Double immunofluorescence labeling of calmodulin and tubulin in dividing plant cells

Abstract

Using rabbit antibodies to purified spinach calmodulin and monoclonal anti-tubulin, we have investigated via immunofluorescence microscopy the distribution of calmodulin relative to that of tubulin at all stages of the cell cycle in onion and pea root meristematic cells. Calmodulin is associated with the mitotic spindle and with the phragmoplast at cytokinesis, but patterns of calmodulin that coincide with those of interphase microtubule arrays have not been demonstrated with any of the several fixation and processing regimes tested. Calmodulin is not likely to be involved in regulating the formation of the preprophase band of microtubules or its disappearance during spindle formation because a localized cortical band of calmodulin is only very rarely seen in cells at these stages.