Elliott Robbins

HISTOCHEMICAL AND ULTRASTRUCTURAL STUDIES ON HELA CELL CULTURES EXPOSED TO SPINDLE INHIBITORS WITH SPECIAL REFERENCE TO THE INTERPHASE CELL

Mammalian cells of the HeLa (S3) strain, when exposed to spindle inhibitors, have been found to undergo several morphological transformations during interphase as well as during mitosis. Some of these have been studied both histochemically and ultrastructurally. The lysosomes, represented by the multivesicular bodies in HeLa cells, form clusters and become circumferentially disposed instead of occupying the polarized juxtanuclear position characteristic of these organelles. In the electron microscope it is seen that they have acquired a dense osmiophilic core that is separated from the bounding unit membrane by an electron lucent halo. The Golgi apparatus fragments under the influence of spindle inhibitors and also takes up a circumferential distribution in a pattern similar to that of the lysosomes. On the ultrastructural level, no significant modifications in this organelle are seen. Also noted in the interphase cell are numerous 60-80 Å fibrils coursing through the cytoplasm as well as a paucity of spindle our microtubules. A striking similarity has been pointed out between the behavior of the lysosomes in the drugtreated interphase cell and the untreated, normal mitotic cell. A possible explanation of some of the changes noted has been given in terms of an interruption of protoplasmic flow resulting from the disappearance of microtubules.

Mitotically Synchronized Mammalian Cells: A Simple Method for Obtaining Large Populations

Eliminating most of the ionic calcium from growth medium does not affect cell growth, but it allows simple and preferential detachment of HeLa cells in mitosis from nearly confluent monolayers.

Polyribosome Disaggregation during Metaphase

Polyribosomes as examined by both sucrose-gradient analysis and electron microscopy disaggregate during metaphase in both normal HeLa cells and those arrested in metaphase by treatment with colchicine.

Observations on microextensions from the surface of isolated vertebrate cells

Abstract Microextensions from the surface of tissue cells in vitro were examined by light and electron microscopy, and their activities were recorded by time-lapse motion pictures. Two types of these extensions were described on the basis of their structure and behavior. Those of one type are strands of cytoplasm spun out from the retreating borders of retracting cell processes. These retraction fibrils were immobile and showed no special structure in electron micrographs. Microextensions of the second type were actively projected from the surface of the cells and, during their short existence, were in constant waving motion. High resolution pictures showed these to be supported by rigid rodlike cores. The structure and behavior of these microspikes suggest their role as organelles for selective attachment to solid surfaces in the environment.

The homology of spindle tubules and neuro-tubules in the chick embryo retina

SummaryAn ultrastructural study of the 8 day chick embryo retina has been performed using gluteraldehyde and osmium tetroxide fixation. It has been noted that the centrioles of ganglion cells show clavate extensions similar to those seen in the basal bodies of photoreceptors and that these appear to give rise to the neurotubules. The neurotubules thus are shown to originate from the same organelle and have the same morphology as the spindle tubules in the mitotic cell, although the mode of origin is quite different. Some implications of these observations have been discussed.

Effect of Calcium on Intracellular Sodium and Potassium Concentrations in Plant and Animal Cells

Effect of Calcium on Intracellular Sodium and Potassium Concentrations in Plant and Animal Cells

Differential nuclear fluorescence during the cell cycle

Abstract With a modified quinacrine dihydrochloride staining method interphase nuclei show differences in their fluorescent characteristics. In human embryonic fibroblasts and synchronized HeLa cells (S3), it could be demonstrated that these patterns reflect their position within the cell cycle. This study provides further evidence for conformational changes of chromatin during interphase and offers a cytological method for distinguishing cell cycle stages.

Histone synthesis in polyoma- and SV40-infected cells

Abstract Using acrylamide gel electrophoresis of acid-soluble nuclear proteins (labeled with tryptophan- 3 H and lysine- 14 C) to monitor histone synthesis, it was found that the virus-promoted synthesis of cellular DNA is accompanied by a stimulation of histone synthesis in (1) polyoma-infected primary mouse kidney cells, (2) polyoma-infected hamster BHK21 cells, (3) SV40 2 -infected mouse 3T3 cells, and (4) SV40-infected, X-irradiated (5000 rads) mouse 3T3 cells. An induction of mitotic activity was also found in the X-irradiated, SV40-infected 3T3 cells.

RAPID EMBEDDING OF CELL CULTURE MONOLAYERS AND SUSPENSIONS FOR ELECTRON MICROSCOPY

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On the role of ions in mitosis

This paper describes some current work pertaining to transformation of cells by oncogenic viruses. Part I includes: (1) the effect of a deoxyribonucleic acid (DNA) tumor virus (SV40) on the antigenic characteristics of transformed hamster cells; (2) in vitro and in vivo methods of detecting virus-specific surface antigens; (3) the role that the host cell may play in the expression of virus-coded antigens; and (4) the presence of virus-induced antigens as a possible mechanism of the apparent nononcogenicity of certain virus variants. Part I I discusses (1) the physicochemieal properties of the nucleic acid of a ribonucleie acid (RNA) tumor virus--the Moloney sarcoma-leukemia virus (MSV-MLV) complex (2) a preliminary analysis of viral RNA rephcation in cells transformed by MSu MLV, and (3) application to human tumors.