Ca<sup>2+</sup>-Stimulated Exocytosis in Maize Coleoptile Cells

Sutter, Jens-Uwe; Homann, Ulrike; Thiel, Gerhard

doi:10.1105/tpc.12.7.1127

Cited by 26 publications

(22 citation statements)

References 24 publications

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“…For example, if a large number of water-permeable vesicles fused simultaneously and abruptly with the cell membrane, this step-wise increase in P f would result in an appreciable P f i : The suggested abrupt vesicle fusion may resemble-perhaps on a somewhat slower time scale-a synaptic event, in which fusion of hundreds of vesicles can occur over a course of a few milliseconds in response to a signal. In fact, intracellular pressure pulses in guard-cell protoplasts stimulated fast vesicle fusion with the plasma membrane (Bick et al, 2001); similarly, fast increase in cytosolic [Ca 21 ] caused fast exocytosis in maize coleoptile cells (Sutter et al, 2000), and vigorous, fast, and reversible membrane internalization upon shrinking has been visualized very recently in intact guard cells (Shope et al, 2003). Vesicle fusion may alter P f by changing the membrane density of aquaporin proteins (further level of complexity might be added by the nonhomogeneity of vesicle pools; Sutter et al, 2000) and, additionally, P f could also change via the regulation of the activity of aquaporins already embedded in the cell membrane.…”

Section: Models Of Volume Increasementioning

confidence: 99%

“…In fact, intracellular pressure pulses in guard-cell protoplasts stimulated fast vesicle fusion with the plasma membrane (Bick et al, 2001); similarly, fast increase in cytosolic [Ca 21 ] caused fast exocytosis in maize coleoptile cells (Sutter et al, 2000), and vigorous, fast, and reversible membrane internalization upon shrinking has been visualized very recently in intact guard cells (Shope et al, 2003). Vesicle fusion may alter P f by changing the membrane density of aquaporin proteins (further level of complexity might be added by the nonhomogeneity of vesicle pools; Sutter et al, 2000) and, additionally, P f could also change via the regulation of the activity of aquaporins already embedded in the cell membrane. Finally, the swelling in response to the hypoosmotic challenge could occur immediately or after a delay during which the initial steps of the response did not reach a certain threshold.…”

Section: Models Of Volume Increasementioning

confidence: 99%

“…Among the hypotonicity-mediating signals could be a varying level of cytosolic free [Ca 21 ], as in animal cells (e.g. Dube et al, 1990), remodeling the cytoskeletal submembranal network or affecting endo-or exocytosis, as reported for AQP2 and AQP4 in mammal cells (Madrid et al, 2001;Brown, 2003), or in plant cells (Sutter et al, 2000), or phosphorylation and gating of aquaporins, or any combination of the above, or other, additional signals. These hypotheses about processes underlying the P f dynamics are being currently examined in experiments employing modifiers of cytoskeleton and membrane trafficking, and modifiers of protein phosphorylation status.…”

Section: The Effect Of Osmolaritymentioning

confidence: 99%

“…4. Another hypothesis that may explain the delay and the null apparent P f during the delay is based on endo-/exocytotic vesicle recycling (see, for example, Sutter et al, 2000). In a similar mechanism, a vigorous exopinocytosis (utilizing vesicles, which, at the time of fusion with the plasma membrane are actively squeezed out) might be spilling out the water as soon as it enters by osmosis via the plasma membrane (resembling the contracting vacuole of the paramaecium); when the vesicle retrieval from the membrane is halted (while fusion continues) and/or when the fusing-vesicles become devoid of the squeezing-out mechanism, the delay ends.…”

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Dynamic Changes in the Osmotic Water Permeability of Protoplast Plasma Membrane

2004

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The osmotic water permeability coefficient (P f ) of plasma membrane of maize (Zea mays) Black Mexican Sweet protoplasts changed dynamically during a hypoosmotic challenge, as revealed using a model-based computational approach. The bestfitting model had three free parameters: initial P f , P f rate-of-change (slope Pf ), and a delay, which were hypothesized to reflect changes in the number and/or activity of aquaporins in the plasma membrane. Remarkably, the swelling response was delayed 2 to 11 s after start of the noninstantaneous (but accounted for) bath flush. The P f during the delay was #1 mm s 21 . During the swelling period following the delay, P f changed dynamically: within the first 15 s P f either (1) increased gradually to approximately 8 mm s 21 (in the majority population of low-initial-P f cells) or (2) increased abruptly to 10 to 20 mm s 21 and then decreased gradually to 3 to 6 mm s 21 (in the minority population of high-initial-P f cells). We affirmed the validity of our computational approach by the ability to reproduce previously reported initial P f values (including the absence of delay) in control experiments on Xenopus oocytes expressing the maize aquaporin ZmPIP2;5. Although mercury did not affect the P f in swelling Black Mexican Sweet cells, phloretin, another aquaporin inhibitor, inhibited swelling in a predicted manner, prolonging the delay and slowing P f increase, thereby confirming the hypothesis that P f dynamics, delay included, reflected the varying activity of aquaporins.The regulation of plant aquaporins is becoming a focus of research in an increasing number of laboratories Tyerman et al., 2002). However, the reports on the regulation of the water permeability of plant cells are still relatively few, very likely reflecting the technical difficulties inherent in such measurements.In order to quantify the permeability of a plant cell to water, one of the approaches consists of isolating protoplasts and monitoring the initial rate of change of their volume upon an osmotic challenge. If the osmotic potential of the external solution is changed instantaneously, the osmotic water permeability (termed P f or P os ) can be deduced from the initial rate of volume relaxation (e.g. Zhang et al., 1990;Verkman, 2000). There are at least two problems with this approach: (1) even when an instantaneous change of solution is possible, a systematic error is introduced, causing an underestimate of P f because, already during the initial phase of protoplast swelling, the volume, the surface area, and the internal concentration of solutes do not remain constant; and (2) instantaneous bath perfusion has technical-and physiological-limitations: unlike animal cells, isolated plant cell protoplasts (the terms protoplast and cell will be used here interchangeably) do not stick well to the chamber floor and defeat attempts of rapid (let alone, instantaneous) solution flushes. Very fast external solution exchange has been achieved by immobilizing the protoplast with a suction micropipette (e.g. Ramah...

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Section: Models Of Volume Increasementioning

confidence: 99%

Section: Models Of Volume Increasementioning

confidence: 99%

Section: The Effect Of Osmolaritymentioning

confidence: 99%

mentioning

confidence: 99%

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Dynamic Changes in the Osmotic Water Permeability of Protoplast Plasma Membrane

2004

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“…Elevation of [Ca 2+ ] cyt induced by auxin is shown to be in the range of about 100 nM (Felle, 1988;Shishova and Lindberg, 2004). This is enough to activate the secretory system within 10-20 s after the increase in Ca 2+ concentration (Sutter, Homann, and Thiel, 2000). The elongation process is accompanied by a fast increase in the cell surface and supported by the building of a new cell wall, which is strongly dependent on vesical secretion from the Golgi apparatus.…”

Section: Plant Sciencementioning

confidence: 92%

Proton pump and plant cell elongation

Кирпичникова

Chen

Teplyakova

et al. 2018

BioComm

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Plant cell elongation growth is an integral process involved in different plant movements (tropisms); it provides the possibility to reach different resources of energy, water and nutrition and is therefore important for metabolism and development. Cell multiple enlargement along the longitudinal axis is commonly accepted to be under the control of the phytohormone auxin. One of the key enzymes involved in elongation is the plasma membrane H + -ATPase, which is known to acidify the cell wall. Investigation of the role of the proton pump at the plasma membrane was initiated by Prof. Vsevolod V. Polevoi and still is in progress in the group of Prof. Maria F. Shishova at the Department of Plant Physiology and Biochemistry, St. Petersburg State University. Different mechanisms of post-translation regulation of H + -pump activity are discussed in this review. We also suggest a possible scheme of elongation growth based on the shift in plant cell sensitivity to auxin and on its facility to elongate.

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