我国南海有毒底栖甲藻蛎甲藻属(Ostreopsis)系统学和产毒特性研究

The Ostreopsis is the toxic benthic dinoflagellate genus which produce palytoxin(PLTX) and its analogs, one of the most potent toxic compounds. The species of this genus are widely distributed in tropical and subtropical seas. They are extending to the temperate waters. Harmful events associated with Ostreopsis, have been reported more frequently over the last decade including in areas where those benthic genera were hardly known. Except that of ciguatera fish poisoning (CFP) produced by Gambierdiscus, one of the most popular algal toxins in benthic ecosystem, the palytoxin produced by Ostreopsis is another important toxins in benthic ecosystem and are responsible for one of the most common algal toxin-related illnesses globally and often with significant long-term ecosystem negative effects. So far Ostreopsis have not been extensively investigated worldwide. The biodiversity of this genus have never been studied in the nearshores in the south China benthic ecosystems. The phylogeny, toxicity, and degree to which various environmental factors regulating the distribution and toxicity of individual Ostreopsis populations are largely unknown and would be a major focus on the study. The South China Sea and islands within the areas is a typical tropical and subtropical ecosystems with rich substrates for benthic dinoflagelles growth. We propose to study the biodiversity, phylogeny and toxicity of benthic Ostreopsis in the area. The objectives for the study are to answer the following scientific questions: The biodiversity and the distribution pattern of the species in the area, the phylogeny of Ostreopsis species and their relationship with strains from the nearby waters, the toxicity of the species and the environmental parameters that affect the local distribution and the toxin production.

蛎甲藻属是一类可形成有害藻华的底栖有毒甲藻，能够产生目前已知毒性最强的非蛋白类藻毒素-海葵毒素，且其分布范围具有不断扩大的趋势，近年来引起了国际有害藻华研究领域的广泛关注，成为该领域研究热点之一。我国对于蛎甲藻的研究极为稀少，本项目拟从形态分类学、分子系统学和毒性研究为切入点，全面揭示我国南海的蛎甲藻属种类多样性、分布特征、分子特性、毒性及产毒调控的环境因素等。为实现上述目标，本研究将通过对我国南海近岸及代表性岛屿的底栖甲藻样品进行广泛采集、分离、鉴定及系统发育研究，确定其生物多样性及其分类学地位；通过实验室批量培养及其不同培养条件的胁迫，研究蛎甲藻的毒性及其环境调控机制。本研究结果将为蛎甲藻属种类在全球分布的态势分析填补我国海区的空白，并对全面了解我国海洋底栖有毒甲藻的生物多样性提供依据，同时为底栖甲藻藻华的防灾减灾提供科学依据。

蛎甲藻属（Ostreopsis）是海洋底栖甲藻的重要门类，部分可以产生剧毒的海葵毒素（Palytoxins, PLTXs）。本项目在中国南海海域进行了大范围采样，并将采样范围扩展到东海、黄海和渤海海域，建立了大量蛎甲藻单克隆株系，并进行了细致的形态学、分子系统学和毒性研究。项目研究结果主要包括4个部分：. 1. 通过大范围的采样和实验室分析，发现在中国南海海域26个调查海区发现蛎甲藻分布，揭示蛎甲藻在我国南海海域的广泛分布。. 2. 通过光镜、扫描电镜等的形态学研究，结合分子系统学，鉴定出中国南海海域广泛分布的蛎甲藻属有两个种：O.ovata和O. lenticularis，这两个种都为中国新纪录种。. 3. 通过小鼠生物毒性试验，在筛查的我国南海116株系砺甲藻中，有41株具有小鼠毒性，症状与已报道海葵毒素造成的小鼠中毒症状一致。. 4、探究了砺甲藻产生的海葵毒素粗提物对凡纳滨对虾氧化应激和免疫反应的影响。揭示了注射海葵毒素提取物后的凡纳滨虾腮和肝胰腺中氧化应激参数（LPO和MDA），免疫酶（T-AOC和T-NOS）以及免疫相关基因（Crustin，Toll和cMnSOD）的mRNA表达发生了变化。从机理上为海葵毒素产生危害进行了深度阐释。. 5、利用液质联用的方法对海葵毒素进行了定性定量分析。检测出部分样品含OVTX-c， OVTX-d/e， OVTX-g和OVTX-f等海葵毒素成分。发现了不同地域株系产毒特性存在差异，同一地区不同株系产毒特性也存在差异。. 6、探讨了我国砺甲藻种类产生胞外多糖的特征及其与温度的关系，揭示了温度可以影响蛎甲藻生长速率、色素水平及多糖的产生。. 本项目对中国南海蛎甲藻属的生物多样性、地理分布和毒性的系统研究在国内尚属首次，填补了国内该领域研究的多项空白，为后续研究提供了坚实基础，对于保障海洋水产品安全和消费者健康具有重要意义。