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Cloning of Protamine cDNA of the Medaka ( Oryzias latipes ) and Its Expression during Spermatogenesis
Author(s) -
Tamura Masaru,
Yamamoto Hiroaki,
Onitake Kazuo
Publication year - 1994
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1994.00419.x
Subject(s) - oryzias , protamine , biology , complementary dna , microbiology and biotechnology , spermatogenesis , sperm , cdna library , in situ hybridization , messenger rna , genetics , gene , biochemistry , heparin , endocrinology
Protamines or sperm specific basic proteins are highly basic low molecular weight proteins that substitute histones in the chromatin of sperm during spermatogenesis. They condense sperm DNA into a highly compact, stable and inactive complex. In this study, cDNA of protamine of the medaka, Oryzias latipes , was cloned to elucidate the molecular mechanisms involved in spermatogenesis. A medaka testis cDNA library constructed in lambda gt 11 showed 2.78X10 6 independent recombinants. Several positive clones were obtained by immunoscreening with polyclonal antiserum against medaka protamine. Sequencing showed that one of these positive clones, named MP‐1, encoded arginine clusters characteristic of protamine. The putative amino acid sequence of MP‐1 revealed a remarkable extent of homology with other fish protamines, such as 71% identity with thynnin Y, a sperm specific basic protein isolated from the bluefin tuna, Thunnus thynnus . Northern hybridization using a MP‐1 cDNA probe showed that MP‐1 mRNA is present exclusively in the testes and that it gave three detectable bands: a major band of 280 b, and two others of 400 b and 500 b. In situ hybridization of a complementary RNA probe (digoxigenine‐UTP‐labeled MP‐1 RNA) revealed that MP‐1 mRNA is localized in some secondary spermatocytes and spermatids, but not in primary spermatocytes or spermatogonia. These results differ from those obtained in studies on the rainbow trout by solution hybridization and in situ hybridization.