Analysis of life span by DNA transfection of antioxidant defense genes in oxygen-dependent short-lived mutants.

为了探讨氧自由基在衰老中的作用，分离了线虫中对氧敏感的抗氧化防御基因及其突变体。结果（1）克隆了锰超氧化物歧化酶（Mn-superoxide dismutase，SOD）基因。（2）氧敏感突变株mev-1即使在大气条件下也具有较短的寿命，其寿命随氧浓度的变化而变化。该突变体的Cu，Zn-SOD活性约为野生型的一半。mev-1突变体比野生型以更快的速度积累了更多的荧光物质。此外，积累速率依赖于氧浓度。由于该表型已被广泛用作衰老标记，这些结果表明mev-1可能是早衰的突变体。(3)在Ⅱ号染色体上已经发现了一个Cu，Zu-SOD（sod-1），最近在Ⅲ号染色体上又发现了一个Cu，Zu-SOD（sod-4），mev-1基因可能编码sod-4本身，因为这两个基因位于Ⅲ号染色体上的同一区域。mev-1突变体与野生型之间的mRNA水平没有差异，而mev-1突变体中sod-4基因的显微注射，以了解该基因的作用正在进行中。(4)另一种氧敏感突变体mev-3，在高浓度氧下培养，其发育、繁殖力和平均寿命分别受到抑制、降低和缩短。该基因的分子克隆正在进行中。

To investigate the possible role of oxygen free radicals in aging, antioxidant defense genes and mutants of the nematode C.elegans which are hypersensitive to oxygen were isolated. Then we tried to inject these genes into these oxygen-sensitive mutants to know their roles.Results(1) We cloned a Mn-superoxide dismutase (SOD) gene(2) An oxygen-sensitive mutant mev-1 has a short life span even under atmospheric condition and the life span changes depending on concentration of oxygen. This mutant has about half the wild-type level of Cu, Zn-SOD activity. The mev-1 mutant accumulated more fluorescent material at a greater rate than does wild type. Furthermore, the accumulation rates depended on concentration of oxygen. Since this phenotype has been widely used as an aging marker, these results suggested which mev-1 may be a mutant of premature aging.(3) It has already been found a Cu, Zu-SOD (sod-1) on the chromosome II.Recently, another Cu, Zu-SOD (sod-4) has been found on the chromosome III.The mev-1 gene may code the sod-4 itself because these genes are located at the same region on the chromosome III.By RT-PCR method, there were no difference in the mRNA level between the wild type and mev-1 mutant.Microinjection of the sod-4 gene in the mev-1 mutants to know the role of the gene is in progress.(4) Another oxygen-sensitive mutnat mev-3 of which development, fecundity and mean life span was retarded, reduced and shortened, respectively, when animals were incubated under high concentration of oxygen. Molecular cloning of the gene is in progress.