title: Insect sex chromosomes, XI. 3H-TdR induces random aberrations in the X chromosome(s) of Gryllotalpa fossor (Orthoptera).
abstract: The pattern of titrated thymidine (3H-TdR), a direct precursor of DNA, induced aberrations on the X chromosome of Gryllotalpa fossor was examined. 3H-TdR produced aberrations randomly distributed over the entire length of the X chromosome; breaks were observed in both the eu- and the heterochromatic arms of the X chromosome in both the sexes. Since the eu- and the heterochromatic arms cannot be distinguished cytologically in this insect, the presence of aberrations on both arms of the same X chromosome in the male and damage to both X chromosomes in the female indicate that both euchromatic and heterochromatic regions (facultative or constitutive) are equally liable to aberrations induced by H-TdR. This is in contrast to the non-random induction of aberrations by 3H-UdR, which causes chromosome damage due to the proximity of the labeled RNA to the DNA template during transcription.
authors.affiliation: Department of Zoology, University of Delhi, India.
authors.forename: S
authors.initials: S
authors.lastname: Sarkar
authors.forename: S R
authors.initials: SR
authors.lastname: Rao
mesh_terms: D000818:Animals; D002869:Chromosome Aberrations; D005260:Female; D008297:Male; D016296:Mutagenesis; D009987:Orthoptera; D013936:Thymidine / Q000633:toxicity*; D014316:Tritium / Q000633:toxicity*; D014960:X Chromosome / Q000528:radiation effects*
chemical_list: D014316:Tritium; D013936:Thymidine