ABSTRACT
The distribution and synthesis of the testis-specific variants of histones H1 and H2B, TH1 and TH2B, respectively, and of the somatic histones were studied in rat testis cells. Rat testis cells were labeled in vivo with intratesticular injections of [3H]lysine. The cells and nuclei were then separated into different developmental classes by velocity sedimentation and the histones were analyzed. TH1 and TH2B, as well as the somatic histones, were present in spermatocytes and round spermatids, but none of them were detectable in elongated spermatids. The synthesis and nuclear accumulation of TH1 and TH2B took place throughout pachytene, as well as in earlier stages, but not in the round spermatids. In addition, there was synthesis during pachytene of a histone that migrates electrophoretically with H2A. However, somatic histone synthesis, with the possible exception of H2A and H2B, was not detectable at the pachytene stage. In vivo treatment of rats with hydroxyurea reduced DNA synthesis in the testis to 1% of control values and significantly reduced the synthesis of H3, H2B, H2A, and H4, with the greatest effect being on H3 and H4. However, the hydroxyurea treatment did not significantly decrease the synthesis of TH1, H1, or TH2B. These results prove that the synthesis of several histones during the meiotic prophase is not dependent upon concurrent S-phase DNA synthesis.
Subject(s)
Histones/biosynthesis , Meiosis , Spermatogenesis , Testis/metabolism , Animals , Cell Nucleus/metabolism , DNA Replication/drug effects , Hydroxyurea/pharmacology , Male , Rats , Spermatocytes/metabolism , Tissue DistributionSubject(s)
Spermatogonia/radiation effects , Spermatozoa/radiation effects , Testis/radiation effects , Animals , Cell Differentiation/radiation effects , Cell Division/radiation effects , Cell Survival/radiation effects , Cesium Radioisotopes , Gamma Rays , Isoenzymes , L-Lactate Dehydrogenase/metabolism , Male , Mice , Mice, Inbred C3H , Specific Pathogen-Free Organisms , Sperm Head/radiation effects , Testis/enzymology , Time FactorsSubject(s)
Cell Separation/methods , Testis/cytology , Animals , Cell Division , Centrifugation, Isopycnic/methods , Diatrizoate Meglumine , Edetic Acid , Male , Mice , Mice, Inbred Strains , Osmolar Concentration , Sperm Head , Spermatids/cytology , Spermatocytes/cytology , Spermatogenesis , Spermatogonia/cytology , TrypsinSubject(s)
Hemoglobins/biosynthesis , Peptides/pharmacology , Reticulocytes/metabolism , Ribosomes/metabolism , Animals , Carbon Isotopes , Cell-Free System , Centrifugation, Density Gradient , Chromatography, Ion Exchange , Depression, Chemical , Electrophoresis , Heme/pharmacology , Hemoglobins/pharmacology , Humans , Leucine/metabolism , Methods , Peptide Biosynthesis , Rabbits , Reticulocytes/cytology , Reticulocytes/drug effects , Solubility , Species Specificity , Valine/metabolismSubject(s)
Benzoates , Hemoglobins , Peptides , Animals , Chemical Phenomena , Chemistry , Cysteine , Electrophoresis , Humans , Hybridization, Genetic , Mercury , Mice , Molecular Weight , Rabbits , UltracentrifugationABSTRACT
A cell-free protein-synthesizing system made from rabbit reticulocytes was used to incorporate (14)C-amino acids into hemoglobin. Electrophoretic analyses of the soluble products of this cell-free system revealed a fraction containing rabbit (14)C-alpha chains in addition to the rabbit (14)C-hemoglobin. The addition of isolated human hemoglobin beta chains to this system during active synthesis inhibited the release of newly synthesized rabbit (14)C-beta chains into solution from the ribosome fraction. This inhibition was possibly a result of hybrid hemoglobin formation between rabbit alpha and human beta chains. A model of hemoglobin construction in which soluble alpha chains are intermediates is suggested. These alpha chains may aid in the release of beta chains from the polyribosomes during the completion of the hemoglobin molecule.
