Resumo

MONTOYA A, Alba Eunery  et al. Frequency of leptin gene markers in creole and colombian cattle: I. Romosinuano, chino santandereano, sanmartinero and velásquez breeds. Rev. Cient. (Maracaibo) [online]. 2009, vol.19, n.1, pp.38-48. ISSN 0798-2259.

Leptin is a 146 amino acids hormone that it is secreted predominantly by white adipocytes. It has been associated to different productive and reproductive traits of farm’s animals. The aims of this study were to determine polymorphisms of three molecular markers of the leptin gene: A Single Nucleotide Polymorphism (SNP), the microsatellites ST (or BM1500) at the 3’UTR region, and WD at the 5’UTR. The amplification was made for PCR technique and was run in agarosa gel after the restriction for SNP and polyacrylamide gel for microsattelites. In order to establish the association of these markers with body weight, rib eyes area, and backfat thickness, Analysis of Variance (ANOVA) was used and data was obtained using ultrasound images. Samples were taken from 252 animals of three creole and one Colombian breed cattle out of different nuclei from Colombia. For the SNP, T allele frequency was larger in Sanmartinero breed and lower in Chino Santandereano breed. For the microsatellite BM 1500 five different alleles were found (136, 138, 144, 146 and 148). Among these, alleles 136 (between 0.31 y 0.76) and 144 (between 0.15 and 0.65) appeared more often. Also, in WD 13 alleles were identified, being allele 183 (between 0.038 and 0.630) and allele 177 (between 0.14 and 0.46) the most common. Finally, for the Velasquez breed the only association found occurred between the microsatellite ST allele 146 and larger body weight in individuals between 18 - 24 months (P £ 0.05).

Palavras-chave : Meat quality; molecular markers; animal breeding; leptin; ultrasound.