Heat and hyposmotic stimulation increase in [Ca^2＋]i by Ca^2＋ influx in rat synoviocytes

Rheumatoid arthritis （RA）, which is marked by inflammatory synovitis, is a common, chronic autoimmune-disease, whose pathogenesis is complex and still unclear. In order to explore the effects of heat and hyposmotic stimuli on synoviocytes in rheumatoid arthritis, the changes of [Ca^2＋]i induced by heat, hyposmotic and 4α-PDD stimuli were observed in synoviocytes. [Ca^2＋]i elevation induced by heat 28℃, hyposmotic and 4α-PDD stimuli is found to be positively relative to increasing temperature, decreasing osmolality and rising concentration of 4α-PDD. Results show that there is reciprocity among these stimuli and desensitization, and that [Ca^2＋]i elevation depends on Ca^2＋ influx, but not necessarily links to Ca^2＋ release from intracellular stores and voltage-dependent Ca^2＋ channel in synoviocytes. The above characteristics of Ca^2＋ influx are similar to those of TRPV4. A probable mechanism has been suggested that heat and hyposmotic stimulation might increase the level of [Ca^2＋]i by activating the TRPV4-like channel and Ca^2＋ influx in the synoviocytes.     

The new sideway of CNTF signal transduction pathway

The action of ciliary neurotrophic factor (CNTF) on intercellular free Ca²⁺ concentrations [Ca²⁺]_i induced by glutamate (Glu) in primary cultured hippocampal neurons were detected with Fura2/AM, a Ca²⁺-sensitive fluorophore, and the morphological influence of G-protein on it was objected. Glu could induce rapid increase of [Ca²⁺]_i in hippocampal neurons. CNTF had no significant action on [Ca²⁺]_i in resting hippocampal neurons. However, after incubation of CNTF for 5 min, the increase of [Ca²⁺]_i in hippocampal neurons rapidly induced by Glu was inhibited. Pretussis toxin (PTX)-sensitive G protein could block the action. These results indicate that a new non-genomic rapid sideway might exist in the upper stream of CNTF signal transduction pathway, which was related to Ca²⁺ signal transduction. Keywords:     

Action mechanisms of a new erythrocyte-derived depressing factor

To investigate the action mechanisms of a new erythrocyte-derived depressing factor (EDDF), the focus is placed on the effect of EDDF on both cytosolic and nuclear free calcium (Ca²⁺) transportation in vascular smooth muscle cell (VSMC), as well as the apoptosis and cell cycle of VSMC of rats. EDDF has been extracted from human erythrocytes. The changes of Ca²⁺ levels in cytoplasm ([Ca²⁺]_i) and nucleus ([Ca²⁺]_n) have been observed using a laser scanning confocal microscope together with fluo-3/AM as a calcium indicator. Flow cytometric technique was used to study the effect of EDDF on cell cycle and apoptosis of VSMC. [Ca²⁺], and [Ca²⁺]_n were significantly decreased through several different pathways: ( i ) it reduced the Ca²⁺ influx by blocking L-type voltage-dependent calcium channel (L-VDC) and R-type voltage-dependent calcium channel (R-VDC); (ii) it inhibited the Ca²⁺ release from inositol 1, 4, 5-trisphosphate (IP₃) sensitive calcium store; and (iii) activated Ca²⁺-ATPase of sarcoplasmic reticulum (SR) and promoted the transportation of Ca²⁺ from cytoplasm to SR. However, EDDF seemed to have little inhibitory effect on the Ca²⁺ release from ryonodine sensitive calcium pool. It was also found that EDDF (10⁻⁴ g/mL) significantly decreased the proportion of S phase of human umbilical vein (HUV) and inhibited the proliferation of VSMC induced by angiotensin II (Angll, 10⁻⁵ mol/L). The apopotosis did not occur when VSMC was cultured under normal condition. While VSMC apoptosis was induced by Angll (10⁻⁵ mol/L) and EDDF (10⁻⁴ g/mL) seemed to have little effect on it. The inhibitory effect of EDDF on the elevation of [Ca²⁺]_i and [Ca²⁺]_n of VSMC might play an essential role in its action mechanisms and the ways it affects the Ca²⁺ handling of VSMC demonstrate that EDDF was different from other endogenous blood pressure regulators and some known antihypertensive drugs. EDDF could inhibit the proliferation of VSMC, which indicated that it might be beneficial to the prevention and treatment of hypertension and arteriosclerosis.     

Ca2+ signals induced from calcium stores in pancreatic islet β cells

In single rat pancreatic β cells, using fura-2 microfluorometry to measure [Ca²⁺]i response upon different stimuli, the ways of calcium regulation have been studied. When the extracellular calcium concentration was 2.5 mmol/L, either 60 mmol/L KCl, 20 mmol/L D-glucose or 0.1 mmol/L tolbutamide induced increase in [Ca²⁺]i. Such increase in [Ca²⁺]i was absent when the same stimuli were applied under zero extracellular calcium. These results indicate that the increase of [Ca²⁺]i is induced by the activation of voltage-dependent calcium channels in β cells. The manifold forms of [Ca²⁺]i change induced by glucose imply that the effects of glucose are complex. 5 mmol/L caffeine or 5 mmol/L MCh increase the [Ca²⁺]i, which is independent of the external calcium, suggesting that [Ca²⁺]i can be regulated by Ca²⁺ release from not only the IP₃-sensitive but also the ryanodine sensitive calcium stores in β cells. The latency of Ca responses for IP₃ pathway (5 s) is faster than that for ryanodine pathway (30 s). It is concluded that there are multiple calcium stores in rat pancreatic β cells.     

Research at channel level on the effect of LaCl3 on Radish (Raphanus satirus L.) vacuolar membrane

We recorded slow vacuolar (SV-type) channel currents of Radish vacuoles successfully for the first time by using the whole-vacuolar patch-clamp recording mode. SV- type currents would increase and threshold potentials of activation would shift towards more negative values with the increase of concentrations of cytosolic Ca²⁺. When 2.5 mmol/ L LaCl₃ and 4 mmol/L EGTA were added to bath solutions, SV-type currents were suppressed remarkably. Then adding LaCl₃ with different concentrations to pipette solutions, we found that LaCl₃ with higher concentrations (＞4 ´ 10^-7 mol/L) had a strong inhibitory effect on SV-type currents, while LaCl₃ with lower concentrations (≤4 ´ 10^-7 mol/L) promoted channel currents. This promoting effect provides an important basis at channel level for researching further the effects of rare earth on physiological activities of plants and the production-increase effects of rare earth fertilizers on crops.     

Studies on the interaction of DNA and Ru (1,10-phenanthroline)2− (dipyrido[3,2−a:2′,3′−c]phenazine)2+

The interaction of Ru(phen)₂(dppz)²⁺(phen=1,10-phenanthroline,dppz=dipyrido[3,2−1:2′,3′−c]phenazine) and the calfthymus DNA were studied with fluorescence and ultraviolet visible absorption spectroscopy. The ultraviolet visible absorption spectrum of Ru(phen)₂(dppz)²⁺ calfthymus DNA, and their interaction demonstrated that Ru(phen)₂(dppz)²⁺ intercalated into the double helix of DNA via the ligand dppz. Fe(CN)₆ ⁴⁻ and NaCl can not quench the fluorescence of Ru(phen)₂(dppz)²⁺-DNA, which was in agreement with the intercalation mode. Foundation item: Supported by National Natural Science Foundation of China Biography: LING Lian-sheng (1972-), male, PhD, candidate.     

α-LTX and α-LTXN4C induce [Ca2+]i elevation through different mechanisms in pancreatic β cells

α-latrotoxin (α-LTX) is the only neurotoxin from black-widow spider which has secretagogue effects in the vertebrates. It causes massive neurotransmitter and hormone release via two instinct mechanisms after binding with its high-affinity membrane recep…     

Icariin suppresses bone resorption activity of rabbit osteoclasts in vitro

The effect of icariin on the bone resorption activity of rabbit osteoclasts is assessed in vitro. Osteoclasts were isolated from Japanese white rabbits and cultured on plates with a sterilized bone slice in each well. After treatment with icariin at various concentrations, the bone resorption activity of osteoclasts was evaluated by examining pit areas, superoxide anion (·O2-) generation, size and number of actin rings and intracellular calcium concentration [Ca2 ]i. As revealed by these data, icariin elicited continuous decline of [Ca2 ]i, making actin ring constricted and ·O2- generation decreased. These events resulted in smaller and fewer pits which indicate suppressed bone resorption activity of rabbit osteoclasts by icariin.     

H-ATPase in the plasma membrane of Arabidopsis pollen cells is involved in extracellular calmodulin-promoted pollen germination

In this paper, the role of the plasma membrane (PM) H⁺-ATPase in extracellular calmodulin (CaM)-promoted pollen germination and in tube growth of Arabidopsis thaliana was investigated. Pollen germination, pollen tube growth rate, free cytosolic Ca²⁺ concentration ([Ca²⁺]_cyt) and Ca²⁺ channel activity in the PM of pollen cells were measured. In response to fusicoccin or CaM treatment, in vitro pollen germination and pollen tube growth rate, [Ca²⁺]_cyt and activity of a hyperpolarization-activated Ca²⁺-permeable channel increased. Sodium vanadate inhibited the promotion of these parameters by extracellular CaM. The results suggest that H⁺-ATPase may be involved in extracellular CaM-regulated pollen germination and in tube growth by modulation of the hyperpolarization-activated Ca²⁺ channel in the PM of A. thaliana pollen cells.     

Nitric oxide suppresses stomatal opening by inhibiting inward-rectifying K<Stack><Subscript>in</Subscript><Superscript>+</Superscript></Stack> channels in <Emphasis Type="Italic">Arabidopsis</Emphasis> guard cells

We explore nitric oxide （NO） effect on K^＋in, channels in Arabidopsis guard cells. We observed NO inhibited K^＋in, currents when Ca^2＋ chelator EGTA （Ethylene glycol-bis（2-aminoethylether）-N,N,N′,N;tetraacetic acid） was not added in the pipette solution; K^＋in currents were not sensitive to NO when cytosolic Ca^2＋ was chelated by EGTA. NO inhibited the Arabidopsis stomatal opening, but when EGTA was added in the bath solution, inhibition effect of NO on stomatal opening vanished. Thus, it implies that NO elevates cytosolic Ca^2＋ by activating plasma membrane Ca^2＋ channels firstly, then inactivates K^＋in, chartnels, resulting in stomatal opening suppressed subsequently.     

The seasonal variations of δ~(18)O , Cl~- , Na~+ , NO_3~- and Ca~(2+) in the snow and firn recovered from Princess Elizabeth Land, Antarctica

Snow and firn samples recovered from two snow pits (2.5 and 4.5m deep) and one 50-m firn core along the route of the 1996/1997 Chinese First Antarctic Inland Traverse Expedition in Princess Elizabeth Land, East Antarctica, have been measured for chemical composition and oxygen isotope ratio. In the two snow pits, the variations of NO3- are partly in phase with that of δ18O, while the variations of Cl~ and Na+ are in inverse phase with that of δ18O. The variations of CI- , Na+ , NO3- and δ18O show obvious seasonal variations and annual stratag-raphy. However, with the depth increasing, the seasonal variations of δ18O are gradually smoothed below 3 m (corresponding to about 10-year mass accumulation) in depth while the seasonal variations of Cl- , Na+ and NO3- are kept fairly well in the whole profile of the 50-m firn core (corresponding to about 250-year mass accumulation). The results provide a useful tool for dating the snow stratum in this region. On the contrary, no obvious seasonal variations of Ca2 + are found in the profiles.     

Degradation of 2, 4-D acid using Mn2+ as catalyst under UV irradiation

In this paper, the oxidative degradation of 2, 4-dichlorophenoxyacetic acid (2, 4-D) using Mn²⁺/H₂O₂ reagent under UV irradiation was studied. The results show that 2, 4-D was degraded more completely in Mn²⁺/H₂O₂ solution than traditional Fenton solutions. The effects of the concentration of Mn²⁺, H₂O₂ and pH were also investigated. And under the optimal condition of 1.48×10⁻⁴ mol/L, 8.99×10⁻⁵ mol/L and pH 3.38, the formation of ·OH was the most, both the decomposition rate of H₂O₂ and the degradation rate of 2, 4-D were the fastest. In addition, the photoreaction process was monitored using spin-trapping electron paramagnetic resonance (EPR), and the results indicated that the oxidative process was predominated mainly by the hydroxyl radical (·OH) gennerated in the system. Biography: HUANG Yingping (1964–), Professor, Ph. D., research direction: pollution ecology and water pollution control.     

Kinetics of C2(a3Πu) radical reactions with NO, N2O, O2, H2 and NH3

Pulsed laser photolysis/laser-induced fluorescence (LP-LIF) is utilized to measure rate constants for C₂(a³Π_u) reactions with NO, N₂O, O₂, H₂ and NH₃. Multiphoton dissociation of C₂Cl₄ at 266 nm is employed for the generation of C₂(a³Π_u) radicals. The C₂(a³Π_u) concentration is monitored by the fluorescence of the (0, 0) band of the (d³Π_g&#8596;a³Π_u) transition at 516.5 nm. C₂(a³Π_u) removal rate constants for the reactions are determined as k_NO = (5.46 ± 0.10) × 10^-11 cm³ molecule^-1 s^-1 , k_N2O = (1.63 ± 0.20) × 10^-13 cm³ molecule^-1 s^-1 , k_N2O = (1.58 ± 0.16) × 10^-11 cm³ molecule^-1 s^-1, k_O2 = (5.92 ± 1.00) × 10^-14 cm³ molecule^-1 s^-1, k_H2< 1.0× 10^-14 cm³ molecule^-1 s^-1. Based on the data analysis and theoretical calculation, we suggest that the C₂(a³Π_u) reactions with H₂ and NH₃ proceed via the hydrogen abstraction mechanism, barriers exist at the entrance channel of the reactions of C₂(a³Π_u) with H₂ and NH₃.     

Kinetic studies of the decomposition reaction of adducts of dinuclear Fe(Ⅱ)/O2

Kinetic studies of the decomposition reaction of dinuclear Fe(Ⅱ) adducts [Fe₂(N-Et-HPTB){O₂P(OPh)₂}](Cl- O₄)₂ (1) and [Fe₂(N-Et-HPTB) {O₂P(Ph)₂}] (ClO₄)₂ (2) with O₂ have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe(Ⅱ)/O₂ adducts was first-order in the experimental conditions, and the activation parameters were obtained. ?H^¹ = 85.62 kJ·mol^-1, ?S¹ = 19.43 J·mol^-1·K^-1 for compound (1) and ?H^¹ = 97.97 kJ·mol^-1, ?S^¹ = 55.68 J·mol^-1·K^-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane mono- oxygenase (MMOH).     

A Novel Degradation Pathway of Zn（dmid） （ phen）2 in Pyridine

The light-oxidation degradation processes of Zn(dmid)(phen)2(dmid = 4, 5-dimercapto-1,3-dithiole-2 one, phen = 1,10-phenanthroaline) in pyridine solvent has been monitored, h has been found under the light, dmid^2- of Zn(dmid)(phen)2 in pyridine solution could generate NCS^- and NCS^-replaces dmid^2- to form Zn(NCS)2 (phen)2 simultaneously. The crystal structure of Zn(NCS)2 (phen)2 has been determined. In the crystal of Zn(NCS)2 (phen)2. two NCS^- ligands are arranged in syn-configuration, and there is strong π-π interaction between the two adjacent parallel phen.     

Potash-rich volcanic rocks and lamprophyres in western Shandong Province: 40Ar-39Ar dating and source tracing

Highly precise ⁴⁰Ar-³⁹Ar dating results demonstrate that the ages of potash-rich volcanic rocks in western Shandong Province are 114.7–124.3 Ma, and that of the lamprophyres is 119.6 Ma. The potash-rich volcanic rocks have relatively high (⁸⁷Sr÷⁸⁶Sr)_i ratios (0.708715–0.711418) and distinctly negative ε_nd values (−11.47–−17.54), and are enriched in radiogenic lead (²⁰⁶Pb÷²⁰⁴Pb=17.341−17.622, ²⁰⁷Pb÷²⁰⁴Pb=15.525−15.538, ²⁰⁸Pb÷²⁰⁴Pb = 37.563−37.684). Similarly, the lamprophyres also have quite low ε_nd values (−11.57–−19.64). Based on the fact that the Sr, Nd and Pb isotopic compositions of potash-rich volcanic rocks are very consistent with that of the clinopyroxene separates, and by integrating comprehensive analyses of their tectonic settings, and extensive comparisons of the Sr, Nd isotopic compositions with that of the related simultaneous rocks, it is concluded that the potash-rich volcanic rocks and lamprophyres in western Shandong Province were most possibly derived from the partial melting of enriched mantle which was caused by source contamination and metasomatism of subducted continental crustal materials.     

Direct electrochemistry and electrocatalysis of horseradish peroxidase in MnO2 nanosheet film

A novel material MnO2 nanosheet has been used as the support matrix for the immobilization of horseradish peroxidase （HRP）. HRP entrapped in MnO2 nanosheet film exhibits facile direct electron transfer with the electron transfer rate constant of 6.86 s^-1. The HRP/MnO2 nanosheet film gives a reversible redox couple with the apparent formal peak potential （E^0＇） of -0.315 V （vs. Ag/AgCl） in pH 6.5 phosphate buffer solution （PBS）. The formal potential E^0＇ of HRP shifts linearly with pH with a slope of -53.75 mV.pH^-1, denoting that an electron transfer accompanies single-proton transportation. The immobilized HRP shows an electrocatslytic activity to the reduction of H2O2. The response time of the biosensor for H2O2 is less than 3 s, and the detection limit is 0.21 μmol · L^-1 based on signal/noise = 3.     

Laser cooling using anti-stokes fluorescence in Yb3+-doped fluorozirconate glasses

The fluorozirconate glasses ZBLANP (ZrF₄−BaF₂−LaF₃−NaF−PbF₂) doped with different Yb³⁺ concentration were prepared. The Raman spectra and absorption spectra are measured to substantiate the existence of phonon-assisted emission. After analyzing the normalized absorption spectra of samples with different Yb³⁺-doped concentration, we calculated the maximum cooling effect in the 3 wt% Yb³⁺-doped sample pumped at 1 012.5 nm. The corresponding cooling capability is about −4.09 °C/W and the cooling efficiency reaches 1.76%. Foundation item: Supported by the Key Science Foundation of Wuhan (9601P0223) Biography: Xu Tian-ming (1978-), female, Master candidate, research direction: information optics and nonlinear optics.     

Separation and analysis of the soluble trimer of Aβ1-40 and its effects on the rise in intracellular calcium

Alzheimer’s disease (AD) is one of the progressive neurodegenerative diseases associated with protein conformational transition, generally known as protein conformational disorders[1]. The general characteriza- tions of AD are the intracellular fibrillar…