RNA in the ejaculate spermatozoon: a window into molecular events in spermatogenesis and a record of the unusual requirements of haploid gene expression and post-meiotic equilibration

Abstract

Several reports demonstrating the presence of messenger RNAs for sperm-specific nucleoproteins, the protamines PRM-1, PRM-2, and the transition protein TP-1 as well as beta-actin, c-MYC, HLA1, and beta 1 integrin have challenged the accepted view of the transcriptional dormance of terminally differentiated spermatozoa. Whatever nuclear activity the ejaculate spermatozoon may possess, these data suggest that spermatozoa are a repository of information regarding meiotic and post-meiotic gene expression in the human and are likely to contain transcripts for many homologues of genes identified from animal models, which play an essential role in spermiogenesis. The use of ejaculate spermatozoa as a wholly non-invasive biopsy of the spermatid should now be evaluated. At the same time, spermatozoal RNAs require further analysis and characterization. One explanation for their persistence in ejaculate spermatozoa is that they serve to equilibrate imbalances in spermatozoal phenotypes brought about by melotic recombination and segregation. Transcript exchange is likely considering the presence of inter-cellular cytoplasmic bridges between haploid spermatids, which also offers a route for the translocation and expansion of non-mendelian trials linked to retrotransposon activity.

Paternal influence on the time of first embryonic cleavage post insemination and the implications for subsequent bovine embryo development in vitro and fertility in vivo

“…As pointed out by Watson (2000), it is possible that the sperm of some bulls may be more susceptible to damage by cryopreservation. Indeed, if one accepts the suggestion that the contribution of the sperm to the zygote is more than merely the haploid male genome (Navara et al, 1995) then the post-syngamy fate of other sperm structures becomes very important (Sutovsky et al, 1996) and the possible importance of sperm RNA (Miller, 1997) to the events before embryonic genome activation can not be dismissed. In humans, evidence for a paternal in¯uence on embryo development comes from the studies of Urman et al (2000) using ejaculated, epididymal, or testicular spermatozoa.…”

Novel transcripts of carbonic anhydrase II in mouse and human testis

“…Temporal specific expression of many genes during spermatogenesis is accomplished by transcriptional and translational regulation (Penttila et al, 1995;Schafer et al, 1995;Kleene, 1996;Miller, 1997;Sassone-Corsi, 1997;Eddy and O'Brien, 1998). We have studied the expression of several genes during chicken spermatogenesis that utilize alternative promoters to 'TATA box' in meiotic and post-meiotic cells.…”

Adenylyl cyclase isoforms in rat testis and spermatozoa from the cauda epididymidis

“…Although spermatozoa are considered to be terminally differentiated and transcriptionally inactive, the detection of RNA transcripts in these cells is well established (Miller 1997). That tmAC III is one of five tmAC enzymes translated into protein (Fig.…”