节球藻毒素对草鱼淋巴细胞凋亡毒性效应及机理

节球藻毒素是水华水体中发现的一种新型蓝藻毒素，鱼类很容易受到节球藻毒素的影响.本研究发现节球藻毒素能够体外诱导草鱼淋巴细胞发生凋亡.电镜观察从形态学上发现节球藻毒素诱导的草鱼淋巴细胞呈现明显的细胞质浓缩、染色质凝集以及边缘化等典型细胞凋亡特征.梯队状DNA进一步证实凋亡的发生.1、10和 100 μg·L^-1的节球藻毒素体外诱导草鱼淋巴细胞12 h后，凋亡率分别达到19.4%、31.6%和71.6%，具有明显的剂量效应特征.节球藻毒素诱导的草鱼淋巴细胞凋亡与胞内活性氧物质增加、线粒体膜电位下降、胞钙含量上升、Bcl₂基因下调和Bax基因上调有关；此外，Caspase-3和Caspase-9两种酶参与该凋亡过程.表明节球藻毒素能够通过线粒体通路诱导鱼体淋巴细胞发生凋亡.

Toxic effect of nodularin on the apoptosis of grass carp (Ctenopharyngodon idellus) lymphocytes and related mechanisms.

Nodularin is a new kind of cyanobacterial toxins found in water blooms worldwide, and fish is very easily to suffer from the negative effects induced by this toxin. This study found that nodularin could induce the apoptosis of Ctenopharyngodon idellus lymphocytes in vitro. The observation of transmission electron microscopy showed that under the impacts of nodularin, the lymphocytes presented typical apoptosis features, such as obvious cytoplasm condensation and nuclear chromatin agglutination and marginalization. The DNA ladder fragmentation further confirmed the occurrence of the apoptosis of the lymphocytes. After incubated with 1, 10, and 100 μg·L-1 of nodularin for 12 h, the percentages of apoptotic lymphocytes reached 19.4%, 31.6%, and 71.6%, respectively, suggesting a dose dependent manner. The nodularin induced apoptosis was related to the increase of intracellular reactive oxygen species (ROS), decline of mitochondrial transmembrane electric potential, up regulation of intracellular Ca2+, down regulation of Bcl2, and up regulation of Bax. Meanwhile, the activation of Caspase-3 and Caspase-9 were involved in the process of apoptosis. These results strongly indicated that nodularin could induce the apoptosis of fish lymphocytes via mitochondria pathway.