School of Earth and Environmental Sciences, University of St. Andrews, St. Andrews, KY16 9AL, UK.
Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
Sci Rep. 2020 Jul 30;10(1):12797. doi: 10.1038/s41598-020-69556-0.
Biomolecules play key roles in regulating the precipitation of CaCO biominerals but their response to ocean acidification is poorly understood. We analysed the skeletal intracrystalline amino acids of massive, tropical Porites spp. corals cultured over different seawater pCO. We find that concentrations of total amino acids, aspartic acid/asparagine (Asx), glutamic acid/glutamine and alanine are positively correlated with seawater pCO and inversely correlated with seawater pH. Almost all variance in calcification rates between corals can be explained by changes in the skeletal total amino acid, Asx, serine and alanine concentrations combined with the calcification media pH (a likely indicator of the dissolved inorganic carbon available to support calcification). We show that aspartic acid inhibits aragonite precipitation from seawater in vitro, at the pH, saturation state and approximate aspartic acid concentrations inferred to occur at the coral calcification site. Reducing seawater saturation state and increasing [aspartic acid], as occurs in some corals at high pCO, both serve to increase the degree of inhibition, indicating that biomolecules may contribute to reduced coral calcification rates under ocean acidification.
生物分子在调节 CaCO3生物矿化的沉淀中起着关键作用，但它们对海洋酸化的反应还知之甚少。我们分析了在不同海水 pCO2 条件下培养的大型热带鹿角珊瑚的骨骼内晶体氨基酸。我们发现，总氨基酸、天冬氨酸/天冬酰胺（Asx）、谷氨酸/谷氨酰胺和丙氨酸的浓度与海水 pCO2 呈正相关，与海水 pH 值呈负相关。珊瑚之间几乎所有的钙化率变化都可以用骨骼总氨基酸、Asx、丝氨酸和丙氨酸浓度的变化以及钙化介质 pH 值（可能是支持钙化的溶解无机碳的指示）来解释。我们表明，在体外实验中，天冬氨酸在 pH 值、饱和度状态和珊瑚钙化部位推断出的近似天冬氨酸浓度下抑制方解石的沉淀。降低海水饱和度状态和增加[天冬氨酸]，如在一些高 pCO2 条件下的珊瑚中发生的那样，都有助于增加抑制程度，表明生物分子可能导致海洋酸化下珊瑚钙化率降低。
