Somatic Cell Genetics of Higher Plants: Appraising the Application of Bacterial Systems to Higher Plant Cells Cultured in Vitro

1979 ◽  
pp. 195-237 ◽  
Author(s):  
DONNA PARKE ◽  
PETER S. CARLSON
1994 ◽  
Vol 107 (8) ◽  
pp. 2249-2257 ◽  
Author(s):  
T. Asada ◽  
H. Shibaoka

As part of our efforts to understand the molecular basis of the microtubule-associated motility that is involved in cytokinesis in higher plant cells, an attempt was made to identify proteins with the ability to translocate microtubules in an extract from isolated phragmoplasts. Homogenization of isolated phragmoplasts in a solution that contained MgATP, MgGTP and a high concentration of NaCl resulted in the release from phragmoplasts of factors with ATPase and GTPase activity that were stimulated by microtubules. A protein fraction with microtubule-dependent ATPase and GTPase activity caused minus-end-headed gliding of microtubules in the presence of ATP or GTP. Polypeptides with microtubule-translocating activity cosedimented with microtubules that had been assembled in vitro from brain tubulin and were dissociated from sedimented microtubules by addition of ATP or GTP. After cosedimentation and dissociation procedures, a 125 kDa polypeptide and a 120 kDa polypeptide were recovered in a fraction that supported minus-end-headed gliding of microtubules. The rate of microtubule gliding that was caused by the fraction that contained the 125 kDa and 120 kDa polypeptides as main components was 1.28 microns/minute in the presence of ATP and 0.50 microns/minute in the presence of GTP. This fraction contained some microtubule-associated polypeptides in addition to the 125 kDa and 120 kDa polypeptides, but a fraction that contained only these additional polypeptides did not cause any translocation of microtubules. Thus, it appeared that the 125 kDa and 120 kDa polypeptides were responsible for translocation of microtubules. These polypeptides with plus-end-directed motor activity may play an important role in formation of the cell plate and in the organization of the phragmoplast.


1985 ◽  
Vol 100 (5) ◽  
pp. 1793-1798 ◽  
Author(s):  
P J Dawson ◽  
J S Hulme ◽  
C W Lloyd

The monoclonal antibody (anti-IFA) raised (Pruss et al., 1981, Cell 27:419-428) against an intermediate filament antigen, which is widespread throughout phylogeny, has been shown here to cross-react with higher plants. On immunoblotting, anti-IFA cross-reacted with proteins in homogenates of carrot suspension cells and of meristematic cells from onion root tips. A 50-kD cross-reactive protein was enriched in a fraction that consisted of detergent-insoluble bundles of 7-nm fibrils from carrot protoplasts (Powell et al., 1982, J. Cell Sci. 56:319-335). By use of indirect immunofluorescence, anti-IFA stained formaldehyde-fixed onion meristematic cells and carrot protoplasts in patterns approximating those obtained with monoclonal anti-tubulins. That anti-IFA was not recognizing plant tubulins was established by use of immunoblots of two-dimensional gels on which the proteins that comprised isolated fibrillar bundles and taxol-purified carrot tubulins had been separated. The two groups of proteins had different positional coordinates: anti-IFA recognized the fibrillar bundle proteins, and anti-tubulins recognized plant microtubule proteins with no cross-reaction to the heterologous proteins. Likewise, formaldehyde-fixed taxol microtubules from carrot cells could be stained with anti-tubulin but not with anti-IFA. It is concluded that an epitope common to intermediate filaments from animals co-distributes with microtubules in higher plant cells.


1993 ◽  
Vol 105 (4) ◽  
pp. 891-901 ◽  
Author(s):  
J. Chang-Jie ◽  
S. Sonobe

Microtubules in plant cells, as in animal cells, are dynamic structures. However, our lack of knowledge about the constituents of microtubules in plant cells has prevented us from understanding the mechanisms that control microtubule dynamics. To characterize some of these constituents, a cytoplasmic extract was prepared from evacuolated protoplasts (miniprotoplasts) of tobacco BY-2 cells, and microtubules were assembled in the presence of taxol and disassembled by cold treatment in the presence of Ca2+ and a high concentration of NaCl. SDS-PAGE analysis of triple-cycled microtubule protein revealed the presence of 120 kDa, 110 kDa and a group of 60–65 kDa polypeptides in addition to tubulin. Since these polypeptides had copolymerized with tubulin, through the three cycles of assembly and disassembly, and they bundle microtubules, we tentatively identified the three polypeptides as microtubule-associated proteins (MAPs). To characterize these factors further, triple-cycled microtubule protein was fractionated by Mono-Q anion-exchange chromatography and the microtubule-bundling activity of each fraction was examined. Fractions having microtubule-bundling activity contained only the 65 kDa MAP, an indication that the 65 kDa MAP is responsible for the bundling of microtubules. Purified 65 kDa MAP formed cross-bridge structures between adjacent microtubules in vitro. Polyclonal antibodies were raised in mice against the 65 kDa MAP. Immunofluorescence microscopy revealed that the 65 kDa MAP colocalized with microtubules in BY-2 cells throughout the cell cycle. Western blotting analysis of extracts from several species of plants suggested that the 65 kDa MAP and/or related peptides are widely distributed in the plant kingdom.


2000 ◽  
Vol 6 (S2) ◽  
pp. 296-297
Author(s):  
M.K. Kandasamy ◽  
R.B. Meagher

Plant organelles, including the dominant chloroplasts, migrate intracellularly on cytoplasmic strands (Fig. 1A-D). The chloroplasts in the leaf cells orient and redistribute in response to light to ensure maximum photosynthetic productivity. Their orderly distribution is also essential for proper transmission of organelle genome during cell proliferation. The movement and positioning of chloroplasts have been suggested to be mediated by the actin and tubulin-based cytoskeleton in green algae and higher plants. However, the actin structures controlling these processes have not been clearly delineated because of the difficulty in preserving and detecting the fine actin filaments in plant cells using conventional fixation methods and currently available antibodies.We investigated the role of the actin cytoskeleton in the regulation of chloroplast movement and positioning by studying: 1) the structural relationships of microfilaments and chloroplasts in leaf cells of Arabidopsis; and 2) effects of an anti-actin drug, Latrunculin B (LAT-B), on intracellular distribution of chloroplasts.


1970 ◽  
Vol 3 (3) ◽  
pp. 251-294 ◽  
Author(s):  
E. A. C. MacRobbie

In a recent review of the transport of salts and water across multicellular secretory tissues in animals (Keynes, 1969), a summary was given of the various types of active transport of ions necessary to explain the experimental observations in a very wide range of tissues, and five basic types of ion pump were discussed. The question of whether plants and animals have any common mechanisms for the transport of salts and water was specifically excluded. The original aim of the present review was to survey the types of ion pump found in plant cells and tissues, and to compare these with those found in animals. Its aims narrowed very considerably in writing. It now reviews ion transport processes in giant algal cells, and tries to assess progress towards understanding the mechanisms involved. It indicates the existence of similar ion transports in higher plant cells, but it does not present a complete review of the experimental work on higher plants.


2014 ◽  
Vol 65 (1-2) ◽  
pp. 17-24 ◽  
Author(s):  
Krystyna Kudlicka ◽  
R. M. Brown, Jr

Knowledge of the control and regulation of cellulose synthesis is fundamental to an understanding of plant development since cellulose is the primary structural component of plant cell walls. <em>In vivo</em>, the polymerization step requires a coordinated transport of substrates across membranes and relies on delicate orientations of the membrane-associated synthase complexes. Little is known about the properties of the enzyme complexes, and many questions about the biosynthesis of cell wall components at the cell surface still remain unanswered. Attempts to purify cellulose synthase from higher plants have not been successful because of the liability of enzymes upon isolation and lack of reliable <em>in vitro</em> assays. Membrane preparations from higher plant cells incorporate UDP-glucose into a glucan polymer, but this invariably turns out to be predominantly β -1,3-linked rather than β -1,4-linked glucans. Various hypotheses have been advanced to explain this phenomenon. One idea is that callose and cellulose-synthase systems are the same, but cell disruption activates callose synthesis preferentially. A second concept suggests that a regulatory protein as a part of the cellulose-synthase complex is rapidly degraded upon cell disruption. With new methods of enzyme isolation and analysis of the <em>in vitro</em> product, recent advances have been made in the isolation of an active synthase from the plasma membrane whereby cellulose synthase was separated from callose synthase.


Author(s):  
R. Malcolm Brown

It is the general belief of many investigators that the pathway of cellulose biogenesis occurs via soluble pools of hexose phosphate monomers and the plasma membrane which is thought to be the site of polymerization and/or crystalization. Brown and coworkers and Ray (see 1) have proposed to the contrary that the Golgi apparatus is the site of cellulose biogenesis in certain scale-producing algae and higher plants respectively. While it has been fairly well established that cellulose can be biosynthesized by the Golgi apparatus, considerable doubt has been expressed that this type of system could be applicable to cellulose biogenesis in higher plant systems. Conversely, the problems associated with in vitro cellulose biosynthesis in Golgi-enriched homogenates raises questions about the in vivo localization of B-(1,4)-glucan synthetase activity.


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