scholarly journals Hypoxia-Induced Ethanol Production in Arabidopsis Root Apex Cells Affects Endocytic Vesicle Recycling and F-Actin Organisation

2022 ◽  
Author(s):  
Tomoko Kagenishi ◽  
Frantisek Baluska ◽  
Ken Yokawa
Keyword(s):  
Plant Stress ◽  
Root Apex ◽  
Membrane Properties ◽  
Cross Wall ◽  
Endocytic Vesicle ◽  
Vesicle Recycling ◽  
Hypoxic Conditions ◽  
Cellular Events ◽  
Low Concentrations ◽  
Species Production

Ethanol (EtOH) is a short-chain alcohol that is abundant in nature. EtOH is endogenously produced by plants under hypoxic conditions, and exogenously applied EtOH improves plant stress tolerance at low concentrations (<1%). However, no direct observations have shown how EtOH affects cellular events in plants. In intact Arabidopsis roots, 0.1% EtOH promoted reactive oxygen species production in root apex cells. EtOH also accelerated exocytic vesicle recycling and altered F-actin organisation, both of which are closely related to cell membrane properties. In addition to exogenous EtOH application, hypoxic treatment resulted in EtOH production in roots and degradation of the cross-wall actin cytoskeleton in root epidermal cells. We conclude that hypoxia-induced EtOH production affects endocytic vesicle recycling and associated signalling pathways.

scholarly journals Characterization of adenosine deaminase (ADA) in Hemolymph of Biomphalaria glabrata

2005 ◽  
Vol 65 (2) ◽  
pp. 371-376 ◽  
Author(s):  
M. R. Vale ◽  
R. V. Pereira ◽  
S. M. Almeida ◽  
Y. M. Almeida ◽  
S. F. L. C. Nunes
Keyword(s):  
Adenosine Deaminase ◽  
Incubation Temperature ◽  
Small Variation ◽  
Healthy Human ◽  
Ph Variation ◽  
Cellular Events ◽  
Low Concentrations ◽  
Key Enzyme ◽  
Assay Conditions

Adenosine is an important signaling molecule for many cellular events. Adenosine deaminase (ADA) is a key enzyme for the control of extra- and intra-cellular levels of adenosine. Activity of ADA was detected in hemolymph of B. glabrata and its optimum assay conditions were determined experimentally. The pH variation from 6.2 to 7.8 caused no significant change in ADA activity. Using adenosine as a substrate, the apparent Km at pH 6.8 was 734 µmols.L-1. Highest activity was found at 37ºC. Standard assay conditions were established as being 15 minutes of incubation time, 0.4 µL of pure hemolymph per assay, pH 6.8, and 37ºC. This enzyme showed activities of 834 ± 67 µmol.min-1.L-1 (25ºC) and 2029 ± 74 µmol.min-1.L-1 (37ºC), exceeding those in healthy human serum by 40 and 100 times, respectively. Higher incubation temperature caused a decrease in activity of 20% at 43ºC or 70% at 50ºC for 15 minutes. The ADA lost from 26 to 78% of its activity when hemolymph was pre-incubated at 50ºC for 2 or 15 minutes, respectively. Since the ADA from hemolymph presented high levels, it can be concluded that in healthy and fed animals, adenosine is maintained at low concentrations. In addition, the small variation in activity over the 6.2 to 7.8 range of pH suggests that adenosine is maintained at low levels in hemolymph even under adverse conditions, in which the pH is altered.

scholarly journals Osmolytes: Proline metabolism in plants as sensors of abiotic stress

2017 ◽  
Vol 9 (4) ◽  
pp. 2079-2092 ◽  
Author(s):  
Ashu Singh ◽  
Manoj Kumar Sharma ◽  
R. S. Sengar
Keyword(s):  
Stress Tolerance ◽  
Large Range ◽  
Plant Stress ◽  
Proline Accumulation ◽  
Metal Chelator ◽  
Low Concentrations ◽  
Plant Stress Tolerance ◽  
Higher Doses ◽  
Research Pattern

Proline accumulation occurs in a large range of plant species in retaliation to the numerous abiotic stresses. An exclusive research pattern suggests there is a pragmatic relation between proline accumulation and plant stress tolerance. In this review, we will discuss the metabolism of proline accumulation and its role in stress tolerance in plants. Pertaining to the literature cited clearly indicates that not only does it acts as an osmolyte, it also plays important roles during stress as a metal chelator and an antioxidative defence molecule. Moreover, when applied exogenously at low concentrations, proline enhanced stress tolerance in plants. However, some reports point out adverse effects of proline when applied at higher doses. Role of proline gene in seed germination, flowering and other developmental programmes; thus creation of transgene overexpressing this gene would provide better and robust plants. In this context this review gives a detailed account of different proline gene over-expressed in all the trans-genic crops so far.

Division and differentiation during normal and liguleless-1 maize leaf development

Development ◽  
1990 ◽  
Vol 110 (3) ◽  
pp. 985-1000 ◽  
Author(s):  
A.W. Sylvester ◽  
W.Z. Cande ◽  
M. Freeling
Keyword(s):  
Cross Wall ◽  
Normal Leaf ◽  
Division Rate ◽  
Maize Leaf ◽  
Second Stage ◽  
Cellular Events ◽  
Division Pattern ◽  
Third Stage ◽  
Anticlinal Division ◽  
Three Stages

The maize leaf is composed of a blade and a sheath, which are separated at the ligular region by a ligule and an auricle. Mutants homozygous for the recessive liguleless-1 (lg1) allele exhibit loss of normal ligule and auricle. The cellular events associated with development of these structures in both normal and liguleless plants are investigated with respect to the timing of cell division and differentiation. A new method is used to assess orientation of anticlinal division planes during development and to determine a division index based on recent epidermal cross-wall deposition. A normal leaf follows three stages of development: first is a preligule stage, in which the primordium is undifferentiated and dividing throughout its length. This stage ends when a row of cells in the preligule region divides more rapidly in both transverse and longitudinal anticlinal planes. During the second stage, ligule and auricle form, blade grows more rapidly than sheath, divisions in the blade become exclusively transverse in orientation, and differentiation begins. The third stage is marked by rapid increase in sheath length. The leaf does not have a distinct basal meristem. Instead, cell divisions are gradually restricted to the base of the leaf with localized sites of increased division at the preligule region. Divisions are not localized to the base of the sheath until near the end of development. The liguleless-1 homozygote shows no alteration in this overall pattern of growth, but does show distinct alteration in the anticlinal division pattern in the preligule region. Two abnormal patterns are observed: either the increase in division rate at the preligule site is absent or it exhibits loss of all longitudinal divisions so that only transverse (or cell-file producing) divisions are present. This pattern is particularly apparent in developing adult leaves on older lg1 plants, in which sporadic ligule vestiges form. From these and results previously published (Becraft et al. (1990) Devl Biol. 14), we conclude that the information carried by the Lg1+ gene product acts earlier in development than formation of the ligule proper. We hypothesize that Lg1+ may be effective at the stage when the blade-sheath boundary is first determined.

Increased vulnerability to inducible atrial fibrillation caused by partial cellular uncoupling with heptanol

2002 ◽  
Vol 283 (3) ◽  
pp. H1116-H1122 ◽  
Author(s):  
Toshihiko Ohara ◽  
Zhilin Qu ◽  
Moon-Hyoung Lee ◽  
Keiko Ohara ◽  
Chikaya Omichi ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Conduction Block ◽  
Membrane Properties ◽  
Maximal Velocity ◽  
Epicardial Surface ◽  
Low Concentrations ◽  
Before And After ◽  
Rapid Pacing ◽  
Action Potential Duration Restitution ◽  
Over Time

We hypothesized that partial cellular uncoupling produced by low concentrations of heptanol increases the vulnerability to inducible atrial fibrillation (AF). The epicardial surface of 12 isolated-perfused canine left atria was optically mapped before and after 1–50 μM heptanol infusion. At baseline, no sustained (>30 s) AF could be induced in any of the 12 tissues. However, after 2 μM heptanol infusion, sustained AF was induced in 9 of 12 tissues ( P < 0.001). Heptanol >5 μM caused loss of 1:1 capture during rapid pacing, causing no AF to be induced. AF was initiated by conduction block across the fiber leading to reentry, which broke up after one to two rotations into two to four independent wavelets that sustained the AF. Heptanol at 2 μM had no effect on the cellular action potential duration restitution or on the maximal velocity rate over time of the upstroke. The effects of heptanol were reversible. We conclude that partial cellular uncoupling by heptanol without changing atrial active membrane properties promotes wavebreak, reentry, and AF during rapid pacing.

Observations on bud formation and proliferations on cytokinin-treated root segments of Ophioglossum petiolatum

1969 ◽  
Vol 47 (10) ◽  
pp. 1579-1583 ◽  
Author(s):  
R. L. Peterson
Keyword(s):  
Apical Cell ◽  
Root Apex ◽  
Leaf Primordia ◽  
Distilled Water ◽  
Water Control ◽  
Cortical Cells ◽  
Root Segments ◽  
Low Concentrations ◽  
High Concentrations ◽  
Intact Root

Root segments of the fern Ophioglossum petiolatum with either an intact root apex or with the apex removed were treated with distilled water (control) or a range of concentrations of kinetin or benzyladenine in aqueous solution. Buds initiated on segments treated with distilled water or low concentrations of cytokinins had an apical meristem consisting of an apical cell with derivatives and a few leaf primordia located immediately beneath an air cavity formed by the lysis of cortical cells of the parent root. There was little cortical proliferation associated with the initiation of these buds. However, application of cytokinins at relatively high concentrations induced considerable proliferation of root tissue and a concomitant organization of numerous apical meristems in this tissue. Each induced meristem was structurally similar to those initiated on control root segments or those treated with low concentrations of cytokinins with the exception that leaf primordia were not as readily visible. Groups of tracheid-like cells were present in the callus-like outgrowths and, in root segments treated with 10.0 mg/l kinetin, large starch-filled parenchyma cells were evident at the periphery of the proliferations.

AMIDOMYCIN, A NEW ANTIBIOTIC FROM A STREPTOMYCES SPECIES. PRODUCTION, ISOLATION, ASSAY, AND BIOLOGICAL PROPERTIES

1957 ◽  
Vol 3 (7) ◽  
pp. 953-965 ◽  
Author(s):  
W. A. Taber ◽  
L. C. Vining
Keyword(s):  
Candida Albicans ◽  
Plant Pathogens ◽  
Degradation Products ◽  
Biological Properties ◽  
Puccinia Graminis ◽  
Serial Transfer ◽  
Streptomyces Species ◽  
Low Concentrations ◽  
Agar Media ◽  
Species Production

Antifungal preparations were obtained from cultures of Streplomyces PRL 1642 by solvent extraction of the solids collected after the pH was adjusted to 3.5. The active factor, named amidomycin, was purified by repeated crystallization from aqueous ethanol or petrol (b.p. 60°–80 °C.) to give stable, colorless, optically active needles, m.p. 192 °C.Amidomycin suspended in agar media retarded the growth of many filamentous fungi and noticeably inhibited the plant pathogens Ustilago maydis, Ustilago trebouxii, as well as the human pathogen, Hormodendrum pedrosoi. It also inhibited the germination of uredospores of Puccinia graminis at low concentrations. Certain yeasts were completely inhibited by small concentrations of amidomycin; the quantity required was affected by the number of cells in the inoculum.None of the bacteria examined was inhibited by this antibiotic. At certain concentrations it was lethal to Candida albicans as determined by the inability of previously exposed and washed cells to grow on nutrient agar.Although a few isolated colonies of Candida albicans usually developed on plates containing approximately double the concentration required to inhibit growth of the inoculum streak, serial transfer of progeny from such colonies onto agar containing amidomycin did not produce cultures having progressively increasing resistance.Two degradation products of amidomycin, D(–)-valine and 3,6-diisopropyl-2,5-diketomorpholine, are inactive.

scholarly journals Membrane transporter dimerization driven by differential lipid solvation energetics of dissociated and associated states

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Rahul Chadda ◽  
Nathan Bernhardt ◽  
Elizabeth G Kelley ◽  
Susana C M Teixeira ◽  
Kacie Griffith ◽  
...  
Keyword(s):  
Free Energy ◽  
Short Chain ◽  
Membrane Properties ◽  
Global Changes ◽  
Water Penetration ◽  
Low Concentrations ◽  
Solvent Environment ◽  
Lipid Solvent ◽  
Association Equilibria ◽  
Membrane Defect

Over two-thirds of integral membrane proteins of known structure assemble into oligomers. Yet, the forces that drive the association of these proteins remain to be delineated, as the lipid bilayer is a solvent environment that is both structurally and chemically complex. In this study we reveal how the lipid solvent defines the dimerization equilibrium of the CLC-ec1 Cl-/H+ antiporter. Integrating experimental and computational approaches, we show that monomers associate to avoid a thinned-membrane defect formed by hydrophobic mismatch at their exposed dimerization interfaces. In this defect, lipids are strongly tilted and less densely packed than in the bulk, with a larger degree of entanglement between opposing leaflets and greater water penetration into the bilayer interior. Dimerization restores the membrane to a near-native state and therefore, appears to be driven by the larger free-energy cost of lipid solvation of the dissociated protomers. Supporting this theory, we demonstrate that addition of short-chain lipids strongly shifts the dimerization equilibrium towards the monomeric state, and show that the cause of this effect is that these lipids preferentially solvate the defect. Importantly, we show that this shift requires only minimal quantities of short-chain lipids, with no measurable impact on either the macroscopic physical state of the membrane or the protein's biological function. Based on these observations, we posit that free-energy differentials for local lipid solvation define membrane-protein association equilibria. With this, we argue that preferential lipid solvation is a plausible cellular mechanism for lipid regulation of oligomerization processes, as it can occur at low concentrations and does not require global changes in membrane properties.

Fine structure of the primary root phloem of Pisum

1968 ◽  
Vol 16 (1) ◽  
pp. 37 ◽  
Author(s):  
SY Zee ◽  
TC Chambers
Keyword(s):  
Primary Root ◽  
Root Apex ◽  
Sieve Element ◽  
Cross Wall ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Phloem Parenchyma ◽  
Pisum Sativum L ◽  
Companion Cells ◽  
Stem Internode

The morphogenesis of the sieve elements, companion cells, and phloem parenchyma in the region between 0.5 and 2.0 mm from the actively growing root apex of seedlings of Pisum sativum L. cv. Telephone is described. The overall developmental pattern is essentially similar to that already described for the secondary phloem of the young stem internode of the same species, although differences in the development of some organelles do exist between the two types of phloem. The development of the sieve element is traced from the earliest stages of cross wall formation up to the morphologically mature stages. Very few sieve elements reach morphological maturity in this region. The possibility that the functional translocatory sieve elements are those at earlier stages of development is discussed.

scholarly journals Aeration mitigates endoplasmic reticulum stress in Saccharomyces cerevisiae even without mitochondrial respiration

2021 ◽  
Vol 8 (4) ◽  
pp. 77-86
Author(s):  
Huong Thi Phuong ◽  
Yuki Ishiwata-Kimata ◽  
Yuki Nishi ◽  
Norie Oguchi ◽  
Hiroshi Takagi ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Protein Folding ◽  
Er Stress ◽  
Molecular Oxygen ◽  
Mitochondrial Respiration ◽  
Oxidative Protein Folding ◽  
Hypoxic Conditions ◽  
Low Concentrations ◽  
Client Proteins

Saccharomyces cerevisiae is a facultative anaerobic organism that grows well under both aerobic and hypoxic conditions in media containing abundant fermentable nutrients such as glucose. In order to deeply understand the physiological dependence of S. cerevisiae on aeration, we checked endoplasmic reticulum (ER)-stress status by monitoring the splicing of HAC1 mRNA, which is promoted by the ER stress-sensor protein, Ire1. HAC1-mRNA splicing that was caused by conventional ER-stressing agents, including low concentrations of dithiothreitol (DTT), was more potent in hypoxic cultures than in aerated cultures. Moreover, growth retardation was observed by adding low-dose DTT into hypoxic cultures of ire1∆ cells. Unexpectedly, aeration mitigated ER stress and DTT-induced impairment of ER oxidative protein folding even when mitochondrial respiration was halted by the ro mutation. An ER-located protein Ero1 is known to directly consume molecular oxygen to initiate the ER protein oxidation cascade, which promotes oxidative protein folding of ER client proteins. Our further study using ero1-mutant strains suggested that, in addition to mitochondrial respiration, this Ero1-medaited reaction contributes to mitigation of ER stress by molecular oxygen. Taken together, here we demonstrate a scenario in which aeration acts beneficially on S. cerevisiae cells even under fermentative conditions.

Membrane-disordering effects of β-amyloid peptides

2001 ◽  
Vol 29 (4) ◽  
pp. 617-623 ◽  
Author(s):  
W. E. Müller ◽  
C. Kirsch ◽  
G. P. Eckert
Keyword(s):  
Cell Membranes ◽  
Biological Effects ◽  
Senile Plaques ◽  
Initial Step ◽  
Phospholipid Bilayer ◽  
Membrane Properties ◽  
Major Constituent ◽  
Amyloid Peptides ◽  
Low Concentrations ◽  
Β Amyloid

β-Amyloid (Aβ) protein is the major constituent of senile plaques and cerebrovascular deposits characteristic of Alzheimer's disease (AD). The causal relationship between Aβ and AD-specific lesions like neurodegeneration and atrophy is still not known. The present article summarizes our studies indicating that rather low concentrations of Aβ significantly alter the fluidity of cell membranes and subcellular fractions from different tissues and different species including humans, as a possible initial step of its biological effects. Using different fluorescent probes our data show clearly that Aβ peptides specifically disturb the acylchain layer of cell membranes in a very distinct fashion. By contrast, membrane properties at the level of the polar heads of the phospholipid bilayer at the interface with membrane proteins are much less affected.

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