[Behavior of mice with robertsonian translocations of chromosomes].

The behaviour of mice with normal karyotype and those with robertsonian translocations was studied. The ability of the animals to solve an extrapolatory task was analysed. The experimental procedure was initiated with presentation of a food bait which the animal could reach only through a small opening in a screen. As the mouse started drinking, the food cup was moved leftward or rightward disappearing from the animal's view. The problem was to move in the direction of food, in which case the mouse could find it behind one of two feeding holes, to the right or to the left of the starting point. Laboratory mice were not able to solve this problem, whereas mice containing Rb(8, 17)1 IEM in karyotype demonstrated the extrapolatory ability - they solve the task correctly in a significant majority of cases. By means of a series of backcrosses of Rb(8, 17)1 IEM carriers on CBA strain (these mice have no extrapolatory ability) and subsequent inbreeding, a novel inbred strain was obtained, coisogenic to CBA and possessing the robertsonian translocation Rb(8, 17)1 IEM. These mice with the CBA genetic background solve the extrapolatory problem successfully, the level of correct choices being significantly above the 50% chance level. At the same time, their performance was lower than that of outbred mice with Rb(8, 17)1 IEM, the phenomenon possibly being the result of the influence of CBA genetic background. Mice with Rb(8, 17)6 Sic were also shown to possess the extrapolatory ability.(ABSTRACT TRUNCATED AT 250 WORDS)