Movements of tobacco mosaic virus inclusion bodies within tobacco callus cells.

Abstract

Cytoplasmic streaming caused linear or rotatory movements of tobacco mosaic virus inclusion bodies in the living tobacco callus cells. The inclusions were moved back and forth by active streaming between the peripheral region of the cell and the nuclear zone. The movements of individual inclusions depended on contacts with streaming cytoplasmic strands; on the age, size, and shape of the cell; and on the size, type, and number of inclusion bodies. Virus inclusions appeared as hexagonal crystals, paracrystals, and spherical bodies with or without crystals. Gray plates and small angular virus crystals with at least one angle of 120° were also seen. Inclusions not in contact with the streaming strands had slight or no movements. The cyclotic forces at a site of converging and diverging active strands exerted a stress on the inclusions, especially the spherical bodies and the loosely held groups of small virus crystals. The elastic paracrystalline fibrous inclusions, if long enough, curved in various forms under the influence of cyclosis. These inclusions, sharp at the ends, passed through the nucleus and also through walls of adjoining cells when pushed by streaming cytoplasm. Fibrous inclusions were occasionally intercepted by a newly formed wall in a dividing callus cell. Small angular virus crystals which formed hexagonal crystals on fusion appeared to move into and out of the nucleus. An unusual type of TMV inclusion appeared in the form of clumps of granular material, highly birefringent in polarized light. Transformation was observed of the nucleus into a multilobular structure with 3 or 4 nucleoli in some of the virus-infected cells.