| Energy metabolism is one of the basic characteristics of life,closely related to the growth of the body,regulating the growth condition of the body.Growth as an important economic characters of fish fanning,is also one of the important indices for evaluating breeding level and economic benefit.However,with the continuous expansion of tilapia breeding scale,the phenomenon of inbreeding and Germplasm degradation is more and more serious,and the loss of fast and long excellent characters is also increasingly exposed.Breeding and improving new varieties of tilapia with excellent long birth traits have already become the direction of breeding industry.For the generation of the new species of tilapia,the traditional breeding methods have the disadvantages of long breeding cycle and poor genetic stability of excellent characters.With the help of DNA marker technology and traditional breeding methods,we can not only shorten breeding cycle,increase selection intensity,facilitate directional breeding,but also make heredity of good characters obtain stability.In this study,the PFK gene,LPL gene,MC4R gene,GHSR gene,GHSR gene and GLUT4 gene which related to the energy metabolism of Nile tilapia were selected as candidate genes.According to the DNA full sequence of the 5 genes published in the Gen Bank database,19 pairs of primers were designed and synthesized.PCR-SSCP technique was used to detect and sequence the single nucleotide polymorphisms of the amplified products,and 31 of the SNP loci were obtained.The different bands(genotypes)on the electrophoresis atlas were expressed in letters a to f,respectively,and the correlation analysis of the polymorphism sites with the growth index of tilapia(body weight,body length,head length,body width and body height)was carried out by single factor variance analysis(one-way ANOVA)in SPSS21.0..The results of this study are as follows:1.Among the 5 pairs of primers designed for PFK gene of Nile tilapia,13 SNP loci were detected in the primer amplification sequence(PFK-3,4,6,8),which were 1118A?G?1178T?C?1398T?C?1613T?C?1622C?T?1793A?G?1804G?A?1816T?C?1903A?G?2446T-C?2602A?C?2641A?G?3601T?G,and one SNP loci were in Hardy-Weinberg equilibrium state(P>0.05),two in Hardy-Weinberg Unbalanced state(P<0.05),ten SNP loci were in Hardy-Weinberg equilibrium(P<0.01).2.Among the 3 pairs of primers designed for LPL gene of Nile tilapia,9 SNP loci were detected in the primer amplification sequence(LPL-2,4,5),which were 526G?T?707C?824A?G?841T?G?1562C?T?2067G?C?2098A?T?2333G?A?2335T?A.The loci were found at the site of 526G?T in Hardy-Weinberg Unbalanced state(P<0.05),707C?T?1562C?T?2335T?A in Hardy-Weinberg equilibrium(P<0.01).3.Among the 2 pairs of primers designed for MC4R gene of Nile tilapia,5 SNP loci were detected in the primer amplification sequence(MC4R-1,2),which were 291A?T?348T?C?366C?T?424T?C?810G?A,respectively.The results showed that the locus348T?C?366C?T was in Hardy-Weinberg Very unbalanced state(P<0.01).4.Among the 3 pairs of primers designed for GHSR gene of Nile tilapia,2 SNP loci were detected in the primer amplification sequence(GHSR-2,3),that is,1076C?T and 1238A?G,the site balance test showed that the site 1076C?T was in the Hardy-Weinberg unbalanced state(P<0.01).5.Among the 6 pairs of primers designed for GLUT4 gene of Nile tilapia,2 SNP loci were detected in the primer amplification sequence(GLUT4-4),which were187A?G and 1360T?C respectively,the site balance test showed that the site 187A?G was in Hardy-Weinberg unbalanced state(P<0.01).There were allele loss danger.6.The analysis of the PFK gene SNP loci of Nile tilapia found that 4 growth indexes of body length,head length,body width and body height of TT female individuals at 1622bp were higher than those of CC female individuals(P<0.05),and the head length and body width of GG female individuals at 2641bp were higher than those of the AA female individuals(P<0.05).Therefore,it is concluded that type TT and GG may be the dominant genotype of female growth,while CC and AA may be at a disadvantage.7.The SNP loci of LPL gene of Nile tilapia showed that the weight of GG females was greater than that of TG type females(P<0.05)at 526bp.The 5 growth indexes of CT female individuals at 707bp were higher than those of type CC female individuals(P<0.01),and the body weight of TT female was greater than that of CC female individuals(P<0.05),and the body weight of CT female was greater than that of the TT female individual(P<0.05).Therefore,it is concluded that GG,CT and TT may be the dominant genes for female growth,and the superiority of CT is higher than that of TT.8.The analysis of SNP loci of GLUT4 gene of Nile tilapia found that 4 growth indexes of body weight,body length,body width and body height of TT female individuals at 1360bp were higher than those of CT female individuals(P<0.05).Therefore,it is concluded that TT may be the dominant gene for female growth.9.The SNP analysis of 2 genes of MC4R and GHSR in Nile tilapia found that there was no significant correlation between all the growth traits of the 2 genotypes(P>0.05). |
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