Cellular toxicity pathways of inorganic and methyl mercury in the green microalga Chlamydomonas reinhardtii

• Published in: Scientific reports Vol. 7; no. 1; pp. 8034 - 12
• Main Authors: Beauvais-Flück, Rebecca, Slaveykova, Vera I, Cosio, Claudia
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 14.08.2017; Nature Publishing Group UK; Nature Portfolio
• Subjects: Algae; Aquatic microorganisms; Bioavailability; Chlamydomonas reinhardtii; Ecotoxicology; Energy metabolism; Food contamination; Food webs; Life Sciences; Mercury; Metabolism; Oxidation; Photosynthesis; Physiology; Toxicants; Toxicity; Toxicology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-08515-8

Contamination by mercury (Hg) is a worldwide concern because of Hg toxicity and biomagnification in aquatic food webs. Nevertheless, bioavailability and cellular toxicity pathways of inorganic (IHg) and methyl-Hg (MeHg) remain poorly understood. We analyzed the uptake, transcriptomic, and physiological responses in the microalga Chlamydomonas reinhardtii exposed to IHg or MeHg. Bioavailability of MeHg was up to 27× higher than for IHg. Genes involved in cell processes, energy metabolism and transport were dysregulated by both Hg species. Physiological analysis revealed an impact on photosynthesis and reduction-oxidation reaction metabolism. Nevertheless, MeHg dysregulated a larger number of genes and with a stronger fold-change than IHg at equivalent intracellular concentration. Analysis of the perturbations of the cell's functions helped to derive a detailed mechanistic understanding of differences in cellular handling of IHg and MeHg resulting in MeHg having a stronger impact. This knowledge is central for the prediction of impact of toxicants on organisms.