Expression Verification And Validation Of Space Radiation Biomarker And Metabolite Analysis

Space environment is characterized as high vacuum, weak magnetic field, sharp differences in temperature, microgravity and strong radiation. Preliminary study found that the ionizing radiation was the major factor of biological damages caused by spaceflights. After the 20th Satellite spaceflight experiment we detected one differentially expressed protein involved in metabolism process by proteomic analysis-protein Nucleoside Diphosphate Kinase I (NDPK1), which is involved in the regulation reaction of nucleotide phosphate metabolites and repair of DNA double-strand breaks. NDPK1 might be a potential biomarker that responds to space radiation but still needs further verification and validation. In the present thesis, rice seeds were flown by spacecraft Shenzhou VI and irradiated by on-ground simulated radiations with different doses. The gene and protein expression level of NDPK1 were measured by RT-PCR and two-dimensional gel electrophoresis for sensitivity verification and specificity validation. And the dosage-expression relations of gene and protein were focused on too. Ultra performance liquid chromatography (UPLC) analysis was used to determine the content of NDPKl catalyzed reaction products for discussing the DNA repair effect caused by space radiation from the metabolism level.The results showed that gene and protein expression levels of NDPK1 presented up-regulations both in space verification samples and on-ground radiation validation samples. While the protein expression abundance increased with dosage increasing. It indicated that NDPK1 worked as a biomarker and showed sensitivity and specificity to radiation. Content of ADP -one of the products of NDPK1 catalytic reaction-was found increasing, which further suggested that the effect of radiation might enhance the enzymatic activity of the protein. NDPK1 is involved in DNA damage repair, further confirming the space radiation effects of damage to rice.