scholarly journals Studies in The Metabolism of Plant Cells

1950 ◽  
Vol 3 (4) ◽  
pp. 487 ◽  
Author(s):  
DC Weeks ◽  
RN Robertson
Keyword(s):  
Cytochrome Oxidase ◽  
Enzyme Inhibitor ◽  
Plant Cells ◽  
Carrot Root ◽  
Root Cells ◽  
Oxidase System

It has been established with the use of the enzyme inhibitor carbon monoxidethat the cyanide-sensitive salt respiration in carrot root cells is mediatedby the cytochrome-cytochrome oxidase system. The cyanide-stable ground respirationis not mediated by the cytochrome-cytochfome oxidase system.

scholarly journals Dynamic continuity of cytoplasmic and membrane compartments between plant cells.

1988 ◽  
Vol 106 (3) ◽  
pp. 715-721 ◽  
Author(s):  
O Baron-Epel ◽  
D Hernandez ◽  
L W Jiang ◽  
S Meiners ◽  
M Schindler
Keyword(s):  
Cell Communication ◽  
Plant Cells ◽  
Tumor Promoter ◽  
Ionophore A23187 ◽  
Animal Cells ◽  
Root Cells ◽  
Dynamic Membrane ◽  
Membrane Compartments ◽  
Intercellular Movement ◽  
Soybean Cell

Fluorescence photobleaching was employed to examine the intercellular movement of fluorescein and carboxyfluorescein between contiguous soybean root cells (SB-1 cell line) growing in tissue culture. Results of these experiments demonstrated movement of these fluorescent probes between cytoplasmic (symplastic) compartments. This symplastic transport was inhibited with Ca2+ in the presence of ionophore A23187, and also with the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Both of these agents have previously been demonstrated to inhibit gap junction-mediated cell-cell communication in animal cells. In a companion experiment, a fluorescent phospholipid analogue, N-4-nitrobenzo-2-oxa-1,3-diazole phosphatidylcholine (NBD-PC), was incorporated into soybean cell membranes to examine whether dynamic membrane continuity existed between contacting cells, a transport route not existing between animal cells. Photobleaching single soybean cells growing in a filamentous strand demonstrated that phospholipid did exchange between contiguous cells.

scholarly journals Beyond Microcystins: Cyanobacterial Extracts Induce Cytoskeletal Alterations in Rice Root Cells

2020 ◽  
Author(s):  
Dimitris Pappas ◽  
Manthos Panou ◽  
Ioannis-Dimosthenis S. Adamakis ◽  
Spyros Gkelis ◽  
Emmanuel Panteris
Keyword(s):  
Plant Cells ◽  
Time Dependent ◽  
Rice Root ◽  
Enzyme Assays ◽  
Root Cells ◽  
Alpha Tubulin ◽  
Actin Organization ◽  
Seedling Roots ◽  
Time Periods ◽  
Plant Cytoskeleton

Microcystins (MCs) are cyanobacterial toxins and potent inhibitors of protein phosphatases 1 (PP1) and 2A (PP2A), which are involved in plant cytoskeleton (microtubules and F-actin) organization. Therefore, studies on the toxicity of cyanobacterial products on plant cells have so far being focused on MCs. In this study, we investigated the effects of extracts from 16 (4 MC-producing and 12 non-MC-producing) cyanobacterial strains from several habitats, on various enzymes (PP1, trypsin, elastase), on the plant cytoskeleton and H2O2 levels in Oryza sativa (rice) root cells. Seedling roots were treated for various time periods (1, 12 and 24h) with aqueous cyanobacterial extracts and underwent either immunostaining for α-tubulin or staining of F-actin with fluorescent phalloidin. DCF-DA staining was performed for H2O2 imaging. The enzyme assays confirmed the bioactivity of the extracts of not only MC-rich (MC+), but also MC-devoid (MC-) extracts, which induced major time-dependent alterations on both components of the plant cytoskeleton. These findings suggest that a broad spectrum of bioactive cyanobacterial compounds, apart from MCs or other known cyanotoxins (such as cylindrospermopsin), can affect plants by disrupting the cytoskeleton.

Reflectance Spectra and Some Respiratory Reactions of Bovine, Equine and Human Thrombocytes

1957 ◽  
Vol 188 (2) ◽  
pp. 415-419 ◽  
Author(s):  
Charles R. Goucher ◽  
W. Kocholaty
Keyword(s):  
Cytochrome C ◽  
Redox Potential ◽  
Cytochrome Oxidase ◽  
Sodium Azide ◽  
Visible Region ◽  
Reflectance Spectra ◽  
Absorption Bands ◽  
Oxidase System ◽  
Chromatic Properties

Reflectance spectra of human, bovine and equine thrombocytes reveal the existence of pigments which absorb in the visible region of the spectrum. The chromatic properties of these pigments change with the redox potential of the cell. These spectra alterations suggest the existence of a cytochrome system, but the position of the absorption bands does not permit their identification with known mammalian cytochromes. However, platelet homogenates contain a cytochrome oxidase which oxidizes mammalian cytochrome c and which is inhibited by sodium azide. Platelet extracts also contain a DPNH oxidase system which is inhibited by sodium azide.

scholarly journals Singlet Oxygen in Plants: Generation, Detection, and Signaling Roles

2020 ◽  
Vol 21 (9) ◽  
pp. 3237 ◽  
Author(s):  
Valeriya A. Dmitrieva ◽  
Elena V. Tyutereva ◽  
Olga V. Voitsekhovskaja
Keyword(s):  
Cell Death ◽  
Singlet Oxygen ◽  
Excited Electronic State ◽  
Plant Cells ◽  
Thylakoid Membranes ◽  
Reaction Centers ◽  
Biological Molecules ◽  
Photoinhibition Of Photosynthesis ◽  
Root Cells ◽  
High Concentrations

Singlet oxygen (1O2) refers to the lowest excited electronic state of molecular oxygen. It easily oxidizes biological molecules and, therefore, is cytotoxic. In plant cells, 1O2 is formed mostly in the light in thylakoid membranes by reaction centers of photosystem II. In high concentrations, 1O2 destroys membranes, proteins and DNA, inhibits protein synthesis in chloroplasts leading to photoinhibition of photosynthesis, and can result in cell death. However, 1O2 also acts as a signal relaying information from chloroplasts to the nucleus, regulating expression of nuclear genes. In spite of its extremely short lifetime, 1O2 can diffuse from the chloroplasts into the cytoplasm and the apoplast. As shown by recent studies, 1O2-activated signaling pathways depend not only on the levels but also on the sites of 1O2 production in chloroplasts, and can activate two types of responses, either acclimation to high light or programmed cell death. 1O2 can be produced in high amounts also in root cells during drought stress. This review summarizes recent advances in research on mechanisms and sites of 1O2 generation in plants, on 1O2-activated pathways of retrograde- and cellular signaling, and on the methods to study 1O2 production in plants.

scholarly journals INFLUENCE OF SULFHYDRYL REAGENTS ON THE CYTOCHROME c-CYTOCHROME OXIDASE SYSTEM

1950 ◽  
Vol 185 (2) ◽  
pp. 469-477
Author(s):  
Cornelius W. Kreke ◽  
Sister M. Albertus Schaefer ◽  
Sister M. Angelice Seibert ◽  
Elton S. Cook
Keyword(s):  
Cytochrome C ◽  
Cytochrome Oxidase ◽  
Sulfhydryl Reagents ◽  
Oxidase System

scholarly journals Nanobody-dependent delocalization of endocytic machinery in Arabidopsis root cells dampens their internalization capacity

2020 ◽  
Author(s):  
Joanna Winkler ◽  
Andreas De Meyer ◽  
Evelien Mylle ◽  
Peter Grones ◽  
Veronique Storme ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Protein Complexes ◽  
Function Analysis ◽  
Plant Cells ◽  
Adaptor Protein ◽  
Genetic Mutation ◽  
Loss Of Function ◽  
Expression Domain ◽  
Specific Expression ◽  
Root Cells

AbstractPlant cells perceive and adapt to an ever-changing environment by modifying their plasma membrane (PM) proteome. Whereas secretion deposits new integral membrane proteins, internalization by endocytosis removes membrane proteins and associated ligands, largely with the aid of adaptor protein complexes and the scaffolding molecule clathrin. Two adaptor protein complexes function in clathrin-mediated endocytosis at the PM in plant cells, the heterotetrameric Adaptor Protein 2 (AP-2) complex and the octameric TPLATE complex (TPC). Whereas single subunit mutants in AP-2 develop into viable plants, genetic mutation of a single TPC subunit causes fully penetrant male sterility and silencing single subunits leads to seedling lethality. To address TPC function in somatic root cells, while minimizing indirect effects on plant growth, we employed nanobody-dependent delocalization of a functional, GFP-tagged TPC subunit, TML, in its respective homozygous genetic mutant background. In order to decrease the amount of functional TPC at the PM, we targeted our nanobody construct to the mitochondria and fused it to TagBFP2 to visualize it independently of its bait. We furthermore limited the effect of our delocalization to those tissues that are easily accessible for live-cell imaging by expressing it from the PIN2 promotor, which is active in root epidermal and cortex cells. With this approach, we successfully delocalized TML from the PM. Moreover, we also show co-recruitment of TML-GFP and AP2A1-TagRFP to the mitochondria, suggesting that our approach delocalized complexes, rather than individual adaptor complex subunits. In line with the specific expression domain, we only observed minor effects on root growth, yet realized a clear reduction of endocytic flux in epidermal root cells. Nanobody-dependent delocalization in plants, here exemplified using a TPC subunit, has the potential to be widely applicable to achieve specific loss-of-function analysis of otherwise lethal mutants.

Membrane Potentials in Carrot Root Cells

1977 ◽  
Vol 4 (2) ◽  
pp. 241 ◽  
Author(s):  
W.P Anderson ◽  
R.N Robertson ◽  
B.J Wright
Keyword(s):  
Membrane Potentials ◽  
Xylem Parenchyma ◽  
Carrot Root ◽  
Root Cells ◽  
Membrane Hyperpolarization ◽  
Electrogenic Transport ◽  
Carbonyl Cyanide ◽  
External Conditions ◽  
Complete Nutrient Solution ◽  
Single Exponential

Membrane potentials in carrot root xylem parenchyma cells, aged for at least 5 days after excision from the parent organ, were measured under a variety of external conditions by standard intracellular electrode methods. The respiration blocking agents cyanide and carbon monoxide (in the dark) produced large (up to 90 mV) depolarizations which could be described by single exponential decay curves having rate constants (or half-times) of 0.065 s-1 (t*1/2 = 10.8 s) and 0.094 s-1 (t*1/2 = 7.4 s) respectively. The uncoupler carbonyl cyanide m-chlorophenylhydrazone caused a single exponential membrane depolarization with a rate constant of 0.0054 s-1(t*1/2 = 126 s). These effects are thought to reflect the action of an active electrogenic H+ extrusion pump at the plasmalemma. A second, minor electrogenic transport, causing depolarization of about 10 mV in the restlng state, and due to an obligate electrogenic coupling to Cl- influx has been confirmed in KCl-pretreated tissue. In tissue pretreated in more complete nutrient solution, there is no evidence of a Cl- -coupled electrogenic exchange. This seems to be the first report of two independent electrogenic mechanisms operating in a plant cell and, interestingly, they act in opposite senses, the major H+ extrusion causing membrane hyperpolarization, the minor Cl- -influx-coupled exchange causing depolarization, in the normal resting cell.

Invasion of Soybean Root Cells in Culture by Rhizobium japonicum.

1975 ◽  
Vol 33 ◽  
pp. 582-583
Author(s):  
Dan Raveed ◽  
Minocher Reporter ◽  
Grace Norris
Keyword(s):  
Cell Walls ◽  
Plant Cells ◽  
Culture Conditions ◽  
Final Concentration ◽  
Rhizobium Japonicum ◽  
Symbiotic Association ◽  
Extracellular Material ◽  
Root Cells ◽  
Soybean Root ◽  
Soybean Cell

The initiation of association between cultured soybean root cells and Rhizobia shows specificity under proper conditions of culture. The establishment of these culture conditions for symbiotic association have been described previously. The compatible plant cells produced a filamentous extracellular material which was capable of trapping Rhizobia. Non-compatible cells did not produce extracellular material and were not invaded. In this presentation we have followed the effect of Rhizobial invasion on the wall morphology of the soybean root cells in suspension cultures. Changes in the morphology of the soybean cell walls were then examined as follows.Harosoy root cells were grown in liquid culture in Gamborg's B-5 medium for two weeks. Rhizobium japonicum strain 138 was added to the culture for another 3 days. For this purpose, fixation was carried out by adding glutaraldehyde to the medium to a final concentration of 2%. The cell clumps were fixed 1 hr.

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