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Science notes / Biology, astronomy

Exploring fluoride's mysteries

The way we use fluoride hasn't changed much since the mid 20th century, but a new study could change that. The study, led by Ronald Breaker, a professor in the department of molecular, cellular and developmental biology at Yale University, gets at the specifics of how bacteria fight fluoride. Besides uncovering one of the remaining mysteries of the element, it potentially could lead to new uses for fluoride. The study was published in the journal Science Express.

Streptococcus mutans is the bacterium particularly responsible for tooth decay. Fluoride binds to the teeth's enamel to shield against bacteria. But some researchers believe that fluoride also inhibits the growth of the Streptococcus bacterium.

Breaker's study finds that bacteria's defense against fluoride is triggered by certain sections of RNA messages known as riboswitches that act as fluoride sensors. When fluoride builds up in a bacterial cell, the riboswitches trigger genes in the bacteria that produce more copies of the bacterial enzymes. It also triggers a gene that specifically expels fluoride from the cell. Knowing this, Breaker said, could lead to innovations that inhibit the anti-fluoride mechanisms.

"We're definitely eager to understand how bacteria sense and respond to fluoride," he said. "We want to manipulate the system and intentionally break the system, because we can see some interesting application."

Creating a super-toothpaste might be tricky because bacteria are good at building resistance, but it is not impossible. It could also lead to a treatment for skin infection, since high concentrations of fluoride inhibit bacterial or fungal growth.

-- Hartford Courant

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Stargazers, take some notes

When you see a shooting star, make a wish. But also, take note of its brilliance. After all, NASA is counting on you. With its new Meteor Counter app -- available for iPhone, iPad and iPod touch -- the space administration is calling upon amateur stargazers to help it keep a running tab on meteor showers around the globe.

All you have to do is look up, get lucky, see a glowing hunk of matter hurtle through the mesosphere and then tap a few buttons. The interface is fairly idiot-proof: Just dial in the viewing conditions (hazy, cloudy, overcast) and the light level of the dimmest stars in the sky. Then, each time you see a meteor, tap the screen to indicate how bright it was.

At the end of session, the app will automatically upload the data to a server for review by NASA researchers. Meteor Counter can also be set to record and transmit audio commentary, so, if you have a salient observation to make or just want to get a simple "whoa!" on the official record, you can do that, too.

-- Washington Post