From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Sat May 24 2003 - 13:22:28 MDT
[...in flies at least. Motor neuron degeneration is known to limit maximum
fly longevity. By comparison cancer is the main limiting factor in
rodents, but not in humans. (Only 4% of human centenarians die of
cancer.) In humans atherosclerosis is the main limiting factor, with
declines in immunity playing a secondary role. These two factors may be
connected... There may exist no general theory of aging at all. Instead
the nature of "aging" may vary for different species.)]
J Biol Chem 2003 May 12; [epub ahead of print]
Effects of overexpression of Cu-Zn and Mn superoxide dismutases, catalase
and thioredoxin reductase genes on longevity in Drosophila melanogaster.
The overexpression of antioxidative enzymes such as Cu-Zn superoxide
dismutase (SOD), Mn SOD and catalase has previously been reported to
extend life span in transgenic flies (Drosophila melanogaster). The
purpose of the present study was to determine whether life-extending
effects persist if the recipient control strains of flies are relatively
long-lived. Accordingly, the life spans of large numbers of replicate
control and overexpressor lines were determined in two long-lived genetic
backgrounds, involving a combined total of more than 90 000 flies.
Significant increases in the activities of both Cu-Zn SOD and catalase had
no beneficial effect on survivorship in relatively long-lived y w mutant
flies, and were associated with slightly decreased life spans in wild
type flies of the Oregon-R strain. The introduction of additional
transgenes encoding Mn SOD or thioredoxin reductase in the same genetic
background also failed to cause life span extension. In conjunction with
data from earlier studies, the results show that increasing the
activities of these major antioxidative enzymes above wild type levels
does not decrease the rate of aging in long-lived strains of Drosophila,
although there may be some effect in relatively short-lived strains.
This archive was generated by hypermail 2.1.5 : Sat May 24 2003 - 13:32:31 MDT