title: Selective inhibition of genetic transcription in sea urchin embryos. Incorporation of 5-bromodeoxyuridine into low molecular weight nuclear DNA.
abstract: Experimental evidence suggests that exposure of sea urchin gastrulae to 5-bromodeoxyuridine (BUdR), an analog of thymidine, causes a reduction in the rate of synthesis of some RNA species usually transcribed at this stage of development. In pulse-chase experiments, (3)H (in gastrula stage 8-15S nuclear DNA labeled with BUdR-(3)H) could not be chased, with unlabeled BUdR, into 20-60S size-range DNA; in similar experiments in which gastrulae were pulsed with thymidine-(3)H and then chased with unlabeled thymidine, (3)H in 8-15S nuclear DNA could be extensively chased into 20-60S DNA. DNA-RNA hybridization assays indicate that gastrula stage nuclear DNA in the range of 20-60S has greater sequence homology for gastrula stage RNA-(3)H than does nuclear DNA of similar size-range taken from gastrulae exposed to BUdR for 1 hr. An explanation is offered for the effect of BUdR on transcription and DNA replication in sea urchin embryos.
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism* / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects*; D008297:Male; D008970:Molecular Weight; D009693:Nucleic Acid Hybridization; D012313:RNA / Q000096:biosynthesis; D012617:Sea Urchins / Q000196:embryology*; D014158:Transcription, Genetic / Q000187:drug effects*; D014316:Tritium; D014529:Uridine / Q000378:metabolism
chemical_list: D014316:Tritium; D012313:RNA; D001973:Bromodeoxyuridine; D014529:Uridine