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1.
The expression of the types of tachykinin receptors in the dorsal root ganglion (DRG) neurons by means ofXenopus oocyte expressing system was studied. Poly(A)+ RNAs were extracted from cat cervical and lumbar DRG. Two days after injection of Poly (A)+ RNAs, the oocytes were recorded with the two-electrode voltage clamp technique. In the oocytes injected with DRG poly(A)+ RNA, [Sar9, Met(O2)11]-substance P(Sar -SP, 1 μmol/L), neurokinin A (NKA, 1 μmol/L) or [β-Ala8]-neurokinin A(4?10) (Ala-NKA, 1 μmol/L) produced an inward current comprising a rapid spike and a long sustained oscillatory component for several minutes. Sar-SP induced response was blocked by NK-1 antagonist L-668, 169 (1 μmol/L), but not by NK-2 antagonist L-659, 877(1μmol/L). In contrast, Ala-NKA and NKA responses were only blocked by L-659, 877. The oocytes injected with DH Poly(A)+RNA also responded to Sar-SP and NKA with similar inward currents, which were selectively blocked by L-668, 169 and L-659, 877, respectively. These tachykinins-induced responses had a potent desensitization. The present data indicate expression of NK-1 and NK-2 receptors in DRG neurons, suggesting that there may be tachykinin autoreceptors on the nociceptive primary afferent terminals. 相似文献
2.
本文用Fos作为背角伤害性反应神经元活动的一个标志物,结合免疫细胞化学和神经药理学方法,观察了速激肽受体拮抗剂对福尔马林诱发的脊髓c-fos原癌基因表达的影响。一侧大鼠后肢跖部皮下注射福尔马林,仅在同侧脊髓背角有c-fos表达。Fos阳性神经元最密集分布于I层和Ⅱ层背侧的内侧部,中等量分布于Ⅳ层和V型,少量定位于Ⅱ层腹侧部、Ⅲ、Ⅵ和Ⅹ层。若预先在一侧大鼠后肢跖部皮下注射福尔马林前,鞘内给予神经激肽 相似文献
3.
中国科学 《中国科学:生命科学英文版》2000,43(6):655-662
Using nystatin-perforated whole-cell recording configuration, the modulatory effect of N-methyl-D-aspartate (NMDA) on γ-aminobutyric
acid (GABA)-activated whole-cell currents was investigated in neurons freshly dissociated from the rat sacral dorsal commissural
nucleus (SDCN). The results showed that: (i) NMDA suppressed GABA-and muscimol (Mus)-activated currents (Igaba and IMus), respectively in the Mg2+-free external solution containing 1 μmol/L glycine at a holding potential (V
H
) of −40 mV in SDCN neurons. The selective NMDA receptor antagonist, D-2-amino-5-phosphonovaleric acid (APV, 100 γmol/L),
inhibited the NMDA-evoked currents and blocked the NMDA-induced suppression of Igaba; (ii) when the neurons were incubated in a Ca2+-free bath or pre-loaded with a membrane-permeable Ca2+ chelator, BAPTA AM (10 μmol/L), the inhibitory effect of NMDA on IGAba disappeared. Cd2+ (10 μmol/L) or La3+ (30 μmol/L), the non-selective blockers of voltage-dependent calcium channels, did not affect the suppression of Igaba by NMDA application; (iii) the suppression of IGAba by NMDA was inhibited by KN-62, a calcium/calmodulin-dependent protein kinase II (CaMKII) inhibitor. These results indicated
that the inhibition of GABA response by NMDA is Ca2+-dependent and CaMKII is involved in the process of the Ca2+-dependent inhibition. 相似文献
4.
5.
Vatsouria A Vainshtein M Kuschk P Wiessner A D K Kaestner M 《Journal of industrial microbiology & biotechnology》2005,32(9):409-414
Industrial wastewater is often polluted by Cr(VI) compounds, presenting a serious environmental problem. This study addresses
the removal of toxic, mutagenic Cr(VI) by means of microbial reduction to Cr(III), which can then be precipitated as oxides
or hydroxides and extracted from the aquatic system. A strain of Staphylococcus epidermidis L-02 was isolated from a bacterial consortium used for the remediation of a chromate-contaminated constructed wetland system.
This strain reduced Cr(VI) by using pyruvate as an electron donor under anaerobic conditions. The aims of the present study
were to investigate the specific rate of Cr(VI) reduction by the strain L-02, the effects of chromate and nitrate (available
as electron acceptors) on the strain, and the interference of chromate and nitrate reduction processes. The presence of Cr(VI)
decreased the growth rate of the bacterium. Chromate and nitrate reduction did not occur under sterile conditions but was
observed during tests with the strain L-02. The presence of nitrate increased both the specific Cr(VI) reduction rate and
the cell number. Under denitrifying conditions, Cr(VI) reduction was not inhibited by nitrite, which was produced during nitrate
reduction. The average specific rate of chromate reduction reached 4.4 μmol Cr 1010 cells−1 h−1, but was only 2.0 μmol Cr 1010 cells−1 h−1 at 20 °C. The maximum specific rate was as high as 8.8–9.8 μmol Cr 1010 cells−1 h−1. The role of nitrate in chromate reduction is discussed. 相似文献
6.
The experiments were perfomed on transvcrsus abdominis muscle of Elaphe dione by subendothelial recording. The results indicate that in snake motor nerve endings there exist four types of K* channels, i.e. voltage-dependent fast and slow K channels, Ca2 -activated K channel and ATP-sensitive K channel, (i) The typical wave form of snake terminal current was the double-peaked negativity in standard solution. The first peak was at-tributed to Na influx (INa) in nodes of Ranvier. The second one was blocked by 3, 4-aminopyridine (3, 4-DAP) or te-traethylammonium (TEA), which corresponded to fast K outward current (IKF) through the fast K* channels in terminal part, (ii) After IKF as well as the slow K current (IKS) were blocked by 3, 4-DAP, the TEA-sensitive Ca2 -dependent K current (IK(Ca)) passing through Ca2 -activated K channel was revealed, whose amplitude depended on [K ]and [Ca2 ] It was blocked by Ba2 , Cd2 or Co2 . (iii) IK.F and IK(Ca) were blocked by TEA, while IK.S was retained. It 相似文献
7.
The effects of phosphorus, Zn2+, CO2, and light intensity on growth, biochemical composition, and the activity of extracellular carbonic anhydrase (CA) in Isochrysis galbana were investigated. A significant change was observed when the concentration of phosphorus in the medium was increased from
5 μmol/L to 1000 μmol/L affecting I. galbana’s cell density, biochemical composition, and the activity of extracellular CA. Phosphorous concentration of 50 μmol/L to 500
μmol/L was optimal for this microalgae. The Zn2+ concentration at 10 μmol/L was essential to maintain optimal growth of the cells, but a higher concentration of Zn2+ (≥ 1000 μmol/L) inhibited the growth of I. galbana. High CO2 concentrations (43.75 mL/L) significantly increased the cell densities compared to low CO2 concentrations (0.35 mL/L). However, the activity of extracellular CA decreased significantly with an increasing concentration
of CO2. The activity of extracellular CA at a CO2 concentration of 43.75 mL/L was approximately 1/6 of the activity when the CO2 concentration was at 0.35 mL/L CO2. Light intensity from 4.0 mW/cm2 to 5.6 mW/cm2 was beneficial for the growth, biochemical composition and the activity of extracellular CA. The lower and higher light intensity
was restrictive for growth and changed its biochemical composition and the activity of extracellular CA. These results indicate
that phosphorus, Zn2+, CO2, and light intensity are important factors that impact growth, biochemical composition and the activity of extracellular
CA in I. galbana. 相似文献
8.
The concept of using higher plants to maintain a sustainable life support system for humans during long-duration space missions is dependent upon photosynthesis. The effects of extended exposure to microgravity on the development and functioning of photosynthesis at the leaf and stand levels were examined onboard the International Space Station (ISS). The PESTO (Photosynthesis Experiment Systems Testing and Operations) experiment was the first long-term replicated test to obtain direct measurements of canopy photosynthesis from space under well-controlled conditions. The PESTO experiment consisted of a series of 21–24 day growth cycles of Triticum aestivum L. cv. USU Apogee onboard ISS. Single leaf measurements showed no differences in photosynthetic activity at the moderate (up to 600 μmol m−2 s−1) light levels, but reductions in whole chain electron transport, PSII, and PSI activities were measured under saturating light (>2,000 μmol m−2 s−1) and CO2 (4000 μmol mol−1) conditions in the microgravity-grown plants. Canopy level photosynthetic rates of plants developing in microgravity at ∼280 μmol m−2 s−1 were not different from ground controls. The wheat canopy had apparently adapted to the microgravity environment since the CO2 compensation (121 vs. 118 μmol mol−1) and PPF compensation (85 vs. 81 μmol m−2 s−1) of the flight and ground treatments were similar. The reduction in whole chain electron transport (13%), PSII (13%), and PSI (16%) activities observed under saturating light conditions suggests that microgravity-induced responses at the canopy level may occur at higher PPF intensity. 相似文献
9.
Kedzierska K Bober J Ciechanowski K Gołembiewska E Kwiatkowska E Noceń I Dołegowska B Dutkiewicz G Chlubek D 《Biological trace element research》2005,107(1):21-32
The aim of the study was to verify the hypothesis if copper could influence the activity of sodium-transporting systems in
erythrocyte membrane that could be related to essential hypertension. The examined group of patients consisted of 15 men with
hypertension. The control group was 11 healthy male volunteers. The Na+/H+ exchanger (NHE) activity in erythrocytes was determined according to Orlov et al. The activity of transporting systems (ATP-Na+/K+; co-Na+/K+/Cl−; ex-Na+/Li+; free Na+ and K+ outflow [Na+, K+-outflow]) was determined according to Garay's method. The concentration of copper in plasma was assessed using atomic absorption
spectrometry. The activity of ATP-Na+/K+ (μmol/L red blood cells [RBCs]/h) in hypertensive patients was 2231.5±657.6 vs 1750.5±291 in the control (p<0.05), the activity of co-Na+/K+/Cl− (μmol/L RBCs/h) in hypertensives was 171.3±77.9 vs 150.7±53.9 in the control (NS). Na+-outflow (μmol/L RBCs/h) in hypertensives was 118.3±51.6 vs 113.3±24.4 in the control (NS). The K+-outflow (μmol/L RBCs/h) in hypertensives was 1361.7±545.4 vs 1035.6±188.3 in the control (NS). The activity of ex-Na+/Li+ (μmol/L RBCs/h) in hypertensive patients was 266.1±76.1 vs 204.1±71.6 in the control (p<0.05). NHE activity (mmol/L RBCs/h) in hypertensives was 9.7±2.96 vs 7.7±1.33 in the control (p<0.05). In hypertensive patients, negative correlation was found between the activity of Na+/K+/Cl− co-transport and plasma copper concentration (R
s=−0.579, p <0.05) and between the activity of ex-Na+/Li+ and plasma copper concentration (R
s=−0.508, p<0.05). Plasma copper concentration significantly influences the activity of sodium transporting systems in erythrocyte membrane.
Copper supplementation could be expected to provide therapeutic benefits for hypertensive patients. 相似文献
10.
We tested radioactive methylammonium (14CH3NH
inf3
sup+
) as a tracer for ammonium (NH4
+) in root uptake measurements from soil. Tomato (Lycopersicon esculentum Moll. cv T5) in 3 L pots filled with loamy sand soil received 40, 200, or 600 μmol 14CH3NH3
+ or 15NH4
+. During a 4 h period, the plants absorbed 14CH3NH3
+ at slower rates than 15NH4
+. Estimates of NH4
+ absorption based on 15NH4
+ absorption were 0.9–7.9 μmol NH4
+ g−1 plant dry weight h−1, whereas those based on 14CH3NH3
+ absorption were 0.2–1.0 μmol NH4
+ g−1 plant dry weight h−1. After 4 h, approximately one-half of the applied 15N was not recovered in the plants or soil KCl extracts; apparently, this 15N was either immobilized or nitrified and denitrified by soil biota. By contrast, almost all the 14CH3NH3
+ remained in the soil solution after 4 h, but after a 10 d incubation, approximately 20% had been released as 14CO2. These differences in plant absorption rates and movement through soil pools indicate that CH3NH3
+ cannot be used reliably as an NH4
+ analog in soil. 相似文献
11.
Adam M. Dimech Rob Cross Rebecca Ford Paul W. J. Taylor 《Plant Cell, Tissue and Organ Culture》2007,88(2):157-165
The physiological effects of three auxins [indole-3-butyric acid (IBA), α-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic
acid (2,4-d)] and two cytokinins [thidiazuron (TDZ) and N6-benzylaminopurine (NAA)] on in vitro morphogenesis of Doryanthes excelsa were measured. Longitudinal bud sections derived from immature inflorescences were used as a source of explants. Callus regeneration
was observed at the highest frequencies (46.2%) when grown on media containing 50 μmol L-1 NAA and 0.5 μmol L−1 TDZ. Adventitious shoot organogenesis was observed at the highest frequency (56.8%) when grown on media containing 0.5 μmol L−1 NAA and 50 μmol L−1 TDZ. Regenerated shoots were rooted ex vitro after 6 weeks when dipped in a solution of 50 μmol L−1 NAA or no plant growth regulators were applied. 相似文献
12.
The tachykinins, substance P (SP) and neurokinin A (NKA), are agonists for the NK1 and NK2 receptors, respectively. Tachykinins have various respiratory effects, including bronchoconstriction. This study characterizes
tachykinin binding sites in the rabbit lung. We hypothesize that (2-[125I]iodohistidyl1)Neurokinin A ([125I]NKA) interacts with NK1 and NK2 binding sites in the rabbit lung. The Kd determined from saturation isotherms was 0.69 X/÷1.14 nM (geometic mean X/÷ SEM) and the Bmax was 4.15±0.22 femtomole/mg protein (arithmetic mean±SEM). Competitive inhibition studies with NKA, SP and various selective
tachykinin agonists showed the rank order of potency: [β-Ala8]-Neurokinin A 4–10=SP ≫ NKA ≫ [Sar9,Met(O2)11]-Substance P. [β-Ala8]-Neurokinin A 4–10, a selective NK2 agonist, and SP inhibition of [125I]NKA binding were best described using a two-site model. Competitive inhibition studies using the selective nonpeptide NK2 antagonist (SR 48968) and the selective nonpeptide NK1 antagonist (CP 96,345) revealed Ki's of 5.5 nM and 8.1 nM, respectively. Our data therefore suggest that [125I]NKA binds to both the NK1 and NK2 receptors in the lung.
Special issue dedicated to Dr. Kinya Kuriyama. 相似文献
13.
Light irradiation had remarkable effects on callus growth of Oldenlandia affinis with an optimum intensity of 35 μmol m−2 s−1. Biosynthesis of kalata B1, the main cyclic peptide in O. affinis, was induced and triggered with rising irradiation intensities. The highest concentration of kalata B1, 0.49 mg g−1 DW characterised by the maximum productivity of 3.88 μg per litre and day was analysed at 120 μmol m−2 s−1, although callus growth was repressed. The light saturation point was established to be 35 μmol m−2 s−1, where kalata B1 productivity was in a similar order (3.41 μg per day) due to the higher growth index. O. affinis suspension cultures were shown to accumulate comparable specific kalata B1 concentrations in a delayed growth associated
production pattern. These were dependent on irradiation intensity (0.16 mg g−1 at 2 μmol m−2 s−1; 0.28 mg g−1 at 35 μmol m−2 s−1). The batch cultivation process resulted in a maximum productivity of 27.30 μg per litre and day with culture doubling times
of 1.16 d−1. Submers operation represented a 8-fold product enhancement compared to callus cultivation. 相似文献
14.
Several calcium-dependent protein kinases (CDPKs) are located in plant plasma membranes where they phosphorylate enzymes and transporters, like the H+-ATPase and water channels, thereby regulating their activities. In order to determine which kinases phosphorylate the H+-ATPase, a calcium-dependent kinase was purified from beetroot (Beta vulgaris L.) plasma membranes by anion-exchange chromatography, centrifugation in glycerol gradients and hydrophobic interaction chromatography. The kinetic parameters of this kinase were determined (V
max: 3.5 μmol mg−1 min−1, K
m
for ATP: 67 μM, K
m
for syntide 2: 15 μM). The kinase showed an optimum pH of 6.8 and a marked dependence on low-micromolar Ca2+ concentrations (K
d
: 0.77 μM). During the purification procedure, a 63-kDa protein with an isoelectric point of 4.7 was enriched. However, this protein was shown not to be a kinase by mass spectrometry. Kinase activity gels showed that a 50-kDa protein could be responsible for most of the activity in purified kinase preparations. This protein was confirmed to be a CDPK by mass spectrometry, possibly the red beet ortholog of rice CDPK2 and Arabidopsis thaliana CPK9, both found associated with membranes. This kinase was able to phosphorylate purified H+-ATPase in a Ca2+-dependent manner.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at . 相似文献
15.
Photosynthetic Response of Carrots to Varying Irradiances 总被引:7,自引:3,他引:4
Response to irradiance of leaf net photosynthetic rates (P
N) of four carrot cultivars: Cascade, Caro Choice (CC), Oranza, and Red Core Chantenay (RCC) were examined in a controlled
environment. Gas exchange measurements were conducted at photosynthetic active radiation (PAR) from 100 to 1 000 μmol m−2 s−1 at 20 °C and 350 μmol (CO2) mol−1(air). The values of P
N were fitted to a rectangular hyperbolic nonlinear regression model. P
N for all cultivars increased similarly with increasing PAR but Cascade and Oranza generally had higher P
N than CC. None of the cultivars reached saturation at 1 000 μmol m−2 s−1. The predicted P
N at saturation (P
Nmax) for Cascade, CC, Oranza, and RCC were 19.78, 16.40, 19.79, and 18.11 μmol (CO2) m−2 s−1, respectively. The compensation irradiance (I
c) occurred at 54 μmol m−2 s−1 for Cascade, 36 μmol m−2 s−1 for CC, 45 μmol m−2 s−1 for Oranza, and 25 μmol m−2 s−1 for RCC. The quantum yield among the cultivars ranged between 0.057–0.033 mol(CO2) mol−1(PAR) and did not differ. Dark respiration varied from 2.66 μmol m−2 s−1 for Cascade to 0.85 μmol m−2 s−1 for RCC. As P
N increased with PAR, intercellular CO2 decreased in a non-linear manner. Increasing PAR increased stomatal conductance and transpiration rate to a peak between
600 and 800 μmol m−2 s−1 followed by a steep decline resulting in sharp increases in water use efficiency.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
16.
Mohammad K. Khalesi H. H. Beeftink R. H. Wijffels 《Marine biotechnology (New York, N.Y.)》2009,11(4):488-494
The branching zooxanthellate soft coral Sinularia flexibillis releases antimicrobial and toxic compounds with potential pharmaceutical importance. As photosynthesis by the symbiotic algae
is vital to the host, the light-dependency of the coral, including its specific growth rate (μ day−1) and the physiological response to a range of light intensities (10–1,000 μmol quanta m−2 s−1) was studied for 12 weeks. Although a range of irradiances from 100 to 400 μmol quanta m−2 s−1 was favorable for S. flexibilis, based on chlorophyll content, a light intensity around 100 μmol quanta m−2 s−1 was found to be optimal. The contents of both zooxanthellae and chlorophyll a were highest at 100 μmol quanta m−2 s−1. The specific budding rate showed almost the same pattern as the specific growth rate. The concentration of the terpene flexibilide,
produced by this species, increased at high light intensities (200–600 μmol quanta m−2 s−1). 相似文献
17.
Ganka Chaneva Sevdalina Furnadzhieva Kaledona Minkova Jaromir Lukavsky 《Journal of applied phycology》2007,19(5):537-544
The effect of light intensity (50–300 μmol photons m−2 s−1) and temperature (15–50°C) on chlorophyll a, carotenoid and phycobiliprotein content in Arthronema africanum biomass was studied. Maximum growth rate was measured at 300 μmol photons m−2 s−1 and 36°C after 96 h of cultivation. The chlorophyll a content increased along with the increase in light intensity and temperature and reached 2.4% of dry weight at 150 μmol photons
m−2 s−1 and 36°C, but it decreased at higher temperatures. The level of carotenoids did not change significantly under temperature
changes at illumination of 50 and 100 μmol photons m−2 s−1. Carotenoids were about 1% of the dry weight at higher light intensities: 150 and 300 μmol photons m−2 s−1. Arthronema africanum contained C-phycocyanin and allophycocyanin but no phycoerythrin. The total phycobiliprotein content was extremely high,
more than 30% of the dry algal biomass, thus the cyanobacterium could be deemed an alternative producer of C-phycocyanin.
A highest total of phycobiliproteins was reached at light intensity of 150 μmol photons m−2 s−1 and temperature of 36°C, C-phycocyanin and allophycocyanin amounting, respectively, to 23% and 12% of the dry algal biomass.
Extremely low (<15°C) and high temperatures (>47°C) decreased phycobiliprotein content regardless of light intensity. 相似文献
18.
R. Cermak A. Evelgünne C. Lawnitzak E. Scharrer 《The Journal of membrane biology》1999,171(3):235-243
The Ussing chamber technique was used to measure unidirectional Rb+ fluxes under short-circuit conditions across tissue sheets from proximal, central, and distal jejunum of rats.
Whereas the proximal and central parts of the jejunum did not show any net transport of Rb+, there was a net secretion of around 0.2 μmol hr−1 cm−2 in the distal segment. This secretion could not be influenced significantly by mucosal application of K+ channel blockers such as Ba2+ (5 mm), tetraethylammonium (20 mm) or quinine (1 mm). Serosal ouabain (1 mm) blocked net secretion by increasing mucoserosal flux. Blockers of H+/K+ ATPases could not alter net fluxes of Rb+. Stimulation of Cl− secretion by forskolin (10 μm) or of Na+ absorption by serine (10 mm) failed to influence the observed secretion of Rb+. Adrenaline (10 μm) also had no effect on Rb+ fluxes. Blocking Na+/H+ exchange by 5-(N-Ethyl-N-isopropyl)-amilorid (100 μm) blocked net secretion by increasing mucoserosal flux, as did the addition of Na+ acetate (30 mm) to the mucosal solution.
We conclude that the distal jejunum of the rat secretes K+ under short-circuit conditions. This secretion does not seem to occur via K+ channels, but through a pH dependent mechanism.
Received: 16 February 1999/Revised: 29 June 1999 相似文献
19.
Murray T. Brown 《Journal of applied phycology》1995,7(4):427-432
Using vegetative propagules (ramuli) of the iota carrageenan producing red seaweed Solieria chordalis, a maximum growth rate of 6.8% d−1 was achieved when cultured at 20 °C and 100 μmol photon m−2 s−1 in seawater supplemented with 20 μM NO3-N or 10 μM NO3-N plus 10 μM NH4-N. Ramuli grew less well when nitrogen was supplied solely as NH
4
+
. Maximum carrageenan content was observed at the same temperature, irradiance and salinity as growth, but at lower nitrogen
concentrations. These findings are discussed in relation to results obtained from studies on other iota-carrageenan producing
carrageenophytes. 相似文献
20.
The effects of temperature (20, 24 and 28 °C) and irradiance (15 and 40 μmol photon m−2 s−1) on the nitrate and ammonium uptake rates of the subtropical red alga, Laurencia brongniartii, were investigated to prepare for tank cultivation. Nitrate uptake followed saturation kinetics and was faster at higher
irradiances and temperatures. In contrast, ammonium uptake was linear over the experimental range and was not affected by
an increase in temperature. A parameter, β, was calculated to compare substrate uptake rates of nitrate along the linear portion
of the uptake curve with that of ammonium. For nitrate, β was lower at low irradiance and higher at high irradiance (β = 0.007
± 0.003 and 0.030 ± 0.002 [μmol N L−1 (μmol N gww−1 d−)−1], respectively). However, β was 0.023 ± 0.002 and 0.034 ± 0.002 [μmol N L−1 (μmol N gww−1 d−1)−1] for ammonium, suggesting a preference for ammonium over nitrate. 相似文献