| Gansu golden trout is an important reared freshwater species, which has beencultured for more than thirty years in Gansu Province, China. Gansu golden trout is anew breed developed in Gansu, which had pass the National Aquaculture SpeciesIdentification Committee identifying and was recommend as the species reared in thenorthwestern areas.To study the effect of morphometric attributes on body weight of theGansu Rainbow Trout,morphometric measurement was taken from358samples.Theattributes used in this study include Total length, body length，body width,body depth，head length,eye interorbital distance and bodyweight.A correlation coefficient matrix wasconstructed,in which the body weight was used as the dependent variable and otherattributes as independent variables for path analysis.The path coefficients，determinationcoefficients,and correlation index were calculated,and major morphometric attributeswere determined.Single nucleotide polymorphisms（SNPs）in IGF-â… and IGF-â…¡geneswere identified and genotyped by polymerase chain reaction followed by single strandconformation polymorphism（PCR-SSCP）analysis and DNA sequencing in Gansu goldentrout from the farm of national grade Linxia Salmon trout aquafarm.Correlation analysisbetween polymorphism of the mutational site and growth as well body composition traitswas carried by the least square analysis.Main research results as follows:1.The path coefficients,determination coefficients,and correlation index werecalculated,and major morphometric attributes were determined.The results showed thatall the correlation coefficient between each independent variable and dependentvariable（body weight）were significantly different （P<0.01）.The trait with the strongestdirect effect on body weight was body depth（0.457），then the body width （0.326），bodydepth（0.140）and eye interorbital distance （0.096）.The high value of multiple correlationindex R2at0.893between morphometric attributes and body weight suggests that theselected attributes are practical.The multiple regression equation relating the body weightwas established as y=5.403X1+1.18X2+0.518X3+2.595X4-580.45,where y is bodyweight,X1,X2,X3,X4is body depth,body width, body length,eye interorbital distancerespectively. This paper provided theoretical evidence and perfect measure target for breeding of Gansu Rainbow Trout in aquaculture.2. There is insertion of a base A between IGF-I gene exon38â†'39bp in Gansu trouttest groups,SNP do not be found in the rest of exons and detected allele has been fixed inthe population.The number of AA genotype is102,AB genotype is165and BB genotypeis91in all of358individuals.Analyzing of the association between the differentgenotype and its corresponding growth traits,the result show that the site of differentgenotypes has significant differences on weight gain,body length and body high.Theweight gain, body length and body height of AA genotype is significantly higher than ABgenotype （P<0.01）;The body thick of the AB genotype compare with the BB genotypehas significant difference（P<0.05）,but with the AA genotype the difference is notsignificant.The eye spacing of different genotypes all have no significant difference.Analyzing of the correlation between the gene polymorphism and Gansu trout growthtraits showed that IGF-I gene is a major gene for growth traits of Gansu rainbow troutand a gene which affected its growth traits and link with QTL.3.There is a mutation of Câ†'G at the334bp in the GF-II gene exon2in Gansu goldentrout test groups and the mutation do not lead to amino acid changes.The number of DDgenotype is143, CD genotype is76and CC genotype is139in all of358individuals.Analyzing of the association between the different genotype and its correspondinggrowth traits, the result show that the weight gain, body length, body height and bodythickness of DD genotype was significantly higher than the CC genotype （P<0.05）.Inaddition,the body height of the DD genotype very high above the CD genotypeindividuals（P<0.01）.This locus polymorphism can be used as a genetic marker,Gansutrout growth rate is expected to increase by raising the frequency of favorable genotypeswithin the species, so as to achieve the goal of increasing production.This study indicate that multiple regression equation in which Gansu trout body height,body thickness, body length and eye distance were used as independent variables,multiple regression equation: y=5.403X1+1.18X2+0.518X3+2.595X4-580.45canbe applied early in the seed breeding work of Gansu golden trout. The polymorphisms（SNPs） of IGF-I and IGF-II gene has some relevance with the weight gain, high bodylength and body growth traits of Gansu golden trout, These two gene polymorphisms provide a theoretical basis for favorable genotypes of growth and body composition traitsof Gansu golden trout integrated breeding. |
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