Relationship of HepG2 cell sensitivity to continuous low dose-rate irradiation with ATM phosphorylation

Objective: To investigate the change of ATM phosphorylation in HepG2 cells and its effect on HepG2 cell survival under a continuous low dose-rate irradiation. Methods: HepG2 cells were exposed to equivalent doses of irradiation deliv- ered at either a continuous low dose-rate (7.76 cGy/h) or a high dose-rate (4500 cGy/h). The ATM phosphorylated proteins and surviving fraction of HepG2 cell after low dose-rate irradiation were compared with that after equivalent doses of high dose-rate irradiation. Results: The phosphorylation of ATM protein was maximal at 0.5 Gy irradiation delivered at either a high dose-rate or a continuous low dose-rate. As the radiation dose increased, the phosphorylation of ATM protein decreased under continuous low dose-rate irradiation. However, the phosphorylation of ATM protein was remained stable under high dose-rate irradiation. When the phosphorylation of ATM protein under continuous low dose-rate irradiation was equal to that under high dose-rate irradiation, there was no significant difference in the surviving fraction of HepG2 cells between two ir- radiation methods (P > 0.05). When the phosphorylation of ATM protein significantly decreased after continuous low dose-rate irradiation compared with that after high dose-rate irradiation, increased amounts of cell killing was found in low dose-rate irradiation (P < 0.01). Conclusion: Continuous low dose-rate irradiation increases HepG2 cells radiosensitivity compared with high dose-rate irradiation. The increased amounts of cell killing following continuous low dose-rate exposures are associated with reduced ATM phosphorylated protein.

The Breeding and Cultivation Techniques of Zhangzagu No.22

Zhangzagu No.22 was a new high-quality millet cultivar adapted to the climate characteristics of the summer sowing areas,which was selected by the Zhangjiakou Academy of Agricultural Sciences with sterile line A2 as the female parent and‘32×ISE375×Xia1 father’as the male parent.Zhangzagu No.22 has a growth period of 88 d in summer,and exhibits green seedlings,spindle-shaped panicles,a plant height of 135-145 cm,a panicle length of 23-28 cm,a grain weight per panicle of 18-22 g,a 1000-grain weight of 2.90 g,yellow rice,and resistance to herbicide Nabujing.In 2018,it passed the registration of non-major crop varieties by the Ministry of Agriculture,with the registration number:GPD Millet(2018)130193.This study introduced the breeding process,variety characteristics and related cultivation techniques of Zhangzagu No.22.