Analysis Of Molecular Polymorphisms And Sequences Of Porcine H-FABP Gene

Increasing the lean meat content and improving meat quality are two major objectives of the pig breeding programs. The main fat depot in meat ?intramuscular fat (IMF) is positively correlated with meat quality traits. Appropriate IMF content is desirable, but it has been reduced under optimal range because of the selection of lean meat. Thus the new breeding objective is to increase the lean meat as well as IMF content. The study mainly peformed Chinese native breeds which have relatively high IMF content. The genetic variations in S'-upstream region and the second intron of H-FABP gene were detected by PCR-RFLP, in addition, the corresponding polymorphic fragments were cloned and sequenced. The position of three variant restriction sites and mutative base sequences were ascertained. The future aim of our study is to look for a possible relationship between different genotypes in H-FABP gene and variation in IMF content, further to investigate whether H-FABP locus is the major gene for IMF deposition.DNA Samples from 409 pigs including eight Chinese breeds and one imported Large White breed were analyzed. The H-FABP gene was screened for genetic variation in 5'-upsream and the second intron by PCR-RFLP. One Hinfi -RFLP in S'-upsream region was verified in nine pig breeds. The polymorphic Hinfi site is at position 1322. The frequencies of H allele in Wannanhua, Erhualian, Jinhua, Small Meishan, Diannan Small-ear, Xiangzhu, Rongchang, Beijing Black and Large White were 0.3556, 0.3448, 0.5968, 0.6607, 0.8019, 0.7300, 0.7609, 0.7000, 0.8962, respectively. The ///nfl-RFLP distribution between Large White and the other seven breeds, except for Diannan Small-ear among Chinese breeds, is significantly different (p<0.01). Wannanhua and Erhualian are similar, but both of them are significantly different from the other'seven breeds (p<0.01). One //oelll-RFLP was also confirmed in the second intron. This polymorphic site was only found in Wannanhua and Large White. D allele frequencies were 0.9889 and 0.6146, respectively. A new polymorphic Hinfl* site in the second intron was found in this study. This polymorphic site was only found in Wannanhua and Large White too. B allele frequencies were 0.8649 and 0.5769, respectively. MspI-RFLP was not found in nine breeds.A chi-square analysis suggested that the allele frequencies and genotype frequencies of nine breeds for //mfl*-RFLP were in Hardy-Weinberg equilibrium (P>0.05). But for Haelll-RFLP, Wannanhua pig population was in disequilibrium (PO.01); for ///nfl-RFLP, Xiangzhu population was in disequilibrium (P<0.05).For Hint I - RFLP, eight Chinese breeds had intermediate polymorphism (0.5>PIO0.25) , Large White had low polymorphism (PICO.25) . But for HaeEl- RFLP, Large White had intermediate polymorphism, Wannanhua had low polymorphism and the others' PIC was zero. For ////if I *- RFLP, PIC in nine breeds behaved the same state of that for HaeEl- RFLP.The polymorphic fragments of the above three variant restriction sites were cloned and sequenced. The results revealed a single nucleotide substitution of T-C at position 1324 for Hinfl -RFLP, C-G at position 1811 for Haelll-RFLP and T-C at position 1970 for Hinfl*-RFLP, respectively.