed higher levels of leptin mRNA. This may suggest that the T allele which adds an extra cysteine to the protein imparts a partial loss of biological function and hence could be the causative mutation. leptin cattle obese fat marbling 1. introduction Leptin is the hormone product of the oBese gene that acts on central and peripheral tissues to modulate appetite and energy metaBolism 16 . In ruminant animals as in other species studied leptin is secreted predominantly By adipocytes 5 18

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