| Porphyra yezoensis is an important economic macroalgae in China.Due to the long-term screening of ambient pressure,it has an important ability to resist robotic stress.Porphyra yezoensis serves as an important model organism in the study of molecular biology of algae,it is of some interest in the study of the evolution of eukaryotes in algae.The Chinese space station’s space radiation biological exposure experimental equipment is scheduled to be used in2023 to conduct space radiation exposure experiments with adversarial biological subsystems.Depending on the experimental requirements for the whole process,it is necessary to establish quality assurance parameters.Therefore,in this study,according to the carrying requirements of the space station standard of the space application system of manned space engineering,the free filaments of Porphyra yezoensis were used as subjects to carry out ground simulated space ultraviolet radiation exposure experiments and life support matching experiments to ensure that the filaments meet the scientific requirements after returning t o the ground.The main results are as follows:(1)in order to ensure that the filaments can survive after being irradiated,the immobilized filaments were simulated by space ultraviolet radiation.First,the dose relation between filaments and UV radiation was discussed,and the semi-lethal dose of UV radiation to free-living filaments of Porphyra yezoensis was determined to be 376.50 k J/m~2.The simulated radiation dose was set at 10%and 0.1%of the UV radiation dose received by the EXPOSE-R device at the International Space Station over a one-month period.(2)UV radiation simulation experiments with different dose gradients(10%,1%,0.1%,0%)were carried out to determine that the lowest survival rate of filaments after receiving ultraviolet radiation was more than 60%.At the photosynthetic physiological level,the values of photosynthetic efficiency(Fv/Fm)and the contents of Chla,Car and UVCAS decreased,but recovered after 10 days of culture.The expression of genes related to photosynthesis(PsbA,RbcL)also showed a dose-dependent effect.At the level of oxidative stress,the content of GSH in filaments was not affected before and after recovery,but the contents of TP,CAT and MDA were affected,and the expression of stress-related genes(hsp70)changes in a dose-dependent manner.(3)through the long-term and short-term matching experiments of the immobilized filaments,and the short-term(24 hours)matching experiments,the effects of the limit temperature and abnormal air pressure on the free filaments of Porphyra yezoensis were analyzed.The survival rates of the inner filaments treated for 24 hours at 30℃and 0.6～1.2atm were more than 50%,which met the CMCC standard and could be carried in space.The long-term matching experiment verified that under the environmental conditions of 5～20℃and0.8～1.0 atm,the survival rate of filaments in the first five months was more than 50%,which met the strain quality preservation standard of CMCC.However,since the values of Fv/Fm and the Chla content in the filaments are not recovered,the recovery time of the sample can be appropriately prolonged.In summary,a series of radiation matching experiments were performed by selecting free filaments of Porphyra yezoensis as space-exposed biomaterials.It provides some well-guaranteed parameters for studying the developmental pathway of Porphyra yezoensis and for exploring biological questions related to cell differentiation and phylogenetic evolution in algae.It provides a partial parametric basis for the development of hardware devices for the stress-tolerant biological subsystems carried by the radiation biology exposure platform on the space station. |
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