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Mouse of a Different Color (video)
June 21, 2001

Also on ScienCentral News

ENTER THE GENOME - A special web project by ScienCentral News and Nature, with a plethora of multimedia content. (2/10/01)

E. coli Genome - Scientists have just completed sequencing the genome of harmful Escherichia coli. By comparing it with strains of E. coli that arenít harmful, they hope to find ways not just to treat disease, but perhaps even to prevent it. (1/24/01)

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Animation of The E. coli Lactose Operon in Action (requires QuickTime)

Roslin Institute Gene Expression Lab

"Mighty Mice" - Foundation for Biomedical Research review of recent medical advances

"The Mouse in Science" - info from the University of California Center for Animal Alternatives

"The Mouse That Roared" - article from Yale Medicine

The International Albinism Center explains the absence of pigmentation in humans, similar to the pre-lactose mouse.

A page full of dancing brown mice

The old saying is "Build a better mousetrap and the world will beat a path to your door." But what if you built a better mouse?

Researchers at the University of Virginia School of Medicine may have done just that. And as this ScienCentral News video reports, it’s a mouse of a different color.

In living color

Being able to add, alter or remove certain genes in mice has meant huge advances in human disease treatments. But in major killers like heart disease, diabetes, Alzheimer’s, and cancer, the problem isn’t just whether a gene is present or not—it’s whether it is turned on or not.

"It’s currently possible to control where in the mouse a particular gene is expressed, but it hasn’t been very reliable to control when in the mouse a gene is expressed," says Heidi Scrable at the University of Virginia School of Medicine.

This process of turning genes on and off is called gene expression, and after eleven years scientists at UVA have discovered a way to trigger mouse gene expression that is almost as easy as turning on a light switch. Their work is published in the journal Genes & Development.

Scrable’s group made this switch from a sequence of DNA found in E. coli bacteria that controls the metabolism of lactose, a simple sugar. In E. coli, the gene switch turns on in the presence of lactose, and when transferred into the mouse genome, it acts similarly, but also turning on whatever gene it’s attached to when the mouse ingests a lactose-like sugar.

Scrable’s lab linked the switch to a mouse gene that controls the pigment in their eyes, skin, and fur. Using the switch, they were able to activate the pigment gene in the mice just by adding the special sugar to their drinking water. When they did this, the mice went from albino to colored.

And not only do these chameleon mice give clear visual cues as to their gene expression, they also indicate when the genes stop being expressed, changing back to albino when the sugar cue is no longer fed to them.

"We chose the pigment gene so that we could visualize the success or failures that we were having transferring this system into the mouse," Scrable says. But there is hope that many other scientists will use this technique for controlling genes linked to human disease, allowing them more experimental control over the timing of gene expression.

"For example, currently cancer is treated with aggressive forms of chemotherapy, and that’s to make sure that all of the cancer is eliminated from the body," says Scrable. "What if we could determine the shortest amount of time that we need to expose an animal to chemotherapy in order to get rid of a tumor? With this kind of temporal control we should be able to ask questions like that."

by Lyndie Freeman

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