The Effects of He-Ne Laser and Enhanced Ultraviolet-B Radiation on Proliferating-Cell Nuclear Antigen in Wheat Seedlings

Abstract

The level of ultraviolet-B (UV-B) radiation on the Earth’s surface has increased due to depletion of the ozone layer. Here, we explored the effects of continuous wave He-Ne laser irradiation (632 nm, 5 mW·mm ^-2 , 2 min·d ^-1 ) on proliferating-cell nuclear antigen (PCNA) damage repair function of wheat seedlings exposed to enhanced UV-B radiation (10.08 kJ &middot m ^-2 ·d ^-1 ) at the early growth stages. Wheat seedlings were irradiated with enhanced UV-B, He-Ne laser treatment or a combination of the two. We explored the transcripts of PCNA in each treatment group using RT-PCR. In addition, total proteins were extracted from the 7-day-old wheat leaves, analyzed by SDS-PAGE and identified by western blot. The results showed that the transcription of PCNA was weakened following UV-B radiation compared to the control. However, when seedlings were subjected to elevated UV-B-damaging radiation followed by He-Ne laser irradiation, the expression of PCNA was signifi-cantly higher than UV-B radiation alone. These results suggest that He-Ne laser has an active role in repairing the UV-B damaging effects. In order to further investigate the function of PCNA, dynamic arrangements of PCNA in wheat root-tip cells were observed with confocal laser scanning microscopy (CLSM). The PCNA was marked fluorescent dimming and strength weakened in en-hanced UV-B radiation (UV-B) compared with the control group (CK) during processing. It shows that PCNA may be involved in the separation of chromosomes.