Shining Light (Literally) On The Workings Of Cells

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Scientists would like to know more about how cells work. But seeing what's happening inside a cell isn't easy. It's dark in there, and even if you shine a light, many of the critical chemical reactions are invisible.

Now, a team of researchers has found a way to reveal the invisible by attaching what amounts to a reflective tag to a chemical called RNA, a close relative of DNA. Molecules made of RNA have a variety of important jobs inside cells and frequently, doing those jobs requires the RNA to shuttle from one part of the cell to another.

Seeing Inside Cells

In the video below, researchers were studying how the addition of table sugar (sucrose) affected the growth of cells and the production of RNA.

With the new ability to see RNA inside of cells by making it glow green, they learned that the addition of sucrose (the right frame in the video) dramatically increased the production of RNA – something that hadn't previously been known. No sucrose was added to the cells seen on the left side of the video.

Samie Jaffrey and his colleagues at Weill Cornell Medical School in New York wanted to track those movements. So they came up with a way to attach a kind of chemical tag to the RNA — a tag that will light up when you shine the right wavelength of light on it.

Jaffrey says being able to see how the RNA is moving inside cells should answer a lot of important questions about what the chunks of RNA inside cells are up to, like: "When do they move, in response to what signals in cells? And how is their movement affected in diseases?" This information "will give us more insight into how those RNAs are linked to the disease process," Jaffrey says.

One nice feature of the new technique is that you can watch the RNA move in real time, so you can make movies of RNA's travel around a cell. (See the video at the left).

Sometimes, RNA has to travel a surprisingly long distance, as is the case in certain nerve cells — such as those in the neck of a giraffe. Jaffrey's technique would allow scientists to watch that movement.

Philip Santangelo, a professor of biomedical engineering at Georgia Tech, says the new imaging technique should also be helpful in understanding how viruses cause disease. Many viruses make extensive use of RNA when they infect cells.

"Visualizing RNA is intrinsically important for lots and lots of different disease, and for an understanding of the way cells function," he says.

There are already some techniques for visualizing RNA in cells. Diana Bratu, an assistant professor of biophotonics at Hunter College in New York, says she and others have developed ways to light up RNA, but they've had problems: "Delivery of previous techniques into living cells has been difficult," she says.

She says Samie Jaffrey's new approach should solve those difficulties. "I will certainly contact Samie to incorporate it in my own research."



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