Studies On Relationship Of Genetic Diversity Of IGF-1 Gene With Egg Trait And IGF-1 Gene Expression

In the reseach, we detected genetic variation of the 5' region of the IGF-1 gene in 250 New Yangzhou chickens and 43 White Leghorns by means of PCR-RFLP, analyzed the association of IGF-1 gene polymorphism with egg trait in New Yangzhou chicken and White Leghorn, and explored the approach that how IGF-1 gene polymorphism influented egg trait. Furthermore this study investigated the expression characterization of IGF-1 gene by RT-PCR. The main results are as follows:1. By means of PCR-RFLP, there were two SNPs of 5' region of IGF-1 gene had been found, one SNP of A-T was at PstI site, the other SNP of C-T was at HinfI site. In New Yangzhou chicken, Allele frequencies A, B, C, D were 0.3647, 0.6353, 0.5780, and 0.4220 respectively. In White Leghorn, Allele frequencies A, B, C, D were 0.2209, 0.7791, 0.7674, and 0.2326 respectively. By chi square test, New Yangzhou chickens were in Hardy-Weinberg equilibrium at PstI and HinfI site. White Leghorns were in Hardy-Weinberg equilibrium at HinfI site, but were not in Hardy-Weinberg equilibrium at PstI site.2. Genotypes of PstI site had significantly effect on traits at first egg (P<0.05). The results showed BB genotype had significantly higher egg weight at first egg than AB genotype in New Yangzhou chickens (P<0.05), BB genotype had significantly earlier age at first egg than AB genotype in White Leghorns (P<0.05), and BB genotype had significantly longer shank at first egg than AA and AB genotypes in White Leghorns (P<0.05). While Genotypes of HinfI site had no significantly effect on traits at first egg in New Yangzhou chicken and White Leghorn (P>0.05).3. At PstI site, in White Leghorns BB genotype had significantly (P<0.05) or extremely significantly (P<0.01) higher egg numbers at 29, 39, 49 weeks and egg production at 29, 39, 49, 59 weeks than AA and AB genotypes. In New Yangzhou chickens, BB and AB genotypes had significantly higher egg production at 40 weeks than AA genotype (P<0.05). Though these genotypes had no significant difference in egg numbers at 30, 40, 50, 60 weeks and egg production at 30, 50, 60 weeks(P>0.05), BB and AB genotypes tended to show higher egg numbers and egg production than AA genotype.At HinfI site, in New Yangzhou chickens CC genotype had significantly higher egg numbers and egg production at 50 weeks than CD genotype(P<0.05), and CC genotype tended to show higher egg numbers and egg production at 30, 40, 60 weeks than CD and DD genotype. White Leghorns had no significant difference in egg numbers and egg production in the genotypes.4. Genotypes of PstI site had significantly effect on egg quality(P<0.05). In New Yangzhou chickens, the results showed BB genotype had significantly (P<0.05) or extremely significantly (P<0.01) higher egg weight, albumen weight, yolk weight, shell weight, shell strength, shell thickness, shell colour than AA genotype. In White Leghorns, the results showed BB genotype had significantly higher albumen weight, shell weight, albumen ratio, egg shape index than AA or AB genotype(P<0.05), AB genotype had significantly higher haugh unit, shell strength, shell deformation than AA or BB genotype (P<0.05).Genotypes of HinfI site also had significantly effect on egg quality(P<0.05). In New Yangzhou chickens, the results showed CC genotype had significantly (P<0.05) or extremely significantly (P<0.01) higher egg weight, albumen weight, yolk weight, shell strength, yolk colour, egg shape index than DD or CD genotype, CD genotype had significantly higher shell strength at 60 weeks, haugh unit and albumen ratio at 40 weeks than DD genotype (P<0.05). In White Leghorns, the results showed CD genotype had significantly higher shell colour at 39 weeks, egg weight at 59 weeks, albumen weight at 59 weeks, yolk weight at 59 weeks than CC genotype (P<0.05).5. Genotypes of PstI site had no significant difference in serum IGF-1 concentration (P>0.05), but BB genotype tended to show higher serum IGF-1 concentration at 20, 40, 58 weeks than AA genotype, and the trendency of serum IGF-1 concentration between AA and BB genotypes was the same as the trendency of egg trait between AA and BB genotypes.6. RT-PCR analysis indicated that in cock of New Yangzhou chicken IGF-1 gene expressed in liver, testicle, pectoral muscle, crural muscle, lung, small intestine, heart, spleen, kidney, pituitary and muscular stomach, and in hen of New Yangzhou chicken IGF-1 gene expressed in liver, ovary, pectoral muscle, crural muscle, lung, small intestine, heart, spleen, kidney, pituitary and muscular stomach.