Heiman R G, Atkinson R C, Andruss B F, Bolduc C, Kovalick G E, Beckingham K
Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251, USA.
Proc Natl Acad Sci U S A. 1996 Mar 19;93(6):2420-5. doi: 10.1073/pnas.93.6.2420.
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.
调节蛋白钙调蛋白是钙诱导细胞活性变化的主要介质。为了分析钙调蛋白在完整动物中的作用，我们在黑腹果蝇中产生了钙调蛋白无效突变。母源钙调蛋白在整个胚胎发育过程中支持钙调蛋白缺失的个体，但它们在孵化后2天内作为一龄幼虫死亡。我们在这些幼虫中检测到了两种因钙调蛋白缺失而特有的明显行为异常。在有食物的情况下，头部和身体前部的摆动在缺失钙调蛋白的动物中出现的频率是正常动物的三倍。更引人注目的是，钙调蛋白缺失的幼虫的大多数运动是自发的向后移动。这与野生型情况形成鲜明对比，在野生型中，向后移动仅作为一种刺激引发的回避反应出现。我们发现的自发回避行为与草履虫中一些钙调蛋白突变产生的增强回避反应有惊人的相似之处。因此，我们的结果表明钙调蛋白在膜兴奋性和相关行为反应中的作用具有进化保守性。
