Figure 12

A schematic diagram depicting the mechanism of algal cell death under PG stress. (a) PG may be transferred across the cell membrane by ABC transporters; (b) PG likely stimulates photosynthesis to generate excess ROS; (c) the antioxidant system, including GSH, SOD, POD and CAT, are activated to scavenge ROS; (d) the excess ROS could lead to lipid peroxidation, and the cellular membrane permeability and integrity are damaged, which likely results in necrotic-like cell death; (e) PG may bind to nucleotides, especially purine (ribo)nucleosides, and the excess ROS could cause DNA damage; (f) the damaged DNA may be partially repaired by the nucleotide excision repair system; (g) the excess ROS could disrupt the thylakoid membrane and inhibit photosynthesis as the treatment time increases; (h) PG may target the ribosomes, which could interfere with protein synthesis.