Analysis of DNA repair and protection in the Tardigrade Ramazzottius varieornatus and Hypsibius dujardini after exposure to UVC radiation.
Analysis of DNA repair and protection in the Tardigrade Ramazzottius varieornatus and Hypsibius dujardini after exposure to UVC radiation.
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DOI：
10.1371/journal.pone.0064793
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Rothschild LJ
中科院分区：
文献类型：
--
作者：
Horikawa DD;Cumbers J;Sakakibara I;Rogoff D;Leuko S;Harnoto R;Arakawa K;Katayama T;Kunieda T;Toyoda A;Fujiyama A;Rothschild LJ
居住在陆地环境中的缓步动物对电离辐射和紫外线辐射表现出非凡的抵抗力，尽管人们对这种抵抗力的机制知之甚少。我们发现，陆生缓步动物 Ramazzottius varieornatus 能够耐受大剂量的 UVC 照射，因为它既能在干燥、脱水状态下防止在 DNA 中形成 UVC 诱导的胸腺嘧啶二聚体，又能修复在水合动物中形成的二聚体。在 R. varieornatus 中，2.5 kJ/m2 UVC 辐射诱导的 DNA 中胸腺嘧啶二聚体的积累在暴露于荧光灯但不在黑暗中的动物暴露后 18 小时消失。与该物种的水合标本相比，干燥的脱水 R. varieornatus 具有更高的紫外线辐射耐受性。另一方面，用作对照的淡水缓步动物 Hypsibius dujardini 对 UVC 辐射的耐受性比 R. varieornatus 弱得多，并且它不包含假定的 phrA 基因序列。 R. varieornatus 的脱水生物在 DNA 中积累的 UVC 诱导的胸腺嘧啶二聚体比水合生物少得多。这表明脱水有效地避免了 R. varieornatus 中 DNA 损伤的积累，并赋予该物种更好的紫外线辐射耐受性。因此，我们认为缓步动物对紫外线辐射的耐受性是由于 DNA 损伤修复和 DNA 保护的高能力，这是一种双管齐下的生存策略。
Tardigrades inhabiting terrestrial environments exhibit extraordinary resistance to ionizing radiation and UV radiation although little is known about the mechanisms underlying the resistance. We found that the terrestrial tardigrade Ramazzottius varieornatus is able to tolerate massive doses of UVC irradiation by both being protected from forming UVC-induced thymine dimers in DNA in a desiccated, anhydrobiotic state as well as repairing the dimers that do form in the hydrated animals. In R. varieornatus accumulation of thymine dimers in DNA induced by irradiation with 2.5 kJ/m2 of UVC radiation disappeared 18 h after the exposure when the animals were exposed to fluorescent light but not in the dark. Much higher UV radiation tolerance was observed in desiccated anhydrobiotic R. varieornatus compared to hydrated specimens of this species. On the other hand, the freshwater tardigrade species Hypsibius dujardini that was used as control, showed much weaker tolerance to UVC radiation than R. varieornatus, and it did not contain a putative phrA gene sequence. The anhydrobiotes of R. varieornatus accumulated much less UVC-induced thymine dimers in DNA than hydrated one. It suggests that anhydrobiosis efficiently avoids DNA damage accumulation in R. varieornatus and confers better UV radiation tolerance on this species. Thus we propose that UV radiation tolerance in tardigrades is due to the both high capacities of DNA damage repair and DNA protection, a two-pronged survival strategy.
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DOI：
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发表时间：
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影响因子：
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10.1073/pnas.0800966105
发表时间：
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影响因子：
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