Characterization of ion currents elicited by a stream of fluid during spontaneous and ligand-induced chloride current oscillation in Xenopus laevis oocytes

1998 ◽  
Vol 436 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Swen Hülsmann ◽  
Ulrich Mußhoff ◽  
Michael Madeja ◽  
Bernhard Fischer ◽  
Erwin-Josef Speckmann
Keyword(s):  
Xenopus Laevis ◽  
Current Oscillation ◽  
Chloride Current ◽  
Xenopus Laevis Oocytes ◽  
Ion Currents

scholarly journals Functional Characterization of the Oxantel-Sensitive Acetylcholine Receptor from Trichuris muris

2021 ◽  
Vol 14 (7) ◽  
pp. 698
Author(s):  
Tina V. A. Hansen ◽  
Richard K. Grencis ◽  
Mohamed Issouf ◽  
Cédric Neveu ◽  
Claude L. Charvet
Keyword(s):  
Single Dose ◽  
Mouse Model ◽  
Xenopus Laevis ◽  
Acetylcholine Receptor ◽  
Drug Target ◽  
Functional Characterization ◽  
Xenopus Laevis Oocytes ◽  
Trichuris Muris ◽  
Electrode Voltage

The human whipworm, Trichuris trichiura, is estimated to infect 289.6 million people globally. Control of human trichuriasis is a particular challenge, as most anthelmintics have a limited single-dose efficacy, with the striking exception of the narrow-spectrum anthelmintic, oxantel. We recently identified a novel ACR-16-like subunit from the pig whipworm, T. suis which gave rise to a functional acetylcholine receptor (nAChR) preferentially activated by oxantel. However, there is no ion channel described in the mouse model parasite T. muris so far. Here, we have identified the ACR-16-like and ACR-19 subunits from T. muris, and performed the functional characterization of the receptors in Xenopus laevis oocytes using two-electrode voltage-clamp electrophysiology. We found that the ACR-16-like subunit from T. muris formed a homomeric receptor gated by acetylcholine whereas the ACR-19 failed to create a functional channel. The subsequent pharmacological analysis of the Tmu-ACR-16-like receptor revealed that acetylcholine and oxantel were equally potent. The Tmu-ACR-16-like was more responsive to the toxic agonist epibatidine, but insensitive to pyrantel, in contrast to the Tsu-ACR-16-like receptor. These findings confirm that the ACR-16-like nAChR from Trichuris spp. is a preferential drug target for oxantel, and highlights the pharmacological difference between Trichuris species.

Functional characterization of leucine transport induced in Xenopus laevis oocytes injected with mRNA isolated from midguts of lepidopteran larvae (Philosamia cynthia).

1995 ◽  
Vol 198 (4) ◽  
pp. 961-966
Author(s):  
V F Sacchi ◽  
C Perego ◽  
S Magagnin
Keyword(s):  
Xenopus Laevis ◽  
Functional Characterization ◽  
Xenopus Laevis Oocytes ◽  
Fourfold Increase ◽  
Leucine Uptake ◽  
Lepidopteran Larvae ◽  
Nacl Concentration ◽  
Leucine Transport ◽  
The Difference

The injection of poly(A)+ mRNA prepared from Philosamia cynthia midgut caused time- and dose-dependent increases of leucine transport in Xenopus laevis oocytes, with an increase in leucine uptake 1.5-3 times that of oocytes injected with water. When the NaCl concentration was reduced from 100 to 5 mmol l-1, the difference between mRNA- and water-injected oocytes was greater and a fourfold increase of L-leucine uptake was measured. D-Leucine (10 mmol l-1) completely inhibited the induced uptake of 0.1 mmol l-1 L-leucine. The newly expressed component of L-leucine uptake increased at alkaline pH and was abolished by incubation for 15 min with 15 mmol l-1 phenylglyoxal. The mean Km values, calculated using Na+ activation curves of leucine uptake, were 23.3 +/- 6.1 mmol l-1 in water-injected oocytes and 0.4 +/- 0.2 mmol l-1 for the newly expressed component of leucine uptake in mRNA-injected oocytes. On the basis of these results, we conclude that the increase of L-leucine uptake in mRNA-injected oocytes was due to the expression of a new transport system, which differs from the endogenous ones and shares many features with that found previously in Philosamia cynthia midgut.

scholarly journals Induction of apoptosis using sphingolipids activates a chloride current in Xenopus laevis oocytes

2000 ◽  
Vol 279 (1) ◽  
pp. C158-C165 ◽  
Author(s):  
R. Souktani ◽  
A. Berdeaux ◽  
B. Ghaleh ◽  
J. F. Giudicelli ◽  
L. Guize ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Dna Cleavage ◽  
Ionic Currents ◽  
Chloride Current ◽  
Xenopus Laevis Oocytes ◽  
Cell Shrinkage ◽  
Transport Pathways ◽  
Kinase C ◽  
Induction Of Apoptosis ◽  
A Current

The purpose of this study was to investigate whether the cell shrinkage that occurs during apoptosis could be explained by a change of the activity in ion transport pathways. We tested whether sphingolipids, which are potent pro-apoptotic compounds, can activate ionic currents in Xenopus laevis oocytes. Apoptosis was characterized in our model by a decrease in cell volume, a loss of cell viability, and DNA cleavage. Oocytes were studied using voltage-clamp after injection with N, N-dimethyl-d-erythrosphingosine (DMS) or d-sphingosine (DS). DMS and DS activated a fast-activating, slowly inactivating, outwardly rectifying current, similar to I Cl-swell, a swelling-induced chloride current. Lowering the extracellular chloride dramatically reduced the current, and the channel was more selective for thiocyanate and iodide (thiocyanate > iodide) than for chloride. The current was blocked by 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and lanthanum but not by niflumic acid. Oocytes injected with a pseudosubstrate inhibitor of protein kinase C (PKC), PKC-(19–31), exhibited the same current. DMS-activated current was abolished by preexposure with phorbol myristate acetate. Our results suggest that induction of apoptosis in X. laevis oocytes, using sphingolipids or PKC inhibitors, activates a current similar to swelling-induced chloride current previously described in oocytes.

scholarly journals Characterization of the monocarboxylate transporter 1 expressed in Xenopus laevis oocytes by changes in cytosolic pH

1998 ◽  
Vol 333 (1) ◽  
pp. 167-174 ◽  
Author(s):  
Stefan BRÖER ◽  
Hans-Peter SCHNEIDER ◽  
Angelika BRÖER ◽  
Basim RAHMAN ◽  
Bernd HAMPRECHT ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Intracellular Ph ◽  
Expression System ◽  
Lactate Concentration ◽  
Monocarboxylate Transporter ◽  
Kinetic Properties ◽  
Xenopus Laevis Oocytes ◽  
Lactate Transport ◽  
Monocarboxylate Transporter 1

Several laboratories have investigated monocarboxylate transport in a variety of cell types. The characterization of the cloned transporter isoforms in a suitable expression system is nevertheless still lacking. H+/monocarboxylate co-transport was therefore investigated in monocarboxylate transporter 1 (MCT1)-expressing Xenopus laevis oocytes by using pH-sensitive microelectrodes and [14C]lactate. Superfusion with lactate resulted in intracellular acidification of MCT1-expressing oocytes, but not in non-injected control oocytes. The basic kinetic properties of lactate transport in MCT1-expressing oocytes were determined by analysing the rates of intracellular pH changes under different conditions. The results were in agreement with the known properties of the transporter, with respect to both the dependence on the lactate concentration and the external pH value. Besides lactate, MCT1 mediated the reversible transport of a wide variety of monocarboxylic acids including pyruvate, d,l-3-hydroxybutyrate, acetoacetate, α-oxoisohexanoate and α-oxoisovalerate, but not of dicarboxylic and tricarboxylic acids. The inhibitor α-cyano-4-hydroxycinnamate bound strongly to the transporter without being translocated, but could be displaced by the addition of lactate. In addition to changes in the intracellular pH, lactate transport also induced deviations from the resting membrane potential.

Molecular cloning and characterization of an adaptor protein Shc isoform from Xenopus laevis oocytes

2003 ◽  
Vol 95 (5) ◽  
pp. 311-320 ◽  
Author(s):  
Franck Chesnel ◽  
Christophe Heligon ◽  
Laurent Richard-Parpaillon ◽  
Daniel Boujard
Keyword(s):  
Xenopus Laevis ◽  
Molecular Cloning ◽  
Adaptor Protein ◽  
Xenopus Laevis Oocytes

The Use of Xenopus laevis Oocytes for the Functional Characterization of Heterologously Expressed Membrane Proteins

2000 ◽  
Vol 10 (1-2) ◽  
pp. 1-12 ◽  
Author(s):  
Carsten A. Wagner ◽  
Björn Friedrich ◽  
Iwan Setiawan ◽  
Florian Lang ◽  
Stefan Bröer
Keyword(s):  
Membrane Proteins ◽  
Xenopus Laevis ◽  
Functional Characterization ◽  
Xenopus Laevis Oocytes

Characterization of the repressed 5S DNA minichromosomes assembled in vitro with a high-speed supernatant of Xenopus laevis oocytes

1988 ◽  
Vol 8 (10) ◽  
pp. 4257-4269
Author(s):  
A Shimamura ◽  
D Tremethick ◽  
A Worcel
Keyword(s):  
Xenopus Laevis ◽  
Transcriptional Activation ◽  
High Speed ◽  
Histone H1 ◽  
Xenopus Laevis Oocytes ◽  
Xenopus Laevis Oocyte ◽  
5S Rna ◽  
Rna Transcription

We describe an in vitro system, based on the Xenopus laevis oocyte supernatant of Glikin et al. (G. Glikin, I. Ruberti, and A. Worcel, Cell 37:33-41, 1984), that packages DNA into minichromosomes with regularly spaced nucleosomes containing histones H3, H4, H2A, and H2B but no histone H1. The same supernatant also assembles the 5S RNA transcription complex; however, under the conditions that favor chromatin assembly, transcription is inhibited and a phased nucleosome forms over the 5S RNA gene. The minichromosomes that are fully loaded with nucleosomes remain refractory to transcriptional activation by 5S RNA transcription factors. Our data suggest that this repression is caused by a nucleosome covering the 5S RNA gene and that histone H1 is not required for regular nucleosome spacing or for gene repression in this system.

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