RESTORATION OF STAGGERER MOUSE MATERNAL-BEHAVIOR FOLLOWING LONG-TERM BREEDING SELECTION

Two lines of staggerers from the C57BL/6 strain were tested for distur bances in maternal behavior and locomotion. One line, called Pasteur, included staggerers available at L'Institut Pasteur. The second line, called Selected, included staggerers that had been bred in our laborat ory for several generations for their ability to reproduce. While none of the Pasteur animals showed any evidence of maternal behavior, most of the Selected mutant mice became maternal, carrying about 90% of th e pups until weaning. No group differences were seen in locomotory beh avior. It was concluded that a) as a result of long-term breeding sele ction, homozygous (sg/sg) animals of the C57BL/6 strain may be able to exhibit maternal behavior from birth on, even under standard laborato ry conditions; b) the restoration of the maternal behavior does not eq ually affect all components of this behavior pattern; and c) the impai rment of the maternal behavior showed by the staggerer females is not a necessary consequence of impaired locomotory capacity characteristic of the staggerer.