Large‐scale mortality and limited expression of heat shock proteins of aestivating sea cucumbers Apostichopus japonicus after acute salinity decrease |
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| Authors: | Xian‐Liang Meng Yun‐Wei Dong Shuang‐Lin Dong |
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| Affiliation: | 1. Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China;2. The Key Laboratory of Mariculture, Ministry of Education, Fisheries College, Ocean University of China, Qingdao, China;3. State Key Laboratory of Marine Environmental science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China |
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| Abstract: | This study deals with the mortality and related physiological responses of aestivating sea cucumber Apostichopus japonicus to acute salinity decrease. Aestivating and active sea cucumbers were exposed to a decrease in salinity (from 30 to 20 psu) at a rate of 2.5 psu every 6 h, and then maintained at 20 psu for 96 h. The mortality of aestivating sea cucumbers was ~30%, which was significantly higher than that of active sea cucumbers (~10%). This result indicated that sea cucumbers in aestivation were more susceptible to hypo‐salinity stress. To elucidate the underlying physiological mechanisms, the osmotic pressure in coelomic fluid and the levels of hsp70 and hsp90 mRNA in aestivating and active sea cucumbers were measured. No significant difference in osmoregulation was observed between the two groups. The osmotic pressure of coelomic fluid in both groups changed with decrease in ambient salinity. There were significant differences in the time course and magnitude of hsp70 and hsp90 expression between the two groups. After exposure to decreased salinity, aestivating sea cucumbers showed a delayed up‐regulation of hsp70 and hsp90 expression compared with animals in active state, and these levels decreased rapidly to control values. The expression of hsp70 and hsp90 in aestivating sea cucumbers were significantly lower than those in active sea cucumbers after salinity change. The differences in hsp70 and hsp90 expression between the states may partly explain the higher mortality of sea cucumbers in aestivation when exposed to low salinity. |
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| Keywords: | aestivation
hsp70
hsp90
osmotic pressure salinity sea cucumber |
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