Proteomic responses to ocean acidification in the brain of juvenile coral reef fish

Elevated CO2 levels predicted to occur by the end of the century can affect the physiology and behaviour of marine fishes. For one important survival mechanism, the response to chemical alarm cues from conspecifics, substantial among-individual variation in the extent of behavioural impairment when exposed to elevated CO2 has been observed in previous studies. Whole brain transcriptomic data has further emphasized the importance of parental phenotypic variation in the response of juvenile fish to elevated CO2. In this study, we investigate the genome-wide proteomic responses of this variation in the brain of 5-week old spiny damselfish, Acanthochromis polyacanthus. We compared the accumulation of proteins in the brains of juvenile A. polyacanthus from two different parental behavioural phenotypes (sensitive and tolerant) that had been experimentally exposed to short-term, long-term and inter-generational elevated CO2. Our results show differential accumulation of key proteins related to stress response and epigenetic markers with elevated CO2 exposure. Proteins related to neurological development and glucose metabolism were also differentially accumulated particularly in the long-term developmental treatment, which might be critical for juvenile development. By contrast, exposure to elevated CO2 in the parental generation resulted in only three differentially accumulated proteins in the offspring, revealing potential for inter-generational acclimation. Lastly, we found a distinct proteomic pattern in juveniles due to the behavioural sensitivity of parents to elevated CO2, even though the behaviour of the juvenile fish was impaired regardless of parental phenotype. Our data shows that developing juveniles are affected in their brain protein accumulation by elevated CO2, but the effect varies with the length of exposure as well as due to variation of parental phenotypes in the population.

研究预测，本世纪末将达到的升高二氧化碳（CO₂）浓度，将会对海洋鱼类的生理机能与行为表现产生影响。针对一项关键生存机制——对同种个体（conspecifics）化学警戒线索的响应，既往研究已观察到，个体在暴露于升高的CO₂浓度时，其行为受损程度存在显著的个体间差异。全脑转录组学（transcriptomic）数据进一步证实了亲本表型变异在幼鱼应对升高CO₂浓度响应中的重要作用。
本研究以5周龄的棘雀鲷（Acanthochromis polyacanthus）为实验对象，探究其脑部该类变异的全基因组蛋白质组学（proteomic）响应。我们对来自两种不同亲本行为表型（敏感型与耐受型）的棘雀鲷幼鱼脑部的蛋白质积累水平进行了比较，这些幼鱼分别接受了短期、长期以及跨代升高CO₂浓度的实验暴露处理。
研究结果显示，随着CO₂浓度升高，与应激反应及表观遗传标记相关的关键蛋白质出现了差异积累。尤其在长期发育暴露处理组中，与神经发育和葡萄糖代谢相关的蛋白质同样呈现差异积累，这或许对幼鱼的正常发育至关重要。与之形成鲜明对比的是，亲本代暴露于升高的CO₂浓度仅会导致子代出现3种差异积累的蛋白质，这揭示了跨代驯化的潜在可能性。
此外，我们发现，尽管幼鱼的行为均会因CO₂浓度升高而受损，但由于亲本对升高CO₂浓度的行为敏感性差异，幼鱼脑部呈现出独特的蛋白质组模式。本研究数据表明，发育中的幼鱼脑部蛋白质积累会受到升高的CO₂浓度影响，且这种影响会随暴露时长以及种群中亲本表型变异的不同而产生差异。