Exploring the molecular mechanism of Chlorella vulgaris in response to androstenedione exposure based on genes continuously up-regulated in transcription analysis

Androstenedione (ADSD) is one of the widely detected androgens in diverse aquatic environments. However, there were few reports on the molecular mechanism of Chlorella vulgaris exposure to ADSD. In our previous research, we have investigated the genes associated with chlorophyll metabolism in Chlorella vulgaris response to ADSD. In this study, we focus on continuously up-regulated genes to explore the mechanism underlying Chlorella vulgaris resistance to ADSD toxicity. Chlorella vulgaris was exposed to ADSD with five concentration gradients. The continuously up-regulated genes were enriched by Series Test of Cluster (STC) analysis and verified by qRT-PCR. Microalgae Super Oxidase Dimutase (SOD) and Microalgae Malonic dialdehyde (MDA), two indicators of oxidative stress, were determined by ELISA after exposure to ADSD. The results showed that ADSD can stimulate the production of extracellular polymeric substances (EPS) and lead to enlargement in the cell body of Chlorella vulgaris. In addition, steroid biosynthesis and oxidoreductase activity processes were consistently up-regulated upon exposure to ADSD. In conclusion, our study highlighted the crucial role of phenotypic modification, hormone synthesis, and redox mechanisms in protecting Chlorella vulgaris cells from the harmful effects of ADSD contamination.