海带碘代谢对海洋酸化的应答与调控机制

Kelps are the strongest accumulators of iodine among living organisms. They represent a major pump in the global biogeochemical cycle of iodine, and are also the most important vegetables in the sea of the world. Nevertheless, the chemical state and biological significance of accumulated iodine have remained unknown to this date. Vanadium-dependent bromoperoxidases (vBPOs) and iodoperoxidases (vIPOs) of Saccharina are important peroxidases that catalyse the oxidation of halides in the presence of hydrogen peroxide, leading to the halogenation of various organic substrates. 17 vBPO and 59 vIPO genes were identified and annotated in the Saccharina japonica genome. In this study we would conduct experiments on iodine metabolism of S. japonica under global climate change especially under scenario of ocean acidification (OA). Firstly, we would determine the iodide uptake kinetics under various concentrations of iodide and its effects on algal growth, respiration, and photosynthesis; Secondly, we studied the effects of ocean acidification on iodide uptake rate and accumulation rates under increasing pCO2 from 280μatm，400μatm，700μatm，1000μatm，1500μatm，to 2000μatm, which mimics the CO2 concentration from pre-industrial to now, and extended year of 2100 and 2300. The molecular modulation mechanism of vBPOs and vIPOs were also analyzed in the above conditions; Finally, to simulate and predict the iodine metabolism to changing pCO2 under different CO2 emission scenarios, we would plot algal iodine absorption trails from preindustrial revolution to current, and future CO2 emission scenarios using the constructed iodine uptake kinetic models and pCO2 datasets representing four CO2 emission scenarios under Representative Concentration Pathways (RCP 3.0, RCP 4.5, RCP 6.0, and RCP 8.5).

海带是生物界最大的碘存储器，是碘生物地球化学循环的重要扮演者，同时也是世界上最重要的海洋蔬菜之一，然而海带（Saccharina japonica）碘素代谢机制尚不清楚。本项目以海洋酸化为全球气候变化大背景，以大型经济褐藻—海带为研究对象，在解析其基因组图谱、获取其卤素代谢通路的基础上，以碘代谢为切入点，解析海带碘吸收动力学以及环境碘浓度对其生长发育、光合、呼吸的影响；采用短期酸化应急实验和长期酸化适应性研究相结合的方式，对比研究不同酸化尺度下，海带碘吸收、积累、转化效率以及卤素过氧化物酶（vHPOs）基因表达模式，从生理生态学和分子生物学双重角度阐释海洋酸化对海带碘代谢的影响；结合全球气候变化条件下CO2释放路径数据（RCPs），反演并预测历史及未来海带碘代谢趋势。拟申报项目将为解析褐藻碘代谢机制提供重要参考，为预测未来海带碘素营养构成及碘生物地球化学循环提供数据支持。

海带是生物界最大的碘存储器，是碘生物地球化学循环的重要扮演者，同时也是世界上最重要的海洋蔬菜之一。在人类活动和气候变化的双重压力下，海洋生态系统结构和功能发生了显著变化。海洋藻类群体及其代谢机制演变，成为国际气候变化生态学领域关注的焦点之一。本项目以海洋酸化为全球气候变化大背景，以近岸生态系统典型大型藻类为代表，通过不同时空尺度的生态学实验，解析并预测了气候变化下大型藻群落走势；在此基础上，以大型褐藻—海带为主要研究对象，开展了海水酸化条件下海带碘代谢机制及食物网传递效应研究。研究结果表明海水酸化和适度升温条件下海带碘的吸收效率显著提高，而逆境条件下的碘释放效率显著增加；贝类喂食酸化条件下生长的海带后，其体组织碘含量显著增加，而甲状腺激素水平却明显降低；转录组学和蛋白组学研究结果表明适度酸化显著降低碘素代谢通路中卤代过氧化物酶（vHPOs）基因和蛋白的表达水平。研究结果揭示了气候变化条件下海带碘代谢的应答与调控机制，为准确评估未来碘生物地化循环格局演变提供了理论依据，也为人类碘素合理膳食提供了数据参考。