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> Exp Gerontol. 2008 Jun 11. [Epub ahead of print]
>
> The exceptional longevity of an egg-laying mammal, the short-beaked
> echidna (Tachyglossus aculeatus) is associated with peroxidation-
> resistant membrane composition.
>
> Hulbert AJ, Beard LA, Grigg GC.
>
> Metabolic Research Centre & School of Biological Sciences, University
> of Wollongong, Wollongong, NSW 2522, Australia.
>
> The echidna Tachyglossus aculeatus is a monotreme mammal from
> Australia that is exceptionally long-living. Its documented maximum
> lifespan of 50 years is 3.7 times that predicted from its body mass.
> Other exceptionally long-living mammals (naked mole-rats and humans)
> are known to have peroxidation-resistant membrane composition, raising
> the question about echidnas. Phospholipids were extracted from
> skeletal muscle, liver and liver mitochondria of echidnas and fatty
> acid composition measured. As with other exceptionally long-living
> mammals, membrane lipids of echidna tissues were found to have a lower
> content of polyunsaturates and a higher content of monounsaturates
> than predicted for their body size. The peroxidation index
> (=peroxidation susceptibility) calculated from this membrane
> composition was lower-than-expected for their body size, indicating
> that the cellular membranes of echidnas would be peroxidation-
> resistant. Additionally when the calculated peroxidation index was
> plotted against maximum lifespan, the echidna values conformed to the
> relationship for mammals in general. These findings support the
> membrane pacemaker theory of aging and emphasise the potential
> importance of membrane fatty acid composition in aging and in the
> determination of maximum longevity.
>
> PMID: 18586080 [PubMed - as supplied by publisher]