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1.
Background
In many vascular smooth muscle cells (SMCs), ryanodine receptor-mediated Ca2+ sparks activate large-conductance Ca2+-activated K+ (BK) channels leading to lowered SMC [Ca2+]i and vasodilation. Here we investigated whether Ca2+ sparks regulate SMC global [Ca2+]i and diameter in the spiral modiolar artery (SMA) by activating BK channels.Methods
SMAs were isolated from adult female gerbils, loaded with the Ca2+-sensitive flourescent dye fluo-4 and pressurized using a concentric double-pipette system. Ca2+ signals and vascular diameter changes were recorded using a laser-scanning confocal imaging system. Effects of various pharmacological agents on Ca2+ signals and vascular diameter were analyzed.Results
Ca2+ sparks and waves were observed in pressurized SMAs. Inhibition of Ca2+ sparks with ryanodine increased global Ca2+ and constricted SMA at 40 cmH2O but inhibition of Ca2+ sparks with tetracaine or inhibition of BK channels with iberiotoxin at 40 cmH2O did not produce a similar effect. The ryanodine-induced vasoconstriction observed at 40 cmH2O was abolished at 60 cmH2O, consistent with a greater Ca2+-sensitivity of constriction at 40 cmH2O than at 60 cmH2O. When the Ca2+-sensitivity of the SMA was increased by prior application of 1 nM endothelin-1, ryanodine induced a robust vasoconstriction at 60 cmH2O.Conclusions
The results suggest that Ca2+ sparks, while present, do not regulate vascular diameter in the SMA by activating BK channels and that the regulation of vascular diameter in the SMA is determined by the Ca2+-sensitivity of constriction.2.
Jose F. Perez-Zoghbi Yan Bai Michael J. Sanderson 《The Journal of general physiology》2010,135(3):247-259
Nitric oxide (NO) induces airway smooth muscle cell (SMC) relaxation, but the underlying mechanism is not well understood. Consequently, we investigated the effects of NO on airway SMC contraction, Ca2+ signaling, and Ca2+ sensitivity in mouse lung slices with phase-contrast and confocal microscopy. Airways that were contracted in response to the agonist 5-hydroxytryptamine (5-HT) transiently relaxed in response to the NO donor, NOC-5. This NO-induced relaxation was enhanced by zaprinast or vardenafil, two selective inhibitors of cGMP-specific phosphodiesterase-5, but blocked by ODQ, an inhibitor of soluble guanylyl cyclase, and by Rp-8-pCPT-cGMPS, an inhibitor of protein kinase G (PKG). Simultaneous measurements of airway caliber and SMC [Ca2+]i revealed that airway contraction induced by 5-HT correlated with the occurrence of Ca2+ oscillations in the airway SMCs. Airway relaxation induced by NOC-5 was accompanied by a decrease in the frequency of these Ca2+ oscillations. The cGMP analogues and selective PKG activators 8Br-cGMP and 8pCPT-cGMP also induced airway relaxation and decreased the frequency of the Ca2+ oscillations. NOC-5 inhibited the increase of [Ca2+]i and contraction induced by the photolytic release of inositol 1,4,5-trisphosphate (IP3) in airway SMCs. The effect of NO on the Ca2+ sensitivity of the airway SMCs was examined in lung slices permeabilized to Ca2+ by treatment with caffeine and ryanodine. Neither NOC-5 nor 8pCPT-cGMP induced relaxation in agonist-contracted Ca2+-permeabilized airways. Consequently, we conclude that NO, acting via the cGMP–PKG pathway, induced airway SMC relaxation by predominately inhibiting the release of Ca2+ via the IP3 receptor to decrease the frequency of agonist-induced Ca2+ oscillations. 相似文献
3.
Javier F. Espeleta Zoe G. Cardon K. Ulrich Mayer Rebecca B. Neumann 《Plant and Soil》2017,414(1-2):33-51
Aims
Hydro-biogeochemical processes in the rhizosphere regulate nutrient and water availability, and thus ecosystem productivity. We hypothesized that two such processes often neglected in rhizosphere models — diel plant water use and competitive cation exchange — could interact to enhance availability of K+ and NH4 +, both high-demand nutrients.Methods
A rhizosphere model with competitive cation exchange was used to investigate how diel plant water use (i.e., daytime transpiration coupled with no nighttime water use, with nighttime root water release, and with nighttime transpiration) affects competitive ion interactions and availability of K+ and NH4 +.Results
Competitive cation exchange enabled low-demand cations that accumulate against roots (Ca2+, Mg2+, Na+) to desorb NH4 + and K+ from soil, generating non-monotonic dissolved concentration profiles (i.e. ‘hotspots’ 0.1–1 cm from the root). Cation accumulation and competitive desorption increased with net root water uptake. Daytime transpiration rate controlled diel variation in NH4 + and K+ aqueous mass, nighttime water use controlled spatial locations of ‘hotspots’, and day-to-night differences in water use controlled diel differences in ‘hotspot’ concentrations.Conclusions
Diel plant water use and competitive cation exchange enhanced NH4 + and K+ availability and influenced rhizosphere concentration dynamics. Demonstrated responses have implications for understanding rhizosphere nutrient cycling and plant nutrient uptake.4.
Background
Hepatic encephalopathy (HE) is a complex disorder associated with increased ammonia levels in the brain. Although astrocytes are believed to be the principal cells affected in hyperammonemia (HA), endothelial cells (ECs) may also play an important role by contributing to the vasogenic effect of HA.Methods
Following acute application and removal of NH4Cl on astrocytes and endothelial cells, we analyzed pH changes, using fluorescence imaging with BCECF/AM, and changes in intracellular Ca2+ concentration ([Ca2+]i), employing fluorescence imaging with Fura-2/AM. Using confocal microscopy, changes in cell volume were observed accompanied by changes of [Ca2+]i in astrocytes and ECs.Results
Exposure of astrocytes and ECs to 1 – 20 mM NH4Cl resulted in rapid concentration-dependent alkalinization of cytoplasm followed by slow recovery. Removal of the NH4Cl led to rapid concentration-dependent acidification, again followed by slow recovery. Following the application of NH4Cl, a transient, concentration-dependent rise in [Ca2+]i in astrocytes was observed. This was due to the release of Ca2+ from intracellular stores, since the response was abolished by emptying intracellular stores with thapsigargin and ATP, and was still present in the Ca2+-free bathing solution. The removal of NH4Cl also led to a transient concentration-dependent rise in [Ca2+]i that resulted from Ca2+ release from cytoplasmic proteins, since removing Ca2+ from the bathing solution and emptying intracellular Ca2+ stores did not eliminate the rise. Similar results were obtained from experiments on ECs. Following acute application and removal of NH4Cl no significant changes in astrocyte volume were detected; however, an increase of EC volume was observed after the administration of NH4Cl, and EC shrinkage was demonstrated after the acute removal of NH4Cl.Conclusions
This study reveals new data which may give a more complete insight into the mechanism of development and treatment of HE.5.
Schaloske RH Lusche DF Bezares-Roder K Happle K Malchow D Schlatterer C 《BMC cell biology》2005,6(1):13
Background
Stimulation of Dictyostelium discoideum with cAMP evokes an elevation of the cytosolic free Ca2+ concentration ([Ca2+]i). The [Ca2+]i-change is composed of liberation of stored Ca2+ and extracellular Ca2+-entry. The significance of the [Ca2+]i-transient for chemotaxis is under debate. Abolition of chemotactic orientation and migration by Ca2+-buffers in the cytosol indicates that a [Ca2+]i-increase is required for chemotaxis. Yet, the iplA - mutant disrupted in a gene bearing similarity to IP3-receptors of higher eukaryotes aggregates despite the absence of a cAMP-induced [Ca2+]i-transient which favours the view that [Ca2+]i-changes are insignificant for chemotaxis. 相似文献6.
Jijun Huang Min Zhang Peng Zhang He Liang Kunfu Ouyang Huang-Tian Yang 《Purinergic signalling》2016,12(3):465-478
Purinergic signaling mediated by P2 receptors (P2Rs) plays important roles in embryonic and stem cell development. However, how it mediates Ca2+ signals in human embryonic stem cells (hESCs) and derived cardiovascular progenitor cells (CVPCs) remains unclear. Here, we aimed to determine the role of P2Rs in mediating Ca2+ mobilizations of these cells. hESCs were induced to differentiate into CVPCs by our recently established methods. Gene expression of P2Rs and inositol 1,4,5-trisphosphate receptors (IP3Rs) was analyzed by quantitative/RT-PCR. IP3R3 knockdown (KD) or IP3R2 knockout (KO) hESCs were established by shRNA- or TALEN-mediated gene manipulations, respectively. Confocal imaging revealed that Ca2+ responses in CVPCs to ATP and UTP were more sensitive and stronger than those in hESCs. Consistently, the gene expression levels of most P2YRs except P2Y1 were increased in CVPCs. Suramin or PPADS blocked ATP-induced Ca2+ transients in hESCs but only partially inhibited those in CVPCs. Moreover, the P2Y1 receptor-specific antagonist MRS2279 abolished most ATP-induced Ca2+ signals in hESCs but not in CVPCs. P2Y1 receptor-specific agonist MRS2365 induced Ca2+ transients only in hESCs but not in CVPCs. Furthermore, IP3R2KO but not IP3R3KD decreased the proportion of hESCs responding to MRS2365. In contrast, both IP3R2 and IP3R3 contributed to UTP-induced Ca2+ responses while ATP-induced Ca2+ responses were more dependent on IP3R2 in the CVPCs. In conclusion, a predominant role of P2Y1 receptors in hESCs and a transition of P2Y-IP3R coupling in derived CVPCs are responsible for the differential Ca2+ mobilization between these cells. 相似文献
7.
Summary Discrepancies about the role of L-type voltage-gated calcium channels (VGCC) in acetylcholine (ACh)-induced [Ca2+]i oscillations in tracheal smooth muscle cells (TSMCs) have been seen in recent reports. We demonstrate here that ACh-induced
[Ca2+]i oscillations in TMCS were reversibly inhibited by three VGCC blockers, nicardipine, nifedipine and verapamil. Prolonged (several
minutes) application of VGCC blockers, led to tachyphylaxis; that is, [Ca2+]i oscillations resumed, but at a lower frequency. Brief (15–30 s) removal of VGCC blockers re-sensitized [Ca2+]i oscillations to inhibition by the agents. Calcium oscillations tolerant to VGCC blockers were abolished by KB-R7943, an inhibitor
of the reverse mode of Na+/Ca2+ exchanger (NCX). KB-R7943 alone also abolished ACh-induced [Ca2+]i oscillations. Enhancement of the reverse mode of NCX via removing extracellular Na+ reversed inhibition of ACh-induced [Ca2+]i oscillations by VGCC blockers. Inhibition of non-selective cation channels using Gd3+ slightly reduced the frequency of ACh-induced [Ca2+]i oscillations, but did not prevent the occurrence of tachyphylaxis. Altogether, these results suggest that VGCC and the reverse
mode of NCX are two primary Ca2+ entry pathways for maintaining ACh-induced [Ca2+]i oscillations in TSMCs. The two pathways complement each other, and may account for tachyphylaxis of ACh-induced [Ca2+]i oscillations to VGCC blockers. 相似文献
8.
Tomás?Gutiérrez Valentina?Parra Rodrigo?Troncoso Christian?Pennanen Ariel?Contreras-Ferrat César?Vasquez-Trincado Pablo?E?Morales Camila?Lopez-Crisosto Cristian?Sotomayor-Flores Mario?Chiong Beverly?A?Rothermel Sergio?Lavandero
Background
Cardiac hypertrophy is characterized by alterations in both cardiac bioenergetics and insulin sensitivity. Insulin promotes glucose uptake by cardiomyocytes and its use as a substrate for glycolysis and mitochondrial oxidation in order to maintain the high cardiac energy demands. Insulin stimulates Ca2+ release from the endoplasmic reticulum, however, how this translates to changes in mitochondrial metabolism in either healthy or hypertrophic cardiomyocytes is not fully understood.Results
In the present study we investigated insulin-dependent mitochondrial Ca2+ signaling in normal and norepinephrine or insulin like growth factor-1-induced hypertrophic cardiomyocytes. Using mitochondrion-selective Ca2+-fluorescent probes we showed that insulin increases mitochondrial Ca2+ levels. This signal was inhibited by the pharmacological blockade of either the inositol 1,4,5-triphosphate receptor or the mitochondrial Ca2+ uniporter, as well as by siRNA-dependent mitochondrial Ca2+ uniporter knockdown. Norepinephrine-stimulated cardiomyocytes showed a significant decrease in endoplasmic reticulum-mitochondrial contacts compared to either control or insulin like growth factor-1-stimulated cells. This resulted in a reduction in mitochondrial Ca2+ uptake, Akt activation, glucose uptake and oxygen consumption in response to insulin. Blocking mitochondrial Ca2+ uptake was sufficient to mimic the effect of norepinephrine-induced cardiomyocyte hypertrophy on insulin signaling.Conclusions
Mitochondrial Ca2+ uptake is a key event in insulin signaling and metabolism in cardiomyocytes.9.
Gregory D. Tredwell Jacob G. Bundy Maria De Iorio Timothy M. D. Ebbels 《Metabolomics : Official journal of the Metabolomic Society》2016,12(10):152
Introduction
Despite the use of buffering agents the 1H NMR spectra of biofluid samples in metabolic profiling investigations typically suffer from extensive peak frequency shifting between spectra. These chemical shift changes are mainly due to differences in pH and divalent metal ion concentrations between the samples. This frequency shifting results in a correspondence problem: it can be hard to register the same peak as belonging to the same molecule across multiple samples. The problem is especially acute for urine, which can have a wide range of ionic concentrations between different samples.Objectives
To investigate the acid, base and metal ion dependent 1H NMR chemical shift variations and limits of the main metabolites in a complex biological mixture.Methods
Urine samples from five different individuals were collected and pooled, and pre-treated with Chelex-100 ion exchange resin. Urine samples were either treated with either HCl or NaOH, or were supplemented with various concentrations of CaCl2, MgCl2, NaCl or KCl, and their 1H NMR spectra were acquired.Results
Nonlinear fitting was used to derive acid dissociation constants and acid and base chemical shift limits for peaks from 33 identified metabolites. Peak pH titration curves for a further 65 unidentified peaks were also obtained for future reference. Furthermore, the peak variations induced by the main metal ions present in urine, Na+, K+, Ca2+ and Mg2+, were also measured.Conclusion
These data will be a valuable resource for 1H NMR metabolite profiling experiments and for the development of automated metabolite alignment and identification algorithms for 1H NMR spectra.10.
Lysann Wagner Thomas Pannicke Ina Frommherz Katja Sauer Ju Chen Antje Grosche 《Neurochemical research》2016,41(4):677-686
Glial cells in the diseased nervous system undergo a process known as reactive gliosis. Gliosis of retinal Müller glial cells is characterized by an upregulation of glial fibrillary acidic protein and frequently by a reduction of inward K+ current amplitudes. Purinergic signaling is assumed to be involved in gliotic processes. As previously shown, lack of the nucleotide receptor P2Y1 leads to an altered regulation of K+ currents in Müller cells of the ischemic retina. Here, we asked first whether this effect is mediated by the IP3 receptor subtype 2 (IP3R2) known as the major downstream signaling target of P2Y1 in Müller cells. The second question was whether lack of IP3R2 affects neuronal survival in the control and ischemic retina. Ischemia was induced in wild type and IP3R2-deficient (IP 3 R2 ?/?) mice by transient elevation of the intraocular pressure. Immunostaining and TUNEL labelling were used to quantify neuronal cell loss. The downregulation of inward K+ currents in Müller cells from ischemic IP 3 R2 ?/? retinae was less strong than in wild type animals. The reduction of the number of cells in the ganglion cell layer and of calretinin- and calbindin-positive cells 7 days after ischemia was similar in wild type and IP 3 R2 ?/? mice. However, IP3R2 deficiency led to an increased number of TUNEL-positive cells in the outer nuclear layer at 1 day and to an enhanced postischemic loss of photoreceptors 7 days after ischemia. This implies that IP3R2 is involved in some but not all aspects of signaling in Müller cells after an ischemic insult. 相似文献
11.
Yahong An Heng Zhou Min Zhong Jin Sun Sheng Shu Qiaosai Shao Shirong Guo 《Plant cell reports》2016,35(5):1081-1101
Key message
The application of exogenous 24-epibrassinolide promotes Brassinosteroids intracellular signalling in cucumber, which leads to differentially expressed proteins that participate in different life process to relieve Ca(NO 3 ) 2 damage.Abstract
NO3 ? and Ca2+ are the main anion and cation of soil secondary salinization during greenhouse cultivation. Brassinosteroids (BRs), steroidal phytohormones, regulate various important physiological and developmental processes and are used against abiotic stress. A two-dimensional electrophoresis gel coupled with MALDI-TOF/TOF MS was performed to investigate the effects of exogenous 24-epibrassinolide (EBL) on proteomic changes in cucumber seedling roots under Ca(NO3)2 stress. A total of 80 differentially accumulated protein spots in response to stress and/or exogenous EBL were identified and grouped into different categories of biological processes according to Gene Ontology. Under Ca(NO3)2 stress, proteins related to nitrogen metabolism and lignin biosynthesis were induced, while those related to cytoskeleton organization and cell-wall neutral sugar metabolism were inhibited. However, the accumulation of abundant proteins involved in protein modification and degradation, defence mechanisms against antioxidation and detoxification and lignin biosynthesis by exogenous EBL might play important roles in salt tolerance. Real-time quantitative PCR was performed to investigate BR signalling. BR signalling was induced intracellularly under Ca(NO3)2 stress. Exogenous EBL can alleviate the root indices, effectively reduce the Ca2+ content and increase the K+ content in cucumber roots under Ca(NO3)2 stress. This study revealed the differentially expressed proteins and BR signalling-associated mRNAs induced by EBL in cucumber seedling roots under Ca(NO3)2 stress, providing a better understanding of EBL-induced salt resistance in cucumber seedlings. The mechanism for alleviation provides valuable insight into improving Ca(NO3)2 stress tolerance of other horticultural plants.12.
N. B. Matveeva V. A. Teplov S. I. Beylina 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2010,4(1):70-76
In order to elucidate the function of inositol 1,4,5-trisphosphate (IP3)-activated reticular Ca2+ channel (IP3R) in autooscillatory contractile activity of Physarum polycephalum plasmodium, we applied 2-aminoethoxydiphenyl borate (2-APB), a membrane-permeable inhibitor of IP3-induced Ca2+ release. Taking into account that for the type 1 IP3 R the inhibitory efficacy of 2-APB decreases with the rise of the IP3 level [Bilmen, J.G. and Michelangeli, F., Cell Signal., 2002, vol. 14, no. 11, pp. 955–960], 2-APB was applied to plasmodium in normal conditions and after the treatment with glucose
or 3-O-methylglucose, the attractants capable to induce an elevation of the IP3 production. We found that 20–50 μM 2-APB induced a reversible cessation of contractile autooscillations, which occurred in
two different modes: as a fast stop and a gradual damping. The damping of oscillations was accompanied by an increase in their
period, a prolongation of the contraction phase, and, often, by an increase in the mean level of the contraction force. The
number of species responding by the fast stop at a 2-APB concentration of 50 μM was two times greater than at 20 μM 2-APB.
In the presence of the attractants in concentrations of 10 and 50 mM, the fast stop was never observed at 20 μM of 2-APB.
Moreover, the damping of oscillations was preceded by a period of varying duration, when the regular oscillatory mode was
maintained. We conclude that the fast stop results from the direct inter-action of 2-APB with IP3R of Physarum polycephalum plasmodium and that IP3R is indispensable for the plasmodial oscillator. 相似文献
13.
Kota Kera Dennis D. Fine Daniel J. Wherritt Yoshiki Nagashima Norimoto Shimada Takeshi Ara Yoshiyuki Ogata Lloyd W. Sumner Hideyuki Suzuki 《Metabolomics : Official journal of the Metabolomic Society》2018,14(5):71
Introduction
Oxygen from carbon dioxide, water or molecular oxygen, depending on the responsible enzyme, can lead to a large variety of metabolites through chemical modification.Objectives
Pathway-specific labeling using isotopic molecular oxygen (18O2) makes it possible to determine the origin of oxygen atoms in metabolites and the presence of biosynthetic enzymes (e.g., oxygenases). In this study, we established the basis of 18O2-metabolome analysis.Methods
18O2 labeled whole Medicago truncatula seedlings were prepared using 18O2-air and an economical sealed-glass bottle system. Metabolites were analyzed using high-accuracy and high-resolution mass spectrometry. Identification of the metabolite was confirmed by NMR following UHPLC–solid-phase extraction (SPE).Results
A total of 511 peaks labeled by 18O2 from shoot and 343 peaks from root were annotated by untargeted metabolome analysis. Additionally, we identified a new flavonoid, apigenin 4′-O-[2′-O-coumaroyl-glucuronopyranosyl-(1–2)-O-glucuronopyranoside], that was labeled by 18O2. To the best of our knowledge, this is the first report of apigenin 4′-glucuronide in M. truncatula. Using MSn analysis, we estimated that 18O atoms were specifically incorporated in apigenin, the coumaroyl group, and glucuronic acid. For apigenin, an 18O atom was incorporated in the 4′-hydroxy group. Thus, non-specific incorporation of an 18O atom by recycling during one month of labeling is unlikely compared with the more specific oxygenase-catalyzing reaction.Conclusion
Our finding indicated that 18O2 labeling was effective not only for the mining of unknown metabolites which were biosynthesized by oxygenase-related pathway but also for the identification of metabolites whose oxygen atoms were derived from oxygenase activity.14.
Ralph H. Schaloske Dagmar Blaesius Christina Schlatterer Daniel F. Lusche 《Journal of biosciences》2007,32(3):1281-1289
Cyclic AMP (cAMP) is a natural chemoattractant of the social amoeba Dictyostelium discoideum. It is detected by cell surface cAMP receptors. Besides a signalling cascade involving phosphatidylinositol 3,4,5-trisphosphate (PIP3), Ca2+ signalling has been shown to have a major role in chemotaxis. Previously, we have shown that arachidonic acid (AA) induces an increase in the cytosolic Ca2+ concentration by causing the release of Ca2+ from intracellular stores and activating influx of extracellular Ca2+. Here we report that AA is a chemoattractant for D. discoideum cells differentiated for 8–9 h. Motility towards a glass capillary filled with an AA solution was dose-dependent and qualitatively comparable to cAMP-induced chemotaxis. Ca2+ played an important role in AA chemotaxis of wild-type Ax2 as ethyleneglycolbis(b-aminoethyl)-N,N,N′,N′-tetraacetic acid (EGTA) added to the extracellular buffer strongly inhibited motility. In the HM1049 mutant whose iplA gene encoding a putative Ins(1,4,5)P3-receptor had been knocked out, chemotaxis was only slightly affected by EGTA. Chemotaxis in the presence of extracellular Ca2+ was similar in both strains. Unlike cAMP, addition of AA to a cell suspension did not change cAMP or cGMP levels. A model for AA chemotaxis based on the findings in this and previous work is presented. 相似文献
15.
Background
Differentiating Dictyostelium discoideum amoebae respond upon cAMP-stimulation with an increase in the cytosolic free Ca2+ concentration ([Ca2+]i) that is composed of liberation of stored Ca2+ and extracellular Ca2+-influx. In this study we investigated whether intracellular cAMP is involved in the control of [Ca2+]i. 相似文献16.
Background
At fertilisation, mammalian oocytes are activated by oscillations of intracellular Ca2+ ([Ca2+]i). Phospholipase Cζ, which is introduced by fertilising spermatozoon, triggers [Ca2+]i oscillations through the generation of inositol 1,4,5-triphosphate (IP3), which causes Ca2+ release by binding to IP3 receptors located on the endoplasmic reticulum (ER) of the oocyte. Ability to respond to this activating stimulus develops during meiotic maturation of the oocyte. Here we examine how the development of this ability is perturbed when a single spermatozoon is introduced into the oocyte prematurely, i.e. during oocyte maturation.Results
Mouse oocytes during maturation in vitro were fertilised by ICSI (intracytoplasmic sperm injection) 1 – 4 h after germinal vesicle break-down (GVBD) and were subsequently cultured until they reached metaphase II (MII) stage. At MII stage they were fertilised in vitro for the second time (refertilisation). We observed that refertilised oocytes underwent activation with similar frequency as control oocytes, which also went through maturation in vitro, but were fertilised only once at MII stage (87% and 93%, respectively). Refertilised MII oocytes were able to develop [Ca2+]i oscillations in response to penetration by spermatozoa. We found however, that they generated a lower number of transients than control oocytes. We also showed that the oocytes, which were fertilised during maturation had a similar level of MPF activity as control oocytes, which were not subjected to ICSI during maturation, but had reduced level of IP3 receptors.Conclusion
Mouse oocytes, which were experimentally fertilised during maturation retain the ability to generate repetitive [Ca2+]i transients, and to be activated after completion of maturation. 相似文献17.
E. M. Sukhova V. S. Sukhov 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2018,12(2):146-159
A decrease of the plasma membrane H+-ATPase activity in plant cells is associated with the formation of response to adverse factors and reception of signals. A theoretical analysis of the influence of the H+-ATPase activity on the flow of CO2 into a plant cell has been conducted. With this purpose the model of transport processes and electrogenesis in the plant cell developed previously was used, which takes into account transport systems, including H+-ATPase, in the plasma membrane and tonoplast. The CO2 fraction (\({P_{c{o_2}}}\)) in the total amount of inorganic carbon (Ci) in the external medium was used as an indicator of the CO2 amount entering the plant cell; this parameter depends on the extracellular pH, which, in particular, is influenced by the H+-ATPase activity. Excitable and non-excitable cells were simulated. It was shown that a decrease of the H+-ATPase activity causes a \({P_{c{o_2}}}\)reduction in both variants of the model, and this reduction has an extremum: after passing through minimal values, \({P_{c{o_2}}}\)reaches a stationary level. The dynamics of \({P_{c{o_2}}}\)decrease may be related to the Ca2+ influx into the cytoplasm of the plant cell. The reduction of \({P_{c{o_2}}}\)depended on the extent of the H+-ATPase inactivation and on its initial activity. As a whole, it was shown that the inactivation of the H+-ATPase can affect the CO2 uptake in a plant cell and thereby regulate photosynthetic processes. 相似文献
18.
A. S. Efremova V. P. Zinchenko 《Biochemistry (Moscow) Supplemental Series A: Membrane and Cell Biology》2008,2(4):372-379
Previous studies have shown that micromolar concentrations of calmodulin inhibitor calmidazolium induce fast activation of nonselective Ca2+ channels in plasma membranes of Ehrlich ascites carcinoma cells (Zinchenko, V.P., Kasymov, V.A., Li, V.V., and Kaimachnikov, N.P., Biofizika (Rus.), 2005, vol. 50 (6), pp. 1055–1069). In order to detect this type of Ca2+ channels in other cells and to establish common regulatory mechanisms, we studied calmidazolium effects on rat thymocytes. It was found that calmidazolium induces biphasic increases in Ca2+ content in cytosol of rat thymocytes due to Ca2+ entry from external medium and reflects the activity of nonselective Ca2+ channels permeable for Mn2+ and Ni2+ ions. The rate and the amplitude of the fast phase are decreased, while those of the slow phase are increased in the presence of specific inhibitors of Ca2+-independent phospholipase A2 (bromoenol lactone and palmitoyl trifluoromethyl ketone). The rate and the amplitude of the fast phase are also inhibited by arachidonic acid and the lipoxygenase inhibitor nordihydroguaiaretic acid, while the Ca2+-dependent phospholipase A2 inhibitor bromophenacyl bromide, the cyclooxygenase inhibitor indomethacin, the specific store-operated Ca2+ channel inhibitor gadolinium and the phospholipase C inhibitor U73122 have no such effect. The rate of the fast phase only slightly depends on temperature, while that of the slow phase shows a strong temperature dependence and increases with a rise in temperatures (Q 10 = 2). The amplitude of the fast phase of the Ca2+ signal increases with a decrease of temperatures due to prolongation of the maximum activity of the Ca2+ channel. The data obtained suggest that iPLA2 is an intermediate link in the activation of calmidazolium-induced nonselective Ca2+ channels. The iPLA2 products lysophospholipids and arachidonic acid activate and inhibit Ca2+ channels, respectively. The fact that these compounds manifest different affinities for Ca2+ channels shed additional light on the mechanisms of biphasic Ca2+ elevation in thymus cell cytosol and prolongation of the active state of Ca2+ channels at low temperatures. 相似文献
19.
Man Kit Tse Ting Shing Hung Ching Man Chan Tiffany Wong Mike Dorothea Catherine Leclerc Marc Moreau Andrew L. Miller Sarah E. Webb 《中国科学:生命科学英文版》2018,61(11):1352-1368
The development of the CNS in vertebrate embryos involves the generation of different sub-types of neurons and glia in a complex but highly-ordered spatio-temporal manner. Zebrafish are commonly used for exploring the development, plasticity and regeneration of the CNS, and the recent development of reliable protocols for isolating and culturing neural stem/progenitor cells (NSCs/NPCs) from the brain of adult fish now enables the exploration of mechanisms underlying the induction/specification/differentiation of these cells. Here, we refined a protocol to generate proliferating and differentiating neurospheres from the entire brain of adult zebrafish. We demonstrated via RT-qPCR that some isoforms of ip3r, ryr and stim are upregulated/downregulated significantly in differentiating neurospheres, and via immunolabelling that 1,4,5-inositol trisphosphate receptor (IP3R) type-1 and ryanodine receptor (RyR) type-2 are differentially expressed in cells with neuron- or radial glial-like properties. Furthermore, ATP but not caffeine (IP3R and RyR agonists, respectively), induced the generation of Ca2+ transients in cells exhibiting neuron- or glial-like morphology. These results indicate the differential expression of components of the Ca2+-signaling toolkit in proliferating and differentiating cells. Thus, given the complexity of the intact vertebrate brain, neurospheres might be a useful system for exploring neurodegenerative disease diagnosis protocols and drug development using Ca2+ signaling as a read-out. 相似文献
20.