ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

FLUORESCENCE MICROSCOPY OF LIVING PLANT CELLS (1997)

Gilroy, Simon

Palo Alto, Calif. : Annual Reviews

Annual Review of Plant Physiology and Plant Molecular Biology 48 (1997), S. 165-190

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ISSN: 1040-2519

Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff

Topics: Biology

Notes: Abstract Since its inception, light microscopy has shown the elegance and subtlety with which function is expressed in the form of the cells, tissues, and organs of the plant. Recently, light microscopy has seen a resurgence in use fueled by advances in microscope design and computer-based image analysis. The structural resolution afforded by static, fixed samples is being increasingly supplemented by approaches using fluorescent analogs and selective fluorescent indicators, which visualize the dynamic processes in living, functioning cells. This review describes some of these approaches and discusses how they are taking us a step closer to viewing the intricate complexity with which plants organize and regulate their functions down to the subcellular level.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1146/annurev.arplant.48.1.165

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2

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Sphingolipid signalling in Arabidopsis guard cells involves heterotrimeric G proteins (2003)

Coursol, Sylvie ; Fan, Liu-Min ; Stunff, Hervé Le ; [et al.]

[s.l.] : Macmillian Magazines Ltd.

Nature 423 (2003), S. 651-654

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] In animals, the sphingolipid metabolite sphingosine-1-phosphate (S1P) functions as both an intracellular messenger and an extracellular ligand for G-protein-coupled receptors of the S1P receptor family, regulating diverse biological processes ranging from cell proliferation to apoptosis. ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/nature01643

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3

Electronic Resource

From common signalling components to cell specific responses: insights from the cereal aleurone (2002)

Ritchie, Sian M. ; Swanson, Sarah J. ; Gilroy, Simon

Oxford, UK : Blackwell Science, Ltd

Physiologia plantarum 115 (2002), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Studies into the molecules underlying plant signal transduction events continue to reveal the involvement of highly conserved factors such as Ca2+, calmodulin, cyclic GMP and phospholipases in a remarkably diverse array of physiological processes. The hormonal response systems in the aleurone cells of the cereal grain and in the stomatal guard cell are beginning to reveal how diversity of response can be hard wired into these cells despite the use of these common signalling intermediates. In both the aleurone and the guard cell ABA signalling operates through the action of phospholipase D and alterations in a Ca2+-dependent signalling system. The role of phospholipase D is highly analogous in these two divergent cell types, perhaps reflecting the closeness of this enzyme to a conserved ABA receptor. However, specificity in response becomes evident in elements downstream from PLD, such as in the Ca2+ signalling system. For example, ABA has opposite effects on cytoplasmic Ca2+ in the aleurone and guard cell. Combining the Ca2+-dependent signalling activities in networks with parallel regulatory activities such as cyclic GMP appears to underlie the flexible regulatory systems that are the hallmark of plant cell function.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1150303.x

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4

Electronic Resource

Calmodulin stimulation of unidirectional calcium uptake by the endoplasmic reticulum of barley aleurone (1993)

Gilroy, Simon ; Jones, Russell L.

Springer

Planta 190 (1993), S. 289-296

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ISSN: 1432-2048

Keywords: Aleurone ; Calcium uptake ; Calmodulin ; Endoplasmic reticulum ; Gibberellic acid ; Hordeum ; (Ca2+ uptake)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The role of calmodulin (CaM) in gibberellic acid (GA3)-stimulated Ca2+ uptake was investigated in endomembranes isolated from aleurone cells of barley (Hordeum vulgare L.). Unidirectional Ca2+ -uptake activity of endoplasmic reticulum (ER) was higher in membranes isolated from aleurone layers treated for 16 h with GA3 and Ca2+ compared with those isolated from layers incubated in Ca2+ alone. However, the level of uptake from Ca2+-treated tissue could be stimulated to that of the GA3-treated cells by applying exogenous CaM which increased the V max of the Ca2+ transporter approximately threefold. Calcium uptake in ER from GA3-treated tissue was inhibited by the CaM antagonist W7 in 50% of experiments, whereas the activity in membranes from non-GA3-treated tissue was unaffected. Treatment with GA3 also led to a twofold increase in CaM levels in aleurone layers within 4–6 h, paralleling the time course of the stimulation of Ca2+ uptake and preceding the stimulation of α-amylase secretion. We propose that the elevation of Ca2+ uptake into the ER induced by GA3 may be coordinated and regulated by elevated levels of membrane-associated CaM and this may regulate Ca2+-dependent α-amylase synthesis in the lumen of the ER.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00196956

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5

Electronic Resource

Root hair growth in Arabidopsis thaliana is directed by calcium and an endogenous polarity (1997)

Bibikova, Tatiana N. ; Zhigilei, Angelica ; Gilroy, Simon

Springer

Planta 203 (1997), S. 495-505

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ISSN: 1432-2048

Keywords: Key words:Arabidopsis (root hair growth) ; Cytosolic calcium ; Pollen tube ; Root hair ; Tip growth ; Tradescantia (pollen tube growth)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract. Tip growth of plant cells has been suggested to be regulated by a tip-focused gradient in cytosolic calcium concentration ([Ca2+]c). However, whether this gradient orients apical growth or follows the driving force for this process remains unknown. Using localized photoactivation of the caged calcium ionophore Br-A23187 we have been able to artificially generate an asymmetrical calcium influx across the root hair tip. This led to a change in the direction of tip growth towards the high point of the new [Ca2+]c gradient. Such reorientation of growth was transient and there was a return to the original direction within 15 min. Root hairs forced to change the direction of their growth by placing a mechanical obstacle in their path stopped, reoriented growth to the side, and grew past the mechanical blockage. However, as soon as the growing tip had cleared the obstacle, growth returned to the original direction. Confocal ratio imaging revealed that a tip-focused [Ca2+]c gradient was always centered at the site of active growth. When the root hair changed direction the gradient also reoriented, and when growth returned to the original direction, so did the [Ca2+]c gradient. This normal direction of apical growth of Arabidopsis thaliana (L.) Heynh. root hairs was found to be at a fixed angle from the root of 85 ± 6.7 degrees. In contrast, Tradescantia virginiana (L.) pollen tubes that were induced to reorient by touch or localized activation of the caged ionophore, did not return to the original growth direction, but continued to elongate in their new orientation. These results suggest that the tip-focused [Ca2+]c gradient is an important factor in localizing growth of the elongating root hair and pollen tube to the apex. However, it is not the primary determinant of the direction of elongation in root hairs, suggesting that other information from the root is acting to continuously reset the growth direction away from the root surface.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004250050219

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6

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Increases in cytosolic Ca2+ are not required for abscisic acid-inhibition of inward K+ currents in guard cells of Vicia faba L. (2000)

Romano, Lisa A. ; Jacob, Tobias ; Gilroy, Simon ; [et al.]

Springer

Planta 211 (2000), S. 209-217

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ISSN: 1432-2048

Keywords: Key words: Abscisic acid ; Cytosolic calcium ; Guard cell ; K+ channels ; Vicia (K+ channels)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract. The inward K+ channels (IKin) of guard cells are inhibited upon application of abscisic acid (ABA). It has been postulated that IKin inhibition requires an elevation in cytosolic free Ca2+ levels ([Ca2+]c) because: (i) experimental increases in [Ca2+] c can mimic the ABA effect, and; (ii) ABA can trigger an elevation of [Ca2+]c in guard cells. However, not all guard cells respond to ABA with a [Ca2+]c increase, and the magnitude of the increases that do occur is variable. Therefore, an obligate role for Ca2+ in the regulation of downstream effectors of ABA response, such as the IKin channels, remains in question. In this study, we developed a methodology for simultaneous patch clamping and confocal ratiometric Ca2+ imaging of Vicia faba L. guard-cell protoplasts. This allowed us to directly assess the relationship between ABA-induced changes in [Ca2+]c and IKin inhibition. In the presence of extracellular Ca2+, the extent of [Ca2+]c elevation correlated with the extent of IKin inhibition. However, upon chelation of either extracellular Ca2+, [Ca2+]c, or both, extracellular Ca2+ and [Ca2+]c, [Ca2+]c elevation did not occur in response to ABA yet IKin currents were still strongly inhibited. These data illustrate that Ca2+-independent regulation is involved in ABA-inhibition of stomatal opening processes.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004250000286

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7

Electronic Resource

Effect of aluminum on cytoplasmic Ca2+ homeostasis in root hairs of Arabidopsis thaliana (L.) (1998)

Jones, David L. ; Gilroy, Simon ; Larsen, Paul B. ; [et al.]

Springer

Planta 206 (1998), S. 378-387

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ISSN: 1432-2048

Keywords: Key words: Aluminum ; Arabidopsis (Al toxicity) ; Cytoplasmic calcium ; Mutant (Arabidopsis ; Al sensitivity) ; Root hair ; Touch

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract. Aluminum inhibition of root growth is a major world agricultural problem where the cause of toxicity has been linked to changes in cellular calcium homeostasis. Therefore, the effect of aluminum ions (Al) on changes in cytoplasmic free calcium concentration ([Ca2+]c) was followed in root hairs of wild-type, Al-sensitive and Al-resistant mutants of Arabidopsis thaliana (L.) Heynh. Generally, Al exposure resulted in prolonged elevations in tip-localized [Ca2+]c in both wild-type and Al-sensitive root hairs. However, these Al-induced increases in [Ca2+]c were not tightly correlated with growth inhibition, occurring up to 15 min after Al had induced growth to stop. Also, in 32% of root hairs examined growth stopped without a detectable change in [Ca2+]c. In contrast, Al-resistant mutants showed little growth inhibition in response to AlCl3 exposure and in no case was a change in [Ca2+]c observed. Of the other externally applied stresses tested (oxidative and mechanical stress), both were found to inhibit root hair growth, but only oxidative stress (H2O2, 10 μM) caused a prolonged rise in [Ca2+]c similar to that induced by Al. Again this increase occurred after growth had been inhibited. The lack of a tight correlation between Al exposure, growth inhibition and altered [Ca2+]c dynamics suggests that although exposure of root hairs to toxic levels of Al causes an alteration in cellular Ca2+ homeostasis, this may not be a required event for Al toxicity. The elevation in [Ca2+]c induced by Al also strongly suggests that the phytotoxic action of Al in root hairs is not through blockage of Ca2+-permeable channels required for Ca2+ influx into the cytoplasm.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004250050413

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8

Electronic Resource

A decade of plant signals (1994)

Gilroy, Simon ; Trewavas, Tony

New York, NY : Wiley-Blackwell

BioEssays 16 (1994), S. 677-682

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ISSN: 0265-9247

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/bies.950160914

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Tonoplast-localized Ca2+pumps regulate Ca2+signals during pattern-triggered immunity inArabidopsis thaliana (2020)

Hilleary, Richard ; Paez-Valencia, Julio ; Vens, Cullen ; [et al.]

National Academy of Sciences

In: PNAS - Proceedings of the National Academy of Sciences of the United States of America. 2020; 117(31): 18849-18857. Published 2020 Jul 20. doi: 10.1073/pnas.2004183117.

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Publication Date: 2020-07-20

Description: One of the major events of early plant immune responses is a rapid influx of Ca2+into the cytosol following pathogen recognition. Indeed, changes in cytosolic Ca2+are recognized as ubiquitous elements of cellular signaling networks and are thought to encode stimulus-specific information in their duration, amplitude, and frequency. Despite the wealth of observations showing that the bacterial elicitor peptide flg22 triggers Ca2+transients, there remain limited data defining the molecular identities of Ca2+transporters involved in shaping the cellular Ca2+dynamics during the triggering of the defense response network. However, the autoinhibited Ca2+-ATPase (ACA) pumps that act to expel Ca2+from the cytosol have been linked to these events, with knockouts in the vacuolar members of this family showing hypersensitive lesion-mimic phenotypes. We have therefore explored how the two tonoplast-localized pumps, ACA4 and ACA11, impact flg22-dependent Ca2+signaling and related defense responses. The double-knockoutaca4/11exhibited increased basal Ca2+levels and Ca2+signals of higher amplitude than wild-type plants. Both the aberrant Ca2+dynamics and associated defense-related phenotypes could be suppressed by growing theaca4/11seedlings at elevated temperatures. Relocalization of ACA8 from its normal cellular locale of the plasma membrane to the tonoplast also suppressed theaca4/11phenotypes but not when a catalytically inactive mutant was used. These observations indicate that regulation of vacuolar Ca2+sequestration is an integral component of plant immune signaling, but also that the action of tonoplast-localized Ca2+pumps does not require specific regulatory elements not found in plasma membrane-localized pumps.

Print ISSN: 0027-8424

Electronic ISSN: 1091-6490

Topics: Biology , Medicine , Natural Sciences in General