Regulation of foreign DNA uptake by mouse spermatozoa

We have studied some features of DNA uptake in both mature and immature mam malian spermatozoa. Mature sperm collected from the cauda epididymis are ab le to incorporate foreign DNA in a buffer containing only salts and calcium . Immature spermatozoa, however, are unable to bind DNA. This seems to be c aused by the lack of a functional receptor in the sperm membrane since once this membrane is disrupted by sonication, DNA can be detected in the posta crosome region of the sperm nucleus, matching the distribution of the matur e spermatozoa. Comparison between the DNA binding proteins of mature and im mature spermatozoa allowed us to identify two bands that could be part of t he putative membrane receptor for the DNA. On the other hand, DNA uptake in mature sperm is prevented by the seminal plasma. We have identified two co mponents of the seminal plasma, a calcium-dependent DNase present in the se minal vesicle fluid and several DNA binding proteins secreted by the ventra l prostate, that could account for the inhibitory activity. Taken as a whol e, our results indicate that DNA uptake by the mammalian spermatozoa is a v ery specific and highly regulated phenomenon, (C) 2001 Academic Press.