Research Unit in Environmental and Evolutionary Biology (URBE), Laboratory of Evolutionary Genetics and Ecology (LEGE), NAmur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium.
Research Unit in Environmental and Evolutionary Biology (URBE), Institute of Life, Earth & Environment (ILEE), University of Namur, Namur, Belgium.
BMC Biol. 2023 Apr 7;21(1):72. doi: 10.1186/s12915-023-01554-w.
Bdelloid rotifers are micro-invertebrates distributed worldwide, from temperate latitudes to the most extreme areas of the planet like Antarctica or the Atacama Desert. They have colonized any habitat where liquid water is temporarily available, including terrestrial environments such as soils, mosses, and lichens, tolerating desiccation and other types of stress such as high doses of ionizing radiation (IR). It was hypothesized that bdelloid desiccation and radiation resistance may be attributed to their potential ability to repair DNA double-strand breaks (DSBs). Here, these properties are investigated and compared among nine bdelloid species collected from both mild and harsh habitats, addressing the correlation between the ability of bdelloid rotifers to survive desiccation and their capacity to repair massive DNA breakage in a phylogenetically explicit context. Our research includes both specimens isolated from habitats that experience frequent desiccation (at least 1 time per generation), and individuals sampled from habitats that rarely or never experienced desiccation.
Our analysis reveals that DNA repair prevails in somatic cells of both desiccation-tolerant and desiccation-sensitive bdelloid species after exposure to X-ray radiation. Species belonging to both categories are able to withstand high doses of ionizing radiation, up to 1000 Gy, without experiencing any negative effects on their survival. However, the fertility of two desiccation-sensitive species, Rotaria macrura and Rotaria rotatoria, was more severely impacted by low doses of radiation than that of desiccation-resistant species. Surprisingly, the radioresistance of desiccation-resistant species is not related to features of their original habitat. Indeed, bdelloids isolated from Atacama Desert or Antarctica were not characterized by a higher radioresistance than species found in more temperate environments.
Tolerance to desiccation and radiation are supported as ancestral features of bdelloid rotifers, with a group of species of the genus Rotaria having lost this trait after colonizing permanent water habitats. Together, our results provide a comprehensive overview of the evolution of desiccation and radiation resistance among bdelloid rotifers.
蛭形轮虫是一种分布于世界各地的微小无脊椎动物，从温带地区到地球的最极端区域，如南极洲或阿塔卡马沙漠。它们已经在任何液态水暂时存在的栖息地中殖民，包括陆地环境，如土壤、苔藓和地衣，能够耐受干燥和其他类型的压力，如高剂量的电离辐射（IR）。据推测，蛭形轮虫的干燥和辐射抗性可能归因于它们潜在的修复 DNA 双链断裂（DSB）的能力。在这里，在从温和和恶劣栖息地收集的九个蛭形轮虫物种中研究和比较了这些特性，在系统发育明确的背景下探讨了蛭形轮虫生存干燥和修复大量 DNA 断裂的能力之间的相关性。我们的研究包括从经常经历干燥（至少每代 1 次）的栖息地分离的标本，以及从很少或从未经历干燥的栖息地采样的个体。
我们的分析表明，在 X 射线辐射暴露后，耐干燥和敏感的蛭形轮虫物种的体细胞中，DNA 修复占主导地位。属于这两个类别的物种都能够承受高达 1000 Gy 的高剂量电离辐射，而不会对其生存产生任何负面影响。然而，两个敏感的干燥物种， Rotaria macrura 和 Rotaria rotatoria 的繁殖力比耐干燥的物种受到低剂量辐射的影响更严重。令人惊讶的是，耐干燥的物种的辐射抗性与它们原始栖息地的特征无关。实际上，与在较温和的环境中发现的物种相比，从阿塔卡马沙漠或南极洲分离的蛭形轮虫并不具有更高的辐射抗性。
耐受干燥和辐射被认为是蛭形轮虫的祖先特征，Rotaria 属的一组物种在殖民永久性水栖息地后失去了这种特征。总之，我们的结果提供了蛭形轮虫干燥和辐射抗性进化的全面概述。
