K. Tessanne, H. C. Hines, and M. E. Davis1
The Ohio State University Department of Animal Sciences
The ob gene, which produces the 16-kilodalton protein leptin, is believed to be involved in the regulation and deposition of fat. In this study, two microsatellites and two restriction fragment length polymorphisms were used to identify polymorphisms in the bovine leptin genes of The Ohio State University beef cattle research herd, located at the Eastern Ohio Resource Development Center (EORDC). The microsatellites were those described by Wilkins and Davey (1997) and by Stone et al. (1996 [GenBank Accession No. G18586]), while the PCR-RFLPs were those characterized by Lien et al. (1997). Polymerase Chain Reaction (PCR) amplification of DNA from 160 beef bulls was performed using fluorescent primers designed for both of the microsatellites, as well as for the PCR-RFLPS. PCR products amplified with the PCR-RFLP primers were subjected to restriction enzyme digestion using Hinfl and BsaAI restriction endonucleases. Samples of the microsatellite PCR products, combined with the enzyme digestion products, were examined with an ABI 377 DNA Sequencer (Perkin-Elmer/Applied Biosystems), using GENESCAN 672 software. The genotypes were then determined with the aid of Perkin-Elmer/ABI Genotyper software. After all animals were genotyped, carcass data collected on the EORDC cattle were analyzed using the General Linear Models procedure of the SAS computer program. Significant differences in allelic frequencies between the high and low IGF-I selection lines were found at the Wilkins & Davey microsatellite (WD-MS) and Stone microsatellite (Stone-MS) sites, but not at the PCR-RFLP site. The WD-MS genotypes had a significant effect on ribeye area (P < 0.02). However, no other statistically significant relationships were found. Noteworthy relationships (P < 0.20) were found between both the Stone-MS and the PCR-RFLP genotypes and marbling score and between the PCR-RFLP genotypes and kidney, pelvic, and heart fat (KPH) percentage.
1 For more information, contact at: The Ohio State University, 221 Plumb Hall, 2027 Coffey Road, Columbus, OH 43210, 614-292-4984, Fax 614-292-7116, e-mail: davis.28@osu.edu