Study On The Polymorphisms Of 7 CNVRs And The Relationships With The Growth And Reproduction Of Xiang Pig

In this article, copy number variations(CNVs) in whole genome was detected based on the genotyping data by Illumina Porcine SNP 60 k chip taking120 pigs of Kele and Xiang pig breeds. The present paper was aimed to investigate the polymorphisms of CNVs in different pig breeds and the influence of related properties such as growth and reproduction of Xiang pig, taking four pig breeds as control, including Yorkshire, Kele, Nuogu and Rongchang pig breeds.The main results of this study included:1. According to the Porcine SNP60 chip genotyping results, we had predicted 633 CNVs, which were combined into 213 CNVRs. Seven candidate CNVRs, 37, 60, 79, 91, 92, 143 and 187 were chosen to be further investigated to prove the present in pig population because they distributed with different frequencies of copys between Xiang pig with large and small litter sizes.2. The polymorphisms of seven CNVs were determined by quantitative real time PCR(q PCR) method in five pig breeds. The results showed that the dominant status of CNVR37 were loss and gain in Xiang pig, loss and normal in Nuogu and Rongchang pigs, while it was normal in Yorkshire and Kele pigs. The major type of CNVR37 was deletion in Xiang pig with large litter size, while it was increase in population with small litter size. For CNVR60, the dominant event was normal in five pig breeds, but there did present some samples from Xiang pig with loss or gain event, and the ratio in the two groups of Xiang pig was different.These two CNVs were not related with body measurement and litter size of Xiang pig.3. The major type of CNVR79 was loss in Xiang pig, loss and normal types were about equally in Yorkshire, but it was not diverse in other three pig breeds.There were three CNV types in Xiang pig with large litter size, while dominant one was loss in Xiang pig with small litter size. The association analysis indicated that the copy number variation of Xiang pig individuals was associated with the body length, bust, the first, second and third litter sizes. Therefore, the CNVR79 might have effects on the growth and reproduction traits of Xiang pig.4. The dominant status of CNVR91 was loss in Xiang pig, while it was not diverse in other four pig breeds. For CNVR92, it was dominantly normal in Nuogu pig, but it was loss in other four pig breeds. The correlation analysis showed that the copy number of CNVR91 in Xiang pig was slightly correlated with the body width, bust, first and third litter sizes, and the CNVR92 was slightly correlated with the body width and bust. Thus, these two CNVs were seem to have effects on the growth of Xiang pig and the CNVR91 might also influence the fecundity of Xiang pig.5.The detection for CNVR143 indicated that main statue of copy number in Xiang and Nuogu pigs were gain, while it was not diverse in other three pig breeds. The dominant status of CNVR187 was loss in Xiang pig, but it was gain in Kele pig, while it was normal in other three pig breeds. The correlation analysis showed that the copy number of CNVR187 in Xiang pig was slightly correlated with the second litter size, so it might have effects on fecundity of Xiang pig.6. To test the relationship between CNV polymorphism and the expression of MTF-1 and INPP5 B genes in testicular tissue of Xiang pig, the copy number of CNVR79 was first determined in male Xiang pig in the same months old. The result displayed that the copy number of CNVR79 was dominant with normal type in male Xiang pig which was much different from that of female Xiang pig. The results for m RNA level detection of MTF-1 and INPP5 B genes suggested that the copy number of CNVR79 might have no effects on the gene expression in testis of Xiang pig in 2 month old.To sum up, these results indicated that the seven candidate CNVs not only emerged with polymorphism among five pig breeds but also within Xiang pig breed and a part of CNVs might have effects on the growth and reproduction ofXiang pig. Although the m RNA expression of MTF-1 and INPP5 B genes in two month old testicular tissue of Xiang pig had no connection with the copy number variation, it was worthy of futher exploration to compare the expression pattern in other tissues on different years old of Xiang pig. This paper provided the foundation for the regulatory mechanism of growth and fecundity in Xiang pig.