Growth and toxin production of paralytic shellfish toxin producing dinoflagellate in relation with adaptation mechanism to nutritional environment.

1.麻痹性贝毒（PSP）的病原甲藻塔玛亚历山大藻（Alexandiumtamarense）和链状亚历山大藻（A.catenella）对氨基酸具有选择性利用，表明它们具有氨基酸转运体等特殊的氨基酸合成机制。3.当氮源共存时，塔玛亚历山大藻和链状亚历山大藻对硝酸盐的利用优先于有机氮的利用，从而降低了它们的光合作用当它们使用氨基酸时，这些结果表明，这两个物种能够通过在自养和异养营养模式之间的转换来适应不同的营养环境; 4.证实了PSP毒素结合蛋白的存在，并认为这种毒素可能是塔玛链格孢和塔玛链格孢在氨基酸利用过程中毒素含量下降的原因; 5.黑暗条件下的检测表明，氨基酸的利用是两个物种生存的重要因素之一6.分离了亚历山大藻光合作用和氨基酸利用相关蛋白的cDNA，并鉴定了部分基因的表达模式; 7.亚历山大藻在自然环境中的发生和毒素含量与氨基酸浓度的关系比与硝酸盐和亚硝酸盐的关系更为密切。此外，扇贝排泄物对塔玛甲藻和链状甲藻的生长和产毒有显著的促进作用。8.对分离自马来西亚沃茨的亚历山大藻进行了生长和产毒研究，为阐明有毒甲藻的增殖机制提供基础数据。

1.Alexandrium tamarense and A.catenella, causative dinoflagellates of paralytic shellfish poisoning (PSP), showed selective use of amino acids for their nitrogen source, indicating that they possess some specific mechanism for incorporation of amino acids such as amino acid transporter.2.Ability to utilize organic N-source could not be confirmed for A.minutum, suggesting that nutritional character is different each other even within a same genus of Alexandrium.3.A.tamarense and A.catenella were found to use nitrate prior to organic nitrogen when these nitrogen sources coexist and to reduce their photosynthetic activity when they are using amino acid. These results suggest that these species can adapt to various nutritional environment by switching the nutrition mode between autotroph and heterotroph.4.Existence of PSP toxin binding protein was confirmed and suggested this type of toxin might explain the decrease of toxin contents in the process of amino acid utilization in A.tamarense and A.catenella.5.Examination under dark condition suggested that utilization of amino acid is one of the survival strategies for Alexandrium under unsuitable environmental condition for photosynthetic autotrophy.6.cDNAs encoding proteins involving photosynthesis and utilization of amino acid were isolated and a part of their gene expression patterns was recognized.7.Occurrence and toxin contents of Alexandrium in natural environment were suggested to be more closely related to the concentration of amino acid than that of nitrate or nitrite. In addition, excretion of scallop was found to significantly promote the growth and toxin production of A.tamarense and A.catenella.8.Growth and toxin production were examined for the Alexandrium isolated from Malaysian waters to collect basic data for the elucidation of expanding mechanisms of toxic dinoflagellates.