扇贝循环系统生理功能对极端温度与低氧胁迫的响应与调控机理

In the lase decade, extremely high or quick change of water temperature and expanding of hypoxia area have been threatening the survival of coastal marine organism. Of all marine invertebrates, scallops are more fragile to environmental stress, hence can be severely affected by marine environment disasters. Regulation of physiological activities is important way for mollusks and other invertebrate to adapt the environment change. Modulation of circulatory function such as cardiac activity and blood supply distribution is essential to guarantee the metabolic demand and help the animal to conquer the stress. But unfortunately, for lacking appropriate technique, research on the response and modulate mechanism of scallop’s circulatory function to environment stress lags behind. In this project, Doppler ultrasonic imaging technique is applied to study the circulatory physiological profiles of scallops Chlamys farreri and Chlamys nobilis, under extreme temperature and hypoxia stress, aiming to reveal: (1)the basal circulatory characteristics of the scallop; (2)the coordination between the circulatory physiological dynamics and metabolic activity of different organs during stress reaction; (3) the regulate effect of key neurotransmitters- neuropeptide (FMRF amide) and catecholamine, to circulatory physiological functions. Results will give firm support to understand the important role of circulatory system and its modulating mechanism under environmental stresses. Comparison will also be made to confirm the impact of different temperature adaptation range on the resilience of the two scallop species to stress factors.

近十几年来，气候变化导致的极端温度和低氧区扩大等环境问题频繁威胁着近海海洋生物的生存。扇贝对环境胁迫的抗性相对较低，因而成为受影响最大的种类之一。生理活动的调整是贝类等无脊椎动物适应环境变化的重要途径，而心脏活动、血液供给分配等循环生理功能的适应性变化则是保障代谢需求、协助机体应对胁迫的关键。目前由于缺少合适的监测技术，扇贝循环生理功能对胁迫的响应机理研究一直难以开展。本项目应用“基于多普勒超声成像的循环生理研究技术”，选择两种不同耐温习性的扇贝—栉孔扇贝（Chlamys farreri)和华贵栉孔扇贝（C. nobilis)，重点聚焦极端温度和低氧胁迫因子，开展三方面研究：①环境胁迫下扇贝不同器官循环生理指标变动规律；②循环生理指标与机体代谢水平变化的偶联关系；③神经内分泌系统对循环系统生理功能的调控作用。研究结果以期揭示扇贝循环生理功能调整在机体应对胁迫中的作用及其种间差异。

海洋低氧区扩大以及极端温度事件频发严重威胁着近海海洋贝类的生存。面对不利环境，贝类通过生理活动调整来促进内稳态恢复。循环系统生理是维持机体内稳态的重要一环，研究其对环境变化的响应规律与调控机理是揭示贝类如何应对环境胁迫并重建内稳态的有效途径。本项目聚焦极端温度和低氧胁迫因子，应用多普勒超声成像技术研究：①环境胁迫下扇贝不同组织器官循环生理指标变化；②循环生理指标与机体代谢水平变化的偶联关系；③神经内分泌系统对循环系统生理功能的调控作用。.确定了栉孔扇贝和华贵栉孔扇贝4种关键循环生理指标的正常范围阈值，发现心率、鳃的生理指标与温度显著相关；华贵栉孔扇贝心率存在昼夜节律，摄食活动对其会产生影响。.高温胁迫会对两种扇贝的循环生理功能产生显著影响：持续高温胁迫下栉孔扇贝循环生理指标异常波动之后大幅下降，循环系统发生器质性损伤；快速升温胁迫下各生理指标也产生类似变化，但扇贝的耐受性较持续高温要强。华贵栉孔扇贝在典型的波动式高温条件下，其心率与鳃的血流指标也呈现波动变化。低氧胁迫下，华贵栉孔扇贝心率与收缩峰值血流速度先上升之后维持稳定，舒张末期血流速度无显著变化，各组织供血比例发生变化，其中闭壳肌血量显著降低。.高温和低氧胁迫下相应组织的4种关键代谢酶活指标与循环生理指标变动之间并非如预期假设的高度同步，而是仅存在部分耦合关系。鳃血流指标-柠檬酸合成酶，闭壳肌血流量-ATP含量间存在一定协同变化规律。结果表明环境胁迫条件下，贝类代谢机能调整可能涉及其它生理层面。.验证了三种儿茶酚胺类激素对华贵栉孔扇贝的循环生理指标会产生显著影响，其效应浓度为0.2和1μM，而2μM浓度则会抑制扇贝的循环生理功能。.本项目研究结果深化了对扇贝循环生理机能应对环境胁迫的机制，发现循环生理与组织代谢水平间并非简单的协同关系。研究结果为深入揭示环境胁迫下贝类循环生理调控机理提供了数据支持。