Platypus Genome Found Fittingly Strange

[Randy Burge-2]

Platypus Genome Found Fittingly Strange
Cobbled-Together Creature Yields New Evolutionary Insights

By Rick Weiss
Washington Post Staff Writer
Thursday, May 8, 2008; Page A01

http://www.washingtonpost.com/wp-dyn/content/article/2008/05/07/AR2008050702
048.html

When the British naturalist George Shaw received a weird specimen from
Australia in 1799 -- one with a mole's fur, a duck's bill and serpentlike
spurs on its rear legs -- he did what any skeptical scientist would do: He
looked for the stitching and glue that would reveal it to be a hoax.

"It was impossible not to entertain some distant doubts as to the genuine
nature of the animal," Shaw wrote of the seemingly built-by-committee
creature, which he eventually named "platypus," for its flat, webbed feet.

Now, more than 200 years later, a team of scientists has determined the
platypus's entire genetic code. And right down to its DNA, it turns out, the
animal continues to strain credulity, bearing genetic modules that are in
turn mammalian, reptilian and avian.

There are genes for egg laying -- evidence of its reptilian roots. Genes for
making milk, which the platypus does in mammalian style despite not having
nipples. Genes for making snake venom, which the animal stores in its legs.
And there are five times as many sex-determining chromosomes as scientists
know what to do with.

"It's such a wacky organism," said Richard Wilson, director of the Genome
Sequencing Center at Washington University in St. Louis, who with colleague
Wesley Warren led the two-year effort, described today in the journal
Nature.

Yet in its wackiness, Wilson said, the platypus genome offers an
unprecedented glimpse of how evolution made its first stabs at producing
mammals. It tells the tale of how early mammals learned to nurse their
young; how they matched poisonous snakes at their venomous game; and how
they struggled to build a system of fertilization and gestation that would
eventually, through relatives that took a different tack, give rise to the
first humans.

"As we learn more about things like platypuses," Wilson said, "we also learn
more about ourselves and where we came from and how we work."

Platypuses (preferred over "platypi" in U.S. dictionaries) live on a sliver
of Earth along Australia's east coast, in Tasmania and in Papua New Guinea.
They are not endangered, but few people see them since they spend their days
in burrows built into stream banks. But Ornithorhynchus anatinus has a
global fan base, it seems, serving as the mascot for countless companies,
products and events.

The animal's complete genetic code, or genome, turns out to have 2.2 billion
molecular "letters" of DNA, or about two-thirds as many as the human genome,
and contains 18,500 genes, about the same as humans.

<snip>

http://www.washingtonpost.com/wp-dyn/content/article/2008/05/07/AR2008050702
048.html



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