Changes in the distribution of intramembranous particles in hen erythrocytes during cell fusion induced by the bivalent-cation ionophore A23187.
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ABSTRACT:
SUBMITTER: Vos J
PROVIDER: S-EPMC1164023 | biostudies-other | 1976 Sep
REPOSITORIES: biostudies-other
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Project description:1. Ca2+ (0.4-16 mM) had no detectable action on the agglutination of hen erythrocytes by Sendai virus. 2. Pretreatment of the cells with Ca2+ (0.1-8 mM) in the presence of the bivalent cation ionophore A23187 led, however, to a significant decrease in the subsequent agglutination of the cells by the virus. 3. It thus appears that the entry of Ca2+ into the interior of these cells decreases cellular agglutination by Sendai virus; possible interpretations of this phenomenon are discussed in terms of the movement of intramembranous particles. 4. With a small number of virions, maximum cell fusion by Sendai virus occurred in the presence of EGTA [ethanedioxybis(ethylamine)tetra-acetate]. 5. Virus-induced cell fusion was significantly decreased by Ca2+, even at a concentration of 0.2 mM; it is suggested that this may result from diminished interactions between virus particles and erythrocyte membranes.
| S-EPMC1163947 | biostudies-other
Project description:Using two cDNA clones which encode hamster genes specifically induced by glucose starvation, we demonstrated that an 8- and 30-fold increase, respectively, in the transcription rates of these genes was coordinately effected by calcium ionophore A23187 treatment, resulting in a similar increase in the steady-state levels of their mRNAs. This response was observed within several hours of ionophore treatment in several mammalian cell types and appeared to be specifically mediated by A23187 but not by other ionophores in general. To define the regulatory sequence which mediates this Ca2+-induced response, we showed by gene transfection techniques that the 5' flanking sequence of a rat glucose-regulated gene contained the region for induction by A23187. The system reported here offers attractive features for the study of specific gene regulation by Ca2+.
| S-EPMC366848 | biostudies-literature
Project description:Previous studies have demonstrated that A23187, an ionophore which selectively transports divalent cations across cell membranes, has profound effects on human erythrocytes: it causes red cells to take up calcium; lose potassium, water, and ATP; convert from biconcave discs to echinocytes and spheroechinocytes; and become more rigid. The present study has explored the influence of calcium uptake induced by the ionophore on the behavior of individual erythrocyte membranes by the micropipette aspiration technique. Exposure of erythrocytes to calcium and A23187 for intervals of up to 30 minutes resulted in marked changes in membrane viscoelastic properties, including the development of increased resistance to aspiration. The most striking manifestation of altered membrane mechanics was apparent after 10 minutes on incubation. Cells pulled into the pipette for a few seconds and the extruded back into the medium retained the deformity imposed by the pipette for several seconds to a few minutes before regaining the form they manifested prior to initial aspiration. The calcium-induced changes in erythrocyte behavior observed in this study strongly support the concept that extrinsic proteins located inside the membrane provide mechanical support to the cell wall, and that increased levels of calcium cause precipitation or cross-linking of the proteins responsible for the increased resistence to deformation and recoil observed after aspiration into micropipettes.
| S-EPMC2032159 | biostudies-other
Project description:PurposeTo investigate whether treatment with commercially available ready-to-use A23187 ionophore (GM508-CultActive) improves embryo development outcome in patients with a history of embryo developmental problems.MethodsThis is a uni-center prospective study in which sibling oocytes of patients with embryos of poor quality on day 5 in the previous cycle were treated or not with CultActive.ResultsTwo hundred forty-seven metaphase II (MII) oocytes from 19 cycles performed between 2016 and 2019 were included in the study. After ICSI, the sibling oocytes were assigned to the treatment group or to the control group, following an electronically generated randomization list. A number of 122 MII were treated with CultActive and 125 MII had no treatment and were assigned to the control group. No difference in fertilization rate (p = 0.255) or in the capacity of embryos to reach good quality on day 5 (p = 0.197) was observed between the two groups. The utilization rates defined as the number of embryos transferred or cryopreserved per mature oocyte (p = 0.438) or per fertilized oocytes (p = 0.299) were not significantly different between the treated group and the control group.ConclusionThe results of the current study do not support the use of CultActive in cases with embryo developmental problems.
| S-EPMC9174380 | biostudies-literature
Project description:BackgroundIntracytoplasmic sperm injection (ICSI) has tremendous advantages for resolving the problem of male infertility. However, ICSI fertilization can fail in some patients because of various reasons, primarily because of the failure of oocyte activation. Oocytes have been activated using calcium ionophore (A23187) in previous clinical cases of ICSI fertilization failure. However, studies on the efficiency of calcium ionophore (A23187) activation, its effects on the developmental potential of embryos, and its effects on pregnancy outcomes after embryo transfer are relatively limited.MethodsIn this study, we investigated the safety and long-term efficacy of calcium ionophore (A23187) by analyzing its effects on fertilization, embryonic development, aneuploidy, and pregnancy outcomes in patients undergoing preimplantation genetic testing (PGT) cycles.ResultsComparative analyses of the activation followed by PGT (A-PGT) and PGT groups revealed no significant differences between the oocyte cleavage rate and high-quality embryo rate (98.19% vs. 98.63% and 63.13% vs. 68.39%, respectively, p > 0.05). Although the blastocyst formation rate was significantly lower in the A-PGT group than that in the PGT group (52.22% vs. 59.90%, p < 0.05), no significant difference was observed in the blastocyst aneuploidy rates of the two groups (24.49% vs. 24.55%, p > 0.05). Furthermore, no significant differences were observed between the two groups in terms of the live birth rate (43.75% vs. 52.99%), week of delivery, and birth weight of the infants after transfer of euploid blastocysts (p > 0.05). Furthermore, the 2PN rate, oocyte cleavage rate, blastocyst formation rate, and live birth rate were found to be significantly lower in the A-ICSI group than those in the ICSI group (p < 0.01), but there was no significant difference between the two groups in the week of delivery and birth weight of live births (p > 0.05).DiscussionThese results suggest that the use of calcium ionophore (A23187) activation as an option in cases of ICSI fertilization failure does not affect the ploidy of developing blastocysts and has no significant effects on the week of delivery or birth weight after transfer. Thus, we provide a scientific basis for the clinical safety of oocyte activation using calcium ionophore (A23187).
| S-EPMC9846205 | biostudies-literature
Project description:1. The cholesterol content of hen erythrocytes was modified by treating the cells with phospholipid liposomes. 2. Depletion of cellular cholesterol, by using liposomes of dipalmitoylglycerophosphocholine or phosphatidylcholine from hen erythrocytes, had no effect on the susceptibility of the cells to fusion induced by oleoylglycerol, but markedly decreased fusion induced by Sendai virus. 3. By contrast, enrichment of cellular cholesterol by using liposomes of dipalmitoylglycerophosphocholine and cholesterol increased cell fusion induced by oleoylglycerol, poly(ethylene glycol) and Sendai virus. 4. Virus-induced cell fusion of guinea-pig erythrocytes, which were enriched in cholesterol by feeding a cholesterol-rich diet to the animals, was also enhanced. 5. Hen erythrocytes that were treated with liposomes prepared from egg phosphatidylcholine contained increased quantities of phospholipid phosphorus and fused readily on incubation with retinol, independently of their cholesterol content. 6. It is suggested that cholesterol may enhance cell fusion by acting to facilitate a phase separation of protein-free areas of lipid bilayer, which subsequently provide the sites for cell fusion.
| S-EPMC1165002 | biostudies-other
Project description:1. When the ionophore A23187 and Ca2+ were added to normal human erythrocytes, the incorporation of 32P into phosphatidate was enhanced within 1 min, but there was only slight labelling of other phospholipids. 2. Labelling of phosphatidate in these cells did not continue to increase after about 20min at 37 degrees C; by this time, radioactivity in phosphatidate was about ten times higher inionophore A23187-treated cells than in controls. A net synthesis of phosphatidate was measured in response to the increase in intracellular Ca2+ concentration; the content of this phospholipid in the cell was increased by approximately 50%. 3. In the presence of 2.5 mM-Ca2+ a maximum effect was seen with about 0.5 mug of ionophore/ml. 4. The concentration of Ca2+ giving half-maximal labelling of phosphatidate in the presence of 10 mug of ionophore A23187/ml was about 10 muM. 5. A rapid decrease of ATP content in the cell occurred in ionophore-treated cells. 6. Labelling of phosphatidate appeared to be secondary to the production of 1,2-diacylglycerol in the cells; accumulation of 1,2-diacylglycerol was only seen after about 15 min. After 60 min, the 1,2-diacylglycerol content of the cells was five to seven times that of untreated control cells. 7. The change in the shape of erythrocytes treated with Ca2+ and ionophore appeared to be related to accumulation of 1,2-diacylglycerol. 8. The source of 1,2-diacylglycerol has not been definitely identified, but its fatty acid compositon was similar to that of phosphatidylcholine. However, it has an unusually high content of hexadecenoic acid, a fatty acid not common in the major erythrocyte phospholipids. 9. Accumulation of 1,2-diacyglycerol also occurred in energy-starved cells, even in the absence of calcium; in this case it appeared to be produced by phosphatidate breakdown.
| S-EPMC1163740 | biostudies-other
Project description:In addition to the microvesicles released during the treatment of human erythrocytes with Ca2+ and ionophore A23187, a new subpopulation of still smaller dense vesicles ('nanovesicles') has now been identified. Nanovesicles are about 60 nm in diameter, have an acetylcholinesterase activity higher than that of microvesicles and appear to be relatively enriched in sphingomyelin and correspondingly depleted of phosphatidylethanolamine. They have a polypeptide composition quite different from those of erythrocyte membranes or microvesicles, consisting largely of components of mol.wts. 60 000 and 26 000 in addition to haemoglobin. These two major polypeptides do not appear to represent contaminating cytoplasmic proteins or proteolytic subfragments of a larger protein.
| S-EPMC1161973 | biostudies-other
Project description:Ionophores are small molecules or peptides that transport metal ions across biological membranes. Their transport capabilities are typically characterized in vitro using vesicles and single ion species. It is difficult to infer from these data which effects ionophores have on living cells in a complex environment (e.g. culture medium), since net transport is influenced e.g. by ion composition, concentration gradients, pH gradient, and active transport. To gain insights into the antibacterial mechanism of the semi-synthetic polyether ionophore 4-Br-A23187, we investigated its effects on the gram-positive model organism Bacillus subtilis. Changes in intracellular ion concentrations were determined using ionomics and the physiological impact was assessed by proteomics. 4-Br-A23187 treatment resulted in an increase in intracellular copper levels, an effect that was dependent on the copper concentration of the medium. The antibiotic effect of 4-Br-A23187 is further aggravated by a decrease in intracellular manganese and magnesium. Effects of copper hyperaccumulation, mirrored by the proteomic response, included oxidative stress, disturbance of proteostasis, metal, and sulfur homeostasis. Especially solvent-exposed iron-sulfur clusters like that of aconitase of the citric acid cycle are readily destabilized by copper. Using calcein fluorescence quenching as a readout, we confirmed in vitro that 4-Br-A23187 acts as copper ionophore.
2022-06-08 | PXD028938 | Pride
Project description:Ca(2+) ionophore A23187 is known to induce the acrosome reaction of mammalian spermatozoa, but it also quickly immobilizes them. Although mouse spermatozoa were immobilized by this ionophore, they initiated vigorous motility (hyperactivation) soon after this reagent was washed away by centrifugation. About half of live spermatozoa were acrosome-reacted at the end of 10 min of ionophore treatment; fertilization of cumulus-intact oocytes began as soon as spermatozoa recovered their motility and before the increase in protein tyrosine phosphorylation, which started 30-45 min after washing out the ionophore. When spermatozoa were treated with A23187, more than 95% of oocytes were fertilized in the constant presence of the protein kinase A inhibitor, H89. Ionophore-treated spermatozoa also fertilized 80% of oocytes, even in the absence of HCO3(-), a component essential for cAMP synthesis under normal in vitro conditions. Under these conditions, fertilized oocytes developed into normal offspring. These data indicate that mouse spermatozoa treated with ionophore are able to fertilize without activation of the cAMP/PKA signaling pathway. Furthermore, they suggest that the cAMP/PKA pathway is upstream of an intracellular Ca(2+) increase required for the acrosome reaction and hyperactivation of spermatozoa under normal in vitro conditions.
| S-EPMC3831971 | biostudies-literature