CHICAGO – To identify laboratory mice, researchers punch a specific set of holes in their ears. The pattern scars but never closes over, and the holes serve as a mouse’s lifetime social security number.

So researchers in the laboratory of Ellen Heber-Katz of the Wistar Institute in Philadelphia were surprised recently to discover a strain of mice with a genetic mutation that gives it partial regenerative powers. The holes not only closed but were filled with the same kind of tissue that was there before, including nerves, hair follicles and tendons.

“It was like the Terminator when he gets shot and the holes just close right up,” Heber-Katz said. “That’s what it reminded me of. I was absolutely amazed.”

The serendipitous discovery of this super-mouse – which can also heal damage to the heart without forming debilitating scar tissue – may reveal ways of manipulating immune system genes.

Northwestern University’s Hans-Georg Simon, who is now working with Heber-Katz, hopes to further uncover the genetic basis of regeneration.

“We are building what is called a regeneration gene array,” Simon said. “We want to identify which genes are turned on or off during regeneration.”

There is some evidence, for example, that the Tbx5 gene Simon has identified may be involved in the mouse’s regeneration of heart tissue.

“There’s a critical mass of new information that wasn’t there five or 10 years ago,” Simon said. “We are looking at genes, proteins, how cells communicate with each other and we have new tools at our disposal.”

(c) 2006, Chicago Tribune.

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Distributed by McClatchy-Tribune Information Services.

AP-NY-10-02-06 0618EDT

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