Electrogenic pumps in higher plant cells

1974 ◽  
Vol 52 (5) ◽  
pp. 1011-1021 ◽  
Author(s):  
N. Higinbotham ◽  
W. P. Anderson
Keyword(s):  
Energy Source ◽  
Plant Cells ◽  
Higher Plant ◽  
Electrogenic Transport ◽  
Electrogenic Pumps

The evidence for the existence of electrogenic pumps in higher plant cells is reviewed. A new theory of electrogenic transport is given. Which ion is pumped and the energy source for electrogenic transport are discussed.

Isolation of polypeptides with microtubule-translocating activity from phragmoplasts of tobacco BY-2 cells

1994 ◽  
Vol 107 (8) ◽  
pp. 2249-2257 ◽  
Author(s):  
T. Asada ◽  
H. Shibaoka
Keyword(s):  
Motor Activity ◽  
Molecular Basis ◽  
Plant Cells ◽  
Cell Plate ◽  
Gtpase Activity ◽  
High Concentration ◽  
Higher Plant ◽  
Main Components ◽  
Brain Tubulin

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.

Development of the Quadripolar Meiotic Cytoskeleton in Spore Mother Cells of the Moss Funaria Hygrometrica

1988 ◽  
Vol 91 (1) ◽  
pp. 127-137
Author(s):  
C. H. BUSBY ◽  
B.E. S. GUNNING
Keyword(s):  
Meiotic Prophase ◽  
Metaphase Plate ◽  
Plant Cells ◽  
Preprophase Band ◽  
The Other ◽  
Higher Plant ◽  
Funaria Hygrometrica ◽  
Condensed Form ◽  
Prophase Nucleus ◽  
Mother Cells

Evidence presented in the accompanying paper that plastids function as microtubule (MT)-organizing centres for development of the quadripolar cytoskeleton of pre-meiotic spore mother cells (SMCs) in the moss Funaria hygrometrica is complemented here by observations on the MT system in these cells. Early in meiotic prophase numerous MTs align progressively along the two plastids as they elongate. Concomitant with (and perhaps causal for) plastid rotation, new MT arrays grow from each tip of each plastid to both tips of the other plastid. The ‘along-plastid’ and ‘between-plastid’ arrays ultimately form the edges of a tetrahedron, enclosing the prophase nucleus. MT breakdown at the centre of each edge leaves four cones of MTs, one emanating from each vertex, located at the plastid tips. These partially fuse in between-plastid pairs to give a twisted spindle with broad knife-edge poles oriented at right angles to one another, i.e. a condensed form of the quadripolar precursor. The twist causes the metaphase plate and the subsequent phragmoplast and organelle band to be saddle-shaped, and the daughter nuclei to be elongated perpendicular to one another along the two knife edges. The tetrahedral array returns during interkinesis and again breaks down into four cones of MTs centred on the plastid tips; these, however, now become individual half spindles for the two perpendicularly arranged second division spindles. When meiosis is completed the four haploid nuclei thus come to lie at the vertices of a tetrahedron that was established by MT-mediated plastid positioning during meiotic prophase. The tetrahedral cage of MTs precedes meiosis yet predicts the planes of division, and in these two respects it is the meiotic counterpart of the preprophase band of MTs, which develops before mitosis in most higher plant cells.

scholarly journals Maturation of ribosomal RNA's in suspensions of higher plant cells a DNA-RNA hybridization study

FEBS Letters ◽  
1973 ◽  
Vol 35 (1) ◽  
pp. 71-75 ◽  
Author(s):  
R. Miassod ◽  
J.-P. Cecchini ◽  
L.Becerra de Lares ◽  
J. Ricard
Keyword(s):  
Plant Cells ◽  
Hybridization Study ◽  
Higher Plant

scholarly journals Cell Cycle-Specific Disruption of the Preprophase Band of Microtubules in Fern Protonemata: Effects of Displacement of the Endoplasm by Centrifugation

1992 ◽  
Vol 101 (1) ◽  
pp. 93-98 ◽  
Author(s):  
TAKASHI MURATA ◽  
MASAMITSU WADA
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Plant Cells ◽  
Preprophase Band ◽  
Higher Plant ◽  
The Future ◽  
Prophase Nucleus ◽  
Original Region ◽  
Fern Protonemata

The preprophase band (PPB) of microtubules (MTs), which appears at the future site of cytokinesis prior to cell division in higher plant cells, disappears by metaphase. Recent studies have shown that displacement of the endoplasm from the PPB region by centrifugation delays the disappearance of the PPB. To study the role of the endoplasm in the cell cycle-specific disruption of the PPB, the filamentous protonemal cells of the fern Adiantum capilius-veneris L. were centrifuged twice so that the first centrifugation displaced the endoplasm from the site of the PPB and the second returned it to its original location. The endoplasm, including the nucleus of various stages of mitosis, could be returned by the second centrifugation to the original region of the PPB, which persists during mitosis in the centrifuged cells. When endoplasm with a prophase nucleus was returned to its original location, the PPB was not disrupted. When endoplasm with a prometa-phase telophase nucleus was similarly returned, the PPB was disrupted within 10 min of termination of centrifugation. In protonemal cells of Adiantum, a second PPB is often formed near the displaced nucleus after the first centrifugation. In cells in which the endoplasm was considered to have been returned to its original location at the prophase/prometaphase transition, the second PPB did not disappear even though the initial PPB was disrupted by the endoplasm. These results suggest that cell cycle-specific disruption of the PPB is regulated by some factor(s) in the endoplasm, which appears at prometaphase, i.e. the stage at which the PPB is disrupted in non-centrifuged cells.

Enzyme der Vakuolen aus Wurzelzellen von Maiskeimlingen. Ein Beitrag zur funktionellen Bedeutung der Vakuole bei der intrazellulären Verdauung

1966 ◽  
Vol 21 (9) ◽  
pp. 871-878 ◽  
Author(s):  
Ph. Matile
Keyword(s):  
Cytochrome C ◽  
Alanine Aminotransferase ◽  
Hydrolytic Enzymes ◽  
Plant Cells ◽  
Mitochondrial Enzymes ◽  
Centrifugal Field ◽  
Higher Plant ◽  
Cytochrome C Reductase ◽  
Intracellular Digestion

The isolation of vacuoles from rootlets of corn seedlings based on the slicing and chopping of the plasmolized tissue is described. The isolated vacuoles have densities higher than 1,029 g cm-3; in the centrifugal field they rapidly move centripetally if the extracts are brought to a density of 1,185 g cm-3 by the addition of 30% of “Urografine”. Thus a simple separation of isolated vacuoles from the extracts could be achieved.The following hydrolytic enzymes have been localized in isolated vacuoles: protease, RNase, DNase, phosphatase and two different unspecific esterases. Furthermore two transaminases, aspartate and alanine-aminotransferase and two oxyreductases cytochrome-c-reductase and diaphorase are present in preparations of isolated vacuoles. The absence of mitochondrial enzymes and of enzymes known to be localized in the groundplasm indicated the purity of the preparations of vacuoles.It is concluded that the vacuoles of higher plant cells represent organelles in which the processes of intracellular digestion take place.

Isolation of protoplasts from higher plant cells

1969 ◽  
Vol 56 (1) ◽  
pp. 41-41 ◽  
Author(s):  
P. G. Pinto da Silva
Keyword(s):  
Plant Cells ◽  
Higher Plant
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