Friday, September 11, 2009

What Makes Us Human

It is understood that in the field of molecular evolution new genes can only evolve from duplicated or rearranged versions of preexisting genes. Furthermore, it seemed unlikely that evolutionary processes could produce a functional protein-coding gene from what was once inactive DNA.

But that view is changing as some evidence suggests that this phenomenon does in fact occur. It has been found that genes have arisen from non-coding DNA in yeast,flies, and also primates. No such genes had been found to be unique to humans until now, and the discovery raises questions about how these genes might make humans different from other primates.

One gene was identified in chronic lymphocytic leukemia. This is the first evidence for entirely novel human-specific protein-coding genes originating from ancestrally noncoding sequences. A non-coding sequence involves RNA (ncRNA) is a molecule that is not translated into a protein.In other words, a gene that was once dormant is now active.

The consequence of the finding is that while many coding sequences exist, there are some that are dormant in primates, but become active in humans. This makes us different

Monday, March 9, 2009

Flu in U.S. found resistant to main antiviral drug: Evolution in Action

Virtually all the flu in the United States this season is resistant to the leading antiviral drug Tamiflu, and scientists and health officials are trying to figure out why.
The problem is not yet a public health crisis because this has been a below-average flu season so far and the chief strain circulating is still susceptible to other drugs — but infectious disease specialists are worried nonetheless.
Last winter, about 11 percent of the throat swabs from patients with the most common type of flu that were sent to the Centers for Disease Control and Prevention for genetic typing showed a Tamiflu-resistant strain. This season, 99 percent do.
"It's quite shocking," said Dr. Kent Sepkowitz, director of infection control at Memorial Sloan-Kettering Cancer Center in New York. "We've never lost an antimicrobial this fast. It blew me away."
The single mutation that creates Tamiflu resistance appears to be spontaneous, and not a reaction to overuse of the drug. It may have occurred in Asia, and it was widespread in Europe last year.

Resistance appeared several years ago in Japan, which uses more Tamiflu than any other country, and experts feared it would spread.
But the Japanese strains were found only in patients already treated with Tamiflu, and they were "weak" — that is, they did not transmit to other people.
"This looks like a spontaneous development of resistance in the most unlikely places — possibly in Norway, which doesn't use antivirals at all," Monto said.
Dr. Henry Niman, a biochemist in Pittsburgh who runs, a Web site that tracks the genetics of flu cases around the world, has been warning for months that Tamiflu resistance in H1N1 was spreading.
He argues that it started in China, where Tamiflu use is rare, was seen last year in Norway, France and Russia, then moved to South Africa (where winter is June to September), and back to the northern hemisphere in November.

This is another example of evolution in action. Mutations occur which change the DNA features of a virus, where it was resistant to drugs, is not so now.