Gene expression profiling in gills of the great spider crab Hyas araneus in respond to ocean acidification and warming, supplementary data

Hypercapnia and elevated temperatures resulting from climate change may have adverse consequences for many marine organisms. While diverse physiological and ecological effects have been identified, changes in those molecular mechanisms, which shape the physiological phenotype of a species and limit its capacity to compensate, remain poorly understood. Here, we use global gene expression profiling through RNA-Sequencing to study the transcriptional responses to ocean acidification and warming in gills of the boreal spider crab Hyas araneus exposed medium-term (10 weeks) to intermediate (1,120 µatm) and high (1,960 µatm) PCO2 at different temperatures (5°C and 10°C).
The analyses reveal shifts in steady state gene expression from control to intermediate and from intermediate to high CO2 exposures. At 5°C acid-base, energy metabolism and stress response related genes were upregulated at intermediate PCO2, whereas high PCO2 induced a relative reduction in expression to levels closer to controls. A similar pattern was found at elevated temperature (10°C). There was a strong coordination between acid-base, metabolic and stress-related processes. Hemolymph parameters at intermediate PCO2 indicate enhanced capacity in acid-base compensation potentially supported by upregulation of a V-ATPase. The likely enhanced energy demand might be met by the upregulation of the electron transport system (ETS), but may lead to increased oxidative stress reflected in upregulated antioxidant defense transcripts. These mechanisms were attenuated by high PCO2, possibly as a result of limited acid-base compensation and metabolic down-regulation.
Our findings indicate a PCO2 dependent threshold beyond which compensation by acclimation fails progressively. They also indicate a limited ability of this stenoecious crustacean to compensate for the effects of ocean acidification with and without concomitant warming.

气候变化引发的高碳酸血症（Hypercapnia）与温度升高，可能对众多海洋生物造成不良后果。尽管学界已探明多种生理与生态效应，但调控物种生理表型、限制其代偿能力的分子机制变化，仍有待深入阐释。
本研究借助RNA测序（RNA-Sequencing）开展全球基因表达谱分析，针对北黄道蟹（Hyas araneus）的鳃组织，探究其中长期（10周）暴露于中等（1120 µatm）与高（1960 µatm）二氧化碳分压（PCO2），并分别在5℃与10℃温度条件下，对海洋酸化与升温的转录响应。
分析结果显示，稳态基因表达在对照组至中等CO₂暴露组、中等至高CO₂暴露组间均发生显著偏移。在5℃条件下，与酸碱平衡、能量代谢及应激反应相关的基因在中等PCO₂条件下被上调；而高PCO₂则会使基因表达水平相对回落，趋近对照组。在升温条件（10℃）下亦观测到类似模式。酸碱平衡、代谢与应激相关通路存在显著协同调控。中等PCO₂条件下的血淋巴参数表明，酸碱代偿能力有所增强，这可能依赖于V型ATP酶（V-ATPase）的上调表达。潜在增加的能量需求可通过电子传递系统（electron transport system, ETS）的上调得以满足，但也可能引发氧化应激增强，表现为抗氧化防御相关转录本的上调。高PCO₂条件下上述机制受到抑制，这可能与酸碱代偿受限及代谢下调有关。
本研究结果表明，存在依赖于PCO₂的临界阈值，超过该阈值后，机体通过驯化实现的代偿能力会逐步丧失。同时也表明，这种狭温性甲壳动物（stenoecious）在伴随或不伴随升温的海洋酸化胁迫下，其代偿能力十分有限。