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Closing in on true cause of ageing / New Scientist | 24 September 2022


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Uh oh .... here we go again on same ol' "were gettin' closer" cliche.

Anyway, as the article suggests, certain animals don't seem to follow DNA clocks (bowhead whales). I don't think DNA clocks will work for CR'd organisms. " Because the
maximum lifespan isn’t known " . Unless Al's gotta paper on that proving otherwise 😉


Closing in on true cause of ageing

New Scientist | 24 September 2022

DNA clocks, which allow us to accurately work out how old almost any mammal is,
are challenging old ideas of what really leads to ageing, discovers Michael Le Page

----Rhinos are among the many
mammals whose age can be
estimated using DNA clocks----

THE age of almost any mammal
can now be accurately estimated
from a tissue sample by analysing
chemical tags on DNA. The finding
comes from a study of nearly
200 species and could overturn
our understanding of ageing.
The team involved says the
fact that all mammals seem to
have the same “ageing clocks”
shows that ageing is the result
of developmental programs that
have been retained during the
evolution of mammals, rather
than being solely due to
accumulating damage.
If something is conserved
across different species, it
is a sign that it is biologically
important, says Steve Horvath at
the University of California, Los
Angeles, who led the work. “You
simply would not be able to build
these pan-mammalian clocks if
there wasn’t something here
that’s conserved.”

The clocks are already being
used by other teams to help study
ageing and potential anti-ageing
therapies. For instance, one team
has shown that giving old mice
young blood sets these clocks back
in many organs, says Horvath.
The new finding is a result of
looking at which bits of DNA in
cells have chemical tags called
methyl groups added to them.
These methyl groups get naturally
added to or removed to alter the
activity of genes, in what are
known as epigenetic changes.
These methylation patterns
vary greatly in different types of
cells. However, in 2011, Horvath
showed that in human blood
cells, certain small bits of DNA
accumulate methyl groups in a
consistent way over time, and so
can be used to roughly estimate
a person’s age.

In 2013, his team identified
another “epigenetic clock”
that signals the age of any human tissue, not just blood,
suggesting there is an ageing
process common to all human
cells. The team has also identified
“epigenetic clocks” for different
species, such as elephants.
The latest clocks are based on
studies of nearly 12,000 samples
from 59 different tissue types
across 185 species of mammal.
This included several species each
of lemurs, whales, goats, rhinos,
bats, seals, kangaroos, wallabies,
shrews and sloths, as well as the
rock hyrax, Pacific walrus and
platypus (bioRxiv, doi.org/jcn9).
“What we show is that there
are these certain locations –
genomic regions – that gain
methylation in an extremely
consistent way in all of these
very different mammalian
species,” says Horvath.

Based on these regions, the
team has developed three versions
of the clock. One estimates an
individual animal’s age in years.
Another estimates age relative
to the maximum lifespan of the
species, which can be converted
into years if the maximum
lifespan is known. Because the
maximum lifespan isn’t known
for some species, the team also
developed a third version that
calculates age relative to that at
which sexual maturity is reached.
The clocks are about 97 per cent
accurate overall, but this varies
from species to species. For
bowhead whales, they were
particularly poor, but this is probably because the existing
method used to calculate the
age of bowheads is inaccurate,
says Horvath.
Because the clocks work
in such a wide range of
mammals, he thinks they
will work for any mammal,
not just the species in the study.
The team also did a number of
other tests, showing, for instance,
that the clocks run more slowly in
mouse strains that are genetically
engineered to live longer, and
that they get set back to an earlier
age when specialised cells are
reprogrammed to turn them
back into stem cells.

The work has impressed
others in the field. “This is a really
good study,” says David Gems at
University College London.
The findings run counter to
the overriding thinking on what
causes ageing. The dominant idea
is that it is due to accumulation
of damage, for example to DNA,
such as that caused inside cells
by highly reactive molecules
known as free radicals. But
Gems says the epigenetic clocks
add to growing evidence for an
alternative idea that he calls
the programmatic theory.
The basic premise of this is that
the body’s failure to completely
switch off the developmental
processes that build our bodies
is the key to ageing. For instance,
pruning connections between
neurons in the brain is a vital part
of development when we are
young, but might contribute
to cognitive decline in later life.
“It doesn’t argue that molecular
damage plays no role in ageing,
rather that ageing is largely caused
by other things,” says Gems.

Horvath found many of the
sites that gain methylation tags
with age are next to genes related
to development. These results
support the idea that ageing
is linked to developmental
processes common to all
mammals – and probably all
vertebrates, too, says Horvath.

“That, to me, is a smoking gun,
that there are these processes that
are conserved,” he says. “There
must be some sort of a program.”
“The body’s failure to
switch off developmental
processes that build our
bodies is the key to ageing”


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Hi Khrram!

I also subscribe to New Scientist -- their articles tend to be sensationalist; I much prefer Science News, which is a much better Science rag.

About the article:  methylation is only one way that the activity of a particular gene can be altered; there are other known (and unknown) epigenetic modifiers.

Different tissue types in the same living animal plant or fungus have different epigenetic modifiers, likely activating a gene in one tissue while deactivating the same gene in another tissue.

  --  Saul

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1 hour ago, Saul said:

Hi Khrram!

I also subscribe to New Scientist -- their articles tend to be sensationalist; I much prefer Science News, which is a much better Science rag.



Please realize that science mags like NS operate on a business model, as does the NY Times, etc. They gotta put food on the table, like everyone. Many of the experienced top journalist know the game and try to play it the best as the can given basic human desires for "hope" and "art" and "entertainment". That's what sells. As Chomsky noted in Manufacturing Consent, the top editors play the instrument carefully, fine tuning the violin strings, staying music and listenable, to squeeze as much "fact" and  "hope" and "art" and "entertainment" as possible. A difficult superposition. 

Yes, I follow Science News, too. It sticks to topics and agenda that are far less philosophical than NS. Both mags have different goals and agendas. You gotta read 'em differently 😉

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I subscribe to, and read, both as well.

(BTW, Science News is published by Science Service, which I think hosts the Intel Science Competition (which used to be called the Westinghouse Scholarship Competition, or something similar.

I was a Westinghouse Honorable Mention in 1960.)

  --  Saul

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