Magazine

Of Fish And Free Radicals


-- Researchers at Purdue University have discovered that genetically modified organisms may make good eating -- but could produce devastating results. When new genes are inserted into a fish's chromosome to make it grow larger, that big fish is better at attracting mates, but its offspring are less likely to survive into adulthood. If such transgenic fish were to invade the wild, they could displace normal males and father a generation of short-lived offspring that could wipe out the species. The team based its findings on lab observations of fish mating behavior and computer models.

-- Scientists have long believed that molecules called oxygen free radicals, released by white blood cells, fight bacteria but can also harm healthy tissue. Overproduction of free radicals has been implicated in a huge range of diseases, and drug companies have spent billions pursuing antioxidant drugs. Now, a team at University College London claims in Nature that the basic theory is wrong. They found that free radicals do not attack bacteria at all. Instead, an enzyme produced by the immune system kills the microbes. How does a whole body develop from a clump of identical-looking cells? Scientists know that certain cells in an embryo tell others what to do. But they're still trying to figure out which genes are at work and how these transformations begin.

Now comes a new method of tackling this question. When genes are active, they make a messenger molecule called MRNA, which carries the genetic instructions to cells' protein factories. Researchers commonly use fluorescent probes that home in on specific MRNAs. These probes glow when the MRNA is present, signaling that the gene is active. In a new twist, Teri Jo Mauch at the University of Utah is using three fluorescent colors to chart the action of three genes simultaneously at various spots in many cells within chick embryos. Three-gene detection had been done before in fruit flies, but this is a first for the study of higher animals -- and it's more precise. Not only does it offer a better understanding of normal embryo development, it could also help scientists learn to engineer new tissues to repair damaged organs. Adults who need a heart transplant can survive for months with an artificial one while awaiting a human organ. But babies and small kids will die within 10 days if a compatible heart can't be found. University of Pittsburgh researchers have developed a prototype artificial heart that's roughly the size of a quarter. Bioengineering Chairman Harvey S. Borovetz says it may be able to support kids up to 2 years of age for as long as six months.

The hang-up in developing pint-size mechanical hearts is the small market. Only about 500 pediatric patients a year need a heart transplant -- a fraction of the 35,000 adult candidates. Pitt has spent $750,000 of its own money and hopes to win $20 million from the National Institutes of Health to complete development. No matter what, "we're going to move ahead," Borovetz declares. "This is too important." Forget retinal scans and face recognition. Future biometrics may entail nothing more intrusive than taking a photo of your ear. Experts at Britain's University of Leicester have developed a high-speed identification system based on the shape and features of that organ, and they found that, like fingerprints, no two ears seem exactly alike.

The university's head of forensic pathology, Professor Guy Rutty, says the software works like fingerprint systems: It compares 14 to 18 points on a photo or imprint of the ear. In the past, ear prints have been matched manually, but this approach is faster and more accurate.

Unlike fingerprints, however, ears can be viewed at a distance. This makes them a good candidate for security applications in airports and other public places. For instance, says Rutty, ears can help identify a person from security camera footage -- and in time, he adds, a global database of ear prints could be built.

The university ran its trial jointly with K9 Forensic Services Ltd. in nearby Northampton. And while only 1,500 ears were scanned, each one, so far, appears to be unique. More testing is scheduled for coming months -- time enough for a cunning criminal to buy a pair of earmuffs.


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