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Alkalinization

The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Christoph-martin Geilfus – 1st expert on this subject based on the ideXlab platform

  • the ph of the leaf apoplast is critical for the formation of pseudomonas syringae induced lesions on leaves of the common bean phaseolus vulgaris
    Plant Science, 2020
    Co-Authors: Christoph-martin Geilfus, Li Wang, Jiawen Wu

    Abstract:

    Abstract Inoculating a virulent strain of Pseudomonas syringae pv. phaseolicola (Pph) into the leaf of common bean (Phaseolus vulgaris) causes the leaf apoplast to alkalinize. Whether or not this apoplastic pH event facilitates virulence of Pph in interaction with common bean is unclear. For elucidating this topic, (i) Pph colonization of the common bean leaf apoplast, (ii) the formation of bacterial lesions, and (iii) apoplastic sucrose concentration were investigated in relation to the apoplastic leaf pH. For this, the Pph-induced leaf apoplastic Alkalinization was attenuated by spray application of either a synthetic auxin or an acidic pH buffer. Apoplastic pH was quantified in planta via microscopy-based pH imaging. Apoplastic washing fluids were extracted to quantify both colonization of bacteria in leaf apoplast and the concentration of apoplastic sucrose. Results reveal that the apoplastic Alkalinization facilitated bacterial colonization of the apoplast. Number of colony forming units and area of bacterial lesions were reduced when Pph-induced apoplastic Alkalinization was attenuated by foliar application of a synthetic auxin or acidic pH buffer. Application of both agents attenuated the Pph-induced increase of sucrose in the leaf apoplast, which is nutrient for bacteria. Data demonstrate that the Pph-mediated leaf apoplastic alkalinisation favours bacterial colonization.

  • transient Alkalinization of the leaf apoplast stiffens the cell wall during onset of chloride salinity in corn leaves
    Journal of Biological Chemistry, 2017
    Co-Authors: Christoph-martin Geilfus, Raimund Tenhaken, Sebastien Carpentier

    Abstract:

    Abstract During chloride salinity, the pH of the leaf apoplast (pHapo) transiently alkalizes. There is an ongoing debate about the physiological relevance of these stress-induced pHapo changes. Using proteomic analyses of expanding leaves of corn (Zea mays L.), we show that this transition in pHapo conveys functionality by (i) adjusting protein abundances and (ii) affecting the rheological properties of the cell wall. pHapo was monitored in planta via microscopy-based ratio imaging, and the leaf-proteomic response to the transient leaf apoplastic Alkalinization was analyzed via ultra-high performance liquid chromatography–MS. This analysis identified 1459 proteins, of which 44 exhibited increased abundance specifically through the chloride-induced transient rise in pHapo. These elevated protein abundances did not directly arise from high tissue concentrations of Cl− or Na+ but were due to changes in the pHapo. Most of these proteins functioned in growth-relevant processes and in the synthesis of cell wall–building components such as arabinose. Measurements with a linear-variable differential transducer revealed that the transient Alkalinization rigidified (i.e. stiffened) the cell wall during the onset of chloride salinity. A decrease in t-coumaric and t-ferulic acids indicates that the wall stiffening arises from cross-linkage to cell wall polymers. We conclude that the pH of the apoplast represents a dynamic factor that is mechanistically coupled to cellular responses to chloride stress. By hardening the wall, the increased pH abrogates wall loosening required for cell expansion and growth. We conclude that the transient Alkalinization of the leaf apoplast is related to salinity-induced growth reduction.

  • the ph of the apoplast dynamic factor with functional impact under stress
    Molecular Plant, 2017
    Co-Authors: Christoph-martin Geilfus

    Abstract:

    Abstract The apoplast is an interconnected compartment with a thin water-film that alkalinizes under stress. This systemic pH increase may be a secondary effect without functional implications, arising from ion movements or proton-pump regulations. On the other hand, there are increasing indications that it is part of a mechanism to withstand stress. Regardless of this controversy, Alkalinization of the apoplast has received little attention. The apoplastic pH (pH apo ) increases not only during plant–pathogen interactions but also in response to salinity or drought. Not much is known about the mechanisms that cause the leaf apoplast to alkalinize, nor whether, and if so, how functional impact is conveyed. Controversial explanations have been given, and the unusual complexity of pH apo regulation is considered as the primary reason behind this lack of knowledge. A gathering of scattered information revealed that changes in pH apo convey functionality by regulating stomatal aperture via the effects exerted on abscisic acid. Moreover, apoplastic Alkalinization may regulate growth under stress, whereas this needs to be verified. In this review, a comprehensive survey about several physiological mechanisms that alkalize the apoplast under stress is given, and the suitability of apoplastic Alkalinization as transducing element for the transmission of sensory information is discussed.

Pedro J Aparicio – 2nd expert on this subject based on the ideXlab platform

  • blue light requirement for hc03 uptake and its action spectrum in monoraphidium braunii
    Photochemistry and Photobiology, 1998
    Co-Authors: Nuria Giraldez, Pedro J Aparicio, Miguel Angel Quinones

    Abstract:

    The uptake and assimilation of HCO3 by the green unicellular alga Monoraphidium braunii can be monitored by the Alkalinization of the external medium or by the O2 evolution associated with the uptake and reduction of this anion. The activation of HCO3 uptake in this microalga required the irradiation of the cell suspensions with low photon fluence rates of short wavelength radiation. Thus, when the cells were irradiated with strong red light in the presence of HCO3, very little Alkalinization of the external medium or O2 evolution could be observed. The O2 evolution rates measured under red light could be due to the assimilation of the CO2 derived from the HCO3 present in the medium. The blue light-dependent O2 evolution rates were not diminished by a periplasmic carbonic anhydrase inhibitor, suggesting that HCO3 -dependent O2 evolution was due to the photoactivation of a selective HCO3 uptake system at the plasma membrane. The action spectrum for HCO3- uptake in M. braunii was very similar to those reported for NO3- and CI- suggested that a flavoprotein may be the photoreceptor for this response.

  • effects of short pulses of blue light on the Alkalinization associated with the uptake of no3 and cl by the green alga monoraphidium braunii and related action spectra
    Photochemistry and Photobiology, 1995
    Co-Authors: Federico G Witt, Pedro J Aparicio

    Abstract:

    In Monoraphidium braunii, uptake of NO3−, NO2− and Cl− is associated with proton transport and triggered by blue light (BL). Only 10 s after cells able to reduce NO3− to NH4+ were irradiated with continuous, low-fluence BL in the presence of NO3−, an Alkalinization of the medium began and only became interrupted by switching off the BL with a 60–90 s time lag. With 30 s BL pulses, the NO3−-dependent Alkalinization lasted 3–5 min until it stopped. When the cells were exposed to continuous BL in the presence of Cl−, the Alkalinization also started within 10 s but lasted only 3 min. After that, the pH remained constant and decreased when the BL was switched off. With 30 s BL pulses, the Cl−-dependent Alkalinization lasted 3 min and then decreased to its initial value. The NO3−-dependent Alkalinization shown by cells unable to reduce NO3− to NH4+ was similar to that observed in the presence of Cl−. These Alkalinization rates fit the Bunsen-Roscoe reciprocity law. With 2 s pulses of high-fluence BL, the delay time of the NO3 – or Cl−-dependent Alkalinizations was only 2 s, one of the fastest BL responses reported so far. The action spectra for Cl− and NO3− uptakes proved to be very similar and matched the absorption spectra of flavins, including the 267 nm peak.

  • EFFECTS OF SHORT PULSES OF BLUE LIGHT ON THE Alkalinization ASSOCIATED WITH THE UPTAKE OF NO3− AND CL− BY THE GREEN ALGA MONORAPHIDIUM BRAUNII AND RELATED ACTION SPECTRA
    Photochemistry and Photobiology, 1995
    Co-Authors: Federico G Witt, Pedro J Aparicio

    Abstract:

    In Monoraphidium braunii, uptake of NO3−, NO2− and Cl− is associated with proton transport and triggered by blue light (BL). Only 10 s after cells able to reduce NO3− to NH4+ were irradiated with continuous, low-fluence BL in the presence of NO3−, an Alkalinization of the medium began and only became interrupted by switching off the BL with a 60–90 s time lag. With 30 s BL pulses, the NO3−-dependent Alkalinization lasted 3–5 min until it stopped. When the cells were exposed to continuous BL in the presence of Cl−, the Alkalinization also started within 10 s but lasted only 3 min. After that, the pH remained constant and decreased when the BL was switched off. With 30 s BL pulses, the Cl−-dependent Alkalinization lasted 3 min and then decreased to its initial value. The NO3−-dependent Alkalinization shown by cells unable to reduce NO3− to NH4+ was similar to that observed in the presence of Cl−. These Alkalinization rates fit the Bunsen-Roscoe reciprocity law. With 2 s pulses of high-fluence BL, the delay time of the NO3 – or Cl−-dependent Alkalinizations was only 2 s, one of the fastest BL responses reported so far. The action spectra for Cl− and NO3− uptakes proved to be very similar and matched the absorption spectra of flavins, including the 267 nm peak.

David S. Goldfarb – 3rd expert on this subject based on the ideXlab platform

  • uric acid stones and hyperuricosuria
    Advances in Chronic Kidney Disease, 2012
    Co-Authors: Tapan H Mehta, David S. Goldfarb

    Abstract:

    Recent work has highlighted the strong relationships among obesity, diabetes, and the metabolic syndrome as causes of low urinary pH. Low urinary pH in turn is the major urinary risk factor for uric acid stones. Unlike calcium stones, uric acid stones can be dissolved and easily prevented with adequate urinary Alkalinization. Recognizing the relevant risk factors should lead to increased identification of these radiolucent stones. The cornerstone of therapy is raising urinary pH; xanthine dehydrogenase inhibitors should be used only when urinary Alkalinization cannot be achieved.