Studies On The Myofiber Characters And Conformation Polymorphism Of Myogenin In Chicken

The histology characteristics of muscle affect meat quality remarkably, which is an important index for evaluating meat quality, most studies indicated that the histology characteristics of muscle has definitely pertinence with the meat quality,especially diameter of muscle fiber and density of muscle fiber. The myofiber characters are quantity traits,which are controlled by some genes. In development of myofiber, the proliferation and differentiation of muscle cell is controlled by some native and negative regulations. Myogenin is a native regulation, it should be the candidate gene for myofiber characters.In this study, samples were selected from F-2 chickens derived from GUSHI chick to ANKA chick,the histology characteristics of muscle was measured with paraffin section;the second intron of myogenin was cloned,and the mutation in part coding region of myogenin was detected with PCR-SSCP. The results were as follows:1,The analysis of phenotypic values indicated that the measured traits on myofiber performance were segregating well in F₂ individuals. Most coefficients of variability were above 10%,and C.V. of thigh were more than C.V. of breast. About absolute value of Skewness coefficient and Kurtosis coefficient,some were more than 1, another were less than l,so the traits were demonstrated as fit as to normal distribution, but some were of skewed distribution. Thus they were quantitative characters controlled by many genes with small and large efects.2,Correlation Analysis among the characters of Muscle fiber indicated that There was an extremely significant negative correlation between the cross section area of muscle fiber,the length diameter,diameter of major axis and minor axis,circumference,and density of muscle fiber,Correlative coefficient is -0.797,-0.756,-0.780,-0.704 individually for breast muscle;Correlation coefficient is -0.740,-0.739,-0.762,-0.712 individually for thigh muscle. There was an extremely significant native correlation between muscle fiber cross section area and carcass characters (except Slaughter ratio) , a significant negative correlation between muscle fiber cross section area and shear force, a significant native correlation between muscle fiber cross section area and shear force in breast muscle. There was an extremely significant native or significant native correlation between muscle fiber cross section area and carcass characters,an extremely significant negative correlation between muscle fiber cross section area and the percents of water-lossing,a significant native correlation between muscle fiber cross section area and shear force in thigh muscle. There was an extremely significant native or a significant native correlation between density of muscle fiber and carcass characters in breast or thigh muscle individually;There were no significant native correlation between density of muscle fiber and shear force in both parts,There was a significant negative correlation between density of muscle fiber and shear force in both parts.3, Part,mating model and sex had effect on performances of the myofiber characters,about interactions among factors,diameter of fresh muscle fibre was influenced by part and sex significantly,area ratio of myofiber was influenced by mating model and sex extremely significantly;interactions among three factors had an effect on each character.4,The 2nd intron of chicken myogenin was cloned and found that it's splicing sites follow the consensus(5'AG/N, 3'N/GT),The sequence which has 452bp? was submitted to GENEBANK(EF031036).5,The mutation was found in the first exon, and have a significant association with myofiber characters. the association analysis on PCR-SSCP genetypes related with G102A polymorphism and myofiber characters shows,there was a significant association between genetype and cross section area,diameter or circumference,and BB genetype was significant more than that of AA genetype;density of muscle fiber of AA genetype was extremely significant more than that of BB genetype;the ratio of thigh muscle between major axis and minor axis has a significant difference among three genetypes. diameter of fresh muscle fibre of thigh muscle between major axis and minor axis has an extremely significant difference among three genetypes. All above demonstrated that myogenin had an important role on myofiber development.6,The association analysis on genetype and carcass characters or meat characters shows,there was a significant association or an extremely significant association between genetype and semi-eviscerated weight,eviscerated weight,eviscerated percentage,live weight aged 12 weeks,breast meat weight,breast meat percentage,thigh meat weight or thigh meat percentage. there was no significant association or an extremely significant association between genetype and other carcass characters,the percents of water-lossing or shear force.all above demonstrated that myogenin had effect on part carcass characters,but has no effect on meat characters.