塔玛亚历山大藻对海湾扇贝胚胎发育过程的影响

研究了塔玛亚历山大藻（Alexandrium tamarense）ATHK株对海湾扇贝受精卵孵化的影响，并探讨了可能的影响机制。将海湾扇贝受精卵暴露于不同密度的塔玛亚历山大藻ATHK中，观察其对胚胎孵化各阶段的影响，并利用光镜和透射电镜对实验组和对照组胚胎的外部形态和内部结构进行连续观察。结果表明：该藻对海湾扇贝受精卵孵化有显著的抑制作用，其IC50约为800 mL-1；2000 mL-1的ATHK延缓或破坏了胚胎的正常发育，胚胎内部出现大量溶酶体，原肠胚腔不能形成，且部分细胞出现胞质肿胀、线粒体自溶的现象，细胞不能进行正常的功能性分化；观察发现实验组中有些担轮幼虫的外形畸变，鞭毛发育迟缓；至24 h（D型幼虫）时，ATHK组中的D型幼虫数量远远低于对照组（P<0.05），且死亡率明显高于对照组。观察还发现ATHK藻细胞和胚胎碰撞接触的现象，这种碰撞接触可能对有害物质的释放和转移有一定的刺激作用。

Effects of Alexandrium tamarense on embryonic development of Argopecten irradians

Dinoflagellate Alexandrium tamarense can produce paralytic shellfish poisoning(PSP) toxin and has significantly impacted the marine aquaculture and human beings worldwide.We have reported that A.tamarense had adverse effects on the activity and early development of shellfish and A.tamarense ATHK strain inhibited the egg hatching of A.irradians significantly.However,its effects on different phases of embryonic development of scallop and its mechanism were still obscure.In order to better understand its impacts on embryonic development of scallop and its mechanism,the effect of A.tamarense ATHK strain on hatching of Argopecten irradians Lamark was investigated,and its harmful mechanism was discussed in this paper.The fertilized eggs of A.irradians were exposed to A.tamarense,and the impacts on different phases of embryonic development of scallop were analyzed.The appearance and interior structure of the scallop larvae in the control and the experimental group were observed under optical microscope and transmission election microscope(TEM).The results showed that ATHK inhibited the hatching of A.irradians,and the median inhibiting concentration(IC50) was 800 mL-1.ATHK at the density of 2000 mL-1 arrested or destroyed the embryonic development.It was observed that there were a plenty of lysosomes in embryos with swollen cells and autolyzed mitochondria,and the archenteron was not able to form in time,which may result in the failure of embryo functional development.Some of the trochophore larvae exposed to A.tamarense(ATHK strain) showed malformation and the flagellum couldn't develop normally.The percentage of D-shape larvae in the ATHK treatment group was significantly lower and its mortality rate was obviously higher than that in the control after 24 h exposure.It was also observed that the ATHK cells contacted the scallop embryos,which may stimulate the production of toxic substances in some way.