Further phenotypical characterisation of two substrains of C57BL/6J inbredmice differing by a spontaneous single-gene mutation

Males from two substrains of C57BL/6J mice, which have been found to differ for open-held exploration, radial-maze learning, and the sizes of their hi ppocampal intra- and intra-pyramidal mossy fibre (IIPMF) terminal fields, w ere compared for offensive aggression, thermoregulatory nest-building, and their behaviour in the Light-Dark choice test. The substrain with the small er IIPMF showed higher aggression and more nest-building behavior than the one with the larger IIPMF, whereas only tentative differences were found in the Light-Dark choice test. These Endings confirm and expand on previously found genetic links between the IIPMF and behaviours in mice. These substr ains provide a powerful tool to localise the gene involved and subsequently investigate the pathway leading from gene to behaviour. (C) 1999 Elsevier Science B.V. All rights reserved.