Science

Check out the big brain on the genetically modified mouse

Check out the big brain on the...
The mouse embryo developed a giant brain after being injected with the human version of a DNA sequence called HARE5 (Image: Silver lab, Duke University)
The mouse embryo developed a giant brain after being injected with the human version of a DNA sequence called HARE5 (Image: Silver lab, Duke University)
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The mouse embryo developed a giant brain after being injected with the human version of a DNA sequence called HARE5 (Image: Silver lab, Duke University)
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The mouse embryo developed a giant brain after being injected with the human version of a DNA sequence called HARE5 (Image: Silver lab, Duke University)
The mouse embryo developed a giant brain after being injected with the human version of a DNA sequence called HARE5 (Image: Silver lab, Duke University)
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The mouse embryo developed a giant brain after being injected with the human version of a DNA sequence called HARE5 (Image: Silver lab, Duke University)

Scientists at Duke University have pinpointed a regulator of gene activity that could lend insight into why we're so different from chimpanzees despite having a near-identical genetic makeup (94 per cent of our DNA is the same). When injected into a mouse embryo, the human version of a particular DNA sequence important for brain development caused the embryo to grow a considerably larger brain than other embryos treated with the chimpanzee version.

Humans and chimps split along the evolutionary ladder around four to six million years ago. Our brains then expanded dramatically as we picked up sophisticated abilities for things like abstract language, math, and reasoning. But it's not clear how that could happen without a larger DNA divergence.

The team at Duke went data mining through databases of human and chimp genomes. They identified 106 DNA enhancers – short bits of DNA that control gene activity – that are significantly different between the two species. Of these, six are believed to be involved in brain development. And one of those six, which the researchers dubbed HARE5, looked particularly promising because it is near a key gene in brain development and disease.

Human HARE5 and chimpanzee HARE5 were then implanted in mouse embryos. The human enhancer triggered earlier in development and proved more active in general than the chimp enhancer, leading to a 12 percent difference in brain volume, principally in the neocortex, which is involved in high-level functions such as language and reasoning. The researchers noticed the difference before even checking to see which was which (they monitored the embryo developments "blind," or without indication of genotype).

"What we found is a piece of the genetic basis for why we have a bigger brain," said co-author Gregory Wray. "It really shows in sharp relief just how complicated those changes must have been. This is probably only one piece – a little piece [of the puzzle]."

The human HARE5 and chimp HARE5 mice will now be studied further as they mature into adulthood. The researchers hope this will teach them more about how HARE5 affects brain structure and behavior. The other five HARE sequences will also be tested in hopes that they will reveal part of the secret behind mysteries like why humans get diseases such as autism and Alzheimer's while chimps do not.

A paper describing the research was published in the journal Current Biology.

Source: Duke University

13 comments
Bob Ehresman
This reminds me of "The Secret Of NIMH".
Brian Trembley
NIMH or Pinky and the Brain
Chizzy
They're Pinky and The Brain Yes Pinky and The Brain One is a genius The other's insane
They're laboratory mice Their genes have been spliced They're Pinky They're Pinky and The Brain, Brain, Brain, Brain Brain, Brain, Brain, Brain Brain
Before each night is done Their plan will be unfurled By the dawning of the sun They'll take over the world
They're Pinky and The Brain Yes Pinky and The Brain Their twilight campaign Is easy to explain
To prove their mousey worth They'll overthrow the Earth They're Pinky They're Pinky and The Brain, Brain, Brain, Brain Brain, Brain, Brain, Brain
Narf!
JAT
Are these people NUTZ??? They're going to create walking, talking mice... kinda like Mickey but maybe not so benign! If these things ever escape from the lab they could reproduce and take over the world! What next, applying the same experiment to Chimps? Oh Boy! It would be Hollywood fantasy come to real life. Idiots at Duke!
Joseph Mertens
So you can make nearly any animal have the potential to be sentient what a can of worms that is/will be.
b@man
94%... that other 6% makes us light years apart. We share 50% of our DNA with bananas.
Nelson Hyde Chick
Monstrous!!!
162pilot
A mouse with a big brain is amazing in potential but on its own isnt anything to scream about it wont learn to talk or think like us due to their tiny life spans, a mouse does well with its brain because thats the brain it evolved, a human brain is diffrent it takes much longer to reach a state where constant protection is unneccasary a human couldnt walk by the time a mouse has lived a full life
Wulfher
The article has a mistake, humans and chimps share 99% of their DNA. Gizmag, let's be thorough please!