We are closer to rats than cats

Human beings are more closely related to rats than to meat-eating animals, US scientists have reported.

    Deciphering the human genome is proving difficult

    The National Human Genome Research

    Institute and several universities came to this conclusion after comparing the same stretch of

    DNA in 12 animals, including a pig and a dog,

     with human DNA.

    "It provides some pretty definitive evidence that we are

    indeed closer to rodents than we are to carnivores," Dr Eric

    Green, scientific director of the NHGRI

    said on Wednesday.

    Rodent relatives

    "Our data really puts the nail in the case. In the (genetic) sequence

    you can find changes in the genome that clearly occurred in

    both humans and rodents but did not occur in others." 

     

    The survey also backs up the argument that so-called junk

    DNA is nothing of the sort - it must do something important

    because it stays virtually identical across many species.

    It also supports the theory 

    that genes are only a small part

    of the genetic story.

    DNA is very difficult to interpret - its long code is

    built on compounds known by the

    abbreviations A,C,T and G.

     

    DNA labyrinth

    Reading the long string of four letters repeating in

    various combinations is proving to be even trickier than

    scientists thought it would be.

    "In the (genetic) sequence you can find changes in the genome that clearly occurred in both humans and rodents but did not occur in others"

    --

    Dr Eric Green, scientific director of the NHGRI   

    At first they believed the

    genes - the sequences that control production of the body's protein

    building blocks - would be the only functioning

    parts of the sequence.

    But it turns out there are sequences which control the

    genes, and perhaps which do even more.

    "It now seems that about five percent of our genomes are

    functionally important," Green said.

    Discoveries

    "Only a third of that code is for genes. That means that

    two-thirds of what is functionally important is not (gene)

    encoding DNA. We don't even know what it looks like so how are

    we going to find it?"

    Green hopes to do so by comparing the genomes of different

    species.

    "This is the idea that you can truly use sequences from

    multiple genomes and analyze them all at once to try and find

    the small percent that is shared among all of them," he said.

    "We believe this is going to be a very valuable way to find

    those sequences that are very important. 

    "We will discover new types of functional elements in the

    coding DNA that we didn't even know existed," Green added.

    SOURCE: Reuters


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