| Attractin is an autosomal recessive gene and received great attention within the last few decades. Attractin in different lines has been identified attractin to have multiple roles in regulating physiological process. It affects the balance between agonist and antagonist at receptors on melanocytes, modifies behaviour and basal metabolic rate , intervenes developing the central nervous system and its function, and modulates an interaction between activated T cell and macrophages. The attractin gene encodes a protein that is involved in the suppression of diet-induced obesity, its expression level in the brain has a significant relationship with obesity, the role indicates the therapeutic potential of attractin in the treatment of obesity . Furthermore, the murine attractin locus is located in a region harboring several QTL for body weight and fatness. In this study, the polymorphism of attractin site was detected by using PCR-RFLP in a complex inbred pig family, xianghuang pigs and some native breeds. The results were summarized as below:1. The genetic variation of ATRN loci in pigs including CUP resource population (the founder boar and sow were of the Landrace and Yorkshire breeds), Xianghuang pig (the founder boar and sow were of the Duroc and pietrain ),Native breeds(Ningxiang pig, Shaziling pig and Daweizi pig) was detected by PCR-RFLP with Taql. The results showed as: The two exotic breeds including CUP resource population, Xianghuang pig were proved to be polymorphic at TaqI-RFLP site, getting three genotypes: AA, AB, BB. But the three native breeds including Daweizi pig, Ningxiang pig, Shaziling pig were presented only BB genotype and no variation at the TaqI-RFLP site. The x 2value of ATRN genotype distribution at the TaqI-RFLP site in different pigs indicated that ATRN genotype distribution between every exotic pig breed and every exotic pig breed between every native pig breed all had highly significant differences(P<0.01).The ATRN genotype distribution of three native pig breeds was the same completely.2. In a sex-averaged analysis in CUP resource population using CRI-MAP V2.4, ATRN was linked to one microsatellite marker (sw1031) on chromosome17, the recombination frequency and LOD scores is 0.21, 3.19, respectively. It provides an opportunity for further development of linkage maps.3. According the polymorphism of ATRN loci site in exotic pig breed, the genotype was analyzed with the phenotype of the slaughtered individuals. It showed as follow: In CUP resource population, the genotype of ATRN has no significant relation with average daily slaughter gain and slaughter weight, but was in significantrelation with back-fat depth(P<0.05), the BB genotypes was the best; In Xinaghuang pig the results was similar to the CUP resource population. So we can get the conclusion that the BB genotype in ATRN site of the exotic breeds was superior to others in back-fat depth.4. Generally, the native pig breed's back-fat depth is thicker than the exotic's. In this study there was only BB genotype in ATRN loci site of the native breeds, but the BB genotype individuals was the thinnest of back-fat depth in the exotic breeds, so it seems a self-contradict about ATRN. Possible reasons are: â‘ The numbers of sample were too small to detect the other genotypes â‘¡The primers have some limitations weren't enough to detect the polymorphism in the native breeds, if cloud discover three genotypes, the BB genotype of ATRN would be the thinnest of back-fat depth. â‘¢There are have many difference between native pig breeds and exotic pig breeds in nature, so couldn't compare directly.5. Using the primers were shown in this experiment only can get about 890bp ATRN PCR product, was not as 980bp as Edeal et al has reported. Through comparing the ATRN gene sequence was publicized by Genbank, we estimate that 890bp was supposed to right.6. In conclusion, the ATRN were proved to be polymorphic at the Taql-RFLP site in exotic breeds, the BB genotype has significant effect on back-...
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