Regrowing Their Tails Prevents DNA Repair And Can Shorten Lizards' Lives

When it comes to DNA repair, this skink has some tricks up its sleeve, at least as long as it keeps its tail. Geoff While

Many lizards drop their tails to escape predators. Unlike mammals, they are able to regrow the lost tissue, but they pay a high price to do it. One aspect of this is a loss of the telomeres that otherwise keeps cells throughout their body young.

The ends of chromosomes are capped by telomeres, which provide protection against various sorts of damage. With rare exceptions, most of our cells lose telomere length as we age, leading to disease and loss of cell function. Finding a way to extend our telomeres is often seen as a potential fountain of youth that would halt the aging process.

If so, it's a fountain the lizard species Niveoscincus ocellatus may have already found. University of Tasmania PhD student Luisa Fitzpatrick studied these spotted snow skinks before and after some dropped their tails.

She reports in Biology Letters that when times were good, the lizards were actually lengthening the telomeres on their chromosomes. However, those that dropped their tails stopped extending their telomeres until it had finished regrowing.

Fitzpatrick told IFLScience these findings were not quite as she and her co-authors anticipated. They predicted tail regrowth would be accompanied by a shortening of the telomeres, rather than maintenance, and had not expected such impressive telomere extensions the rest of the time. Fitzpatrick said she finds lizards "really interesting to study telomere dynamics in because they can have changes in both directions. That is not seen in humans or lab mammals other than in the first stages of development."

At least part of the secret of the skinks' success is their abundant production of telomerase, an enzyme that restores damaged telomeres. However, to regrow their tails, skinks are forced to up their metabolic rate and cell division, putting telomeres under so much oxidative stress that the telomerase can only fight it to a draw.

The fact lizards can lengthen their telomeres and are also outstanding at tissue regrowth seems, to the untrained eye, unlikely to be a coincidence. Fitzpatrick told IFLScience that “it's possible telomerase is the reason they can regrow their tails,” but this is not yet proven.

Years ago, when asked by the ABC about the application of her work to prevent human aging, Fitzpatrick said she was much more interested in animals. She stood by that comment to IFLScience. She is intrigued by the question of why lizards, at least those with tails intact, age at all. Many fish have similar capacities, and as Fitzpatrick said: “A study in zebrafish found older ones have a lot less telomerase. I'd like to do a comparison of regrowth capacity in young and old lizards.”

If you hope lizards hold the key to eternal life, you'll need someone else to translate their code.

You'd laugh too if you'd found the fountain of youth as long as you kept all appendages attached. Geoff While

 

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