Biomolecular Screening Branch, National Toxicology Program, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, USA.
Mutat Res. 2010 Jan 5;683(1-2):57-67. doi: 10.1016/j.mrfmmm.2009.10.008.
We performed experiments to characterize the inducibility of nucleotide excision repair (NER) in Caenorhabditis elegans, and to examine global gene expression in NER-deficient and -proficient strains as well as germline vs. somatic tissues, with and without genotoxic stress. We also carried out experiments to elucidate the importance of NER in the adult life of C. elegans under genotoxin-stressed and control conditions. Adult lifespan was not detectably different between wild-type and NER-deficient xpa-1 nematodes under control conditions. However, exposure to 6J/m(2)/day of ultraviolet C radiation (UVC) decreased lifespan in xpa-1 nematodes more than a dose of 100 J/m(2)/day in wild-type. Similar differential sensitivities were observed for adult size and feeding. Remarkably, global gene expression was nearly identical in young adult wild-type and xpa-1 nematodes, both in control conditions and 3h after exposure to 50 J/m(2) UVC. Neither NER genes nor repair activity were detectably inducible in young adults that lacked germ cells and developing embryos (glp-1 strain). However, expression levels of dozens of NER and other DNA damage response genes were much (5-30-fold) lower in adults lacking germ cells and developing embryos, suggesting that somatic and post-mitotic cells have a much lower DNA repair ability. Finally, we describe a refinement of our DNA damage assay that allows damage measurement in single nematodes.
我们进行了实验，以表征核苷酸切除修复 (NER) 在秀丽隐杆线虫中的诱导性，并检查 NER 缺陷和功能齐全的菌株以及生殖细胞与体细胞在有无遗传毒性应激时的全基因表达情况。我们还进行了实验，以阐明在遗传毒性应激和对照条件下 NER 在秀丽隐杆线虫成虫生活中的重要性。在对照条件下，野生型和 NER 缺陷型 xpa-1 线虫之间的成虫寿命没有明显差异。然而，xpa-1 线虫暴露于每天 6J/m(2)/天的紫外线 C 辐射 (UVC) 下，其寿命比野生型线虫暴露于每天 100 J/m(2)/天的剂量下更短。在成虫大小和摄食方面也观察到类似的差异敏感性。值得注意的是，在对照条件下和暴露于 50 J/m(2) UVC 后 3 小时，年轻成年野生型和 xpa-1 线虫的全基因表达几乎完全相同。在缺乏生殖细胞和发育胚胎的年轻成虫中（glp-1 菌株），既检测不到 NER 基因，也检测不到修复活性的诱导。然而，在缺乏生殖细胞和发育胚胎的成虫中，数十个 NER 和其他 DNA 损伤反应基因的表达水平（5-30 倍）明显降低，这表明体细胞和有丝分裂后细胞的 DNA 修复能力要低得多。最后，我们描述了我们的 DNA 损伤测定法的一种改进，该方法允许在单个线虫中测量损伤。
