scholarly journals The Pellicle–Another Strategy of the Root Apex Protection against Mechanical Stress?

2021 ◽  
Vol 22 (23) ◽  
pp. 12711
Author(s):  
Izabela Potocka ◽  
Joanna Szymanowska-Pułka
Keyword(s):  
Mechanical Stress ◽  
Root Apex ◽  
Apical Part ◽  
Root Apical Meristem ◽  
Meristematic Zone ◽  
Negative Effects ◽  
Epidermal Surface ◽  
Maize Roots ◽  
Microscopy Analysis ◽  
Confocal Microscopy Analysis

In grasses, the apical part of the root is covered by a two-layered deposit of extracellular material, the pellicle, which together with the outer periclinal wall of protodermal cells forms the three-layered epidermal surface. In this study, the effect of mechanical stress on the pellicle was examined. An experiment was performed, in which maize roots were grown in narrow diameter plastic tubes with conical endings for 24 h. Two groups of experimental roots were included in the analysis: stressed (S) roots, whose tips did not grow out of the tubes, and recovering (R) roots, whose apices grew out of the tube. Control (C) roots grew freely between the layers of moist filter paper. Scanning electron microscopy and confocal microscopy analysis revealed microdamage in all the layers of the epidermal surface of S roots, however, protodermal cells in the meristematic zone remained viable. The outermost pellicle layer was twice as thick as in C roots. In R roots, large areas of dead cells were observed between the meristematic zone and the transition zone. The pellicle was defective with a discontinuous and irregular outermost layer. In the meristematic zone the pellicle was undamaged and the protodermal cells were intact. The results lead to the conclusion that the pellicle may prevent damage to protodermal cells, thus protecting the root apical meristem from the negative effects of mechano-stress.

scholarly journals Effects of acids used in the microabrasion technique: Microhardness and confocal microscopy analysis

2015 ◽  
pp. e506-e512 ◽  
Author(s):  
NIP Pini ◽  
DANL Lima ◽  
GMB Ambrosano ◽  
WJ da Silva ◽  
FHB Aguiar ◽  
...  
Keyword(s):  
Confocal Microscopy ◽  
Microscopy Analysis ◽  
Confocal Microscopy Analysis

Primary vascular patterns in root meristems of Pontederia cordata and their relevance to studies of root development

1980 ◽  
Vol 58 (12) ◽  
pp. 1351-1369 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Apical Meristem ◽  
Vascular System ◽  
Root Apex ◽  
Root Apical Meristem ◽  
Vascular Pattern ◽  
Quiescent Centre ◽  
Vascular Differentiation ◽  
Pontederia Cordata ◽  
Distribution Of Components ◽  
Root Apices

There are several files of metaxylem cells in root apices of Pontederia cordata L., each considered to consist of a series of prospective vessels with their ends in contact. Two longitudinally adjacent vessels may be in the same file of cells produced by the root apex or in adjacent files. As the root grows, successive prospective vessels are added to the apical ends of most of the files but not all files are continued. Addition of prospective vessels appears to take place within the "quiescent centre" of the root apical meristem. Where files are not continued there is no immediate readjustment of remaining files. The longitudinal and transverse distribution of components of the vascular system (including protophloem and protoxylem) is discussed in relation to the means by which the pattern of development may be controlled. Rates of production of vessels and the final lengths of the vessels are estimated. The observations and deductions are discussed in relation to other studies of root growth, vascular differentiation, and vascular pattern formation and maintenance.

Epi-LASIK: A Confocal Microscopy Analysis of the Corneal Epithelium and Anterior Stroma

2012 ◽  
Vol 43 (4) ◽  
pp. 319-322 ◽  
Author(s):  
Manuel Ramírez ◽  
Everardo Hernández-Quintela ◽  
Ramón Naranjo-Tackman
Keyword(s):  
Confocal Microscopy ◽  
Corneal Epithelium ◽  
Microscopy Analysis ◽  
Confocal Microscopy Analysis

scholarly journals Modulation of hexokinase association with mitochondria analyzed with quantitative three-dimensional confocal microscopy.

1991 ◽  
Vol 112 (3) ◽  
pp. 385-395 ◽  
Author(s):  
R M Lynch ◽  
K E Fogarty ◽  
F S Fay
Keyword(s):  
Glucose Metabolism ◽  
Confocal Microscopy ◽  
Cell Metabolism ◽  
Three Dimensional ◽  
Metabolic State ◽  
Metabolic Conditions ◽  
Microscopy Analysis ◽  
Immunocytochemical Studies ◽  
Confocal Microscopy Analysis

Hexokinase isozyme I is proposed to be associated with mitochondria in vivo. Moreover, it has been suggested that this association is modulated in coordination with changes in cell metabolic state. To test these hypotheses, we analyzed the subcellular distribution of hexokinase relative to mitochondria in paraformaldehyde-fixed astrocytes using immunocytochemistry and quantitative three-dimensional confocal microscopy. Analysis of the extent of colocalization between hexokinase and mitochondria revealed that approximately 70% of cellular hexokinase is associated with mitochondria under basal metabolic conditions. In contrast to the immunocytochemical studies, between 15 to 40% of cellular hexokinase was found to be associated with mitochondria after fractionation of astrocyte cultures depending on the exact fractionation conditions. The discrepancy between fractionation studies and those based on imaging of distributions in fixed cells indicates the usefulness of using techniques that can evaluate the distributions of "cytosolic" enzymes in cells whose subcellular ultrastructure is not severely disrupted. To determine if hexokinase distribution is modulated in concert with changes in cell metabolism, the localization of hexokinase with mitochondria was evaluated after inhibition of glucose metabolism with 2-deoxyglucose. After incubation with 2-deoxyglucose there was an approximate 35% decrease in the amount of hexokinase associated with mitochondria. These findings support the hypothesis that hexokinase is bound to mitochondria in rat brain astrocytes in vivo, and that this association is sensitive to cell metabolic state.

scholarly journals Antimalarial Activities of Dermaseptin S4 Derivatives

2000 ◽  
Vol 44 (9) ◽  
pp. 2442-2451 ◽  
Author(s):  
Miriam Krugliak ◽  
Rina Feder ◽  
Vadim Y. Zolotarev ◽  
Leonid Gaidukov ◽  
Arie Dagan ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Antimalarial Activity ◽  
Underlying Mechanism ◽  
Trophozoite Stage ◽  
Fluorescence Confocal Microscopy ◽  
Infected Cells ◽  
Microscopy Analysis ◽  
Confocal Microscopy Analysis ◽  
Micromolar Range ◽  
Significant Growth Inhibition

ABSTRACT The hemolytic antimicrobial peptide dermaseptin S4 was recently shown to exert antimalarial activity. In this study, we attempted to understand the underlying mechanism(s) and identify derivatives with improved antimalarial activity. A number of dermaseptin S4 derivatives inhibited parasite growth with a 50% inhibitory concentration (IC50) in the micromolar range. Among these, the substituted S4 analog K4K20-S4 was the most potent (IC50 = 0.2 μM), while its shorter version, K4-S4(1–13)a, retained a considerable potency (IC50 = 6 μM). Both K4K20-S4 and K4-S4(1–13)a inhibited growth of the parasites more at the trophozoite stage than at the ring stage. Significant growth inhibition was observed after as little as 1 min of exposure to peptides and proceeded with nearly linear kinetics. The peptides selectively lysed infected red blood cells (RBC) while having a weaker effect on noninfected RBC. Thus, K4K20-S4 lysed trophozoites at concentrations similar to those that inhibited their proliferation, but trophozoites were >30-fold more susceptible than normal RBC to the lytic effect of K4K20-S4, the most hemolytic dermaseptin. The same trend was observed with K4-S4(1–13)a. The d isomers of K4K20-S4 or K4-S4(1–13)a were as active as the l counterparts, indicating that antimalarial activity of these peptides, like their membrane-lytic activity, is not mediated by specific interactions with a chiral center. Moreover, dissipation of transmembrane potential experiments with infected cells indicated that the peptides induce damage in the parasite's plasma membrane. Fluorescence confocal microscopy analysis of treated infected cells also indicated that the peptide is able to find its way through the complex series of membranes and interact directly with the intracellular parasite. Overall, the data showed that dermaseptins exert antimalarial activity by lysis of infected cells. Dermaseptin derivatives are also able to disrupt the parasite plasma membrane without harming that of the host RBC.

scholarly journals Effect of mechanical stress on Zea root apex. I. Mechanical stress leads to the switch from closed to open meristem organization

2011 ◽  
Vol 62 (13) ◽  
pp. 4583-4593 ◽  
Author(s):  
I. Potocka ◽  
J. Szymanowska-Pulka ◽  
J. Karczewski ◽  
J. Nakielski
Keyword(s):  
Mechanical Stress ◽  
Root Apex
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