Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
J Photochem Photobiol B. 2011 Jun 2;103(3):234-42. doi: 10.1016/j.jphotobiol.2011.03.018. Epub 2011 Apr 7.
Ultraviolet radiation is an important environmental constraint on the evolution of life. In addition to its harmful effects, ultraviolet radiation plays an important role in generating genetic polymorphisms and acting as a selective agent. Understanding how prokaryotes cope with high radiation can give insights on the evolution of life on Earth. Four representative filamentous bacteria from the family Cytophagaceae with different pigmentation were selected and exposed to different doses of UVC radiation (15-32,400Jm(-2)). The effect of UVC radiation on bacterial survival, growth and morphology were investigated. Results showed high survival in response to UVC for Rudanella lutea and Fibrisoma limi, whereas low survival was observed for Fibrella aestuarina and Spirosoma linguale. S. linguale showed slow growth recovery after ultraviolet exposure, R. lutea and F. limi showed intermediate growth recovery, while F. aestuarina had the fastest recovery among the four tested bacteria. In terms of survival, S. linguale was the most sensitive bacterium whereas R. lutea and F. limi were better at coping with UVC stress. The latter two resumed growth even after 2h exposure (∼10,800Jm(-2)). Additionally, the ability to form multicellular filaments after exposure was tested using two bacteria: one representative of the high (R. lutea) and one of the low (F. aestuarina) survival rates. The ability to elongate filaments due to cell division was preserved but modified. In R. lutea 10min exposure reduced the average filament length. The opposite was observed in F. aestuarina, where the 5 and 10min exposures increased the average filament length. R. lutea and F. limi are potential candidates for further research into survival and resistance to ultraviolet radiation stress.
紫外线辐射是生物进化的一个重要环境限制因素。除了其有害影响外，紫外线辐射在产生遗传多态性和作为选择剂方面起着重要作用。了解原核生物如何应对高强度辐射可以深入了解地球上生命的进化。选择了来自 Cytophagaceae 科的具有不同色素沉着的四种有代表性的丝状细菌，并暴露于不同剂量的 UVC 辐射（15-32,400Jm(-2)）下。研究了 UVC 辐射对细菌存活、生长和形态的影响。结果表明，Rudanella lutea 和 Fibrisoma limi 对 UVC 具有高存活率，而 Fibrella aestuarina 和 Spirosoma linguale 的存活率则较低。S. linguale 在紫外线暴露后生长恢复缓慢，R. lutea 和 F. limi 表现出中等的生长恢复，而 F. aestuarina 在四种测试细菌中恢复最快。就生存而言，S. linguale 是最敏感的细菌，而 R. lutea 和 F. limi 则更能应对 UVC 应激。后两者甚至在暴露 2 小时后（约 10,800Jm(-2)）恢复了生长。此外，还使用两种细菌测试了暴露后形成多细胞丝的能力：一种是高（R. lutea）存活率的代表，另一种是低（F. aestuarina）存活率的代表。由于细胞分裂而伸长丝的能力得以保留，但被修改。在 R. lutea 中，10 分钟的暴露减少了平均丝长度。在 F. aestuarina 中观察到相反的情况，其中 5 分钟和 10 分钟的暴露增加了平均丝长度。R. lutea 和 F. limi 是进一步研究生存和抗紫外线辐射应激的潜在候选者。
