Fig. 1. MSY4 gain-of-function transgenes. (A) The upper construct contains the Prm1 5' and 3' UTRs, and a cDNA encoding an HA-tagged version of MSY4. This construct, PMP, is under Prm1-like translational control. The lower construct, PMH, is a variant of the upper transgene and substitutes the hGH 3' UTR for the Prm1 3' UTR. Both constructs are under the control of the Prm1 promoter. (B) Schematic representation of endogenous and transgenic expression of MSY4. The curve labeled MSY4 represents expression of endogenous MSY4 in pachytene spermatocytes and round spermatids. The curve labeled PMH represents transgenic MSY4 expression from the PMH transgene, initiating in round spermatids and continuing in later stage spermatids. The curve labeled PMP represents transgenic MSY4 expression from the PMP transgene initiating in elongated spermatids. Repression and activation of the endogenous Prm1 message during spermatogenesis is represented by the labeled gray boxes. (C) Northern blot analysis of RNA from transgenic PMH founder males and males derived from both the PMH and PMP transgenic lines. Both the endogenous Msy4 mRNA (upper arrow) and the transgenic mRNAs (lower arrows) were detected with a probe prepared from a Msy4 cDNA clone fragment. The endogenous Msy4 mRNA levels serve as an internal loading control.