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Spontaneous avoidance behavior in Drosophila null for calmodulin expression
R G Heiman1, R C Atkinson, B F Andruss
1Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251, USA.
Abstract:
The regulatory protein calmodulin is a major mediator of calcium-induced changes in cellular activity. To analyze the roles of calmodulin in an intact animal, we have generated a calmodulin null mutation in Drosophila melanogaster. Maternal calmodulin supports calmodulin null individuals throughout embryogenesis, but they die within 2 days of hatching as first instar larvae. We have detected two pronounced behavioral abnormalities specific to the loss of calmodulin in these larvae. Swinging of the head and anterior body, which occurs in the presence of food, is three times more frequent in the null animals. More strikingly, most locomotion in calmodulin null larvae is spontaneous backward movement. This is in marked contrast to the wild-type situation where backward locomotion is seen only as a stimulus-elicited avoidance response. Our finding of spontaneous avoidance behavior has striking similarities to the enhanced avoidance responses produced by some calmodulin mutations in Paramecium. Thus our results suggest evolutionary conservation of a role for calmodulin in membrane excitability and linked behavioral responses.
Insights
Calmodulin (CaM) is crucial for cellular activity. Loss of CaM in Drosophila larvae causes abnormal head swinging and primarily backward movement, suggesting conserved roles in behavior.
Area of Science:
- Neuroscience
- Developmental Biology
- Genetics
Background:
- Calmodulin (CaM) is a key calcium-binding protein regulating cellular processes.
- Understanding CaM's in vivo function requires studying its absence in a whole organism.
Purpose of the Study:
- To investigate the essential roles of calmodulin in a complete animal model.
- To characterize behavioral deficits resulting from a complete loss of calmodulin function.
Main Methods:
- Generation of a calmodulin null mutation in Drosophila melanogaster.
- Observation and quantification of larval behavior, including locomotion and feeding responses.
Main Results:
- Calmodulin null Drosophila larvae survive embryogenesis due to maternal CaM but die post-hatching.
- Null larvae exhibit significantly increased head swinging behavior near food.
- Locomotion in null larvae is predominantly spontaneous backward movement, unlike wild-type avoidance responses.
Conclusions:
- Calmodulin is essential for normal larval development and behavior in Drosophila.
- Spontaneous backward locomotion indicates a critical role for CaM in motor control.
- Findings suggest evolutionary conservation of calmodulin's function in membrane excitability and behavior across species.