radiodurans can withstand 10,000 times the amount of radiation
that would kill a human, earning it monikers like "Super Bug" and "Conan
the Bacterium." Studies revealed a unique, almost bizarre, ability to repair
numerous DNA double strand breaks--the most lethal kind of genetic damage--within
Its DNA is highly damaged at 1.7 million rads. (One thousand rads is deadly to humans.) Its DNA is all chopped up. There are between 1,000 and 2,000 DNA fragments per cell, but they’re all fixed in about 24 hours.
What's significant about this is that genetic damage has just been shown to be the most likely cause of aging. Bacteria, of course, are immortal. Sex cells are immortal, or babies would be born 22 years old. If we could learn the secret of deinococcus radiodurans, could we greatly extend human life spans?
" --from ScienceDaily, 4/4/2000"
Somehow, nature apparently has a way of repairing even
badly damaged DNA. In the case of deinococcus radiodurans, this
hyper-repair is occurring within the nucleus of a cell that isn't in a
reproductive state, so it argues that such a thing can happen at times other
than a zygotic phase. On the other hand, these cells represent undifferentiated
tissue, unlike somatic cells. My fantasy when I read about this is that there
might be some governing protein or proteins specific to their corresponding
genes (every gene produces one protein) that are released in a mitotic cell to
effect this genetic rejuvenation. If that were the case, wouldn't it be
wonderful if we could reproduce this result throughout the whole body! But it
could be that the lack of initial differentiation of embryonic cells is a
prerequisite for this process. On the other hand, the ability of deinococcus
radiodurans to routinely repair DNA damage might argue otherwise.
I know so little about this, but all of a sudden, it's looking interesting.
One of the phenomena cited in relation to aging is the idea that the number of heartbeats in roughly the same for all animals. However, birds live for about four times the number of heartbeats that characterize mammalian species. Birds require a high metabolic rate in order to fly (think of a hummingbird!), and yet, they have fairly long life spans. Parrots have life spans nearly as long as humans.