Research Of Genes Related To Body Weight And Mink Length Of Mink And The Genetic Analysis Of Molecules Causing The Mink Self-Biting Behaviour

Mink is small precious fur-bearing animal,and the furs of mink, fox, and persian lamb are already the three key products in the international fur market. Now the mink industry is facing good development opportunity and prospect, so improving the growth performance of mink will bring more economic benefits to the mink industry. The minks bred in Daxinganling base were chosen as our research object, the SNPs in the coding regions of the IGF-â… , GH, EGF, and MSTN genes were studied by cloning and sequencing combined with PCR-SSCP technique, finally, the correlation between polymorphism caused by mutation sites and body weight, Mink length was analyzed. This study made foundation of marker assisted selection using marker genes related growth performance, and provided way to breed mink, improve growth rate, fur quality of mink at molecular level.Meanwhile, healthy minks(30)and those of self-biting behaviour bred(30)in Jinzhou mink base in Dalian were chosen as our research object. RAPD technique combined with SCAR was used to make analysis of genetic structure of these minks at molecular level. The RAPD markers with significant differences were cloned and sequenced, and then SCAR technique was used to amplify the markers in all the samples as to identify whether the mink was healthy or had self-biting behaviour by the appearance of marker fragments. This study made foundation of breeding for disease resistance and immunity. If combining with traditional breeding technique, it will improve mink breeding, enhance economic benefits of mink industry, and impel the development of cultivation of economic animals. The main results of this study were as follows:(1)The partial cDNA of mink GH gene was cloned successfully, and 1060bp fragment was got. There were three mutation sites in this fragment (located at 269, 538, 539, repectively).(2)Both the fragments amplified by two pairs of primers showed polymorphism. The fragments amplified by primer GH1 was detected by PCR-SSCP, and three genetypes were found (named AA, BB, AB). The body weight and Mink length of BB genetypes were significantly greater than those of AA and AB genetypes, so it was preliminarily considered that B gene was good for the growth of mink. The fragments amplified by primer GH2 was detected by PCR-SSCP, and three genetypes were found (named CC, CD, DD), but there were no significant difference among these genetypes in body weight and Mink length (P>0.05). (3)In the three pairs of primers designed for IGF-â… , two fragments amplified by two pairs of primers showed polymorphism. The fragments amplified by primer IGF-â… ₁ was detected by PCR-SSCP, and two genetypes were found (named AA, AB). The allele A frequency was significantly higher than that of allele B. But the statistical results showed that the body weight and Mink length of AB genetypes were significantly greater than those of AA genetypes (P<0.01), so it was preliminarily considered that allele B was superior. The fragments amplified by primer IGF-â… ₂ was detected by PCR-SSCP, and three genetypes were found (named CC, CD, DD), but there were no significant differences among these genetypes in body weight and Mink length (P>0.05). There was no polymorphism in the fragments amplified by primer IGF-â… ₃.(4)The partial exon sequence of mink EGF gene was cloned successfully, and 1002bp fragment was got. The homologies of EGF gene among mink, mouse, rat, rhesus monkey and human was 94%, 83%, 79% and 78%, respectively. There were three mutation sites in this fragment (located at 45, 196, 498, repectively). The primers designed at two ends of the mutation sites, and the fragments amplified by two pairs of primers showed polymorphism. The fragments amplified by primer EGF1 was detected by PCR-SSCP, and three genetypes were found (named AA, AB, BB). The allele B frequency was significantly higher than that of allele A. The statistical results showed that the body weight and Mink length of BB genetypes were significantly greater than those of AA genetypes (P<0.05),and the body weight of AB genetypes was significantly greater than that of AA genetypes (P<0.05), but there were no significant differences among these genetypes in body Mink length(P>0.05).So it was preliminarily considered that allele B was superior. The fragments amplified by primer EGF2 was detected by PCR-SSCP, and three genetypes were found (named CC, CD, DD). There were no significant differences among these genetypes in body weight (P>0.05). The Mink length of CD genetypes was significantly greater than that of CC genetypes (P<0.05), but there was no significant difference with DD genetypes (P>0.05). There was no polymorphism in the fragments amplified by primer EGF3.(5)The exon sequence of mink MSTN gene was cloned successfully, and 1128bp fragment was got. The homologies among mink MSTN, dog MSTN, fox MSTN, mouse MSTN, wild pig MSTN, bovine MSTN and human MSTN was 94%, 93%, 85%, 94%, 86% and 93%, respectively. There were four mutation sites in this fragment (located at 186, 380, 616, 648, repectively). The primers designed at two ends of the mutation sites, and the fragments amplified by all three pairs of primers showed polymorphism .The fragments amplified by primer MSTN1 was detected by PCR-SSCP, and three genetypes were found (named AA, AB, BB). The allele A frequency was significantly higher than that of allele B. The statistical results showed that the body weight and Mink length of BB genetypes were significantly greater than those of AA genetypes (P<0.05), and the body weight of AB genetypes was significantly greater than that of AA genetypes (P<0.05), but there was no significant difference in body weight between AB and BB genetypes(P>0.05), and there was also no significant difference in Mink length of AB genetypes with AA and BB genetypes. So it was preliminarily considered that allele B was superior.The fragments amplified by primer MSTN₂ was detected by PCR-SSCP, and two genetypes were found (named CC, DD). The allele C frequency was significantly higher than that of allele D. The statistical results showed that the body weight and Mink length of CD genetypes were significantly greater than those of CC genetypes (P<0.05), and it was preliminarily considered that D gene was superior.The fragments amplified by primer MSTN3 was detected by PCR-SSCP, and three genetypes were found (named EE, EF, FF). The allele E frequency was significantly higher than that of allele F. The statistical results showed that the body weight and Mink length of FF genetypes were significantly greater than those of EE genetypes (P<0.05), and it was preliminarily considered that F gene was superior. The statistic influences of genotypic combination among these genes to the body weight andMink length of minks showed that the genotypic combination among four genetypes had significant influence trend to the body weight and Mink length(P<0.05).(6)RAPD and SCAR techniques were used to made genetic analysis to the cause of self-biting behaviour, and among 100 random primers, 26 stable primers amplifying clear PCR product were selected. The fragments amplified by 18 primers showed polymorphism, and the percentage of polymorphism was 26.67%. 26 random primers were used to amplify three times under the same condition in both healthy and sick minks. The amplifying results showed that the repeatability of 11 primers was good enough, and the polymorphism was clear (S103,S112,S120,S139,S144, S167,S176,S178,S356,S358,S360, repeatability). The fragments amplified by primer S103 and S356 had obvious generality and difference, and different marker fragments were recycled, cloned, and sequenced, and finally the sequences of the marker fragment were got. The marker fragments were analyzed, and four pairs of primers were designed, so the RAPD marker was transformed into SCAR marker to detect in both healthy and sick groups. The results showed that the cause of self-biting behaviour had direct reason with the genetic genes, and RAPD marker combined with SCAR marker could identify the healthy and sick minks well.