Transepithelial calcium transport in the chick chorioallantoic membrane. II. Compartmentalization of calcium during uptake

1993 ◽  
Vol 105 (2) ◽  
pp. 381-388 ◽  
Author(s):  
R.E. Akins ◽  
R.S. Tuan
Keyword(s):  
Calcium Transport ◽  
Chorioallantoic Membrane ◽  
Cytosolic Calcium ◽  
Calcium Flux ◽  
Free Calcium ◽  
Extracellular Medium ◽  
Calcium Accumulation ◽  
Chick Chorioallantoic Membrane ◽  
Cellular Compartments ◽  
Endosomal Vesicles

Calcium transport from the eggshell to the developing chick embryo is carried out by the ectoderm cells of the chick chorioallantoic membrane. Primary cells isolated from chick chorioallantoic membrane ectoderm were used to analyze the subcellular distribution of 45Ca2+ accumulated from the extracellular medium. We present evidence suggesting that calcium may be sequestered into endosome-like vesicles during the initial phase of uptake. A combination of techniques were utilized to monitor calcium fluxes and calcium compartmentalization in the cultured chorioallantoic membrane cells: (1) fura-2 fluorescence was used to indicate cytosolic free calcium concentrations, (2) 45Ca2+ tracer was used to follow calcium accumulation in all cellular compartments, and (3) digitonin was used to differentially permeabilize subcellular membranes in order to localize 45Ca2+ by following tracer release profiles. Differences between cytosolic calcium flux and whole cell calcium accumulation suggested that the pathway of calcium uptake from the medium involves sequestration into an internal compartment separate from the cytosol. Kinetic analysis of the digitonin-mediated release of specific subcellular markers (lactate dehydrogenase, NAD-dependent isocitrate dehydrogenase, [3H]inulin, and [3H]-2-deoxyglucose) and preloaded 45Ca2+ indicated that calcium was localized in a compartment similar to endosomal vesicles. Our results are consistent with a transcytotic mechanism for chorioallantoic membrane calcium transport.

scholarly journals Transcriptome-based insights into the calcium transport mechanism of chick chorioallantoic membrane

2022 ◽  
Vol 11 (2) ◽  
pp. 383-392
Author(s):  
Qun Huang ◽  
Ran Yang ◽  
Qia Wang ◽  
Hui Teng ◽  
Hongbo Song ◽  
...  
Keyword(s):  
Calcium Transport ◽  
Transport Mechanism ◽  
Chorioallantoic Membrane ◽  
Chick Chorioallantoic Membrane

scholarly journals Calcium-binding protein of the chick chorioallantoic membrane. I. Immunohistochemical localization

1978 ◽  
Vol 77 (3) ◽  
pp. 743-751 ◽  
Author(s):  
RS Tuan ◽  
WA Scott ◽  
ZA Cohn
Keyword(s):  
Calcium Binding ◽  
Calcium Transport ◽  
External Surface ◽  
Binding Protein ◽  
Chorioallantoic Membrane ◽  
Immunohistochemical Localization ◽  
Calcium Binding Protein ◽  
Transport Function ◽  
Chick Chorioallantoic Membrane

The preparation of a specific antiserum (anti-CaBP) against the calcium-binding protein (CaBP) of the chorioallantoic membrane (CAM) is described. The anti-CaBP appeared to be specific for the CaBP by immunodiffusion and immunoelectrophoresis. Application of the anti-CaBP in immunofluorescence histochemistry revealed that the CaBP is present in the CAM only at developmental ages corresponding with the expression of the calcium transport function of the membrane. Furthermore, the CaBP is localized to the ectoderm of the CAM, appears to be exposed to the entire external surface of the ectoderm, and can be shown to be associated with cells enzymatically dissociated from the CAM. These results are consistent with a functional role of the CaBP in the CAM calcium transport process.

scholarly journals The Chick Chorioallantoic Membrane: A Model of Molecular, Structural, and Functional Adaptation to Transepithelial Ion Transport and Barrier Function during Embryonic Development

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Maria Gabriella Gabrielli ◽  
Daniela Accili
Keyword(s):  
Calcium Transport ◽  
Chorioallantoic Membrane ◽  
Allantoic Fluid ◽  
Model System ◽  
Functional Adaptation ◽  
Acid Base ◽  
Functional Potential ◽  
Chick Chorioallantoic Membrane ◽  
Wide Range ◽  
Respiratory Gases

The chick chorioallantoic membrane is a very simple extraembryonic membrane which serves multiple functions during embryo development; it is the site of exchange of respiratory gases, calcium transport from the eggshell, acid-base homeostasis in the embryo, and ion andH2O reabsorption from the allantoic fluid. All these functions are accomplished by its epithelia, the chorionic and the allantoic epithelium, by differentiation of a wide range of structural and molecular peculiarities which make them highly specialized, ion transporting epithelia. Studying the different aspects of such a developmental strategy emphasizes the functional potential of the epithelium and offers an excellent model system to gain insights into questions partly still unresolved.

scholarly journals Influence of the calcium-sensitive fluorophore, Quin 2, on platelet function

Blood ◽  
1986 ◽  
Vol 67 (2) ◽  
pp. 354-361 ◽  
Author(s):  
GH Rao ◽  
JD Peller ◽  
CP Semba ◽  
JG White
Keyword(s):  
Platelet Function ◽  
Light Emission ◽  
Cytosolic Calcium ◽  
Functional Restoration ◽  
Calcium Flux ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Experimental Conditions ◽  
Calcium Dependent ◽  
Dose Dependent Increase

Abstract Recent investigations using Quin 2, a fluorophore used to monitor cytosolic free calcium shifts, have shown that strong agonists cause a dramatic dose-dependent increase in platelet fluorescence. However, weak agonists stimulated little or no increase in light emission of Quin 2-loaded platelets, suggesting that calcium flux is not involved in activation by these agents. The present study has sought an alternative explanation for the failure of weak stimuli to cause a rise in cytosolic free calcium in platelets containing Quin 2. Conditions used to prepare, wash, load, gel-filter, and evaluate the fluorophore- filled cells were examined for their compatibility with retention of sensitivity to activation by weak agonists. The technique used to measure shifts in cytosolic calcium with Quin 2 requires multiply washed, unstirred platelets. Under these conditions, platelets do not aggregate or secrete in response to weak agonists. Quin 2, at concentrations greater than 40 mumol/L, inhibits the response of platelets to strong agonists, and completely blocks their reaction to weak agonists. Quin 2 inhibition of platelet function appears related to high buffering capacity for free calcium, although other mechanisms cannot be ruled out. This suggestion is supported by the observation that Quin 2-induced blockade can be overcome by membrane modulation, which is a calcium-dependent process. However, since both agonists are weak, significant elevation in cytosolic calcium concurrent with functional restoration could not be demonstrated under the experimental conditions used for monitoring calcium. Thus, the conditions used to prepare platelets for Quin 2 evaluation and Quin 2 itself appear to be responsible for the failure of weak agonists to cause evidence of a calcium shift in fluorophore-loaded cells.

Intracellular Ca2+ signals in Dictyostelium chemotaxis are mediated exclusively by Ca2+ influx

1997 ◽  
Vol 110 (22) ◽  
pp. 2845-2853 ◽  
Author(s):  
T. Nebl ◽  
P.R. Fisher
Keyword(s):  
Calcium Concentration ◽  
Absolute Magnitude ◽  
Cytosolic Calcium ◽  
Ruthenium Red ◽  
Free Calcium ◽  
Dependent Manner ◽  
Extracellular Medium ◽  
Maximum Increase ◽  
Concentration Dependent Manner ◽  
Short Delay

We measured folate- and cAMP-induced changes in cytoplasmic free calcium concentration ([Ca2+]i) using recombinant aequorin reconstituted in living Dictyostelium cells with coelenterazine-h. The resulting semi-synthetic protein displayed increased sensitivity to Ca2+ allowing accurate measurement of chemoattractant-induced transients at low resting levels. Both folate- and cAMP-induced Ca2+ responses were developmentally regulated, exhibited remarkably similar kinetics and were dependent on the relative rather than the absolute magnitude of increases in attractant concentration. They began after a short delay of 5–10 seconds, leading to a maximum increase in cytosolic calcium concentration after approximately 25 seconds and a return to basal level within approximately 60 seconds after stimulation. Responses elicited by the two chemoattractants were dose-dependent and saturated between 4 and 20 microM. They depended on the presence of free extracellular calcium ions and were inhibited in a concentration-dependent manner between 10(−4) and 10(−5) M. In accordance with 45Ca2+-uptake measurements by Milne and Coukell (J. Cell Biol. (1991) 112, 103–110), both responses were also completely inhibited by 15 microM Ruthenium Red, 15 microM carbonylcyanide m-chlorophenyl-hydrazone (CCCP) and 500 microM gadolinium ions. Under conditions that prohibited influx of Ca2+ from the extracellular medium there were no detectable changes in [Ca2+]i that could be related to a separate release of the ion from intracellular stores. Together, these results show that the Ca2+ signals involved in chemotaxis correlate temporally with actin depolymerization (not polymerization) and are mediated by Ca2+ influx, not IP3-mediated intracellular release.

scholarly journals Influence of the calcium-sensitive fluorophore, Quin 2, on platelet function

Blood ◽  
1986 ◽  
Vol 67 (2) ◽  
pp. 354-361
Author(s):  
GH Rao ◽  
JD Peller ◽  
CP Semba ◽  
JG White
Keyword(s):  
Platelet Function ◽  
Light Emission ◽  
Cytosolic Calcium ◽  
Functional Restoration ◽  
Calcium Flux ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Experimental Conditions ◽  
Calcium Dependent ◽  
Dose Dependent Increase

Recent investigations using Quin 2, a fluorophore used to monitor cytosolic free calcium shifts, have shown that strong agonists cause a dramatic dose-dependent increase in platelet fluorescence. However, weak agonists stimulated little or no increase in light emission of Quin 2-loaded platelets, suggesting that calcium flux is not involved in activation by these agents. The present study has sought an alternative explanation for the failure of weak stimuli to cause a rise in cytosolic free calcium in platelets containing Quin 2. Conditions used to prepare, wash, load, gel-filter, and evaluate the fluorophore- filled cells were examined for their compatibility with retention of sensitivity to activation by weak agonists. The technique used to measure shifts in cytosolic calcium with Quin 2 requires multiply washed, unstirred platelets. Under these conditions, platelets do not aggregate or secrete in response to weak agonists. Quin 2, at concentrations greater than 40 mumol/L, inhibits the response of platelets to strong agonists, and completely blocks their reaction to weak agonists. Quin 2 inhibition of platelet function appears related to high buffering capacity for free calcium, although other mechanisms cannot be ruled out. This suggestion is supported by the observation that Quin 2-induced blockade can be overcome by membrane modulation, which is a calcium-dependent process. However, since both agonists are weak, significant elevation in cytosolic calcium concurrent with functional restoration could not be demonstrated under the experimental conditions used for monitoring calcium. Thus, the conditions used to prepare platelets for Quin 2 evaluation and Quin 2 itself appear to be responsible for the failure of weak agonists to cause evidence of a calcium shift in fluorophore-loaded cells.

Calcium transport in turtle bladder

1987 ◽  
Vol 253 (6) ◽  
pp. R917-R921
Author(s):  
S. Sabatini ◽  
N. A. Kurtzman
Keyword(s):  
Calcium Transport ◽  
Calcium Absorption ◽  
Short Circuit ◽  
Open Circuit ◽  
Calcium Flux ◽  
Bladder Epithelium ◽  
Control Value ◽  
Sodium Calcium ◽  
Turtle Bladder ◽  
Absorptive Flux

Unidirectional 45Ca fluxes were measured in the turtle bladder under open-circuit and short-circuit conditions. In the open-circuited state net calcium flux (JnetCa) was secretory (serosa to mucosa) and was 388.3 +/- 84.5 pmol.mg-1.h-1 (n = 20, P less than 0.001). Ouabain (5 X 10(-4) M) reversed JnetCa to an absorptive flux (serosal minus mucosal flux = -195.8 +/- 41.3 pmol.mg-1.h-1; n = 20, P less than 0.001). Amiloride (1 X 10(-5) M) reduced both fluxes such that JnetCa was not significantly different from zero. Removal of mucosal sodium caused net calcium absorption; removal of serosal sodium caused calcium secretion. When bladders were short circuited, JnetCa decreased to approximately one-third of control value but remained secretory (138.4 +/- 54.3 pmol.mg-1.h-1; n = 9, P less than 0.025). When ouabain was added under short-circuit conditions, JnetCa was similar in magnitude and direction to ouabain under open-circuited conditions (i.e., absorptive). Tissue 45Ca content was approximately equal to 30-fold lower when the isotope was placed in the mucosal bath, suggesting that the apical membrane is the resistance barrier to calcium transport. The results obtained in this study are best explained by postulating a Ca2+-ATPase on the serosa of the turtle bladder epithelium and a sodium-calcium antiporter on the mucosa. In this model, the energy for calcium movement would be supplied, in large part, by the Na+-K+-ATPase. By increasing cell sodium, ouabain would decrease the activity of the mucosal sodium-calcium exchanger (or reverse it), uncovering active calcium transport across the serosa.

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