QTL Mapping for Weight Traits on Chromosome 3 in Liangshan Semi-fine Wool Sheep

By using Windows QTL Cartographer v2.5 software, QTLs for five weight traits of Liangshan semi-fine wool sheep were detected based on nine microsatellite markers on chromosome 3. According to the results, ① in reference family 191, the QTL affecting weaning weight was detected at 110.01 cM with an additive effect of 6.860, explaining 29.3% of the phenotypic variance; ② in reference family 190, the QTL affecting weaning daily gain was detected at 227.41 cM with an additive effect of 0.013, explaining 1.7% of the phenotypic variance; ③there was no QTL affect- ing birth weight, 1.5-year weight and 2.5-year weight of Liangshan semi-fine wool sheep.

Correlation and path analysis of morphological and weight traits in marine gastropod Glossaulax reiniana

Using correlation and path analysis, the genetic correlation between weight traits and morphological traits was determined in the marine gastropod Glossaulax reiniana. A total of 100 G. reiniana individuals from a wild population were used. Shell width （X1）, shell height （X2）, umbo-callus height （X3）, body width （X4）, operculum length （X5）, operculum width （X6）, body weight （Y1） and soft-tissue weight （Y2） were measured, and the correlation coefficient matrix calculated. Morphological traits were used as independent variables and weight traits as dependent variables for path coefficient analysis. Path coefficients, correlation indices and determination coefficients were also determined. Results indicate that the correlation coefficients associated with each morphological and weight trait were all highly significant （P〈0.01）. After deleting redundant independent variables, the following optimum multiple regression equations were obtained using stepwise multiple regression analysis： Y1=-29.317＋0.362X2＋0.349X4＋ 1.190）（5 for body weight; and Y2=-17.292＋0.166X1＋0.171X2＋0.703X5, for soft-tissue weight. Operculum height had the highest positive direct correlation with both body weight and soft-tissue weight, which was in accordance with the test results obtained from determinate coefficient analysis. The indication of high genetic correlations between weight traits and morphological traits will provide valuable information for G. reiniana breeding programs.

Detection of Quantitative Trait Loci Associated with Several Internal Organ Traits and Teat Number Trait in a Pig Population

Quantitative trait loci （QTL） were detected for 8 internal organ traits, 3 carcass length traits, and teat number trait in 214 pigs in a resource population that included 180 F2 individuals. A total of 39 microsatellite markers were examined on SSC4, SSC6, SSC7, SSC8, and SSC13. The genetic traits included heart weight （HW）, lung weight （LW）, liver and gallbladder weight （LGW）, spleen weight （SPW）, stomach weight （STW）, small intestine weight （S1W）, large intestine weight （LIW）, kidney weight （KW）, carcass length to the first cervical vertebra （CL1）, carcass length to the first thoracic vertebra （CL2）, rib numbers （RNS）, and teat numbers （TNS）. Results indicated that, 3 highly significant QTL （P≤0.01 at chromosome-wise level） for HW （at 30 cM on SSC6）, RNS （at 115 cM on SSC7）, TNS （at 110 cM on SSC7）, and 6 significant QTL （P≤0.05 at chromosome-wise level） for LW （at 119 cM on SSC13）, LGW （at 94 cM on SSC6）, SPW （at 106 cM on SSC8）, SIW （0 cM on SSC4）, LIW （170 cM on SSC 4）, and TNS （at 95 cM on SSC6） were detected. The phenotypic variances for which these QTL were accounted ranged from 0.04 % to 14.06 %. Most of these QTL had not been previously reported.