It is proposed to study regulation of gene expression in the mammalian testis at the levels of transcriptional and translational control. Using DNA clones prepared against specific nRNAs that are temporally regulated during spermatogenesis, the regulation of these genes will be examined at the levels of transcription, processing of nuclear RNA precursors, movement of the mRNA from nucleus to cytoplasm, and in the cytoplasm. Special efforts will be made to identify specific sequences that encode polypeptides unique to haploid cells to determine when during spermatogenesis the genes are first expressed (in diploid or haploid cells). The repression of gene sequences in the haploid cell and the phenomenon of stored information in the form of """"""""inactive"""""""" ribonucleoprotein particles will also be examined. Using established clones for the ribosomal genes, studies will be initiated to answer whether the ribosomal genes are expressed in haploid cells. It is anticipated these studies will answer on a molecular basis whether haploid gene expression occurs, provide a precise answer to how during spermatogenesis the expression of cell type specific gene products are regulated, and reveal critical control points essential for the temporally regulated process of germ cell production.

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National Institute of General Medical Sciences (NIGMS)
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Reproductive Biology Study Section (REB)
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Tufts University
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Kwon, Y K; Hecht, N B (1993) Binding of a phosphoprotein to the 3' untranslated region of the mouse protamine 2 mRNA temporally represses its translation. Mol Cell Biol 13:6547-57
Alcivar, A A; Hake, L E; Hecht, N B (1992) DNA polymerase-beta and poly(ADP)ribose polymerase mRNAs are differentially expressed during the development of male germinal cells. Biol Reprod 46:201-7
Hermo, L; Oko, R; Hecht, N B (1991) Differential post-translational modifications of microtubules in cells of the seminiferous epithelium of the rat: a light and electron microscope immunocytochemical study. Anat Rec 229:31-50
Yelick, P C; Kozak, C; Kwon, Y K et al. (1991) The mouse transition protein 1 gene contains a B1 repetitive element and is located on chromosome 1. Genomics 11:687-94
Oko, R; Hermo, L; Hecht, N B (1991) Distribution of actin isoforms within cells of the seminiferous epithelium of the rat testis: evidence for a muscle form of actin in spermatids. Anat Rec 231:63-81
Johnson, P A; Bunick, D; Hecht, N B (1991) Protein binding regions in the mouse and rat protamine-2 genes. Biol Reprod 44:127-34
Kwon, Y K; Hecht, N B (1991) Cytoplasmic protein binding to highly conserved sequences in the 3' untranslated region of mouse protamine 2 mRNA, a translationally regulated transcript of male germ cells. Proc Natl Acad Sci U S A 88:3584-8
Alcivar, A A; Trasler, J M; Hake, L E et al. (1991) DNA methylation and expression of the genes coding for lactate dehydrogenases A and C during rodent spermatogenesis. Biol Reprod 44:527-35
Morales, C R; Kwon, Y K; Hecht, N B (1991) Cytoplasmic localization during storage and translation of the mRNAs of transition protein 1 and protamine 1, two translationally regulated transcripts of the mammalian testis. J Cell Sci 100 ( Pt 1):119-31
Hecht, N B (1990) Regulation of 'haploid expressed genes' in male germ cells. J Reprod Fertil 88:679-93

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