Chlamydomonas Reinhardtii Response To Oxidative Stress Induced By Mercury

Mercury has become one of the major causes of toxic metal pollution in environment. However, its toxic mechanism is not fully understood. The aim of our study is to examine the induced damage by mercury in the green algae Chlamydomonas reinhardtii in different concentrations and in time course. In particular, we here focused on its oxidative stress caused by its production of free oxygen species (ROS). The unicellular green algae C. reinhardtii as model organism is used to study the physiological responses, biochemical and molecular mechanisms. Here we investigated the response of C. reinhardtii exposure 0, 1,2,4,6, and 8μM of Hg2+. Mercury induced dramatic reduction of growth by 50% at 4μM of Hg2+and increase in TBARS contents (measure of lipid peroxidation) as evidence for the oxidative damage of Hg. Production of reactive oxygen species (ROS) by Hg2+was investigated in C. reinhardtii. Simultaneously, the algae modulated the stress by inducing of antioxidant enzymes SOD, CAT and APX, which showed significant increase in activity and transcripts with the increasing of Hg2+up to 6μM. However, in our result, proline has showed early accumulation in the first hour of exposure to 1 to 6μM Hg2+. Finally, we prove that heme oxygenase participates in the antioxidant defense system in C. reinhardtii tolerance to heavy metal mercury stress.