Genetic Effect And Expression Characterization Of Candidate Genes Of Fatty Acid Binding Protein In Chicken

Fatty acid binding protein (FABP) is one of the important regulatory factors in the body's fat metabolism process. The basic function of FABP is involved in intracellular fatty acid intake, and to help fatty acids transport to the site of triglycerides and phospholipids synthesis as well as the place ofβ-oxidation.This study have scanned the single nucleotide polymorphisms (SNPs) in the Exons and part of intron of the A-FABP, H-FABP, Ex-FABP genes among Rugao chicken, Anka chicken, Wenchang Chicken, and analyzed their relationship with intramuscular fat content in breast; simultaneously detected the expression of different genotypes in the various organizations and the pyramiding genotype in abdominal fat tissue between A-FABP and Ex-FABP in Rugao chicken by quantitative Real-Time RT-PCR. The main results were as follows:1.PCR-SSCP method and DNA sequencing approach were used to identifying the single nucleotide polymorphisms (SNPs) of A-FABP,H-FABP,Ex-FABP genes in exons and part of intron among Rugao Cao chicken,Anka chicken, Wenchang Chicken, and a 1763 A/G mutation in Exon3 of A-FABP gene were found, which caused the alteration of the corresponging amino acid from Ser to Asn.Other mutations, including a 2980 A/G mutation of H-FABP gene, a 2913 A/G mutation in intron 1 of EX-FABP gene, mutations of 3654 C/T,3699 C/T,3700 A/G in intron 3, 4223 G/A and 4271 G/A mutations in Exon 4 of EX-FABP gene, were all silence mutations.2.Association analysis the SNPs with intramuscular fat content of breast muscle belonged to the different genotypes of A-FABP Exon 3 and Ex-FABP Exon 4 in 12 weeks Rugao chicken, showed that the intramuscular fat content of breast muscle was not significant between different sex,while the IMF content of hen was higher than that of cock. In three genotypes of A-FABP gene ,IMF content of the AA and AB genotype was significantly higher than the BB genotype (P <0.05), so the AA genotype was the dominant type with the highest IMF content. Likewise, in three genotypes of Ex-FABP gene, the IMF content of the BB genotype, which was the dominant genotype, was significantly higher than that of the AA type and AB type, and there was no significant difference between the AA and AB genotype. After merging the dominant genotype AA of A-FABP and the dominant genotype BB of Ex-FABP,we found the AABB was still the best genotype. In conclusion, it can be preliminary inferred that A-FABP gene and Ex-FABP gene were effect markers on IMF content.3. The expression of A-FABP gene of different tissues was high in 4 weeks old, then decline in 6 weeks old, but rebound after 10 weeks old, and remains to decline in 12 weeks old. There was significant difference between the mRNA expressions of different A-FABP genotypes in various organizations. The Expression of AA genotype was the highest in abdominal fat and breast muscle,which was significantly different from that of BB type; Besides, the expression of the AB genotype is the highest in heart and liver, which was significant different from that of BB genotype.4.The expression of Ex-FABP gene was high in early stage before 4 weeks old, then decline after 4 weeks old, but rebound after 10-12 weeks old. There was no difference in various organizations, but the highest was in hearts. The Ex-FABP mRNA expression levels analyzed by Q-PCR technique revealed that there was no significant difference between different genotypes in various organizations.5.We had further inspected the Expression of the pyramiding genotypes between A-FABP and Ex-FABP in the abdominal fat tissue at 4, 8, and 12 weeks old, showing that the epression of pyramiding genotype of the A-FABP decreased at different times, while the expression of the Ex-FABP pyramiding genotype also decreased at different times. In the pyramiding genotypes of both genes, the expression level of AABB was the highest, BBAB was the lowest, that is consistent with the differences in intramuscular fat content of the pyramiding genotypes. These results indicated that pyramiding genotypes could be used as one of candidate markers on IMF content.