Horneck G, Rettberg P, Kozubek S, Baumstark-Khan C, Rink H, Schäfer M, Schmitz C
DLR, Institute of Aerospace Medicine, Radiation Biology Division, Koln, Germany.
Radiat Res. 1997 Mar;147(3):376-84.
The influence of the space flight environment, above all microgravity, on the repair of radiation-induced DNA damage was examined during the Spacelab mission IML-2 as (1) rejoining of DNA strand breaks induced by X irradiation in cells of Escherichia coli B/r (120 Gy) and (2) in human fibroblasts (5 and 10 Gy); (3) induction of the SOS response after gamma irradiation (300 Gy) of cells of Escherichia coli PQ37; and (4) survival of spores of Bacillus subtilis HA 101 after UV irradiation (up to 340 J m(-2)). Cells were irradiated prior to the space mission and were kept frozen (E. coli and fibroblasts) until incubation for defined periods (up to 4.5 h) in orbit; thereafter they were frozen again for laboratory analysis. Germination and growth of spores of B. subtilis on membrane filters was initiated by humidification in orbit. Controls were performed in-flight (1g reference centrifuge) and on the ground (1g and 1.4g). We found no significant differences between the microgravity samples and the corresponding controls in the kinetics of DNA strand break rejoining and of the induction of the SOS response as well as in the survival curves (as proven by Student's t test, P < or = 0.1). These observations provide evidence that in the microgravity environment cells are able to repair radiation-induced DNA damage almost normally. The results suggest that a disturbance of cellular repair processes in the microgravity environment might not be the explanation for the reported synergism of radiation and microgravity.
在空间实验室任务IML - 2期间，研究了空间飞行环境，尤其是微重力对辐射诱导的DNA损伤修复的影响，具体包括：（1）大肠杆菌B/r细胞（120 Gy）和人成纤维细胞（5 Gy和10 Gy）经X射线照射后DNA链断裂的重新连接；（2）大肠杆菌PQ37细胞经γ射线照射（300 Gy）后SOS反应的诱导；（3）枯草芽孢杆菌HA 101孢子经紫外线照射（高达340 J m(-2)）后的存活情况。细胞在太空任务前进行照射，并保持冷冻状态（大肠杆菌和成纤维细胞），直到在轨道上孵育特定时间（长达4.5小时）；之后再次冷冻以进行实验室分析。枯草芽孢杆菌孢子在膜滤器上的萌发和生长通过在轨道上加湿启动。在飞行中（1g参考离心机）和地面（1g和1.4g）进行对照。我们发现，在DNA链断裂重新连接动力学、SOS反应诱导以及存活曲线方面，微重力样品与相应对照之间没有显著差异（经学生t检验证明，P≤0.1）。这些观察结果表明，在微重力环境中细胞能够几乎正常地修复辐射诱导的DNA损伤。结果表明，微重力环境中细胞修复过程的紊乱可能不是所报道的辐射与微重力协同作用的原因。
