Polymorphism Identification Of VRTN And KTN1 Gene Transposon Insertion And Its Association With Production Performance

Transposable elements(TEs)are DNA sequences that can move within their original host cells and can be classified into RNA transposons(class ?,retrotransposons)and DNA transposons(class ?)according to their structUres and transposition mechanisms.Retransposons are the main components in the mammalian genome,which are transposed with RNA intermediates.Studies have shown that retrotransposons contribute greatly to the evolution,structure and function of mammalian protein-coding genes greatly.Short interspersed nuclear element(SINE)is an important kind of retrotransposon in mammalian genomes.The insertion of SINE in a protein-coding gene may affect its function.Therefore,this paper selected two protein encoding genes of VRTN and KTN1,explored the contribution of retrotransposon to its sequence and structural variation,explores whether SINE insertion has an effect on the growth and reproduction performance of pigs,and develops new valuable molecular markers of pig genome.The main results are as follows:1.The sequences of VRTN gene,KTN1 gene and their flanks form different breeds of pigs were obtained by BLAST.Then multiple sequence alignments were performed using the Clustralx program,and the transposon annotation was done by RepeatMasker.Three large structural variations were found in the VRTN gene,and the polymorphism of VRTN-sRTIP1,VRTN-sRTIP2 and VRTN-sRTIP3 were verified by PCR.In KTN1 gene,77 transposon fragments were found and mainly majority(98.70%)were SINEs.Nine small and four large structural variations were discovered,the four large structural variations inncluding two SINE insertion polymorphisms in 5th and 12th intron of KTN1,and one 206bp ERV insertion polymorphism in intron 1 and one 287bp LI insertion polymorphism in intron 16.The polymorphism of KTN1-intron5-SINE was identified by experiments.2.Insertion polymorphism detection of VRTN-sRTIP1 in the population indicated that the frequency of SINE+gene in western commercial pigs was higher than that of Chinese local pig breeds.VRTN-sRTIP2 and VRTN-sRTIP3 also showed insertion polymorphic in Bama,Tibetan,Meishan,Erhualian and Landrace.It showed low SINE+gene frequency in all detected breeds except for Meishan pig,.The frequency of SINE insertion in KTN1-intron5-SINE site was higher than no SINE insertion in Yorkshire and Landrace pigs,but shoed opposite phenomenon in Duroc,Sujiang and Bama.3.Production performance correlation analysis was performed with two SINE polymorphic insertion sites located in the VRTN gene and the KTN1 gene in Yorkshire or SuJiang pigs,respectively.The results showed that SINE insertion was significantly correlated with the 100 kg body weight and eye muscle area of Yorkshire,and negatively correlated among the SINE-VRTN molecular marker.Corrected back fat thickness,live litter size and total litter size were not significantly correlated with SINE insertion of VRTN gene.Among the KTN1-intron5-SINE molecular markers,SINE insertion was significantly and positively correlated with weaned litter of Sujiang,and showed no significant correlation with the number of live piglets,the number of weaned pigs and the birth weight.