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)的甲藻亚历山大藻(Alexandrium Tamarense)和链状亚历山大藻(A.catenella)表现出对氨基酸的选择性利用，表明它们对氨基酸转运体等氨基酸的结合具有特定的机制。2.微小亚历山大藻对有机氮源的利用能力尚不确定，表明即使在同一属内，它们的营养特性也是不同的。3.塔玛亚历山大藻和链藻在这两种氮源共存时优先利用硝酸盐，而当它们利用氨基酸时，它们的光合作用活性降低。这些结果表明，这些物种可以通过在自养和异养之间切换营养模式来适应不同的营养环境。4.证实了PSP毒素结合蛋白的存在，表明这种毒素的存在可能解释了塔玛亚历山大藻和链藻在氨基酸利用过程中毒素含量下降的原因。5.暗条件下的试验表明，氨基酸的利用是亚历山大藻在不适合光合作用自生的环境条件下的生存策略之一。6.分离到编码涉及光合作用和氨基酸利用的蛋白质的cDNA，并识别了其部分基因表达模式。7.发生和毒素含量自然环境中亚历山大藻的浓度与氨基酸浓度的关系比与硝酸盐或亚硝酸盐浓度的关系更为密切。此外，扇贝的排泄物还显著促进了塔玛拉藻和链藻的生长和毒素的产生。8.对从马来西亚水域分离的亚历山大藻的生长和毒素产生进行了检测，为阐明有毒甲藻的扩展机制收集基础数据。

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.