Study of the activity of head ganglion cells of larvae of the Drosophila ts-mutant with altered capacity for learning and increased activational properties of calmodulin.

The mitotic activity of cells of the head neural ganglion of Drosophila larvae of two genetic lines, the agts 3-mutant line, which possesses increased calmodulin activational properties and altered capacity for learning, and the wild type CS line, serving as a control, was studied. The value of the mitotic index, as a ratio of the number of dividing cells to their total number, was assessed. The mitotic index was calculated following the exposure of the larvae to a temperature of 37 degrees C for 30 min, and without exposure, at a temperature which was standard for the maintenance of Drosophila ts-mutants, 22 degrees C. A higher mitotic index was observed at 22 degrees C in the agts 3 line as compared with the CS line. Exposure to a temperature of 37 degrees C led to a sharp decrease in mitotic activity in both the lines investigated. The increase in mitotic index at 22 degrees C in the agts 3 line was presumptively related to an increase in the activational properties of calmodulin, which is characteristic for this line. Following preliminary treatment of the neural ganglia by the calmodulin inhibitor, trifluoperazine, at a concentration of 10(-3) M for 30 min, the difference between the mitotic index of the mutant and the control line disappeared due to its approximately three-fold decrease in the agts 3 line; this confirmed the hypothesis advanced and suggested an important role of calmodulin in the regulation of the mitotic activity of cells of the general ganglion of Drosophila larvae.