Scientists have sequenced the genome of
the African coelacanth, an ancient-looking fish with lobed fins, and
found that its appearance has changed little over 300 million years as
its genes are evolving very slowly. A sea-cave dwelling, five-foot long
fish with limb-like fins, the coelacanth was once thought to be
extinct. A living coelacanth was discovered off the African coast in
1938. Since then, questions about these ancient-looking fish -
popularly known as 'living fossils' - have loomed large. Coelacanths
today closely resemble the fossilised skeletons of their more than
300-million-year-old ancestors. Its genome confirms what many
researchers had long suspected: genes in coelacanths are evolving more
slowly than in other organisms. "We found that the genes overall are
evolving significantly slower than in every other fish and land
vertebrate that we looked at," said Jessica Alfoldi, a research
scientist at the Broad Institute of MIT and Harvard and co-first author
of the paper in journal Nature. "This is the first time that we've had a
big enough gene set to really see that," Alfoldi said. Researchers
hypothesise that this slow rate of change may be because coelacanths
simply have not needed to change: they live primarily off of the Eastern
African coast (a second coelacanth species lives off the coast of
Indonesia), at ocean depths where relatively little has changed over the
millennia. "We often talk about how species have changed over time,"
said Kerstin Lindblad-Toh, scientific director of the Broad Institute's
vertebrate genome biology group and senior author. "But there are still
a few places on Earth where organisms don't have to change, and this is
one of them. Coelacanths are likely very specialised to such a
specific, non-changing, extreme environment - it is ideally suited to
the deep sea just the way it is," Lindblad-Toh said. Because of their
resemblance to fossils dating back millions of years, coelacanths today
are often referred to as 'living fossils' - a term coined by Charles
Darwin. But the coelacanth is not a relic of the past brought back to
life: it is a species that has survived, reproduced, but changed very
little in appearance for millions of years. "It's not a living fossil;
it's a living organism. It doesn't live in a time bubble; it lives in
our world, which is why it's so fascinating to find out that its genes
are evolving more slowly than ours," said Alfoldi.
Difficulty or inability to write a coherent text message, even in people who have no problem speaking, may become a "vital" tool in diagnosing a type of crippling stroke, according to a new research. Scientists at Henry Ford Hospital focused on a 40-year-old man visiting the metro Detroit area on business who showed signs of "dystextia," a recently coined term for incoherent text messaging that can sometimes be confused with autocorrect garble. But in his case, the man saw nothing wrong with the garble. The patient had no problem with a routine bedside test of his language abilities - including fluency of speech, reading, writing, comprehension and other factors. However, when asked to type a simple text message, he not only produced garble, but he was unable to see it as such. Despite showing only slight facial asymmetry and no other symptoms, doctors determined the man had suffered an acute ischemic stroke, in which a clot or other blockage cuts off blood supply t...
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