Unincorporated iron pool is linked to oxidative stress and iron levels in Caenorhabditis elegans.
Free radicals or reactive oxygen species (ROS) are relatively short-lived and are difficult to measure directly; so indirect methods have been explored for measuring these transient species. One technique that has been developed using Escherichia coli and Saccharomyces cerevisiae systems, relies on a connection between elevated superoxide levels and the build-up of a high-spin form of iron (Fe(III)) that is detectable by electron paramagnetic resonance (EPR) spectroscopy at g = 4.3. This form of iron is referred to as "free" iron. EPR signals at g = 4.3 are commonly encountered in biological samples owing to mononuclear high-spin (S = 5/2) Fe(III) ions in sites of low symmetry. Unincorporated iron in this study refers to this high-spin Fe(III) that is captured by desferrioxamine which is detected by EPR at g value of 4.3. Previously, we published an adaptation of Fe(III) EPR methodology that was developed for Caenorhabditis elegans, a multi-cellular organism. In the current study, we have systematically characterized various factors that modulate this unincorporated iron pool. Our results demonstrate that the unincorporated iron as monitored by Fe(III) EPR at g = 4.3 increased under conditions that were known to elevate steady-state ROS levels in vivo, including: paraquat treatment, hydrogen peroxide exposure, heat shock treatment, or exposure to higher growth temperature. Besides the exogenous inducers of oxidative stress, physiological aging, which is associated with elevated ROS and ROS-mediated macromolecular damage, also caused a build-up of this iron. In addition, increased iron availability increased the unincorporated iron pool as well as generalized oxidative stress. Overall, unincorporated iron increased under conditions of oxidative stress with no change in total iron levels. However, when total iron levels increased in vivo, an increase in both the pool of unincorporated iron and oxidative stress was observed suggesting that the status of the unincorporated iron pool is linked to oxidative stress and iron levels.
Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, CA 92834, USA.
Natalie A
NA
Rangel
Lawrence
L
Lin
Kanyasiri
K
Rakariyatham
Albert
A
Bach
Kim
K
Trinh
Matthew H S
MH
Clement
Chandra
C
Srinivasan
D000375:Aging / Q000378:metabolism; D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D018869:Heat-Shock Response; D006861:Hydrogen Peroxide / Q000633:toxicity; D007501:Iron / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D016877:Oxidants / Q000633:toxicity; D018384:Oxidative Stress; D010269:Paraquat / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism
D016877:Oxidants; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D007501:Iron; D010269:Paraquat