Radioadapted Chicken Embryo Cells: Challenge Specificity and Alterations in Higher-Order DNA Structure

Karlheinz Tempel
1996 Zeitschrift für Naturforschung C - A Journal of Biosciences  
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 (μg/ml)-, novobiocin (125 -1800
more » ... ocin (125 -1800 μg/ml)-, and hyperthermia (30 min at 43° and 45°)-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.
doi:10.1515/znc-1996-3-412 fatcat:t2znr2k4grb7hczmruqenmbi6a