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Mouse sperm motility affected by factors in the T/t complex
Abstract:
Motility characteristics of epididymal sperm from tw32/+ and T/+ males of several strains were compared to those of sperm from the congenic, wild, type mice. Epididymal sperm from C57BL/6-tw32/+ (B6-tw32/+) males showed a significant decline in vigorous motility and a significant increase in adhesivity to glass during 7.5 hours in vitro, while sperm from B6-+/+ males showed no changes in these characteristics. The apparent mean velocities of epididymal sperm were: B6tw32/+, 32 micro/sec; C3H-tw32/+, 60; B6XC3H hybrids (F2*-tw32/+), 44; and C3HXB6 hybrids (F2-tw32/+), 58. Each of these values was significantly lower than that of sperm from their congenic wild-type strains: B6- +/+, 115; C3H- +/+, 177; F1*-+/+, 168 and F1-+/+, 195 micro/sec. B6-T2J/+ sperm had velocities intermediate to the congenic +/+ and tw32/+ genotypes, whereas C3HT/+ sperm velocity was not significantly different from C3H- +/+. These differences in measured sperm velocity may not reflect real differences in swimming speed, but rather may indicate a difference in the shape of swimming trajectories. Erratic and convoluted swimming trajectories were observed for the majority of sperm from tw32/+ males of all genotypes. Differences in motility patterns of sperm from tw32/+ males could play a role in the abnormally high transmission of tw32 through the male.
Insights
Sperm from tw32/+ mice exhibit reduced motility and increased glass adhesivity compared to wild-type. These motility differences, including erratic trajectories, may explain the high transmission of tw32 in males.
Area of Science:
- Reproductive biology
- Genetics
- Sperm motility analysis
Background:
- The transmission ratio distortion (TRD) of certain genetic elements, like tw32, can be influenced by male reproductive factors.
- Understanding sperm function is crucial for investigating mechanisms of TRD.
Purpose of the Study:
- To compare the motility characteristics of epididymal sperm from tw32/+ and T/+ male mice with their respective wild-type congenic strains.
- To investigate potential correlations between altered sperm motility and the high male transmission of the tw32 genetic element.
Main Methods:
- Comparative analysis of epididymal sperm motility and velocity in various mouse genotypes (tw32/+ and T/+ vs. wild-type).
- In vitro assessment of sperm motility, adhesivity to glass, and swimming trajectory patterns over 7.5 hours.
- Measurement of apparent mean sperm velocities using microscopy.
Main Results:
- Sperm from B6-tw32/+ males showed significantly decreased vigorous motility and increased glass adhesivity compared to B6-+/+ controls.
- Apparent mean velocities of epididymal sperm from tw32/+ males were significantly lower across all tested strains compared to wild-type congenic counterparts.
- Erratic and convoluted swimming trajectories were prevalent in sperm from tw32/+ males, suggesting altered motility patterns.
Conclusions:
- Motility defects, including reduced velocity and abnormal trajectories, are associated with the tw32/+ genotype in mice.
- These observed sperm motility differences may contribute to the high male-biased transmission of the tw32 genetic element.