The antioxidant enzyme superoxide dismutase (SOD-4 ) in oxidative stress and aging in Caenorhabditis elegans

Oxidative stress is a condition that occurs in many organisms when they produce an excess of reactive oxygen species (ROS) which are harmful to organisms, as they can degrade biomolecules. This condition has been linked to many diseases such as Amyothorphic lateral sclerosis (ALS), and many others; likewise, it is linked to the acceleration of the aging process. Organisms protect themselves against production of ROS using antioxidant enzymes, such as superoxide dismutase. Copper/Zinc containing SOD (CuZnSOD) and Manganese containing SOD (MnSOD) are antioxidant enzymes found in all eukaryotic cells. Different studies have shown that the importance of MnSOD and CuZnSOD varies from one organism to another. C. elegans, a multicellular organism, has five SODS as opposed to other organisms that have only two or three. In this study, we used a homozygous knockout of the CuZnSOD (SOD-4) gene. This is a gene whose mRNA transcript is alternatively spliced giving rise to two different gene products SOD-4-1 and SOD-4-2. SOD-4-2 contains a putative transmembrane domain located on exon six and it is perhaps the first known membrane-bound member of the SOD family. The C. elegans Gene Knockout consortium created the homozygous knockout SOD-4 (VC-175) worm used in this experiment. We created an approved new strain, SOD-4 homozygous knockout (XA5500), using eight rounds of outcross technique to promote elimination of secondary mutations and the phenotype was studied in this new strain. XA5500 nematode did not show alteration in development or life-span. However, 10% decrease fecundity was observed compared to wild type (WT) worms suggesting that SOD-4 might play some role in fecundity.