New tool sheds light on cell imaging

In the same way it's hard to see the Milky Way in a major city, researchers sometimes struggle to see tagged structures because of natural background light emitted by cells. In this week's __Proceedings of the National Academy of Sciences__, however, researchers show that a new type of tag helps separate structures from the background. Gerard Marriott, from the University of Wisconsin-Madison, and colleagues found that using a blinking tag made it easier to spot cellular structures in live cel

Edyta Zielinska
Nov 9, 2008
In the same way it's hard to see the Milky Way in a major city, researchers sometimes struggle to see tagged structures because of natural background light emitted by cells. In this week's __Proceedings of the National Academy of Sciences__, however, researchers show that a new type of tag helps separate structures from the background. Gerard Marriott, from the University of Wisconsin-Madison, and colleagues found that using a blinking tag made it easier to spot cellular structures in live cells. "Reading this paper is like, oh wow cool," said linkurl:Antoine Van Oijen,;http://www.the-scientist.com/article/display/54605/ a biophysicist at Harvard Medical School who was not involved in the research, "people who do live cell imaging, always have to deal with background." The living cell is a "dirty environment," explained Marriott -- more specifically, live cells give off their own fluorescence. Any tag used to mark a particular cellular structure has to be brighter than...
light emitted by cells. In this week's __Proceedings of the National Academy of Sciences__, however, researchers show that a new type of tag helps separate structures from the background. Gerard Marriott, from the University of Wisconsin-Madison, and colleagues found that using a blinking tag made it easier to spot cellular structures in live cells. "Reading this paper is like, oh wow cool," said linkurl:Antoine Van Oijen,;http://www.the-scientist.com/article/display/54605/ a biophysicist at Harvard Medical School who was not involved in the research, "people who do live cell imaging, always have to deal with background." The living cell is a "dirty environment," explained Marriott -- more specifically, live cells give off their own fluorescence. Any tag used to mark a particular cellular structure has to be brighter than the background. This limitation makes it linkurl:difficult to detect;http://www.the-scientist.com/2008/7/1/65/1/ very small signals, like single molecules, or detect signals in cells with a large amount of natural fluorescence. The optical lock-in detection (OLID) method the authors describe uses a blinking signal to tag cellular structures, which makes it easier to spot the signal amidst the solid light source emitted by the background. "It's a little bit of a surprise that people haven't done this earlier," said Van Oijen; from the perspective of an electrical engineer, the technique is a bit obvious. "It's one of those things physicists have employed for years to detect a signal above the background." In these experiments, Marriott demonstrated how OLID staining of intact __Xenopus__ spinal cords and muscle in live zebrafish compared with conventional staining which was unable to pick up the fine detail of cellular structures. While most imaging labs have linkurl:the hardware;http://www.the-scientist.com/article/display/15428/ to perform these experiments, "the typical cell imaging labs won't be able to read this paper and do it tomorrow," said Van Oijen. While Marriott published the formula for converting the signal, no simple commercial software is available yet to pull the oscillating signal out of background automatically.

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