It is recently thought that the aging and longevity of life are controlled by the energy metabolism through an insulin-like signal transduction in the lower to higher organisms. Furthermore, it is speculated that the reactive oxygen species (ROS), the by-product on the route of the energy metabolic systems, are responsible for the aging process. It is also believed that the control of ROS production and protection of organic molecule from the produced ROS are somewhat connected to the lifespan extension. Superoxide dismutase (SOD) has a catalytic activity as the reduction of superoxide radicals. In four SOD genes of Caenorhabditis elegans (C. elegans), sod-1 gene encoding a Cu/Zn SOD is mainly expressed in cytoplasm as a subcellular location. This gene is related to aging and acts to resist to oxidative damage. We have decided to investigate the phenotypes in aging, concentrating on two deletion mutants of sod-1 gene derived from National Bioresource Project for the Experimental Animal Nematode C. elegans. One of these deletion mutants, tm783, has its part of promoter regions, exon 1 and 2 deleted. The other strain, tm776, has its exon 3, 4 and 5 completely deleted. Both strains are viable as homozygous. However, the average life span of these strains was slightly decreased compared to the one of wild type N2. We then measured sensitivities of these strains against oxidative stress using agents such as paraquat and oxygen. The oxygen resistances in tm776 and tm783 animals were not very clearly reduced than wild type. In contrast, the paraquat resistances in these strains were markedly decreased compared with wild type. In the sod-1 mutations, the tm783 strains showed a marked sensitivity to paraquat than tm776. It is likely that paraquat produces more ROS in cell at a single time than oxygen. Therefore, it is thought that result of the paraquat sensitivity test could reflect that there are much more activities within the intracellular anti-oxidant systems. tm783 animals may have decreased amount of sod-1 transcript, as this strain has the deletion in promoter region. Conversely, we could hypothesize that as the transcript of tm776 animals does not have the latter part the Cu/Zn SOD activities in tm776 animals are decreased. Thus, it is speculated that control of ROS is extremely important to extend the longevity of organisms such as the regulation of Cu/Zn SOD activities.

Affiliations:
- Kanagawa Pref Inst Pub Health
- Dept Mol Life Sci, Tokai Univ Sch Medicine, Isehara, Kanagawa, Japan