Original Contribution Manganous ion supplementation accelerates wild type development, enhances stress resistance, and rescues the life span of a short – lived Caenorhabditis elegans mutant Yi-Ting Lin, Hanh Hoang, Scott I. Hsieh, Natalie Rangel, Amanda L. Foster 1 , James N. Sampayo 1 , Gordon J. Lithgow 1 , Chandra Srinivasan ⁎ Department of Chemistry and Biochemistry, California State University, Fullerton, Fullerton, CA 92834, USA Received 19 April 2005; revised 21 October 2005; accepted 8 November 2005 Available online 12 December 2005 Abstract Relative to iron and copper we know very little about the cellular roles of manganese. Some studies claim that manganese acts as a radical scavenger in unicellular organisms, while there have been other reports that manganese causes Parkinson’s disease-like syndrome, DNA fragmentation, and interferes with cellular energy production. The goal of this study was to uncover if manganese has any free radical scavenging properties in the complex multicellular organism, Caenorhabditis elegans. We measured internal manganese in supplemented worms using inductively coupled plasma mass spectrometry (ICP-MS) and the data obtained suggest that manganese supplemented to the growth medium is taken up by the worms. We found that manganese did not appear to be toxic as supplementation did not negatively effect development or fertility. In fact, supplementation at higher levels accelerated development and increased total fertility of wild type worms by 16%. Manganese- supplemented wild type worms were found to be thermotolerant and, under certain conditions, long-lived. In addition, the oxidatively challenged C. elegans strain mev-1’s short life span was significantly increased after manganese supplementation. Although manganese appears to be beneficial to C. elegans, the mode of action remains unclear. Manganese may work directly as a free radical scavenger, as it has been postulated to do so in unicellular organisms, or may work indirectly by up regulating several protective factors. © 2005 Elsevier Inc. All rights reserved. Keywords: Aging; Oxidative stress; Antioxidant; Superoxide dismutase; Free radicals; Manganese; Caenorhabditis elegans; Thermotolerance; Heat shock Introduction Manganese (Mn) is an essential ultratrace element similar to chromium, molybdenum, and cobalt. It is needed for a wide variety of physiological processes ranging from the regulation of repro- duction to normal brain function. It is also required for several enzymes including arginase, pyruvate carboxylase, glycosyl trans- ferase, E. coli aminopeptidase, and the mitochondrial antioxidant enzyme, manganese superoxide dismutase (MnSOD). Mn can exist in various oxidation states ranging from -3 to +7, with +2 oxidation state being the most predominant in biological systems. Unlike the well-studied transition metal ions, copper, iron, and zinc, not much is known about ionic manganese in vivo, although several recent studies have focused on trying to understand the biological chemistry of manganese [1]. Ionic manganese appears to have free radical scavenging properties as demonstrated by the fact that aerobic growth defects of several SOD-null bacterial species can be rescued by Mn(II) supplementation [2]. In the aerobic organism Lacto- bacillus plantarum, which lacks SOD, ionic manganese levels are high (30 mM), and it is thought that manganese complexed to intracellular high molecular weight polyphosphate might provide a defense against superoxide [3]. In bacterial systems, low molecular weight manganese complexes are thought to be working in conjunction with antioxidant enzymes such as SOD and catalase to provide a defense against oxygen radicals [2]. Comparison of several lactic acid bacterial species indicates that Free Radical Biology & Medicine 40 (2006) 1185 – 1193 www.elsevier.com/locate/freeradbiomed Abbreviations: ROS, reactive oxygen species; SOD, superoxide dismutase; MnSOD, manganese-containing SOD; CuZnSOD, copper, zinc-containing SOD; ICP-MS, inductively coupled plasma mass spectrometry; Mn, ionic manganese; FUDR, 5-fluoro-2-deoxyuridine; WT (or N2), wild type worm. ⁎ Corresponding author. Fax: +1 714 278 5316. E-mail address: chandra@fullerton.edu (C. Srinivasan). 1 The Buck Institute, 8001 Redwood Blvd., Novato, CA 94945, USA. 0891-5849/$ - see front matter © 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.freeradbiomed.2005.11.007