Post by Lunaria on May 15, 2004 10:49:49 GMT -5
news.bbc.co.uk/1/hi/sci/tech/3703935.stm
Researchers inspecting the genetic code of rats, mice and humans were
surprised to find they shared many identical chunks of apparently "junk"
DNA. . . . This implies the code is so vital that even 75 million years
of evolution in these mammals could not tinker with it. . . . According
to the traditional viewpoint, the really crucial things were genes,
which code for proteins - the "building blocks of life". A few other
sections that regulate gene function were also considered useful. . . .
The rest was thought to be excess baggage - or "junk" DNA. But the new
findings suggest this interpretation was somewhat wanting. . . . David
Haussler of the University of California, Santa Cruz, US, and his team
compared the genome sequences of man, mouse and rat. They found - to
their astonishment - that several great stretches of DNA were identical
across the three species. . . . To guard against this happening by
coincidence, they looked for sequences that were at least 200 base-pairs
(the molecules that make up DNA) in length. Statistically, a sequence of
this length would almost never appear in all three by chance. . . . Not
only did one sequence of this length appear in all three - 480 did. . .
.
"It absolutely knocked me off my chair," said Professor Haussler. "It's
extraordinarily exciting to think that there are these ultra-conserved
elements that weren't noticed by the scientific community before." . . .
The really interesting thing is that many of these "ultra-conserved"
regions do not appear to code for protein. If it was not for the fact
that they popped up in so many different species, they might have been
dismissed as useless "padding". . . . But whatever their function is, it
is clearly of great importance. . . .
We know this because ever since rodents, humans, chickens and fish
shared an ancestor - about 400 million years ago - these sequences have
resisted change. This strongly suggests that any alteration would have
damaged the animals' ability to survive. . . . "These initial findings
tell us quite a lot of the genome was doing something important other
than coding for proteins," Professor Haussler said. . . . "The fact that
the conserved elements are hanging around the most important development
genes, suggests they have some role in regulating the process of
development and differentiation," said Professor Haussler. . . . Despite
all the questions that this research has raised, one thing is clear:
scientists need to review their ideas about junk DNA. . . .
He added: "I think other bits of 'junk' DNA will turn out not to be
junk. I think this is the tip of the iceberg, and that there will be
many more similar findings."
Researchers inspecting the genetic code of rats, mice and humans were
surprised to find they shared many identical chunks of apparently "junk"
DNA. . . . This implies the code is so vital that even 75 million years
of evolution in these mammals could not tinker with it. . . . According
to the traditional viewpoint, the really crucial things were genes,
which code for proteins - the "building blocks of life". A few other
sections that regulate gene function were also considered useful. . . .
The rest was thought to be excess baggage - or "junk" DNA. But the new
findings suggest this interpretation was somewhat wanting. . . . David
Haussler of the University of California, Santa Cruz, US, and his team
compared the genome sequences of man, mouse and rat. They found - to
their astonishment - that several great stretches of DNA were identical
across the three species. . . . To guard against this happening by
coincidence, they looked for sequences that were at least 200 base-pairs
(the molecules that make up DNA) in length. Statistically, a sequence of
this length would almost never appear in all three by chance. . . . Not
only did one sequence of this length appear in all three - 480 did. . .
.
"It absolutely knocked me off my chair," said Professor Haussler. "It's
extraordinarily exciting to think that there are these ultra-conserved
elements that weren't noticed by the scientific community before." . . .
The really interesting thing is that many of these "ultra-conserved"
regions do not appear to code for protein. If it was not for the fact
that they popped up in so many different species, they might have been
dismissed as useless "padding". . . . But whatever their function is, it
is clearly of great importance. . . .
We know this because ever since rodents, humans, chickens and fish
shared an ancestor - about 400 million years ago - these sequences have
resisted change. This strongly suggests that any alteration would have
damaged the animals' ability to survive. . . . "These initial findings
tell us quite a lot of the genome was doing something important other
than coding for proteins," Professor Haussler said. . . . "The fact that
the conserved elements are hanging around the most important development
genes, suggests they have some role in regulating the process of
development and differentiation," said Professor Haussler. . . . Despite
all the questions that this research has raised, one thing is clear:
scientists need to review their ideas about junk DNA. . . .
He added: "I think other bits of 'junk' DNA will turn out not to be
junk. I think this is the tip of the iceberg, and that there will be
many more similar findings."