Testing the Free Radical Theory of Ageing in Bats
A.K. Brunet-Rossinni
Department of Ecology, Evolution, and Behavior, University of Minnesota, 1987 Upper Buford Circle, Saint Paul, MN 55108, USA
The extended longevity of bats, despite their high metabolic rate, may
provide insight to patterns and mechanisms of ageing. I tested the free
radical theory of ageing as an explanation for the extreme longevity of
the little brown bat, Myotis lucifugus (maximum lifespan potential
"MLSP" = 34 yrs). In a comparative study, I measured whole-organism
oxygen consumption and mitochondrial hydrogen peroxide production in
brain, heart, and kidney tissues from M. lucifugus and short-tailed
shrews, Blarina brevicauda (MLSP = 2 yrs). As predicted by the free
radical theory of ageing, M. lucifugus produced approximately half the
amount of hydrogen peroxide as B. brevicauda. Additionally, I compared
oxygen consumption and hydrogen peroxide production of adult (~ 1 yr)
and juvenile (fully developed and fledged young of the year) Myotis
lucifugus to assess oxidative damage to mitochondria (measured as an
increase in hydrogen peroxide production) due to the high metabolic
rate associated with flight. Contrary to my prediction, juveniles had
significantly higher levels of hydrogen peroxide production than
adults. I propose that the decreased free radical production in adults
is the result of within-individual selection of efficient mitochondria
due to selective pressure created by the high energetic demands of
flight.
Key words:
free radical theory, long-lived organism, bats
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