Extracellular Calcium Flux in Root Hairs Responding to Nodulation Factors

1999 ◽  
pp. 149-152
Author(s):  
L. Cárdenas ◽  
J. Feijó ◽  
J. G. Kunkel ◽  
L. Vidali ◽  
J. Domínguez ◽  
...  
Keyword(s):  
Root Hairs ◽  
Extracellular Calcium ◽  
Calcium Flux ◽  
Nodulation Factors

Human placental lactogen release in vitro: paradoxical effects of calcium

1981 ◽  
Vol 240 (5) ◽  
pp. E550-E555
Author(s):  
S. Handwerger ◽  
P. M. Conn ◽  
J. Barrett ◽  
S. Barry ◽  
A. Golander
Keyword(s):  
Calcium Influx ◽  
Extracellular Calcium ◽  
Calcium Flux ◽  
Placental Lactogen ◽  
Human Placental Lactogen ◽  
Paradoxical Effects ◽  
Subsequent Exposure ◽  
Normal Calcium

To study the effects of calcium on the release of human placental lactogen (hPL), placental explants were exposed to media containing lower or higher concentrations of calcium than normally available to the placenta. Explants exposed for 2 h to calcium-poor medium or medium containing either 2 mM EDTA or 2 mM EGTA released 160, 248, and 253% more hPL, respectively, than control explants. In contrast, explants exposed to medium containing higher than normal calcium concentrations released the same amounts of hPL as the control explants. At lower than normal extracellular calcium concentrations, the increased hPL release was inversely proportional to the calcium concentration. The increased release in calcium-poor medium was inhibited by subsequent exposure of the explants to medium containing calcium and was prevented by either barium or magnesium. Changes in barium or magnesium concentrations, however, had no effects on hPL release in the presence of normal extracellular calcium concentrations. Methoxyverapamil (D 600), an inhibitor of calcium flux, stimulated hPL release. Because low extracellular calcium and methoxyverapamil both inhibit calcium influx, these experiments suggest that calcium influx inhibits hPL release. The role of calcium in the regulation of hPL release therefore appears to be different from that reported in other release systems.

scholarly journals Rhizobium Nod factors induce increases in intracellular free calcium and extracellular calcium influxes in bean root hairs

1999 ◽  
Vol 19 (3) ◽  
pp. 347-352 ◽  
Author(s):  
Luis Cardenas ◽  
Jose A. Feijo ◽  
Joseph G. Kunkel ◽  
Federico Sanchez ◽  
Terena Holdaway-Clarke ◽  
...  
Keyword(s):  
Root Hairs ◽  
Extracellular Calcium ◽  
Intracellular Free Calcium ◽  
Free Calcium ◽  
Nod Factors ◽  
Bean Root

scholarly journals Nod Factor Perception During Infection Thread Growth Fine-Tunes Nodulation

2007 ◽  
Vol 20 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Jeroen Den Herder ◽  
Celine Vanhee ◽  
Riet De Rycke ◽  
Viviana Corich ◽  
Marcelle Holsters ◽  
...  
Keyword(s):  
Light And Electron Microscopy ◽  
Cortical Cell ◽  
Root Hairs ◽  
Infection Thread ◽  
Bacterial Invasion ◽  
Nodule Formation ◽  
Nodulation Factors ◽  
Polysaccharide Synthesis ◽  
Infection Threads ◽  
Surface Polysaccharide

Bacterial nodulation factors (NFs) are essential signaling molecules for the initiation of a nitrogen-fixing symbiosis in legumes. NFs are perceived by the plant and trigger both local and distant responses, such as curling of root hairs and cortical cell divisions. In addition to their requirement at the start, NFs are produced by bacteria that reside within infection threads. To analyze the role of NFs at later infection stages, several phases of nodulation were studied by detailed light and electron microscopy after coinoculation of adventitious root primordia of Sesbania rostrata with a mixture of Azorhizobium caulinodans mutants ORS571-V44 and ORS571-X15. These mutants are deficient in NF production or surface polysaccharide synthesis, respectively, but they can complement each other, resulting in functional nodules occupied by ORS571-V44. The lack of NFs within the infection threads was confirmed by the absence of expression of an early NF-induced marker, leghemoglobin 6 of S. rostrata. NF production within the infection threads is shown to be necessary for proper infection thread growth and for synchronization of nodule formation with bacterial invasion. However, local production of NFs by bacteria that are taken up by the plant cells at the stage of bacteroid formation is not required for correct symbiosome development.

scholarly journals Lipochito-Oligosaccharide Nodulation Factors Stimulate Cytoplasmic Polarity with Longitudinal Endoplasmic Reticulum and Vesicles at the Tip in Vetch Root Hairs

2000 ◽  
Vol 13 (12) ◽  
pp. 1385-1390 ◽  
Author(s):  
Deborah D. Miller ◽  
Hetty B. Leferink-ten Klooster ◽  
Anne Mie C. Emons
Keyword(s):  
Endoplasmic Reticulum ◽  
Root Hair ◽  
Root Hairs ◽  
Root Hair Development ◽  
Nodulation Factors ◽  
Hair Development ◽  
Nodulation Factor

Vetch root hair development has four stages: bulge, growing, growth terminating, and full-grown hair. In the assay we used, the nodulation factor induced swellings and outgrowths in growth-terminating hairs. Bulges, swellings, and full-grown hairs have transverse endoplasmic reticulum (ER) and no tip-accumulated vesicles. Growing hairs and outgrowths show vesicle accumulation in the tip and longitudinal subapical ER. Bulge walls and walls of swellings appear mottled.

scholarly journals The extracellular calcium-sensing receptor is required for cholecystokinin secretion in response to l-phenylalanine in acutely isolated intestinal I cells

2011 ◽  
Vol 300 (4) ◽  
pp. G538-G546 ◽  
Author(s):  
Alice P. Liou ◽  
Yoshitatsu Sei ◽  
Xilin Zhao ◽  
Jianying Feng ◽  
Xinping Lu ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Fluorescent Protein ◽  
Direct Detection ◽  
Hormone Secretion ◽  
Extracellular Calcium ◽  
Calcium Flux ◽  
Specific Response ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing ◽  
I Cells

The extracellular calcium-sensing receptor (CaSR) has recently been recognized as an l-amino acid sensor and has been implicated in mediating cholecystokinin (CCK) secretion in response to aromatic amino acids. We investigated whether direct detection of l-phenylalanine (l-Phe) by CaSR results in CCK secretion in the native I cell. Fluorescence-activated cell sorting of duodenal I cells from CCK-enhanced green fluorescent protein (eGFP) transgenic mice demonstrated CaSR gene expression. Immunostaining of fixed and fresh duodenal tissue sections confirmed CaSR protein expression. Intracellular calcium fluxes were CaSR dependent, stereoselective for l-Phe over d-Phe, and responsive to type II calcimimetic cinacalcet in CCK-eGFP cells. Additionally, CCK secretion by an isolated I cell population was increased by 30 and 62% in response to l-Phe in the presence of physiological (1.26 mM) and superphysiological (2.5 mM) extracellular calcium concentrations, respectively. While the deletion of CaSR from CCK-eGFP cells did not affect basal CCK secretion, the effect of l-Phe or cinacalcet on intracellular calcium flux was lost. In fact, both secretagogues, as well as superphysiological Ca2+, evoked an unexpected 20–30% decrease in CCK secretion compared with basal secretion in CaSR−/− CCK-eGFP cells. CCK secretion in response to KCl or tryptone was unaffected by the absence of CaSR. The present data suggest that CaSR is required for hormone secretion in the specific response to l-Phe by the native I cell, and that a receptor-mediated mechanism may inhibit hormone secretion in the absence of a fully functional CaSR.

scholarly journals Analysis of Nod-Factor-Induced Calcium Signaling in Root Hairs of Symbiotically Defective Mutants of Lotus japonicus

2006 ◽  
Vol 19 (8) ◽  
pp. 914-923 ◽  
Author(s):  
Hiroki Miwa ◽  
Jongho Sun ◽  
Giles E. D. Oldroyd ◽  
J. Allan Downie
Keyword(s):  
Calcium Influx ◽  
Lotus Japonicus ◽  
Root Hairs ◽  
Calcium Flux ◽  
Symbiotic Interaction ◽  
Nod Factor ◽  
Root Hair Deformation ◽  
Complementation Groups ◽  
Calcium Spiking ◽  
Timing Of Initiation

Nodulation (Nod)-factor signaling molecules are essential for rhizobia to initiate the nitrogen-fixing symbiotic interaction with legumes. Using a dual dye ratiometric calcium imaging technique, we have shown that 10 nM Nod factor added to roots of Lotus japonicus seedlings induces an intra-cellular calcium increase (calcium flux) that precedes oscillations in intracellular calcium (calcium spiking). The calcium flux was not observed with 1 or 0.1 nM Nod factor, which did induce calcium spiking. The calcium flux was variable in timing of initiation and duration and was observed in approximately half of the root hairs examined. Representatives from 11 complementation groups of symbiotically defective mutants were analyzed for the calcium flux. Mutants from four groups (sym6, ccamk, sym35, and nin) which retained calcium spiking all showed a normal calcium flux. Two classes of mutants (nfr1 and nfr5) lacked both calcium influx and calcium spiking, whereas five classes of mutants (symRK, castor, pollux, nup133, and sym24) defective for calcium spiking retained a calcium flux. There was no correlation between calcium spiking and induction of root hair deformation by Nod factor. We propose that increased bacterial numbers within infection foci in root hairs leads to accumulation of Nod factor to sufficient levels to activate the calcium flux, and this may drive infection thread growth.

scholarly journals A Nuclear-Targeted Cameleon Demonstrates Intranuclear Ca2+ Spiking in Medicago truncatula Root Hairs in Response to Rhizobial Nodulation Factors

2009 ◽  
Vol 151 (3) ◽  
pp. 1197-1206 ◽  
Author(s):  
Björn J. Sieberer ◽  
Mireille Chabaud ◽  
Antonius C. Timmers ◽  
André Monin ◽  
Joëlle Fournier ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Root Hairs ◽  
Nodulation Factors

Use of SEM, X-ray analysis and TEM to localize Fe3+ reduction in roots

1988 ◽  
Vol 46 ◽  
pp. 392-393 ◽  
Author(s):  
William P. Wergin ◽  
P. F. Bell ◽  
Rufus L. Chaney
Keyword(s):  
Electron Microscopy ◽  
Root Hairs ◽  
Rapid Reduction ◽  
X Ray ◽  
Physical Evidence ◽  
Transmission Electron ◽  
Young Root ◽  
Insoluble Precipitate ◽  
Uptake And Transport ◽  
Scanning Electron

In dicotyledons, Fe3+ must be reduced to Fe2+ before uptake and transport of this essential macronutrient can occur. Ambler et al demonstrated that reduction along the root could be observed by the formation of a stain, Prussian blue (PB), Fe4 [Fe(CN)6]3 n H2O (where n = 14-16). This stain, which is an insoluble precipitate, forms at the reduction site when the nutrient solution contains Fe3+ and ferricyanide. In 1972, Chaney et al proposed a model which suggested that the Fe3+ reduction site occurred outside the cell membrane; however, no physical evidence to support the model was presented at that time. A more recent study using the PB stain indicates that rapid reduction of Fe3+ occurs in a region of the root containing young root hairs. Furthermore the most pronounced activity occurs in plants that are deficient in Fe. To more precisely localize the site of Fe3+ reduction, scanning electron microscopy (SEM), x-ray analysis, and transmission electron microscopy (TEM) were utilized to examine the distribution of the PB precipitate that was induced to form in roots.

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