Mapping the inner workings of a living cell

Imaging tool flags new proteins, lipids and DNA to track metabolic changes in animals

Date:

August 6, 2018

Source:

Columbia University

Summary:

Researchers show that a widely used chemical tracer, combined with a cutting-edge microscope, can track metabolic changes within the living cells of animals.FULL STORY

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As living cells absorb heavy water, deuterium is incorporated into newly made proteins, lipids and DNA. When the researchers aimed the light of a stimulated Raman scattering (SRS) microscope at a single cell, each of the macromolecules above could be identified within.

Credit: Wei Min lab/Columbia University

Imaging tools like X-rays and MRI have revolutionized medicine by giving doctors a close up view of the brain and other vital organs in living, breathing people. Now, Columbia University researchers report a new way to zoom in at the tiniest scales to track changes within individual cells.Described in the latest issue of Nature Communications, the tool combines a widely used chemical tracer, D2O, or heavy water, with a relatively new laser-imaging method called stimulated Raman scattering (SRS). The technique's potential applications include helping surgeons quickly and precisely remove tumors, to helping to detect head injuries and developmental and metabolic disorders.

"We can use this technology to visualize metabolic activities in a wide range of animals," said the study's senior author Wei Min, a chemistry professor at Columbia University. "By tracking where and when new proteins, lipids and DNA molecules are made, we can learn more about how animals develop and age, and what goes wrong in the case of injury and disease."

The breakthrough involves the use of heavy water as a chemical tracer. Made by swapping water's hydrogen atoms with their heavier relative, deuterium, heavy water looks and tastes like regular water and in small doses (no more than five tablespoons for humans) is safe to drink. Once metabolized by cells in the body, heavy water is incorporated into newly made proteins, lipids and DNA, where the deuterium forms chemical bonds with carbon.

When these carbon-deuterium bonds are hit with light, they vibrate at varying frequencies, the researchers discovered, allowing each macromolecule to be identified as a protein, lipid or DNA. From these frequency signatures, they could track the growth of new proteins, lipids and DNA in the animal's brain, skin, gut and other organs.

Though heavy water is already used to label proteins and lipids to track metabolic changes, analysis is currently done on a mass spectrometer, on cells extracted from the body. This method now makes it possible to visualize subcellular changes in real time and space. "We get a continuous picture of what's happening inside living animal cells. Previously, we had only a snapshot," said the study's co-lead author, Lingyan Shi, a postdoctoral researcher at Columbia.

Story source Materials provided by Columbia University. Original written by Kim Martineau. Note: Content may be edited for style and length.