Genetic architecture of testis and seminal vesicle weights in mice

Comparisons across 13 inbred strains of laboratory mice for reproductive or gan (paired seminal vesicles and paired testes) weights indicated a very ma rked contrast between the C57BL/6By and NZB/BINJ mice. Subsequently these s trains were selected to perform a quantitative genetic analysis and full ge nome scan for seminal vesicle and testis weights. Al Fg population was gene rated. The quantitative genetic analyses indicated that each was linked to several genes. Sixty-six short sequences for length polymorphism were used as markers in the wide genome scan strategy. For weight of paired testes, h eritability was 82.3% of the total variance and five QTL contributed to 72. 8% of the total variance. Three reached a highly significant threshold (>4. 5) and were mapped on chromosome X (LOD score 9.11), chromosome 4 (LOD scor e 5.96), chromosome 10 (LOD score 5.81); two QTL were suggested: chromosome 13 (LOD score 3.10) and chromosome 18 (LOD score 2.80). Heritability for w eight of seminal vesicles was 50.7%. One QTL was mapped on chromosome 4 (LO D score 9.21) and contributed to 24.2% of the total variance. The distance of this QTL to the centromere encompassed the distance of the QTL linked wi th testicular weight on chromosome 4, suggesting common genetic mechanisms as expected from col relations in the F-2. Both testis and seminal vesicle weights were associated with a reduction in the NZB/BINJ when this strain c arried the y(NPAR) from CBA/H whereas the Y-NPAR from NZB/BINJ in the CBA/H strain did not modify reproductive organ weights, indicating that the Y-NP AR interacts with the non-Y-NPAR genes. The effects generated by this chrom osomal region were significant but small in size.