Research in my lab focuses on the mechanisms of regulation of mRNA translation in mammalian haploid spermatogenic cells. We use transgenic mice to study translational regulation of the sperm mitochondria-associated cysteine-rich protein (Smcp) mRNA, because this is the only approach that provides rigorous in vivo genetic analysis. Previous work has established that the Smcp mRNA is transcribed in early haploid spermatogenic cells, and stored as a translationally inert free-mRNP for about 8 days before translation is activated in late hpaloid cells. Previous work demonstrates that the Smcp 5' UTR and 3'UTR cause 2 and 6 day delays in expression of green fluorescent protein, respectively. Currently we studying the effects of mutations in predicted regulatory elements on the timing of mRNA translation and are searching for proteins that bind to the 5'UTR and 3'UTR. We make extensive use of comparative genomics to gain insight into the possible of mechanisms post-transcriptional gene expression in haploid spermatogenic cells and to identify sequences to mutate for studies in transgenic mice.