Effects of Heavy Ions on Rabbit Tissues: Analysis of Low Levels of DNA Damage in Retinal Photoreceptor Cells

Abstract

When suitable precautions are taken, sedimentation of DNA through reoriented alkaline sucrose gradients in zonal rotors can be used to determine small amounts of DNA damage in mammalian cells without resorting to radioactive precursors. Hence, the method is especially useful for studying the efficacies of DNA repair mechanisms in the neurons of the central nervous system (CNS) and the accumulation of DNA damage in the ageing CNS. Here we describe the technique as it has been used to examine the DNA damage occurring in the photoreceptor cells of the retina of the New Zealand white rabbit during the course of natural ageing or after exposure to heavy ions. This article is an integral part of a series of reports of the latter studies (Lett et al. 1980, Keng and Lett 1981, Cox et al. 1981, 1982, Keng et al. 1982). With the same analytical technique, very low levels of radioactive DNA precursors can be used to advantage in investigations of proliferating cells.

Evaluating Ocular Response in the Retina and Optic Nerve Head after Single and Fractionated High-Energy Protons

“…Our previous study also showed that there were no significant differences in retinal endothelial cell density following single or split dose with two equal dose fractions of 8–28 Gy [ 15 ]. Evaluation of DNA repair of double-strand breaks in the rabbit retina, confirms that little DNA repair for dose recovery was found in the aged rabbit retinas [ 16 , 17 ], although retinal radiosensitivity of mice may be different compared to that of rats or rabbits. Surprisingly, a higher number of TUNEL positive cells were detected in the fractionated dose group compared to that of acute single dose exposure in the ONH region.…”