Metabolism of the cyanobacterial toxin mycrocystin-LR is comparable in different aquatic organisms

The high nutrient load in many aquatic ecosystems leads to increased abundances of blue-green algae (cyanobacteria). Cyanobacteria are known to produce a wide range of toxins with adverse effects on many terrestrial and aquatic organisms. Furthermore, cyanobacterial blooms have been increasingly recognized as animal and human health hazards. In order to withstand chemical stressors, many organisms have developed a detoxication metabolism. It consists of three phases: (1) activation (P450-monooxygenases); (2) conjugation (glutathion S-transferases, and other transferases); and (3) further processing, deposition, or excretion. This study investigated the detoxication metabolism of microcystin-LR which is the most common cyanobacterial toxin. Uptake of microcystin-LR, effects of this toxin on glutathion S-transferase activities, and first detoxication steps were studied in different aquatic organisms. The organisms were choosen from different trophic levels of the aquatic ecosystem but showed a similar startpoint in the detoxication of microcystin-LR.