Radioadapted chicken embryo cells: challenge specificity and alterations in higher-order DNA structure.
Radioadapted chicken embryo cells (X-irradiation in ovo with 10 cGy at the 14th day of development with priming periods of 24 h) were treated in vitro by challenge doses of 14 different DNA- and/or chromatin-interactive agents, including X-rays. A decrease in the cellular damage, as measured by scheduled DNA synthesis, was only observed with X-irradiation. Sedimentation of nucleoids as well as viscosity of alkaline lysates from ethidium bromide (0.35-400 micrograms/ml)-, novobiocin (125-1800 micrograms/ml)-, and hyperthermia (30 min at 43 degrees and 45 degrees)-treated cells suggest a higher tendency of radioadapted cells to undergo positive DNA supercoiling. When DNA from adapted and non-adapted chicken embryo cells was used as substrate, neither its digestion by DNase I nor the inhibition of DNase I activity by various DNA-interactive agents was changed in primed cells. From the previous investigations as well as from the present results it is concluded that an increase of tightening of protein-DNA interactions within the nuclear matrix is a molecular determinant of the elevated radiation resistance in radioadapted chicken embryo cells.
Tempel
K
K
Institut für Pharmakologie, Toxikologie und Pharmazie, Tierärztlichen Fakultät, Universität München.
D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity; D001921:Brain / Q000187:drug effects / Q000196:embryology / Q000528:radiation effects*; D002273:Carcinogens / Q000633:toxicity; D002417:Cattle; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D002843:Chromatin / Q000528:radiation effects; D004247:DNA / Q000737:chemistry / Q000187:drug effects / Q000528:radiation effects*; D006358:Hot Temperature; D008099:Liver / Q000187:drug effects / Q000196:embryology / Q000528:radiation effects*; D014965:X-Rays
D000970:Antineoplastic Agents; D002273:Carcinogens; D002843:Chromatin; D004247:DNA