12 October 2019 | New Scientist | 37it does eat, a python rebuilds with explosive
speed. Within a day, the small intestine has
more than doubled its mass and other organs,
including the liver, pancreas, heart and kidneys
all swell by a half or more. Then, between
24 and 48 hours after eating, its innards start
withering back to starvation mode, and the
whole process is reversed in just two weeks.
Underlying this dramatic transformation
is an equally dramatic burst of gene activity.
Castoe’s team compared this activity in
different organs at different times before and
after feeding. Predictably, many of the genes
are involved in growth. But what intrigues
Castoe are other genes that usually help protect
cells against stress and were previously only
associated with cancer and ageing. Turning
these stress-response genes off while the
growth ones remain on seems to trigger the
organs to shrink back down again. “We think
we’ve discovered a kind of back-door switch
for how to modulate regenerative growth in
a vertebrate,” says Castoe.
The big question is what controls this
dramatic response. The answer seems to
be something in the snake’s blood. Add
plasma – the liquid part of blood – from a
recently fed snake to rat cells in a dish, and
they undergo a burst of growth, switching
on a similar suite of genes to those the snake
cells activate. This suggests that whatever is
signalling to the python’s organs can talk to
mammalian cells too. Castoe’s team is now
hot on the trail of the mysterious signal.
“I don’t think you’d ever want a drug that made
every one of your organs freak out and grow,”
he says. But the possibility of using insights
from pythons to regenerate specific organs
or block the growth of tumours is tantalising.
There is more to this research than
mimicking animal superpowers. Extreme
adaptations also offer a unique window into
our own biology. For example, researchers are
investigating pythons to better understand
how our physiology changes after eating, in
a bid to learn more about conditions such as
diabetes and obesity.
Nature’s fantastic beasts can help us see
what life is capable of, too. “What we’re
learning about basic biology from such a
weird perspective is so valuable,” says Castoe.
“It’s almost like looking at a mountain from
90 degrees to one side.” ❚effort currently has several gaps. But clues
are emerging. Unlike red-eared sliders,
naked mole rats don’t bother producing lots
of antioxidants and so end up with bizarrely
high levels of cellular damage from an early
age. They seem to protect themselves from
the consequences of this damage by boosting
the activity of genes that stop damaged cells
from dividing. These are genes that humans
also possess. The rodent’s metabolism is
unusual too – resembling that of animals on
a calorie-restricted diet, which is associated
with longevity.Regenerating pythons
Interest in naked mole rats is high, but only
time will tell whether we can tap into their
powers to combat ageing and cancer.
Meanwhile, another remarkable animal
holds the promise of an even more futuristic
capability. The python’s special power is
extreme regeneration. These snakes starve
for months before gobbling an entire animal
in one sitting. So, to conserve energy, they let
their internal organs shrivel between meals.
“In a fasting python, the intestine looks like
a little tube that’s empty,” says Todd Castoe at
the University of Texas at Arlington. But whenDon’t miss Rebecca Nesbit discuss which animals we should
save from extinction on 13 October at New Scientist Live
newscientistlive.comClaire Ainsworth is a
freelance writer based
in Hampshire, UKEY
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suggested, means they don’t have to race to
reproduce and so have evolved to devote more
of their resources to combating the cellular
damage caused by their stressful environment.
Over the years, scientists have tested this
resilience by exposing them (or their cells in
a dish) to a range of challenges including UV
light, toxic compounds and high doses of
chemotherapy drugs. The naked mole rat
simply shrugs them off. “Most of the time they
just put their little third finger up at you and
say, ‘I don’t care’,” says Buffenstein.
This resilience means they don’t seem to
age. As they get older, their heart function,
bone density, muscle mass and metabolism
stay healthy. A 30-year-old female mole rate is
still highly fertile. What’s more, their resistance
to developing cancer is legendary. In three
decades of study, Buffenstein’s team has
encountered only five cases of the disease
when examining more than 2000 dead
animals. They have also inserted versions
of genes known to cause cancer into naked
mole rat cells in a lab dish. In other mammals,
this causes aggressive tumours to grow, but
not in these little rodents.
To fully explore the naked mole rat’s
remarkable capabilities, we will need
a complete version of its genome – our bestTa r d i g r a d e s ( l e f t)
are capable of
suspended
animation and
wood frogs (far
left) can survive
freeze-thawing