Ohnishi T, Takahashi A, Ohnishi K, Nakano T, Nagaoka S
Dept. of Biology, Nara Medical University, Kashihara, Japan.
J Gravit Physiol. 2000 Jul;7(2):P69-70.
In recent years, some papers have reported synergism in the biological effects of space radiation and microgravity. However, there is no direct evidence for these phenomena. As one possible mechanism, we investigated whether DNA ligation in the final step of DSBs repair of DNA molecules induced by radiation is depressed by microgravity. Therefore, we have scheduled the space experiments of the effects of microgravity on repair activity of T4 DNA ligase for DSBs prepared with digestion of a restriction enzyme (Sma I) to plasmid DNA. As another possible mechanism, the high mutation frequency may be induced from abnormal base-incorporation during DNA replication under microgravity. Using the Taq polymerase and polymerase III, we have also scheduled whether mutation frequency is affected by microgravity during DNA replication for a damaged DNA base induced by an alkylating agent (N-methyl-N-nitrosourea, MNU).
近年来，一些论文报道了空间辐射和微重力在生物学效应方面存在协同作用。然而，尚无这些现象的直接证据。作为一种可能的机制，我们研究了微重力是否会抑制辐射诱导的DNA分子双链断裂（DSB）修复最后一步中的DNA连接。因此，我们已安排了空间实验，以研究微重力对用限制性内切酶（Sma I）消化质粒DNA制备的DSB的T4 DNA连接酶修复活性的影响。作为另一种可能的机制，高突变频率可能是由微重力下DNA复制过程中异常碱基掺入所诱导。利用Taq聚合酶和聚合酶III，我们还安排了实验，以研究微重力是否会影响由烷基化剂（N-甲基-N-亚硝基脲，MNU）诱导的受损DNA碱基在DNA复制过程中的突变频率。
