SPONTANEOUS AVOIDANCE-BEHAVIOR IN DROSOPHILA NULL FOR CALMODULIN EXPRESSION

The regulatory protein calmodulin is a major mediator of calcium-induc ed changes in cellular activity, To analyze the roles of calmodulin in an intact animal, we have generated a calmodulin null mutation in Dro sophila melanogaster. Maternal calmodulin supports calmodulin null ind ividuals throughout embryogenesis, but they die within 2 days of hatch ing as first instar larvae. We have detected two pronounced behavioral abnormalities specific to the loss of calmodulin in these larvae, Swi nging of the head and anterior body, which occurs in the presence of f ood, is three times more frequent in the null animals, More strikingly , most locomotion in calmodulin null larvae is spontaneous backward mo vement, This is in marked contrast to the wild-type situation where ba ckward locomotion is seen only as a stimulus-elicited avoidance respon se. Our finding of spontaneous avoidance behavior has striking similar ities to the enhanced avoidance responses produced by some calmodulin mutations in Paramecium. Thus our results suggest evolutionary conserv ation of a role for calmodulin in membrane excitability and linked beh avioral responses.