Methane formation in cells (IMAGE) Max-Planck-Gesellschaft Caption ROS-driven methane formation in cells. Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) are generated during cellular metabolism and their production is enhanced by oxidative stress. Cells need iron for survival and reduce iron(III) [Fe3+] to iron(II) [Fe2+]. The interaction of ROS and Fe2+ leads to the Fenton reaction and thus to the formation of highly reactive tetravalent iron (FeIV) compounds and hydroxyl (-OH) radicals. These, in turn, attack methylated sulfur or nitrogen compounds (e.g. methionine), which are produced by cells or taken up from the environment. In doing so, a methyl radical (•CH3) is formed by oxidative demethylation, which then, by abstraction of a hydrogen atom (e.g., from other hydrocarbons), reacts to methane (CH4). Credit Max Planck Institute for Terrestrial Microbiology/Ernst Usage Restrictions Use of images is limited to editorial coverage of scientific topics relating to the activities of the Max Planck Society. Any kind of commercial use (including, in particular, the exploitation of images by means of sale or incorporation in image databases or image catalogues) as well as any promotional use/use for merchandise purposes, disclosure to third parties or granting of related rights to third parties is expressly not permitted. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.