Shifting Balance of Protein Synthesis and Degradation Sets a Threshold for Larval Growth Under Environmental Stress
Shifting Balance of Protein Synthesis and Degradation Sets a Threshold for Larval Growth Under Environmental Stress
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DOI：
10.1086/696830
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发表时间：
2018-02-01
影响因子：
1.6
通讯作者：
Manahan, Donal T.
中科院分区：
文献类型：
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作者：
Frieder, Christina A.;Applebaum, Scott L.;Manahan, Donal T.
外源环境因素改变增长率，但信息仍然缺乏的生化机制和能源权衡的基础上的变化，在海洋无脊椎动物的增长。在这里，我们研究的生化基础差异生长和能量利用（作为腺苷三磷酸[ATP]当量）在双壳类Crassostrea gigas幼虫生长暴露于实验性海洋酸化水平的增加（控制，中，高pCO（2），分别对应于类似于400，类似于800，类似于1100 mu atm）。升高的pCO（2）阻碍了幼虫增加壳和全身蛋白质含量的能力。这种负面影响不是由于不能合成蛋白质本身，因为相对于对照pCO（2），在中等和高pCO（2）处理下，蛋白质合成的大小特异性速率上调高达45%。相反，蛋白质降解速率随着pCO（2）的增加而增加。在对照pCO（2）下，幼虫89%的细胞能量（ATP当量）利用仅由两个过程占，其中蛋白质合成占66%，钠-钾转运占23%。提高蛋白质合成速率所需的能量需求可以通过重新分配现有ATP库中的可用能量或通过增加总ATP的产量来满足。前一种策略在中等pCO（2）下观察到，而后一种策略在高pCO（2）下观察到。pCO（2）的增加也改变了钠-钾转运，但相对于对蛋白质合成的影响，对ATP利用率的影响很小。量化的实际能源成本和权衡维持生理稳态响应压力将有助于揭示机制的弹性阈值的环境变化。
Exogenous environmental factors alter growth rates, yet information remains scant on the biochemical mechanisms and energy trade-offs that underlie variability in the growth of marine invertebrates. Here we study the biochemical bases for differential growth and energy utilization (as adenosine triphosphate [ATP] equivalents) during larval growth of the bivalve Crassostrea gigas exposed to increasing levels of experimental ocean acidification (control, middle, and high pCO(2), corresponding to similar to 400, similar to 800, and similar to 1100 mu atm, respectively). Elevated pCO(2) hindered larval ability to accrete both shell and whole-body protein content. This negative impact was not due to an inability to synthesize protein per se, because size-specific rates of protein synthesis were upregulated at both middle and high pCO(2) treatments by as much as 45% relative to control pCO(2). Rather, protein degradation rates increased with increasing pCO(2). At control pCO(2), 89% of cellular energy (ATP equivalents) utilization was accounted for by just 2 processes in larvae, with protein synthesis accounting for 66% and sodium-potassium transport accounting for 23%. The energetic demand necessitated by elevated protein synthesis rates could be accommodated either by reallocating available energy from within the existing ATP pool or by increasing the production of total ATP. The former strategy was observed at middle pCO(2), while the latter strategy was observed at high pCO(2). Increased pCO(2) also altered sodium-potassium transport, but with minimal impact on rates of ATP utilization relative to the impact observed for protein synthesis. Quantifying the actual energy costs and trade-offs for maintaining physiological homeostasis in response to stress will help to reveal the mechanisms of resilience thresholds to environmental change.