Lr. Johnson et al., SPERM FROM MICE CARRYING ONE OR 2 T-HAPLOTYPES ARE DEFICIENT IN INVESTMENT AND OOCYTE PENETRATION, Developmental biology, 168(1), 1995, pp. 138-149
The t haplotypes, mutant forms of the proximal third of mouse chromoso
me 17 (the t complex), contain factors that contribute to defective sp
erm function in fertilization. Males carrying two t haplotypes (t(x)/t
(y) mice) are sterile; their sperm have very poor motility and are una
ble to penetrate zona-free eggs. Although males carrying one t haploty
pe (t/+) are fertile, genetic evidence suggests that the sperm carryin
g the normal form of chromosome 17 (+(t)) are dysfunctional in fertili
zation, and some or all sperm have abnormal motility. Some of the same
genetic factors that cause sterility in t(x)/t(y) males probably cont
ribute to the dysfunction of +(t) sperm from t/+ males; however, it is
unclear which steps in gamete interaction are defective in sperm from
t/+ males, or whether the defects are similar to those observed in sp
erm from t(x)/t(y) males. We have developed a unique low sperm:egg rat
io IVF assay for sperm function in fertilization. Using this assay, we
have shown that t(w5)/+ Sperm are less able than congenic +/+ sperm t
o penetrate the zona (probably due to their abnormal motility) and to
penetrate the zona-free oocyte. Since t(w5)/t(w32) sperm are unable to
complete these same two steps in sperm-egg interaction, these specifi
c deficits could be involved in both transmission ratio distortion and
sterility. we have also shown that t(w5)/t(w32) Sperm are deficient i
n their ability to bind to the zona and to the oolemma. These results
suggest that t haplotypes contain loci which affect a number of sperm
functions and thus could be a rich source of genes important for sperm
-egg interaction. (C) 1995 Academic Press, Inc.