Oxidative damage shortens the life span of the nematode Caenorhabditis elegans (C elegans), even in an
age-1 mutant that is characterized by a long life and oxygen resistance. We found that daily short-term exposure (3 h) to hyperoxia further extended the life span of
age-1, a phenomenon known as an adaptive response.
age-1 also showed resistance to paraquat and heat. Acute hyperoxic treatment did not extend the life spans of wild type,
daf-16 or
mev-1.
daf-16 mutant had a slightly shorter life span compared to wild type and was sensitive to heat and paraquat. The
daf-16 phenotype resembles that of
mev-1 showing a short life and oxygen sensitivity. We measured mRNA levels of superoxide dismutase genes (
sod-1 through 4), catalase genes (
clt-1 and
ctl-2), known to encode anti-oxidant enzymes, and found they were elevated in
age-1 young adults. On the other hand, in
daf-16 and
mev-1, the expression of
sod-1,
sod-2 and
sod-3 genes was lower rather than in wild type. Conversely,
ctl-1 and
ctl-2 genes expression was significantly elevated in
daf-16 and
mev-1. This suggests that DAF-16, a forkhead/winged-helix transcription factor, whose expression is suppressed by AGE-1, phosphoinositide 3-kinase (PI3-kinase), regulates anti-oxidant genes as well as energy metabolism under atmospheric conditions. However, the level of gene expression of SOD and catalase was not elevated by short-term exposure to 90% oxygen in wild type,
mev-1,
daf-16 and even
age-1. This suggests that SOD and catalase do not play a role in the adaptive response against oxidative stress under hyperoxia, at least under these experimental conditions.