Phallacidin stains the mitotic spindle of the diatom Pinnularia spp.

Abstract

Mitotic spindles of the diatom Pinnularia viritiformis stained with the fluorescent actin-labelling reagent bodipyphallacidin revealed actin among the chromosomes and extending along the spindle to the poles. This is the first report of actin's presence within spindles of this ecologically important group of organisms. Since diatom mitoses have a number of marked differences compared to that of many other eukaryotes (Int Rev Cytol 128 (1991) 63; Cell 14 (1978) 455), the present observations substantially extend the diversity of mitotic spindle types in which there is evidence of spindle actin.