Inhibitory effects of long-wave ultraviolet radiation of isolated chicken liver nuclei on the Mg2+-dependent transition of chromatin structure.
Since the turbidity of nuclear suspensions is known to be correlated with the nuclear morphology, the effects of long-wave ultraviolet (UVA) radiation on Mg2+-dependent structural transition of chromatin in isolated chicken liver nuclei were monitored by measuring the relative turbidity of nuclear suspensions. UVA radiation of the nuclei inhibited the Mg2+-dependent change in relative turbidity of nuclear suspensions in a UVA dose-dependent manner under aerobic conditions but not under N2 conditions. No inhibitory effect of UVA radiation on the change in relative turbidity was observed in the presence of 50 mM NaN3, which scavenges singlet oxygen (1O2) and hydroxyl radicals (*OH). In contrast, 100 mM dimethyl sulfoxide, which primarily scavenges *OH, did not show the inhibitory effect of UVA radiation. The amounts of DNA-protein crosslinks increased with UVA dose under aerobic conditions but not under N2 conditions. The present study showed that UVA radiation of isolated nuclei inhibited the Mg2+-dependent unfolding of condensed chromatin and that O2 is likely to be involved in this process. Furthermore, the formation of DNA-protein crosslinks may contribute to the inhibition.
Arai
S
S
Department of Veterinary Radiology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan.
Nakanishi
Y H
YH
Hayashi
M
M
D000818:Animals; D002467:Cell Nucleus / Q000528:radiation effects; D002645:Chickens; D002843:Chromatin / Q000528:radiation effects* / Q000648:ultrastructure; D046508:Culture Techniques; D008099:Liver / Q000528:radiation effects*; D008274:Magnesium / Q000378:metabolism*; D015636:Magnesium Chloride / Q000378:metabolism; D010100:Oxygen / Q000528:radiation effects; D017510:Protein Folding; D014466:Ultraviolet Rays
D002843:Chromatin; D015636:Magnesium Chloride; D008274:Magnesium; D010100:Oxygen