Hagelbäck Philip, Jönsson K Ingemar
Department of Environmental Science, Kristianstad University, Kristianstad, Sweden.
Front Physiol. 2023 Sep 5;14:1249773. doi: 10.3389/fphys.2023.1249773. eCollection 2023.
Tardigrades are small aquatic invertebrates with well documented tolerance to several environmental stresses, including desiccation, low temperature, and radiation, and an ability to survive long periods in a cryptobiotic state under arrested metabolism. Many tardigrade populations live in habitats where temporary exposure to hypoxia is expected, e.g., benthic layers or substrates that regularly undergo desiccation, but tolerance to hypoxia has so far not been thoroughly investigated in tardigrades. We studied the response to exposure for hypoxia (<1 ppm) during 1-24 h in two tardigrade species, cf. and . The animals were exposed to hypoxia in their hydrated active state. Survival was high in both species after the shortest exposures to hypoxia but tended to decline with longer exposures, with almost complete failure to recover after 24 h in hypoxia. cf. tended to be more tolerant than . When oxygen level was gradually reduced from 8 to 1 ppm, behavioral responses in terms of irregular body movements were first observed at 3-4 ppm. The study shows that both limno-terrestrial and freshwater tardigrades are able to recover after exposure to severe hypoxia, but only exposure for relatively short periods of time. It also indicates that tardigrade species have different sensitivity and response patterns to exposure to hypoxia. These results will hopefully encourage more studies on how tardigrades are affected by and respond to hypoxic conditions.
缓步动物是小型水生无脊椎动物，对包括干燥、低温和辐射在内的多种环境压力具有耐受性，并且能够在代谢停滞的隐生状态下长期存活。许多缓步动物种群生活在预期会暂时缺氧的栖息地，例如经常经历干燥的底栖层或基质，但迄今为止，缓步动物对缺氧的耐受性尚未得到充分研究。我们研究了两种缓步动物（分别为cf.和）在1至24小时内对低氧（<1 ppm）暴露的反应。这些动物在其水合活跃状态下暴露于低氧环境。在最短时间暴露于低氧后，两种物种的存活率都很高，但随着暴露时间延长，存活率趋于下降，在低氧环境中暴露24小时后几乎完全无法恢复。cf.往往比更具耐受性。当氧气水平从8 ppm逐渐降至1 ppm时，在3至4 ppm时首次观察到不规则身体运动方面的行为反应。该研究表明，陆生和淡水缓步动物在暴露于严重低氧后都能够恢复，但仅在相对较短的暴露时间内。这也表明不同的缓步动物物种对低氧暴露具有不同的敏感性和反应模式。这些结果有望鼓励更多关于缓步动物如何受到低氧条件影响以及如何对其做出反应的研究。
