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Altered mice see full color range

March 24, 2007|Thomas H. Maugh II | Times Staff Writer

Genetically engineering mice to give them a third type of photoreceptor in their eyes allows them to see the full spectrum of colors available to humans, apes and monkeys, researchers reported Friday in the journal Science.

The enhancement surprised some neuroscientists, who questioned whether the mice could adapt quickly to the new information.

"The answer is, remarkably, yes," said the study's lead author, Dr. Jeremy Nathans of the Johns Hopkins University School of Medicine. "They did not require additional generations to evolve new sight."

Humans, apes and monkeys have three visual receptors: one for short-wavelength light (blue), one for medium (green) and one for long (red). All other mammals have only the first two receptors, and see the world as a blend of blues, yellows and grays.

Humans with red-green color blindness see in a similar way.

Nathans' team inserted DNA for the long-wavelength receptor into the genome of mice. Psychologist Gerald Jacobs of UC Santa Barbara then determined whether the mice could see red.

Each mouse was placed in a container with three screens, two of the same color, and taught to pick the one that was different. The mice that picked correctly were rewarded with soy milk. After thousands of such tests, the team concluded that three of the five altered mice could identify the red screen 80% of the time.

Researchers hope that inserting the gene into the eyes of humans could correct color blindness. Ophthalmologist Jay Nietz of the Medical College of Wisconsin in Milwaukee has already demonstrated that the procedure works in monkeys.

thomas.maugh@latimes.com

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