Desiccation is a commonly stressful situation experienced by sea cucumber during transportation without/less water. The present study was conducted to investigate the effects of aerial exposure on the survival, oxidative damage, antioxidant capacity, immune-related response and gene expression of Apostichopus japonicus at different low temperatures. After acclimation, sea cucumbers were randomly divided into 3 groups, which were exposed to 5 °C, 10 °C and 15 °C in the closed laboratory condition, respectively. Each group has three parallel replicates. During the experiment, coelomic fluid and respiratory tree of A. japonicus were sampled at the time points of 0, 3, 6, 12, 24 and 48 h post-desiccation for further analysis. The results showed that the survival rates of sea cucumber significantly decreased as time prolonged, and those of 5 °C at 6-48 h of desiccation were significantly higher than 15 °C. Most oxidative damage parameters (e.g., O2- production, MDA, LPO and PC contents) significant increased after 6-12 h of desiccation. Antioxidant enzyme activities and T-AOC in coelomic fluid firstly increased and then decreased during aerial exposure, indicating that sea cucumber could adjust antioxidant defense to reduce the concentrations of ROS and MDA as a strategy for protecting organisms from oxidative damage in the early stage (0-6 h) of desiccation. The relative expression levels of Hsp90 and Hsp70 mRNA in respiratory tree of sea cucumber exhibited similar rise-fall trends with antioxidant parameters, while immune enzyme activities of ACP, AKP, LSZ and T-NOS, and gene expression of TLR, Rel and p105 all significantly decreased as time prolonged. Overall, low temperature postponed the process of ROS formation and the depression of antioxidant and non-specific immune responses of sea cucumber within a certain extent, which implied that it might play a positive role in improvement of desiccation tolerance. This study not only contribute to better understand the adaption mechanisms of A. japonicus to desiccation stress, but also provide valuable information for sea cucumber culture and transportation.

中文翻译：

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空气暴露对低温下海参刺参的氧化应激，抗氧化剂和非特异性免疫反应的影响。

干燥是海参在无水或少水的运输过程中经常遇到的压力情况。本研究旨在研究不同低温下空气暴露对日本刺参的存活，氧化损伤，抗氧化能力，免疫相关反应和基因表达的影响。适应后，将海参随机分为3组，分别在封闭的实验室条件下暴露于5°C，10°C和15°C。每组具有三个平行重复。在实验过程中，在干燥后0、3、6、12、24和48 h的时间点采样了刺槐的体液和呼吸道树，以进行进一步分析。结果表明，随着时间的延长，海参的存活率显着下降，干燥6-48 h时5°C的温度明显高于15°C。干燥6-12小时后，大多数氧化损伤参数（例如O2产生，MDA，LPO和PC含量）显着增加。暴露于空气中时，结肠液中的抗氧化酶活性和T-AOC会先升高然后降低，这表明海参可以调节抗氧化剂防御能力，以降低ROS和MDA的浓度，作为早期保护生物免受氧化损伤的一种策略（0 -6 h）干燥。海参呼吸树中Hsp90和Hsp70 mRNA的相对表达水平表现出与抗氧化参数相似的上升下降趋势，而ACP，AKP，LSZ和T-NOS的免疫酶活性以及TLR，Rel和p105的基因表达全部随着时间的延长显着减少。总体，低温在一定程度上推迟了ROS的形成过程以及海参抗氧化剂和非特异性免疫反应的降低，这可能在提高其耐干旱性方面发挥了积极作用。这项研究不仅有助于更好地了解刺槐对干旱胁迫的适应机制，而且还为海参的培养和运输提供了有价值的信息。