Genetic Variation On LPL Gene And A-FABP Gene

Lean meat percentage of body and meat quality are two important economic characters. The meat quality is continuously declining, although the breeding aim to improve lean meat percentage of body is basically achieved. For Chinese local pig breeds are bound in genetic diversity and excellent meat quality, the breeding aim is turning into keeping and utilizing soundly the advantage of excellent meat quality of Chinese local pig breeds as well as improving lean percentage of body. It was difficult to improve both lean meat percentage of body and meat quality simultaneously through traditional breeding means because the two indexes are negatively correlative. Therefore, molecular marker assisted selection becomes a feasible breeding mean along with the emergence of modern molecular breeding technique. Candidate gene method is one of the main approaches that are often used to study genetic mechanism of quantity trait in animals. At present, LPL gene and A-FABP gene are considered to be the major candidate genes affecting back fat thickness and intramusclular fat content in porcine respectively.In this study, DNA samples from 368 pigs including 3 exotic breeds, 4 Chinese local breeds, 1 cultivated breed and Boar were analyzed. LPL gene and A-FABP gene were studied by PCR-RFLPs and microsatellite respectively. The aim of this study was to find some new polymorphic loci and then establish the foundation for determining the major genes affecting back fat thickness and intramuscular fat content or the available genetic markers linked with them tightly. The main results were as follows.1 At the Smaâ… -RFLP locus of Intron 6 in LPL gene, BB genetype was major in Yorkshire, Haibai pig, and Boar, AA and AB genetype were major in Landrace, Duroc and Neijing pig, while AB and BB genotypes were major in Rongchang pig and Hanjing black pig. There was no character of breeds between genotypes.2 At the Pvuâ…¡-RFLP locus of Intron 6 in LPL gene, the exotic breeds including Large Yorkshire, Landrace, Duroc presented only DD genotype while native breeds and Boar varied. There was difference in genotypes between Chinese lardtype breeds excluding Hanzhong White pig and exotic lean breeds, and it was possible that C allele was correlative with fat deposition and high back fat thickness of native breeds. 3 At the EcoRâ… -RFLP locus of Intron 8 in LPL gene, EF genotype and F allele frequency were prevailing in all of the tested breeds and Boar. 4 At the Hind â…¢-RFLP locus of Intron 8 in LPL gene, the exotic breeds and Rongchang Pig varied while others presented only FF genotype.5 At the microsatellite locus of Intron 1 in A-FABP gene, there were 16 alleles and 9 genotypes. Expect that EM genotype existed in Hanzhong white pig, EM and GN genotypes existed in others. EM and GN prevailed in Yorkshire, Landrace, Duroc, Rongchang pig and Neijiang pig,. 6 At the microsatellite locus of Intron 1 in A-FABP gene, 8 domestic pig breeds and 1 Boar breed were divided into 3 clusters by UPGMA according to Nei's DA genetic distance. Yorkshire, Landrace, Rongchang pig, Hanzhong white pig and Bamei pig were the first cluster, Boar and Hanjiang black pig were the second cluster, while Duroc and Neijiang pig were the third cluster.7 The genotype distribution, allele frequency, He, and PIC were identical between Boar and native breeds at 4 loci of PCR-RFLPs in LPL gene. The genotype distribution, allele frequency, genetic comparability and genetic distance were identical between Boar and native breeds at the microsatellite locus of A-FABP gene. These showed the relationship between Boar in our study and Chinese local pig breeds was close.