Cell shape, chromosome orientation and the position of the plane of division in Vicia faba root cortex cells

1992 ◽  
Vol 103 (3) ◽  
pp. 847-855 ◽  
Author(s):  
J.L. Oud ◽  
N. Nanninga
Keyword(s):  
Vicia Faba ◽  
Cell Shape ◽  
Root Meristem ◽  
Three Dimensional ◽  
Progressive Increase ◽  
Root Cortex ◽  
Division Plane ◽  
Daughter Cells ◽  
Spindle Axis ◽  
Original Cell

Three-dimensional chromosome orientation was studied in thick sections of Vicia faba root meristem, using confocal microscopy and digital image analysis techniques. In the proliferative part of the root meristem, where the cells are organized in longitudinal files, it was expected to find dividing cells with a spindle axis parallel to the file axis and, occasionally, perpendicular to the file axis (resulting in a local file bifurcation). However, we observed a large number of oblique spindle axes. From metaphase to telophase there was a progressive increase in the rotation of the spindle axis. A 90° turn of the metaphase equator plane was never observed. Three-dimensional measurements of both the space occupied by the ana- and telophase chromosome configurations, and the size of the corresponding cortex cells, showed that most cells were too flat for an orientation of the spindle parallel to the file axis. Apparently, cell size limitations forced the spindle to rotate during mitosis. Consequently, the nuclei in the daughter cells were positioned diagonally in opposite directions, instead of on top of each other. In the majority of these cells, a transverse plane of division would intersect the nuclei. Therefore, the new cell wall was sigmoid shaped or oblique. Most daughter cells remained within the original cell file but, occasionally, in extremely flat cells the position of the daughter nuclei forced the cell to set a plane of division parallel to the file axis. This resulted in file bifurcation. It has been concluded that cell shape, the extent of spindle rotation and the position of the division plane are related.

scholarly journals Extracellular matrix and integrin signalling: the shape of things to come

1999 ◽  
Vol 339 (3) ◽  
pp. 481-488 ◽  
Author(s):  
Nancy J. BOUDREAU ◽  
Peter Lloyd JONES
Keyword(s):  
Extracellular Matrix ◽  
Protein Kinases ◽  
Cell Shape ◽  
Large Body ◽  
Three Dimensional ◽  
Small Gtpases ◽  
Intracellular Signalling ◽  
Receptor Protein ◽  
Stringent Requirement ◽  
Mitogen Activated Protein

The extracellular matrix (ECM) and integrins collaborate to regulate gene expression associated with cell growth, differentiation and survival. Biochemical and molecular analyses of integrin signalling pathways have uncovered several critical cytoplasmic proteins that link the ECM and integrins to intracellular pathways that may contribute to anchorage-dependent growth. A large body of evidence now indicates that the non-receptor protein kinases focal adhesion kinase (FAK) and specific members of the mitogen-activated protein kinases (MAPKs), including the extracellular-signal-regulated kinases (ERKs), mediate these ECM- and integrin-derived signalling events. However, little is known about how FAK and MAPKs contribute to biological processes other than cell proliferation or migration. In addition, remarkably little is known concerning the signalling events that occur in cells that adhere to complex multivalent extracellular matrices via multiple integrin receptors. Given the stringent requirement for attaining a proper morphology in ECM/integrin-directed cell behaviour, it is still not clear how cell shape and tissue architecture impact upon intracellular signalling programmes involving FAK and MAPKs. However, the recent discovery that members of the Rho family of small GTPases are able to regulate ECM/integrin pathways that modulate both cell shape and intracellular signalling provides new insights into how cell morphology and signal transduction become integrated, especially within three-dimensional differentiated tissues.

The development of asymmetry and period doubling for oscillatory flow in baffled channels

1996 ◽  
Vol 328 ◽  
pp. 19-48 ◽  
Author(s):  
E. P. L. Roberts ◽  
M. R. Mackley
Keyword(s):  
Reynolds Number ◽  
Oscillatory Flow ◽  
Three Dimensional ◽  
Period Doubling ◽  
Progressive Increase ◽  
Newtonian Flow ◽  
Chaotic Flow ◽  
Spatially Periodic ◽  
Dimensional Simulation ◽  
Time Periodic

We report experimental and numerical observations on the way initially symmetric and time-periodic fluid oscillations in baffled channels develop in complexity. Experiments are carried out in a spatially periodic baffled channel with a sinusoidal oscillatory flow. At modest Reynolds number the observed vortex structure is symmetric and time periodic. At higher values the flow progressively becomes three-dimensional, asymmetric and aperiodic. A two-dimensional simulation of incompressible Newtonian flow is able to follow the flow pattern at modest oscillatory Reynolds number. At higher values we report the development of both asymmetry and a period-doubling cascade leading to a chaotic flow regime. A bifurcation diagram is constructed that can describe the progressive increase in complexity of the flow.

A novel human hepatoma cell line, FLC-4, exhibits highly enhanced liver differentiation functions through the three-dimensional cell shape

2012 ◽  
Vol 227 (7) ◽  
pp. 2898-2906 ◽  
Author(s):  
Thomas Laurent ◽  
Daiki Murase ◽  
Sayaka Tsukioka ◽  
Tomokazu Matsuura ◽  
Seishi Nagamori ◽  
...  
Keyword(s):  
Cell Line ◽  
Cell Shape ◽  
Hepatoma Cell ◽  
Three Dimensional ◽  
Hepatoma Cell Line ◽  
Human Hepatoma ◽  
Human Hepatoma Cell ◽  
Human Hepatoma Cell Line ◽  
Dimensional Cell

Three-Dimensional Simulation for Perikinetic Flocculation of Fine Sediment under the Ionization in Still Water

2011 ◽  
Vol 356-360 ◽  
pp. 2282-2290
Author(s):  
Lin Shuang Liu ◽  
Xin Luo ◽  
Guo Lu Yang ◽  
Ming Hui Yu
Keyword(s):  
Electrostatic Force ◽  
Three Dimensional ◽  
Fine Sediment ◽  
Radius Of Gyration ◽  
Brownian Dynamic ◽  
System A ◽  
Simulation Based ◽  
Dimensional Simulation ◽  
Original Cell ◽  
Random Variation

A simulation based on Brownian dynamic for perikinetic flocculation of fine sediment under the ionization is presented. The Langevin equation is used as dynamical equation for tracking each particle making up a floc. Monte Carlo method was used for simulate random variation in particle movement. An initial condition and periodic boundary condition which conformed to reality well is used for calculation. In each cell 1000 particles of 10𝝁 m, 15𝝁m, 20𝝁m, 25𝝁m, 30𝝁m in diameter were served as primary particles. Floc growth is based on the thermal force and the electrostatic force. The electrostatic force on a particle in the simulation cell is considered as a sum of the electrostatic force from other particles in the original cell. The particles are supposed to be motion with uncharged and charged state in dispersion system. A comparison of the initial flocculent time and smashing time in sludge density 1010kg/m3, 1025 kg/m3, 1050 kg/m3, 1075 kg/m3, 1100 kg/m3were present to show the effect of it on floc growth. The increase of sludge density deferred the flocculation rate. To study morphological shape of floc, the radius of gyration was revealed under different situations. On one hand the radius of gyration presented random variation with uncharged particle, On the other hand, the radius of gyration increases gradually with the increase of polar electrical charges on primal particle. Moreover, the morphological shape for the charged floc was more open than that of unchanged state. Finally, a series of experimental results are present, which is coincide with model well.

scholarly journals The Rejoining Time of Chromatid Breaks Induced by Gamma Radiation in Vicia faba Root Tips at 3 °C

1960 ◽  
Vol 7 (1) ◽  
pp. 79-85 ◽  
Author(s):  
J. R. K. Savage ◽  
G. J. Neary ◽  
H. J. Evans
Keyword(s):  
Root Growth ◽  
Vicia Faba ◽  
Low Dose ◽  
Root Meristem ◽  
Root Tips ◽  
Dose Rates ◽  
Low Dose Rate ◽  
Chromatid Aberration ◽  
Γ Rays ◽  
Chromatid Aberrations

The observation was made previously that the reduction in radiosensitivity in Vicia faba (as measured by postirradiation root growth) by prolonging the exposure time from about 10 minutes to 24 hours is much less marked at 3°C. than at 19°C. If chromosome damage is mainly responsible for the reduced root growth, this observation might be explained by a smaller drop in the "two-hit" aberration component, resulting from an increased time for which breaks are available for rejoining at 3°C. This hypothesis was tested by comparing chromatid aberration frequencies in root meristem cells produced by 105 rads of 60Co γ rays, given at dose rates of 19.4 and 0.073 rads per minute. Beans were maintained in aerated water at 2°C. prior to and during irradiation, and at this temperature the rate of development of cells was such that the two different exposure times both occupied a period during which the cell sensitivity was approximately constant. Immediately subsequent to irradiation, the roots were returned to 19°C. and examined cytologically. All chromatid aberrations were less frequent after low dose rate treatment, but only the chromatid interchange reduction was significant. The average time for which breaks are available for reunion, calculated from Lea's G function, was found to be 12 hours (95 per cent C.L. 6 to 24 hours).

scholarly journals Thrombospondin gene expression by endothelial cells in culture is modulated by cell proliferation, cell shape and the substratum

1990 ◽  
Vol 268 (1) ◽  
pp. 225-230 ◽  
Author(s):  
A E Canfield ◽  
R P Boot-Handford ◽  
A M Schor
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Endothelial Cells ◽  
Cell Shape ◽  
Type I Collagen ◽  
Three Dimensional ◽  
Type I ◽  
Mrna Levels ◽  
Collagen Gels ◽  
Cells Cultured

Endothelial cells plated on the surface of a two-dimensional substratum (gelatin-coated dishes, dishes coated with native type I collagen or collagen gels) form a cobblestone monolayer at confluence, whereas cells plated within a three-dimensional gel matrix elongate into a sprouting morphology and self-associate into tube-like structures. In this study, we have compared the synthesis of thrombospondin by quiescent endothelial cells displaying (a) the same morphological phenotype (cobblestone) on different substrata (gelatin and collagen) and (b) different morphological phenotypes (cobblestone and sprouting) on the same substratum (collagen). We demonstrate that thrombospondin is a major biosynthetic product of confluent, quiescent cells cultured on dishes coated with either gelatin or collagen, and that the synthesis of this protein is markedly decreased when cells are plated on or in three-dimensional collagen gels. Moreover, we demonstrate that cells plated in gel (sprouting) secrete less thrombospondin than do cells plated on the gel surface (cobblestone). The regulation of thrombospondin synthesis is reversible and occurs at the level of transcription, as steady-state mRNA levels for thrombospondin decrease in a manner comparable with the levels of protein secreted by these cells. We also show that mRNA levels for laminin B2 chains are increased when cells are cultured on and in collagen gels compared with on gelatin-coated dishes, suggesting that the syntheses of thrombospondin and laminin are regulated by different mechanisms. When cells are cultured on gelatin- or collagen-coated dishes, thrombospondin gene expression is directly proportional to the proliferative state of the cultures. By contrast, the synthesis of thrombospondin by cells cultured on collagen gels remains at equally low levels whether they are labelled when they are sparse and rapidly proliferating or when they are confluent and quiescent. Fibronectin synthesis was found to increase with increasing confluency of the cells plated on all three substrata. These results demonstrate that thrombospondin gene expression is modulated by cell shape, cell proliferation and the nature of the substratum used for cell culture.

Cytotoxic studies of zinthane on root meristem of Vicia faba L.

Agrica ◽  
2017 ◽  
Vol 6 (1) ◽  
pp. 66
Author(s):  
Roopam Saxena ◽  
Amit Vaish ◽  
Somesh Yadav
Keyword(s):  
Vicia Faba ◽  
Root Meristem ◽  
Vicia Faba L ◽  
Cytotoxic Studies

scholarly journals Nucleus-associated microtubules help determine the division plane of plant epidermal cells: avoidance of four-way junctions and the role of cell geometry.

1990 ◽  
Vol 110 (4) ◽  
pp. 1111-1122 ◽  
Author(s):  
D J Flanders ◽  
D J Rawlins ◽  
P J Shaw ◽  
C W Lloyd
Keyword(s):  
Cell Wall ◽  
Three Dimensional ◽  
Spatial Relationship ◽  
Epidermal Cells ◽  
Enzyme Treatment ◽  
Cross Wall ◽  
Nuclear Surface ◽  
Division Plane ◽  
Parallel Side ◽  
Side Walls

To investigate the spatial relationship between the nucleus and the cortical division site, epidermal cells were selected in which the separation between these two areas is large. Avoiding enzyme treatment and air drying, Datura stramonium cells were labeled with antitubulin antibodies and the three-dimensional aspect of the cytoskeletons was reconstructed using computer-aided optical sectioning. In vacuolated cells preparing for division, the nucleus migrates into the center of the cell, suspended by transvacuolar strands. These strands are now shown to contain continuous bundles of microtubules which bridge the nucleus to the cortex. These nucleus-radiating microtubules adopt different configurations in cells of different shape. In elongated cells with more or less parallel side walls, oblique strands radiating from the nucleus to the long side walls are presumably unstable, for they are progressively realigned into a transverse disc (the phragmosome) as broad, cortical, preprophase bands (PPBs) become tighter. The phragmosome and the PPB are both known predictors of the division plane and our observations indicate that they align simultaneously in elongated epidermal cells. These observations suggest another hypothesis: that the PPB may contain microtubules polymerized from the nuclear surface. In elongated cells, the majority of the radiating microtubules, therefore, come to anchor the nucleus in the transverse plane, consistent with the observed tendency of such cells to divide perpendicular to the long axis. In nonrectangular isodiametric epidermal cells, which approximate regular hexagons in section, the radial microtubular strands emanating from the nucleus tend to remain associated with the middle of each subtending cell wall. The strands are not reorganized into a single dominant transverse bar, but remain as a starlike array until mitosis. PPBs in these cells are not as tight; they may only be a sparse accumulation of microtubules, even forming along non-diametrical radii. This arrangement is consistent with the irregular division patterns observed in epidermal mosaics of isodiametric D. stramonium cells. The various conformations of the radial strands can be modeled by springs held in two-dimensional hexagonal frames, and by soap bubbles in three-dimensional hexagonal frames, suggesting that the division plane may, by analogy, be selected by minimal path criteria. Such behavior offers a cytoplasmic explanation of long-standing empirically derived "rules" which state that the new cell wall tends to meet the maternal wall at right angles. The radial premitotic strands and their analogues avoid taking the longer path to the vertex of an angle where a cross wall is already present between neighboring cells.(ABSTRACT TRUNCATED AT 400 WORDS)

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