International Mammalian Genome Society

The 13th International Mouse Genome Conference
October 31-November 3, 1999

Table of Contents * Structure * Bioinformatics * Sequence * Mapping * New Tools * Gene Discovery * Developmental * Mutagenesis * Functional Genomics

G23 Genetic Analysis of Sperm Aneuploidy and Sperm-Head Morphology in Mice

April Pyle and Mary Ann Handel. Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN

Various strains of mice can be used as model systems to study abnormalities in sperm. In this study, we evaluated the incidence of abnormal sperm-head morphology and frequency of aneuploidy in PL/J mice, which have previously been shown to produce a high frequency of abnormal sperm. We documented a mean of 33% of sperm from PL/J males having morphologically abnormal sperm-head shapes, compared to a mean of 0.95% for C57BL/6J control males. Sperm-head shape abnormalities include no head, microhead, and round head. Since the sperm head is comprised primarily of DNA, we hypothesized that the high incidence of abnormal sperm head shape might reflect an increased level of sperm aneuploidy. We used sperm FISH (fluorescence in situ hybridization) with probes for chromosomes 8, X and Y to determine frequency of aneuploidy. This analysis documented an increased hyperhaploidy frequency for these chromosomes among sperm from PL/J males (3.4 +/- 0.80%) compared to that from C57BL/6J controls (0.4 +/- 0.2%). To determine if the traits of abnormal sperm-head shape and increased frequency of sperm aneuploidy co-segregate and are inherited in a recessive or dominant manner, we have initiated a backcross analysis. The F1 males from crosses of PL/J and C57BL/6J mice do not exhibit a marked increase in either abnormal sperm production or aneuploidy compared to the C57BL/6J controls, and there is no difference among the F1 males produced from reciprocal crosses, thereby ruling out a paternal or maternal effect. These observations suggest that both abnormal sperm-head morphology and sperm aneuploidy are recessive and/or multigenic. Further backcross analyses and studies of the meiotic spindle in dividing spermatocytes can provide insight into the genetic and cellular nature of the sperm head abnormalities found in PL/J mice.


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