Single-celled bacterium works 24-7( Researchers at Washington University...)

Researchers at Washington University in St. Louis have gained the first detailed insight into the way circadian rhythms govern global gene expression in Cyanothece, a type of cyanobacterium (blue-green alga) known to cycle between photosynthesis during the day and nitrogen fixation at night.

In general, this study shows that during the day, Cyanothece increases expression of genes governing photosynthesis and sugar production, as expected. At night, however, Cyanothece ramps up the expression of genes governing a surprising number of vital processes, including energy metabolism, nitrogen fixation, respiration, the translation of messenger RNA (mRNA) to proteins, and the folding of these proteins into proper configurations.

The findings have implications down the road for energy production and storage of clean, alternative biofuels.

The study was published in the April online issue of the Proceedings of the National Academy of Science. The research was funded by the U.S. Department of Energy in the context of a Biology Grand Challenge project administered by the Environmental Molecular Sciences Laboratory at the Pacific Northwest National Laboratory.

One of the mysteries in cellular physiology is this business of rhythm, said Himadri Pakrasi, Ph.D., George William and Irene Koechig Freiberg Professor in Arts & Sciences and lead investigator of this project. "Circadian rhythm controls many physiological processes in higher organisms, including plants and people. Cyanothece are of great interest because, even though one cell lives less than a day, dividing every 10 to 14 hours, together they have a biological clock, telling them when to do what over a 24-hour period. In fact, cyanobacteria are the only bacteria known to have a circadian behavior."

Why does such a short-lived, single-celled organism care what time it is" The answer, according to this study, is that the d
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