To understand the characteristics of autophagy induced by virus infection in microalgae Emiliania huxleyi, we used diverse techniques including transmission electron microscopy, fluorescence microscopy, immunolabeling and biochemical methodologies to investigate the role of autophagy in the interaction between E. huxleyi BOF92 and its specific virus EhV99B1. The results showed that virus infection induced autophagy and vacuolar acidification in host cells, concomitant with up-regulation of autophagy-related genes such as atg1, atg5, atg8 and atg12 (p < 0.01) and Vps34 protein involved in the induction and nucleation of autophagosomes (p < 0.01). The expression level of autophagy marker protein p62 was significantly down-regulated (p < 0.05) during viral infection, indicating enhanced autophagic flux and activated autophagy. The expressions levels of negative regulatory factors such as phosphatidylinositol (PI3K), phosphorylated protein kinase B (p-Akt) and phosphorylated target of rapamycin protein (p-TOR) were significantly decreased in the late stage of viral infection (p < 0.01). Moreover, the level of reactive oxygen species (ROS) increased dramatically (p < 0.01), accompanied by a significant reduction in mitochondrial membrane potential (MMP) and ATP levels (p < 0.01) during viral infection. In conclusion, EhV99B1 infection induces ROS production and mitochondrial membrane damage in host cells, and initiates autophagy by regulating the PI3K/Akt/TOR signal pathway. Therefore, autophagy, as a unique form of programmed cell death, is of great significance to the individual survival and population dynamics of phytoplankton respond to environmental and biological stress.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |