Tiny Water Bears are Huge DNA Thieves: Study - Rawan For Media Artistic and Production
These
genes, the researchers suggest, help the tiny animals, also known as
moss piglets or tardigrades, survive in the harshest of environments.
Water
bears, which live all over the world, are usually 0.020 inches (0.5
millimetres) long and move very slowly and clumsily on their multitude
of legs.
These highly adaptable creatures can survive extreme temperatures.
Even
after being stuck in a freezer at -112 degrees Fahrenheit (-80 Celsius)
for 10 years, they can start moving around again about 20 minutes after
thawing.
By
sequencing these creatures' genome, researchers from the University of
North Carolina (UNC) at Chapel Hill were surprised to find that 17.5
percent -- nearly a sixth -- of the genome came from foreign organisms.
For most animals, less than one percent of their genome comes from foreign DNA.
The microscopic rotifer previously held the record, with eight percent of its genome coming from foreign DNA.
"We
had no idea that an animal genome could be composed of so much foreign
DNA," said co-author Bob Goldstein of UNC's College of Arts and
Sciences.
"We knew many animals acquire foreign genes, but we had no idea that it happens to this degree."
- New insight on evolution .
The
study, published in Monday's edition of the Proceedings of the National
Academy of Sciences, also made unusual findings about how DNA is
inherited.
Goldstein,
first author Thomas Boothby and colleagues found that water bears
obtain about 6,000 foreign genes mostly from bacteria, as well as
plants, fungi and Archaea single-cell organisms.
"Animals
that can survive extreme stresses may be particularly prone to
acquiring foreign genes -- and bacterial genes might be better able to
withstand stresses than animal ones," said Boothby, a postdoctoral
fellow in Goldstein's lab.
Indeed, bacteria have survived the most extreme environments on Earth for billions of years.
Water
bears acquire foreign genes through horizontal gene transfer, a process
by which species swap genetic material instead of inheriting DNA from
parents.
"With
horizontal gene transfer becoming more widely accepted and more
well-known, at least in certain organisms, it is beginning to change the
way we think about evolution and inheritance of genetic material and
the stability of genomes," said Boothby.
Researchers
said the DNA likely gets inside the genome randomly but what remains
allows water bears to survive in the most hostile environments.
Under intense stress, such as extreme dryness, the water bear's DNA breaks up into small pieces, according to the research team.
Once
the cell rehydrates, its membrane and nucleus housing the DNA
temporarily becomes leaky and allows other large molecules to pass
through easily.
They
thus repair their own damaged DNA while also absorbing foreign DNA as
the cell rehydrates, forming a patchworks of genes from different
species.
"So
instead of thinking of the tree of life, we can think about the web of
life and genetic material crossing from branch to branch," Boothby
explained.
"So it's exciting. We are beginning to adjust our understanding of how evolution works."
By AFP, 17 hours 16 minutes ago
The
eight-legged water bear - a hardy, nearly microscopic animal resembling
its mammal namesake - gets a huge chunk of its DNA from foreign
organisms such as bacteria and plants, scientists have revealed.
eight-legged water bear - a hardy, nearly microscopic animal resembling
its mammal namesake - gets a huge chunk of its DNA from foreign
organisms such as bacteria and plants, scientists have revealed.
These
genes, the researchers suggest, help the tiny animals, also known as
moss piglets or tardigrades, survive in the harshest of environments.
Water
bears, which live all over the world, are usually 0.020 inches (0.5
millimetres) long and move very slowly and clumsily on their multitude
of legs.
These highly adaptable creatures can survive extreme temperatures.
Even
after being stuck in a freezer at -112 degrees Fahrenheit (-80 Celsius)
for 10 years, they can start moving around again about 20 minutes after
thawing.
By
sequencing these creatures' genome, researchers from the University of
North Carolina (UNC) at Chapel Hill were surprised to find that 17.5
percent -- nearly a sixth -- of the genome came from foreign organisms.
For most animals, less than one percent of their genome comes from foreign DNA.
The microscopic rotifer previously held the record, with eight percent of its genome coming from foreign DNA.
"We
had no idea that an animal genome could be composed of so much foreign
DNA," said co-author Bob Goldstein of UNC's College of Arts and
Sciences.
"We knew many animals acquire foreign genes, but we had no idea that it happens to this degree."
- New insight on evolution .
The
study, published in Monday's edition of the Proceedings of the National
Academy of Sciences, also made unusual findings about how DNA is
inherited.
Goldstein,
first author Thomas Boothby and colleagues found that water bears
obtain about 6,000 foreign genes mostly from bacteria, as well as
plants, fungi and Archaea single-cell organisms.
"Animals
that can survive extreme stresses may be particularly prone to
acquiring foreign genes -- and bacterial genes might be better able to
withstand stresses than animal ones," said Boothby, a postdoctoral
fellow in Goldstein's lab.
Indeed, bacteria have survived the most extreme environments on Earth for billions of years.
Water
bears acquire foreign genes through horizontal gene transfer, a process
by which species swap genetic material instead of inheriting DNA from
parents.
"With
horizontal gene transfer becoming more widely accepted and more
well-known, at least in certain organisms, it is beginning to change the
way we think about evolution and inheritance of genetic material and
the stability of genomes," said Boothby.
Researchers
said the DNA likely gets inside the genome randomly but what remains
allows water bears to survive in the most hostile environments.
Under intense stress, such as extreme dryness, the water bear's DNA breaks up into small pieces, according to the research team.
Once
the cell rehydrates, its membrane and nucleus housing the DNA
temporarily becomes leaky and allows other large molecules to pass
through easily.
They
thus repair their own damaged DNA while also absorbing foreign DNA as
the cell rehydrates, forming a patchworks of genes from different
species.
"So
instead of thinking of the tree of life, we can think about the web of
life and genetic material crossing from branch to branch," Boothby
explained.
"So it's exciting. We are beginning to adjust our understanding of how evolution works."
By AFP, 17 hours 16 minutes ago
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