Environmental and Water Studies, Department of Civil and Environmental Engineering, Stanford University, 473 Via Ortega, Stanford, CA, USA.
Departments of Ophthalmology, Microbiology and Immunobiology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, USA.
J Photochem Photobiol B. 2014 Jan 5;130:349-56. doi: 10.1016/j.jphotobiol.2013.12.013. Epub 2013 Dec 30.
Microarrays were used to investigate the transcriptional response of Enterococcus faecalis to photostress. E. faecalis are Gram-positive bacteria used as indicators of water quality and have been shown to vary diurnally in response to sunlight. E. faecalis in filtered seawater microcosms were exposed to artificial sunlight for 12h and then placed in the dark for 12h. Transcript abundance was measured at 0, 2, 6, 12, and 24h in the sunlit microcosm and a dark control using microarrays. Culturable E. faecalis concentrations decreased 6-7 orders of magnitude within the first 6h of light exposure. After 12h in the dark, no evidence of dark-repair was observed. Expression data collected after 12h of sunlight exposure revealed a difference in transcript abundance in the light relative to dark microcosms for 35 unique ORFs, 33 ORFs showed increased transcript abundance and 2 ORFs showed reduced transcript abundance. A majority (51%) of the ORFs with increased transcript abundance in the sunlit relative to dark microcosms encoded hypothetical proteins; others were associated with protein synthesis, oxidative stress and DNA repair. Results suggest that E. faecalis exposed to sunlight actively transcribe RNA in response to photostress.
微阵列被用来研究粪肠球菌对光应激的转录反应。粪肠球菌是一种革兰氏阳性细菌，常被用作水质指标，并且已经证明它们会随着阳光的变化而昼夜变化。在过滤海水中的微宇宙中，粪肠球菌暴露在人工阳光下 12 小时，然后放在黑暗中 12 小时。在有光照和黑暗对照的微宇宙中，分别在光照的 0、2、6、12 和 24 小时测量转录丰度。在光暴露的前 6 小时内，可培养的粪肠球菌浓度下降了 6-7 个数量级。在黑暗中 12 小时后，没有观察到暗修复的证据。在光照下暴露 12 小时后收集的表达数据显示，与黑暗微宇宙相比，35 个独特的 ORF 在光照下的转录丰度存在差异，其中 33 个 ORF 的转录丰度增加，2 个 ORF 的转录丰度降低。与黑暗微宇宙相比，在光照下转录丰度增加的 ORF 中，大多数（51%）编码假定蛋白；其他与蛋白质合成、氧化应激和 DNA 修复有关。结果表明，暴露在阳光下的粪肠球菌会主动转录 RNA 以应对光应激。
