Movement of calmodulin between cells in the ovary and embryo of drosophila.

Calmodulin (CaM) is an essential component of calcium signaling in multicellular organisms. We used null mutations of the Drosophila CaM gene (Cam) in combination with clonal analysis and immunolocalization to examine the effects of loss of Cam function in the ovarian germline and developing embryo. These studies have uncovered unexpected and striking movements of CaM protein within these tissues.

Drosophila calmodulin mutants with specific defects in the musculature or in the nervous system.

We have studied lethal mutations in the single calmodulin gene (Cam) of Drosophila to gain insight into the in vivo functions of this important calcium sensor. As a result of maternal calmodulin (CaM) in the mature egg, lethality is delayed until the postembryonic stages. Prior to death in the first larval instar, Cam nulls show a striking behavioral abnormality (spontaneous backward movement) whereas a mutation, Cam7, that results in a single amino acid change (V91G) produces a very different phenotype: short indented pupal cases and pupal death with head eversion defects.

Physiological calcium concentrations regulate calmodulin binding and catalysis of adenylyl cyclase exotoxins.

Edema factor (EF) and CyaA are calmodulin (CaM)-activated adenylyl cyclase exotoxins involved in the pathogenesis of anthrax and whooping cough, respectively. Using spectroscopic, enzyme kinetic and surface plasmon resonance spectroscopy analyses, we show that low Ca(2+) concentrations increase the affinity of CaM for EF and CyaA causing their activation, but higher Ca(2+) concentrations directly inhibit catalysis. Both events occur in a physiologically relevant range of Ca(2+) concentrations.

Expression of calmodulin in Drosophila is highly regulated in a stage- and tissue-specific manner.

 The expression of the Drosophila calmodulin (CAM) gene is surprisingly complex. The nervous system, which shows intense transcription in embryogenesis, contains no detectable transcripts at the end of larval life, but becomes transcriptionally active again at pupariation. The gut shows high levels of expression throughout the life cycle, except during pupal reorganization.