Actin microfilament and microtubule distribution patterns in the expanding root of Arabidopsis thaliana

2005 ◽  
Vol 83 (6) ◽  
pp. 579-590 ◽  
Author(s):  
David A Collings ◽  
Geoffrey O Wasteneys
Keyword(s):  
Arabidopsis Thaliana ◽  
Imaging Techniques ◽  
Cytoskeletal Proteins ◽  
Cell Cortex ◽  
Actin Microfilaments ◽  
Elongation Zone ◽  
Root Tips ◽  
Microtubule Organization ◽  
Microscopy Imaging ◽  
Distal Elongation Zone

Determination of the precise role(s) of actin microfilaments in the control of cell shape and elongation in the root tips of the model genetic system Arabidopsis thaliana (L.) Heynh is frustrated by inadequate microscopy imaging techniques. In this paper, we documented both microfilaments and microtubules in the root tips of Arabidopsis by double immunofluorescence labelling and computer-generated reconstruction of confocal image series. Our procedure, which complements the use of recently developed fluorescent reporter proteins, revealed hitherto undescribed aspects of the Arabidopsis microfilament cytoskeleton that may provide important clues about mechanisms behind cell elongation. We found that preservation of extensive arrays of transverse cortical microfilaments depends on unperturbed microtubule organization. Compared with ordinary epidermal cells, cells situated in the trichoblast or hair-forming cell files were comparatively devoid of endoplasmic microfilaments when in the distal elongation zone, well before hair formation begins. Computer-aided reconstructions also revealed that the nonexpanding end walls of cells in the distal elongation zone have radially oriented microtubules and randomly arranged microfilaments. In dividing cells, microfilaments became more prominent in the cell cortex, and subtle differences between microtubule and microfilament organization were seen within the phragmoplast. These observations will form the basis of understanding the roles of the cytoskeleton in controlling elongation in root tissues. In light of the many Arabidopsis mutants with altered root morphology, our methods offer a reliable approach to assess the function of cytoskeletal proteins and signalling systems in root morphogenesis.Key words: actin microfilaments, Arabidopsis thaliana, distal elongation zone, microtubules, phragmoplast, roots.

Histochemical Examination of Invertase Activities in the Growing Tip of the Plant Root

2017 ◽  
Vol 10 (1) ◽  
pp. 35-45
Author(s):  
N.F. Lunkova ◽  
N.A. Burmistrova ◽  
M.S. Krasavina
Keyword(s):  
Plant Root ◽  
Invertase Activity ◽  
Root Tip ◽  
Elongation Zone ◽  
Root Tips ◽  
Phloem Unloading ◽  
Meristem Cell ◽  
Transition To Elongation ◽  
Different Tissues

Background:A growing part of the root is one of the most active sinks for sucrose coming from source leaves through the phloem. In the root, sucrose is unloaded from conducting bundles and is distributed among the surrounding cells. To be involved in the metabolism, sucrose should disintegrate into hexoses by means of degrading enzymes.Aims:The aim of this research was to explore the possibility of the involvement of one such enzymes, invertase, in phloem unloading as well as distribution of its activity in the functionally different tissues of the plant root tips.Method:To estimate the enzyme activities in root tissues, we applied two techniques: the histochemical method using nitro blue tetrazolium. The localization of phloem unloading was studied with carboxyfluorescein, a fluorescent marker for symplastic transport.Results:Invertase activity was not detected in the apical part of the meristem. It appeared only between the basal part of this zone and the beginning of the elongation zone. There is the root phloem unloading in that area. Invertase activity increased with increasing the distance from the root tip and reached the highest values in the region of cell transition to elongation and in the elongation zone. The activities of the enzyme varied in different tissues of the same zone and sometimes in the neighboring cells of the same tissue. Biochemical determination of invertase activity was made in the maize root segments coincident to the zones of meristem, cell elongation and differentiation. The results of both methods of determination of invertase activity were in agreement.Conclusion:It was concluded that phloem unloading correlated with invertase activity, possibly because of the activation of invertase by unloaded sucrose. Invertase is one of the factors involved in the processes preparing the cells for their transition to elongation because the concentration of osmotically active hexoses increases after cleavage of sucrose, that stimulates water entry into the cells, which is necessary for elongation growth.

scholarly journals Lis1 is essential for cortical microtubule organization and desmosome stability in the epidermis

2011 ◽  
Vol 194 (4) ◽  
pp. 631-642 ◽  
Author(s):  
Kaelyn D. Sumigray ◽  
Hsin Chen ◽  
Terry Lechler
Keyword(s):  
Cortical Microtubule ◽  
Cell Types ◽  
Epidermal Differentiation ◽  
Cell Cortex ◽  
Microtubule Organization ◽  
Specific Subset ◽  
Keratin Filaments ◽  
Perinatal Lethality ◽  
Cytoskeletal Networks ◽  
Centrosomal Proteins

Desmosomes are cell–cell adhesion structures that integrate cytoskeletal networks. In addition to binding intermediate filaments, the desmosomal protein desmoplakin (DP) regulates microtubule reorganization in the epidermis. In this paper, we identify a specific subset of centrosomal proteins that are recruited to the cell cortex by DP upon epidermal differentiation. These include Lis1 and Ndel1, which are centrosomal proteins that regulate microtubule organization and anchoring in other cell types. This recruitment was mediated by a region of DP specific to a single isoform, DPI. Furthermore, we demonstrate that the epidermal-specific loss of Lis1 results in dramatic defects in microtubule reorganization. Lis1 ablation also causes desmosomal defects, characterized by decreased levels of desmosomal components, decreased attachment of keratin filaments, and increased turnover of desmosomal proteins at the cell cortex. This contributes to loss of epidermal barrier activity, resulting in completely penetrant perinatal lethality. This work reveals essential desmosome-associated components that control cortical microtubule organization and unexpected roles for centrosomal proteins in epidermal function.

scholarly journals Changes in cell ultrastructure and morphology of Arabidopsis thaliana roots after coumarins treatment

2014 ◽  
Vol 70 (3) ◽  
pp. 187-198
Author(s):  
Ewa Kupidłowska
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Wall ◽  
Cell Walls ◽  
Root Elongation ◽  
Inhibitory Effect ◽  
Cell Ultrastructure ◽  
Radial Expansion ◽  
Elongation Zone ◽  
Cortical Cells ◽  
Mother Cell Wall

The ultrastructure and morphology of roots treated with coumarin and umbelliferone as well as the reversibility of the coumarins effects caused by exogenous GA, were studied in <em>Arabidopsis thaliana</em>. Both coumarins suppressed root elongation and appreciably stimulated radial expansion of epidermal and cortical cells in the upper part of the meristem and in the elongation zone. The gibberellic acid applied simultaneously with coumarins decreased their inhibitory effect on root elongation and reduced cells swelling.Microscopic observation showed intensive vacuolization of cells and abnormalities in the structure of the Golgi stacks and the nuclear envelope. The detection of active acid phosphatase in the cytosol of swollen cells indicated increased membrane permeability. Significant abnormalities of newly formed cell walls, e.g. the discontinuity of cellulose layer, uncorrect position of walls and the lack of their bonds with the mother cell wall suggest that coumarins affected the cytoskeleton.

The actin cytoskeleton is required to elaborate and maintain spatial patterning during trichome cell morphogenesis in Arabidopsis thaliana

Development ◽  
1999 ◽  
Vol 126 (24) ◽  
pp. 5559-5568 ◽  
Author(s):  
J. Mathur ◽  
P. Spielhofer ◽  
B. Kost ◽  
N. Chua
Keyword(s):  
Arabidopsis Thaliana ◽  
Actin Cytoskeleton ◽  
Spatial Patterning ◽  
Actin Microfilaments ◽  
Cell Morphogenesis ◽  
Actin Organization ◽  
Cytoskeleton Organization ◽  
Branch Formation ◽  
Actin Cytoskeleton Organization ◽  
Trichome Cell

Arabidopsis thaliana trichomes provide an attractive model system to dissect molecular processes involved in the generation of shape and form in single cell morphogenesis in plants. We have used transgenic Arabidopsis plants carrying a GFP-talin chimeric gene to analyze the role of the actin cytoskeleton in trichome cell morphogenesis. We found that during trichome cell development the actin microfilaments assumed an increasing degree of complexity from fine filaments to thick, longitudinally stretched cables. Disruption of the F-actin cytoskeleton by actin antagonists produced distorted but branched trichomes which phenocopied trichomes of mutants belonging to the ‘distorted’ class. Subsequent analysis of the actin cytoskeleton in trichomes of the distorted mutants, alien, crooked, distorted1, gnarled, klunker and wurm uncovered actin organization defects in each case. Treatments of wild-type seedlings with microtubule-interacting drugs elicited a radically different trichome phenotype characterized by isotropic growth and a severe inhibition of branch formation; these trichomes did not show defects in actin cytoskeleton organization. A normal actin cytoskeleton was also observed in trichomes of the zwichel mutant which have reduced branching. ZWICHEL, which was previously shown to encode a kinesin-like protein is thought to be involved in microtubule-linked processes. Based on our results we propose that microtubules establish the spatial patterning of trichome branches whilst actin microfilaments elaborate and maintain the overall trichome pattern during development.

Microtubule organization defects in Arabidopsis thaliana

Plant Biology ◽  
2020 ◽  
Vol 22 (6) ◽  
pp. 971-980
Author(s):  
D. Ma ◽  
R. Han
Keyword(s):  
Arabidopsis Thaliana ◽  
Microtubule Organization

scholarly journals Internalization of Metal–Organic Framework Nanoparticles in Human Vascular Cells: Implications for Cardiovascular Disease Therapy

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1028
Author(s):  
Dana E. Al-Ansari ◽  
Nura A. Mohamed ◽  
Isra Marei ◽  
Atef Zekri ◽  
Yu Kameno ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Imaging Techniques ◽  
Metal Organic Framework ◽  
Microscopy Imaging ◽  
Cellular Assays ◽  
Future Drug ◽  
Metal Organic ◽  
Pulmonary Arterial ◽  
Endocytic Vesicles ◽  
Organic Framework

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Alteration of endothelial cells and the underlying vasculature plays a central role in the pathogenesis of various CVDs. The application of nanoscale materials such as nanoparticles in biomedicine has opened new horizons in the treatment of CVDs. We have previously shown that the iron metal–organic framework nanoparticle, Materials Institut Lavoisier-89 (nanoMIL-89) represents a viable vehicle for future drug delivery of pulmonary arterial hypertension. In this study, we have assessed the cellular uptake of nanoMIL-89 in pulmonary artery endothelial and smooth muscle cells using microscopy imaging techniques. We also tested the cellular responses to nanoMIL-89 using molecular and cellular assays. Microscopic images showed cellular internalization of nanoMIL-89, packaging into endocytic vesicles, and passing to daughter cells during mitosis. Moreover, nanoMIL-89 showed anti-inflammatory activity without any significant cytotoxicity. Our results indicate that nanoMIL-89 formulation may offer promising therapeutic opportunities and set forth a new prototype for drug delivery not only in CVDs, but also for other diseases yet incurable, such as diabetes and cancer.

Microtubule organization during the cell cycle of cultured Vicia hajastana Grossh.

1989 ◽  
Vol 67 (9) ◽  
pp. 545-552 ◽  
Author(s):  
D. H. Simmonds ◽  
E. Conibear ◽  
G. Setterfield
Keyword(s):  
Cell Cycle ◽  
Cell Culture ◽  
Cell Suspension ◽  
Plant Cell Culture ◽  
Cell Suspension Cultures ◽  
Cell Cortex ◽  
Hoechst 33258 ◽  
Microtubule Organization ◽  
Wide Range ◽  
Late Telophase

Microtubule (MT) organization was examined at each stage of the cell cycle in cell suspension cultures of Vicia hajastana Grossh. Simultaneous staining of MTs by immunofluorescence and DNA by Hoechst 33258, and microfluorimetric quantitation of DNA in interphase allowed direct correlation of MT configuration with mitotic stage and with G1, S, and G2 of interphase. The results indicated that in the majority of the cells the cortical MTs were disorganized in early G1, but then organized rapidly into parallel transverse arrays, remained ordered throughout S, and lost order in G2, probably near the onset of mitosis. A wide range of cell sizes were found in S, indicating that entry into S was loosely controlled. Preprophase bands, present in 55–80% of cells in prophase were observed in both disorganized cell clumps and regular cell files, indicating they were not exclusively associated with organized patterns of growth and division. In many cells, short MTs or MT clusters were observed in the cell cortex during all stages of mitosis. These MT remnants may serve as nucleating centres for new cortical MTs, which appear in late telophase as a disordered network. Ordering of MT occurs later in G1, indicating that MT nucleation and organization are two different processes.Key words: interphase, microfluorimetry, microtubules, mitosis, plant cell culture.

Novel light microscopy imaging techniques in nephrology

2003 ◽  
Vol 12 (4) ◽  
pp. 455-461 ◽  
Author(s):  
Robert L. Bacallao ◽  
Weiming Yu ◽  
Kenneth W. Dunn ◽  
Carrie L. Phillips
Keyword(s):  
Light Microscopy ◽  
Imaging Techniques ◽  
Microscopy Imaging
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