scholarly journals Structure of cortical microtubule arrays in plant cells

1978 ◽  
Vol 77 (1) ◽  
pp. 14-34 ◽  
Author(s):  
AR Hardham ◽  
BE Gunning
Keyword(s):  
Osmium Tetroxide ◽  
High Pressures ◽  
Deuterium Oxide ◽  
Cortical Microtubule ◽  
Root Tip ◽  
Cortical Microtubules ◽  
Cellulose Deposition ◽  
Cross Bridges ◽  
Tip Cells ◽  
Root Tip Cells

Serial sectioning was used to track the position and measure the lengths of cortical microtubules in glutaraldehyde-osmium tetroxide-fixed root tip cells. Microtubules lying against the longitudinal walls during interphase, those overlying developing xylem thickenings, and those in pre-prophase bands are oriented circumferentially but on average are only about one-eighth of the cell circumference in length, i.e., 2-4 micrometer. The arrays consist of overlapping component microtubules, interconnected by cross bridges where they are grouped and also connected to the plasma membrane. Microtubule lengths vary greatly in any given array, but the probability that any pass right around the cell is extremely low. The majority of the microtubule terminations lie in statistically random positions in the arrays, but nonrandomness in the form of groups of terminations and terminations in short lines parallel to the axis of cell elongation has been observed. Low temperature induces microtubule shortening and increases the frequency of C-shaped terminations over the 1.7% found under normal conditions; colchicine and high pressures produce abnormally large proportions of very short microtubules amongst those that survive the treatments. Deuterium oxide (D2O) treatment probably induces the formation of additional microtubules as distinct from increasing the length of those already present. The distribution of C-shaped terminations provides evidence for at least local polarity in the arrays. The validity of the findings is discussed, along with implications for the development, maintenance, and orientation of the arrays and their possible relationship to the orientation of cellulose deposition.

On the distribution of microtubule-associated intermediate filament antigens in plant suspension cells

1989 ◽  
Vol 93 (3) ◽  
pp. 427-438 ◽  
Author(s):  
KIM C. GOODBODY ◽  
ALAN J. HARGREAVES ◽  
CLIVE W. LLOYD
Keyword(s):  
Intermediate Filament ◽  
Cortical Microtubule ◽  
Immunogold Labelling ◽  
Insoluble Fraction ◽  
Root Tip ◽  
Cortical Microtubules ◽  
Suspension Cells ◽  
Tip Cells ◽  
Root Tip Cells ◽  
Reactive Antibody

Intermediate filament antigens are known to coalign, patchily, with cortical microtubules in plant cells, but nothing else is established about this relationship or the form the antigens take. This was studied further using cell suspensions, instead of root tip cells, since their cortex is accessible to antibodies without the rigours of cell separation. Both carrot and sweetcorn suspension cells were labelled with three antibodies known to recognize animal intermediate filaments. The mitotic and cytokinetic apparatus could be stained with these antibodies, which, in interphase cells, also labelled cortical microtubule-like arrays. One antibody (AFB), raised against cytoplasmic bundles of 7nm fibrils from carrot cells, immunostained the bundles but only under conditions of fixation that did not allow the finer, microtubule-associated staining pattern to be seen. By exploring various preparatory conditions it was concluded that these two forms of antigen co-exist: they are not experimentally interconvertible but require different conditions for exposure to different antibodies. Double immunofluorescence established that the intermediate filament antigens do not parallel the actin network, nor did cytochalasin D affect their distribution. Taxol, however, bundled the intermediate filament antigens, whereas they are dispersed when microtubules are depolymerized, rather than collapsing in perinuclear whorls. Under conditions permitting the microtubule associated antigens to be stained by immunofluorescence, carrot protoplasts were cleaved on grids, exposing the cortical microtubules. Immunogold labelling then showed that the antibody raised against fibrillar bundles recognizes patches of electron-dense material, along and between the microtubules, rather than individual filaments. To confirm that the plant antigens are capable of forming filaments, a high salt, detergent-insoluble fraction was prepared from the maize line. By dialysing from urea, intermediate-sized filaments could be reconstituted and they immunoblotted with the broadly cross-reactive antibody to intermediate filament antigens (anti-IFA). These studies underline the problems of visualizing in plants, conformations of intermediate filament antigens that are not directly comparable to the extensively studied animal models, and that appear to be sensitive to the way in which cells are manipulated.

scholarly journals AN ATYPICAL CRISTA RESEMBLING A "TIGHT JUNCTION" IN BEAN ROOT MITOCHONDRIA

1968 ◽  
Vol 39 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Eldon H. Newcomb ◽  
Martin W. Steer ◽  
Peter K. Hepler ◽  
William P. Wergin
Keyword(s):  
Phaseolus Vulgaris ◽  
Tight Junction ◽  
Tight Junctions ◽  
Osmium Tetroxide ◽  
Root Tip ◽  
Mitochondrial Matrix ◽  
Phaseolus Vulgaris L ◽  
Animal Cells ◽  
Tip Cells ◽  
Root Tip Cells

The conformation and structure of an atypical crista found in a small percentage of the mitochondria in root tip cells of Phaseolus vulgaris L. have been studied electron microscopically in material fixed in glutaraldehyde followed by osmium tetroxide. In its transformation into an atypical crista, a normal crista elongates, broadens, and flattens, and the inner leaflets of its apposed unit membranes appear to fuse in a manner analogous to the formation of "tight junctions" between certain animal cells. The result is a large platelike, quintuple-layered structure, 240–260 A thick, whose long axis parallels that of the mitochondrion. The outer layers of the "plate," bordering on the mitochondrial matrix, are thickened and exhibit striking patterns in the micrographs. The structure of the plate is compared with that previously described for tight junctions between animal cells.

Sunlight decreased genotoxicity of azadirachtin on root tip cells of Allium cepa and Eucrosia bicolor

2010 ◽  
Vol 73 (5) ◽  
pp. 949-954 ◽  
Author(s):  
W. Kwankua ◽  
S. Sengsai ◽  
C. Kuleung ◽  
N. Euawong
Keyword(s):  
Allium Cepa ◽  
Root Tip ◽  
Tip Cells ◽  
Root Tip Cells

Salt Stress-induced Programmed Cell Death in Rice Root Tip Cells

2007 ◽  
Vol 49 (4) ◽  
pp. 481-486 ◽  
Author(s):  
Jian-You Li ◽  
Ai-Liang Jiang ◽  
Wei Zhang
Keyword(s):  
Cell Death ◽  
Salt Stress ◽  
Programmed Cell Death ◽  
Rice Root ◽  
Root Tip ◽  
Tip Cells ◽  
Root Tip Cells

Cytological evidence bearing on the origin of the B genome in polyploid wheats

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 36-43 ◽  
Author(s):  
K. Kerby ◽  
J. Kuspira
Keyword(s):  
Dna Hybridization ◽  
Triticum Turgidum ◽  
Root Tip ◽  
Cytological Evidence ◽  
B Genome ◽  
Genome Donor ◽  
The One ◽  
Genome Donors ◽  
Tip Cells ◽  
Root Tip Cells

To help elucidate the origin of the B genome in polyploid wheats, karyotypes of Triticum turgidum, Triticum monoccum, and all six purported B genome donors were compared. The analysis utilized a common cytological procedure that employed the most advanced equipment for the measurement of chromosome lengths at metaphase in root tip cells. A comparison of the karyotypes of T. turgidum and T. monococcum permitted the identification of B genome chromosomes of T. turgidum. These consist of two SAT pairs, one ST pair, three SM pairs, and one M pair of homologues. Comparisons of the chromosomes of the B genome of T. turgidum with the karyotypes of the six putative B genome donors showed that only the karyotype of Aegilops searsii was similar to the one deduced for the donor of the B genome in T. turgidum, suggesting that Ae. searsii is, therefore, the most likely donor of the B genome to the polyploid wheats. Support for this conclusion has been derived from geographic, DNA-hybridization, karyotype, morphological, and protein data reported since 1977. Reasons why the B genome donor has not been unequivocally identified are discussed.Key words: phylogeny, karyotypes, Triticum turgidum, Triticum monococcum, B genome, B genome donors.

scholarly journals Squash Preparations of Living Root-Tip Cells

Nature ◽  
1949 ◽  
Vol 164 (4178) ◽  
pp. 930-930 ◽  
Author(s):  
J. CHAYEN
Keyword(s):  
Root Tip ◽  
Living Root ◽  
Tip Cells ◽  
Root Tip Cells
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