VANCOUVER, CANADA—Imagine photographing every seed in a watermelon without cutting a single slice. Scientists can use x-rays to create similar internal portraits of whole cells, they reported here this morning at the annual meeting of the American Association for the Advancement of Science (which publishes ScienceNOW). Like performing a cellular CT scan, researchers rapidly freeze a cell and snap its x-ray image once every 100 milliseconds. They can reconstruct an entire cell from 90-200 images in about 5 minutes. Using the differing light-absorption properties of organelles—the cell’s functional structures—the scientists can automatically identify and color-code this inner machinery, like in the T cell shown above (the nucleus is bright blue, mitochondria are pink, and lysosomes are yellow). Researchers can use the technique to count and calculate the volume of organelles, and even measure how much hemoglobin malarial parasites consume inside red blood cells. Peering inside a whole cell without the laborious slicing and staining of electron microscopy makes x-ray imaging quick, quantitative, and decidedly less mess.
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