To do this, Kimchi and her research group backcrossed strains of laboratory mutant mice that had a specific mutation in the gene responsible for detecting pheromone signals, with wild-derived (undomesticated) mice for ten generations. As a result, in these new backcrossed strains of mice, the scientists managed to reinstate traits typical of wild mice, which were lost through the domestication process and are absent in laboratory strains, including those pertaining to behavior, body structure, hormones, various biological processes and genetic functions. More specifically, they restored, among other things, the ability to react to and escape from danger, spontaneous anxiety-related jumping and freezing behavior, and aggressive attacks toward other females. Another important feature that was restored in the new breed of mice was maternal instinct: Nave (not yet mated and maternal) backcrossed wild-derived female mice were less likely to nurture another's pup they encountered. They were also aggressive toward those pups, as well as among themselves just like wild mice.
The new mouse model created by Kimchi and her team has allowed them to explore, for the first time, the biological roots of aggressive behavior in females, both toward each other, and especially toward the pups of others. It also enabled them to locate a particular gene, which is responsible for the perception of pheromone signals, and to determine this to be the main cause for rejecting a stranger's pup, as well as the aggress
|Contact: Yivsam Azgad|
Weizmann Institute of Science