BASKET-SHAPED STRUCTURES FORMED BY F-ACTIN IN THE NUCLEI OF ELONGATING CELLS OF NICOTIANA-TABACUM

Phalloidin labelled with trimethyl rhodamine isothiocyanate in extract ion buffer was used to stain actin in suspension cells of tobacco. Con focal immunofluorescence microscopy indicated the presence of filament ous actin containing structures in interphase nuclei of elongating cel ls of Nicotiana tabacum 'Bright Yellow 2 Go'. The results were not aff ected by the omission of DMSO from the extraction medium. These struct ures, called actin baskets, were present in about 20% of the cells aft er induced elongation and varied in size, shape, and number per nucleu s. The cytoplasmic actin array remained intact. It is proposed that th e baskets have a transient character and are related to differentiatio n.