The complex space environment can induce mutations in organisms and the main inducing factors are sustained microgravity and ionizing radiation. Microgravity not only influences cytoskeleton, cell morphology and cell proliferation, but also affects gene expression, gene function and signal transduction. Meanwhile, the space-relevant ionizing radiation causes DNA damage, which leads to cell death, abnormal development and malignant transformation.

 With the implementation of China's manned space engineering, the potential damage of long-term flight has become one of the major concerns of space scientists. Human bodies are under microgravity during the aircraft flying on-orbit, so the study of mechanical sensor system in cells, investigation the mechanism of cell aging and abnormal proliferation will give good explanation to maintain health and longevity. And the study results will enrich basic theory of space medicine, and give experiment and theoretical evidence for the astronaut health protection.

 The model plant, rice, was studied from 1996. After several times of space flight, the genetic and variety characters were detected from early generation to stable lines continuously. The mutant traits after space flight were located using SSR markers. Along with space flight, γ-irradiation and heavy-ion irradiation were carried out on ground, the total physiological damage, cytological effects in M1 and mutation effects in M2 were observed. The radiosensitivities of different factors were compared, and the genetic bases of radiosensitivities were analyzed. The characteristics and major mutagenesis of space environments were analyzed.

To analyze the mechanism of damage and repair of mammalian cell in space environment, the model mammalian cell lines such as the rat terminally differentiated PC12 cell lines, mouse NIH3T3, human immortalized lymphocytes and osteosarcoma cell line MG-63 were used from 2007. The space radiation effect was simulated by γ⁶⁰Co-radiation and the long-lasting microgravity effect in space was simulated by clinostat. The chromosome damage and repair were analyzed. Now the mechanism of chromosome instability increase under simulated microgravity is focused on. The main contents include changes of cytoskeleton, cell proliferation, spindle structure, chromosome fragile site and the expression of cell cycle checkpoint.

 Mammalian osteosarcoma cells or osteoblasts were treated with simulated microgravity in a rotating wall vessel (2D-RWVS) bioreactor. Experimental results indicate that simulated microgravity can alter the structure of spindle microtubules, and stimulate the formation of multipolar spindles together with multicentrosomes, which causes the overexpression of SAC proteins to block the abnormal cells in metaphase, thereby inhibiting cell proliferation. By clarifying the relationship between cell proliferation inhibition, spindle structure and SAC changes under simulated microgravity, the molecular mechanism and morphology basis of proliferation inhibition induced by microgravity is revealed. While the experimental results using human peripheral blood lymphocytes indicate simulated microgravity has no effect on the numerical chromosome instability of human peripheral blood lymphocytes, but it enhances the structural chromosome instability of human peripheral blood lymphocytes through the inhibition of DNA replication and the reduction of DNA repair. So, the mechanism of chromosome fragile site induced by simulated microgravity can be explained using the changes which occur in the chromosome structure of human peripheral blood lymphocytes, the DNA replication and repair under the effect of simulated microgravity.

 The major research area is founded by NSFC and NSFH, and the chromosome instability induced by radiation and simulated microgravity are focused. The research works have been published in journals including PloS ONE, Advances in Space Research, Journal of Radiation Research, Micorgraviy Science and Technology.

 KEY PUBLICATIONS:

1. Experimental Study on Effect of Simulated Microgravity on Structural Chromosome Instability of Human Peripheral Blood Lymphocytes. Lijun Wei1, Chuanpeng Liu, Li Kang, Yufeng Liu, Shuliang Shi, Qiong Wu, Yu Li. PLoS ONE. 2014, 9(6): e100595,1-12.

2. Simple sequence repeat markers reveal multiple loci governing grain-size variations in a japonica rice (Oryza sativa L.) mutant induced by cosmic radiation during space flight. Junmin Wang, Lijun Wei, Tianqing Zheng, Xiuqin Zhao, Jauhar Ali, Jianlong Xu, Zhikang Li. Euphytica, 2014,196(2):225-236.

3. Effect of change in spindle structure on proliferation inhibition of osteosarcoma cells and osteoblast under simulated microgravity during incubation in rotating bioreactor. Lijun Wei , Yan Diao, Jing Qi, Alexander Khokhlov, Hui Feng, Xing Yan, Yu Li. PLoS ONE. 2013, 8(10):e76710,1-15.

4. Synergistic Effects of Incubation in Rotating Bioreactors and Cumulative Low Dose 60Co γ -ray Irradiation on Human Immortal Lymphoblastoid Cells. Lijun Wei, Fang Han, Lei Yue, Hongxia Zheng, Dan Yu, Xiaohuan Ma, Huifang Cheng, Yu Li. Microgravity Sci. Technol. 2012, 24:335–344.

5. Analysis of cytogenetic damage in rice seeds induced by energetic heavy ions on-ground and after spaceflight. Wei Lijun，Yang Qian，Xia Hongmei,  et al. Journal of Radiation Research，2006,47(3-4):273-278.

6. Cytological Effects of Space Environment on Different Genotype Rice.  Wei Lijun，Yang Qian，Qian Yu, et al. Journal of Beijing Institute of Technology（English Edition) , 2007,16(2):220-225.

7. Characteristics of phenotype and genetic mutations in rice after spaceflight. Advances in space research. Yu Xin,Wu Hong,Wei Lijun,et al. 2007, 40:528-534.

8. Heavy genetic load associated with the subspecific differentiation of japonica rice(Oryza sativa ssp. japonica L.) Xu Jianlong, Wang Iunmin, Sun Yeqing, Wei Lijun，et al. Journal of Experimental Botany. 2006,57(11):2815-2824.

9. Teaching the cell biology of aging at the Harbin Institute of Technology and Moscow State University. Lijun Wei, Yu Li, Jie He, A.N. Khokhlov. Moscow University Biological Sciences Bulletin. 2012,67(1)：13-16

10. Comparative proteomic analysis of a high-tillering dwarf mutant induced by spaceflight at different tillering stages. Wei Wang, Lijun Wei, Junmin Wang, Jianlong Xu, Yeqing Sun. Acta Agriculturae Nucleatae Sinica, 2011, 25(3):405-415.

11. Space Radiation Effects on Plants. Lijun Wei, Yu qian, Yeqing Sun. Heilongjiang agricultural sciences. 2009(4):1-6

12. The study of damage of rat terminal differentiation PC12 cell under γ-radiation and simulated microgravity. Xiaohuan Ma, Lijun Wei, Hongxia Zheng, Xing Yan, Yu Li. Progress in modern biomedicine. 2008，8(12):2204-2207

13. A Comparative Study on Mutagenic Effects of Space Flight and γ-rays Irradiation in Rice. Wei Li-jun, Wang Jun-min, Yang Qian, Luo Rong-ting, Zhang Ming-xian, Bao Gen-liang, Xu Jian-long, Sun Ye-qing. Scientia agricultural sinica. 2006, 39(7):1306-1312.

14. Mutagenic Differences of Space Environment and Ground γ-irradiation in Rice. Wang Jun-min, Xu Jian-long, Wei Li-jun. Acta agronomica sinica. 2006, 32(7):1006-1010.

15. Teaching the cell biology of aging at the Harbin Institute of Technology and Moscow State University. Lijun Wei, Yu Li, Jie He, A.N. Khokhlov. Moscow University Biological Sciences Bulletin. 2012,67(1): 13-16

16. Teaching cytogerontology in Russia and China. Khokhlov AN, Wei L, Li Y, He J. Adv Gerontol; 2012, 25(3):513-6.

17. Teaching Botany in English in China, Lijun Wei, Mary Peat. The China Papers, 2002.10:46-50.