(Phys.org) —If you asked a biologist what any given cell is going to do next, they might ask you first to tell them its electrical potential, oxygenation, pH, osmolarity or glucose concentration. Depending on how finely-scaled your answer might be, they might be able to predict anything from firing an action potential or entering mitosis, to undergoing apoptosis. But what if you knew the subcellular temperature profile in such detail that each mitochondria, centriole and even regions of the endoplasmic reticulum could be read as easily as a mother her child's fever? That question now drives some of the most exciting research in biology. This year several groups have come up with ingenious thermometric methods ranging from fluorescence lifetime microscopy to exotic diamond nanosensors employing nitrogen vacancy centers. The latest breakthrough, just published in Nature Methods, describes a method that uses a genetically-encoded sensor built from green fluorescent protein (GFP) that is fused to a thermosensing protein borrowed from Salmonella. The researchers used this construct to probe thermogenesis in brown fat mitochondria, and perhaps most astoundingly, were able to correlate temperature with both mitochondrial membrane potential and ATP production.
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