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In recent years, biologists showed that when wild-type mice compete in seminatural “mouse barns” for food, territory and mates, they can suffer health problems not revealed by conventional toxicity tests on caged lab mice. This test previously found mouse reproduction and survival was harmed by inbreeding, certain medicines and fructose comparable with human doses.
Now, in a new study, the sensitive toxicity test detected impaired reproduction in mice caused by genetic mutations that had seemed harmless when studied by developmental techniques. When geneticists swapped two mouse development genes in a 2006 study, the mice suffered no apparent harm. But the new study used the sensitive mouse barn test and found mice with the swapped gene held fewer territories than control mice, and produced fewer offspring that carried the swapped gene. Thus, the new research shows that genes once thought to be redundant actually play distinct roles. And the mouse barn test provides scientists a tool to find out what a change in a gene does to change how an organism functions.Image credit: Wayne Potts, University of Utah
