title: Effect of cytosol on DNA synthesis in isolated mammary gland nuclei from rabbits during pregnancy and early lactation.
abstract: The in vitro DNA synthesis of nuclei isolated from rabbit mammary gland was stimulated by a cytosol fraction from the same tissue. Time-course of this phenomenon was followed during rabbit pregnancy at 5-day intervals. The stimulation was shown to be physiological state-dependent in that it could be detected only in the case of cytosols prepared on day-10 of pregnancy and from day-20 or 25 of pregnancy through day-5 of lactation. Moreover, only nuclei isolated on days-15 or -30 of pregnancy responded to the exogenously added cytosol. The DNA-stimulating activity was partially characterized. It was shown to be protein-like since it was heat-labile, mostly non-dialysable and sensitive to N-ethylmaleimide and trypsin treatment. Sedimentation analysis on sucrose density gradients separated this activity into 3-4 peaks, distinct from the cytoplasmic DNA polymerase.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D003600:Cytosol / Q000502:physiology*; D004247:DNA / Q000096:biosynthesis*; D005033:Ethylmaleimide / Q000494:pharmacology; D005260:Female; D006358:Hot Temperature; D007774:Lactation; D008321:Mammary Glands, Animal / Q000648:ultrastructure*; D011247:Pregnancy; D011270:Pregnancy, Animal; D011817:Rabbits; D013997:Time Factors; D014357:Trypsin / Q000494:pharmacology
chemical_list: D004247:DNA; D014357:Trypsin; D005033:Ethylmaleimide