Say cheese!

Students at the University of Texas have developed bacteria that serve as living photographic film. The students, competitors in MIT’s Genetically Engineered Machines competition, engineered colonies of E. coli bacteria, found in human intestines, to change colour in response to light. Since E. coli cannot detect light, the students installed a light receptor protein borrowed from photosynthetic, light-sensitive algae. They hooked up this protein to the pigment-producing systems in E. coli cells so that cells exposed to light turned black, and those left in the dark stayed white, like millions of pixels on a black-and-white TV screen. By shining light on an object positioned in front of the bacterial “film,” the students could capture ghostly images of that object, including themselves.

-Chris Damdar

Source: Nature

Drink up!

Cranberry juice fights cavities, according to oral biologists at the University of Rochester. Scientists have known for a while that drinking cranberry juice helps lower the incidence of urinary tract infections, by preventing harmful bacteria from sticking to the bladder surface. Dr. Hyun Koo and his team found that cranberry juice also lowers the incidence of cavities, by preventing cavity-causing bacteria from producing plaque which glues them to teeth. According to Koo, something in the cranberry juice disrupts the formation of glucan, a major component of plaque. Koo warns that commercial cranberry juice contains sugar and acid which promote tooth decay, and hopes to identify and extract the chemicals which disrupt plaque formation.

-C.D.

Source: Caries Research

Stripes away!

The half-zebra- and half-horse-like quagga (bottom row, above) was a relative of the zebra once found in South Africa. It went extinct about 100 years ago. How did the plains zebras lose their stripes and become quaggas? Researchers from Yale University, the Smithsonian Institute, and the Max Planck Institute for Evolutionary Anthropology have now gleaned some clues as to how it happened, by studying DNA samples of 13 quagga pelts from museum specimens. They found that the two species diverged between 120,000 and 290,000 years ago. The researchers posit that a population of plains zebras became geographically isolated during an Ice Age, and rapidly evolved into the quagga.

-Mike Ghenu

Source: Biology Letters