亚历山大藻对海湾扇贝受精卵孵化的影响及致毒机制研究

Impacts and Toxic Mechanism of Dinoflagellate Alexandrium Species on Egg-hatching Success of Argopecten irradians Lamarck

研究了亚历山大藻对海湾扇贝受精卵孵化的影响及致毒机制。结果发现:八株产PSP毒素的亚历山大藻和两株不产PSP毒素的相关亚历山大藻均显著抑制海湾扇贝受精卵的孵化,说明这种抑制作用在亚历山大藻中具有一定的普遍性,且与PSP毒素无直接关系;一种PSP标准毒素STX也没有这种抑制作用,进一步证明可能存在其他毒素。以相关亚历山大藻为对象展开进一步研究发现该藻对受精卵孵化的半数抑制密度(ID50)为1 000个.mL-1;其藻液、重悬液、去藻液、内容物和藻细胞碎片均显著影响受精卵的孵化;研究还发现该藻能改变了担轮幼虫破坏细胞膜结构和胞内结构,促使细胞内产生大量溶酶体,但溶酶体的稳定性下降,表明相关亚历山大藻可能通过影响海湾扇贝早期发育阶段的细胞结构和免疫功能而导致孵化失败。

The main aim of this study was to investigate toxic effect and mechanisms of Alexandrium species on eggs-hatching success of Argopecten irradians. The results showed, eight strains of PSP-producer Alexandrium species and two strains of non-PSP-producer A. affine had significantly detrimental effects, which indicated that it was a common feature of Alexandrium species that produced other than PSP toxins responsible for fertilized-egg hatching failure. The dissolved PSP toxins standard saxitoxin （STX） had no such inhibition on egg-hatching success, which further implied that fertilized-egg hatching failure was not related to other non-PSP toxins. A. affine AC - 1, which was non-PSP producer, was chosen to further study the detrimental effects on eggs-hatching success of A. irradians. Results showed, when exposed to 100 cells ·mL^-1, hatching rates were lower significantly than that in control group, when exposed to 3000 cells · mL^-1 , the hatching rate was 0, , and the median inhibiting densities （ID50） was 1000 cells· mL^-1; Algal culture, re-suspended cells, free-cell medium, cell fragments and cell content of A affine all had markedly adverse impacts. A. affine destroyed cellular uhrastructure of the trochophore larvae, damaged cellular membrane structure and cytoplasm structure, and induced a plenty of lysosome; Moreover, A. affine decreased lysosomal stability, made lysosome break easily, and damaged larval immune ability. It is thereby very likely that A. affine AC - 1 had effects on cellular structure and function of A. irradians in early developmental sta- ges to inhibit fertilized-egg hatching of A. irradians.