MIT reels in RNA surprise with microbial o...( CAMBRIDGE Mass.--An ingenious new me...)

CAMBRIDGE, Mass.--An ingenious new method of obtaining marine microbe samples while preserving the microbes' natural gene expression has yielded an unexpected boon: the presence of many varieties of small RNAs snippets of RNA that act as switches to regulate gene expression in these single-celled creatures. Before now, small RNA could only be studied in lab-cultured microorganisms; the discovery of its presence in a natural setting may make it possible finally to learn on a broad scale how microbial communities living at different ocean depths and regions respond to environmental stimuli.

"Microbes are exquisite biosensors," said Edward Delong, a professor of civil and environmental engineering (CEE) and biological engineering. "We had developed this methodology to look at protein-encoding genes, because if we know which proteins the microbes are expressing under what conditions, we can learn about the environmental conditions and how these microbes influence those. The unexpected presence and abundance of these small RNAs, which can act as switches to regulate gene expression, will allow us to get an even deeper view of gene expression and microbial response to environmental changes.

DeLong and co-authors Yanmei Shi, a graduate student in CEE, and postdoctoral associate Gene Tyson describe this work in the May 14 issue of Nature. The team used a technique called metatranscriptomics, which allows them to analyze the RNA molecules of wild microbes, something that previously could be done only with lab-cultured microbes.

Microbes are ultra-sensitive environmental sensors that respond in the blink of an eye to minute changes in light, temperature, chemicals or pressure and modify their protein expression accordingly. But that sensitivity creates a quandary for the scientists who study them. Sort of like the observer effect in quantum physics, by entering the environment or removing the microbes from it, the observer causes the m
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