Further evidence for haploid gene expression during spermatogenesis: heterogeneous, poly(A)- containing RNA is synthesized post-meiotically.

Mouse testicular cells labelled in vivo with 3H-uridine for 1 hour were separated into enriched cell populations representing different stages of spermatogenesis by centrifugation in an Elutriator rotor. RNA extracted with phenol and chloroform was sized by electrophoresis on 2.4% acrylamide gels. The percentage of newly synthesized RNA which was not ribosomal RNA (or its precursors) and was not transfer RNA, was higher in early postmeiotic, as compared to late premeiotic, stages. RNA was also extracted from fractionated cells in the presence of guanidinium chloride and the proportion of total 3H-RNA-containing poly(A) sequences was determined by binding to an oligo-(dT)-cellulose column. RNA that bound in 0.5 NaCl was eluted with low salt buffer and reapplied twice more, after heating each time in DMSO to disaggregate any non-poly(A)-containing RNA. The percentage of newly synthesized RNA which contained poly(A) did not decrease in early postmeiotic, as compared to late premeiotic, stages. We suggest that at least some part of the 6-15S 3H-RNA and 3H-poly(A)-containing RNA represents mRNA(s) transcribed postmeiotically in haploid germ cells.