共查询到20条相似文献,搜索用时 15 毫秒
1.
Suzuki Masaharu; Koide Yasuhiro; Hattori Tsukaho; Nakamura Kenzo; Asahi Tadashi 《Plant & cell physiology》1995,36(6):1067-1074
Deletion analysis of the promoter region of a gene for catalase,cat2, from castor bean (Ricinus communis) was performed to identifythe cis-regulatory elements responsible for the expression ofa rß-glucuronidase (GUS) fusion gene during seed formationand postembryonic development in transgenic tobacco. The analysisshowed that multiple cis-elements contribute to the activityof the cat2 promoter during seed formation and postembryonicdevelopment. The 5'-upstream regions from 1,241 to 816bp, from 720 to 682 bp, and from 632 to535 bp, relative to the site of initiation of translationof cat2, contributed positively to the activity of the cat2promoter during both stages. By contrast, the region from 816to 720 bp had a negative effect at both stages. The regionfrom 682 to 632 bp contributed positively to theactivity during seed formation but negatively during postembyonicdevelopment. Histochemical analysis revealed that the multiplecis-elements determined not only the level of expression ofthe chimeric gene but also the tissue-specificity of such expression.For example, the region from 1,241 to 816 bp allowedexpression of the chimeric gene in the axis of the embryo ofthe dry seed, as well as in the cortex of the middle part ofthe hypocotyl and at the base of epicotyl in the young seedling.
1Present address: Department of Plant Molecular and Cell Biology,University of Florida, Gainesville, Florida 32611-0511, U.S.A.
2Present address: Center for Molecular Biology and Genetics,Mie University, 1515 Kamihama, Tsu, Mie, 519 Japan
3Present address: Faculty of Biotechnology, Fukui PrefecturalUniversity, 4-1-1 Kenjojima, Matsuoka-cho, Yoshida-gun, Fukui,910-11 Japan 相似文献
2.
Mechanoreception in marine copepods: electrophysiological studies on the first antennae 总被引:3,自引:0,他引:3
Yen Jeannette; Lenz Petra H.; Gassie Donald V.; Hartline Daniel K. 《Journal of plankton research》1992,14(4):495-512
Neural activity was recorded extracellularly at the base ofthe first antenna in 15 marine copepods. Controlled mechanicalstimuli were delivered with a vibrator driven by a waveformgenerator. Many species exhibited responses characterized bya large number of small spikes, while others were characterizedby the presence of a small number of large units. Two bay species,Labidocera madurae and Acartia fossae, exhibited large unitsthat could be easily distinguished from the background activityof smaller units. In these species, the antennal receptors firedshort latency (>5 ms) trains of one to several impulses inresponse to a brief mechanical stimulus and sustained trainsto a prolonged sinusoidal stimulus. They were extremely sensitiveto small displacements and sensitivity increased with stimulusfrequency. The receptors responded to stimuli between 40 and1000 Hz and receptors required displacement velocities of 20µm s1 or more to fire. Displacements as small as10 nm were capable of triggering spikes. With an increase inthe amplitude of the displacement, a decrease in the latencyand an increase in the number of units recruited and/or firingfrequency was recorded. Phase-locking to oscillatory stimuliwas observed over a frequency range of 80500 Hz. Neuralactivity increased in response to bending of individual setae.Setae appear innervated and structurally constrained to movementsin specific directions. These experiments suggest that (i) somecopepod setal receptors may be more nearly velocity detectorsthan purely displacement sensors, (ii) they may be capable ofsensing closely spaced stimuli, (iii) the patterns of responsemay code for intensity and duration of the stimulus, and (iv)receptors may be capable of supplying directional information. 相似文献
3.
Measurement of the Apoplastic Activity of K+ and Cl- in the Leaf Epidermis of Commelina communis in Relation to Stomatal Activity 总被引:2,自引:0,他引:2
Bowling, D. J. F. 1987. Measurement of the apoplastic activityof K+ and Cl in the leaf epidermis of Commelina communisin relation to stomatal activity.J. exp. Bot. 38: 13511355. Ionic activity of K+ and Cl in the apoplast of the lowerepidermis of the leaf of Commelina communis was measured usingion selective micro-electrodes. Large gradients across the stomatalcomplex were observed which were related to stomatal aperture.On stomatal closure the activity of K+ and Cl in theapoplast of the guard cell rose from 3·0 mol m3to 100 mol m3 and 33 mol m3 respectively. It wasconcluded that the apoplast is an important pathway for iontransport between the cells. Key words: Stomata, ionic activity, leaves, apoplast 相似文献
4.
The major rate limiting steps in bullfrog peripheral nerve gustatoryresponse latencies were studied by measuring glossopharyngealnerve multi-unit activity, detecting response onset times, andcalculating rates of stimulus diffusion to receptor cells andsignal propagation along first order neurons. The stimulus deliverytechnique minimized physicochemical and mechanical artifacts,as well as neural responses to mechanical stimulation of thetongue. Neural activity was processed in 10 ms bins. Responseonsets were determined by a criterion that compared the statisticalprobability of the neural events during stimulus liquid presentationswith those during both Ringer's solution presentations afteradaptation to Ringer's and no-stimulus control conditions. Thiscriterion yielded response latencies of 70110 ms for10 mM CaCl2, 2 mM quinine hydrochloride, and 105 M and106 M cantharidin or Ringer's, and H2O. No responsesoccurred during presentations of 107 M cantharidin orRinger's after adaptation to Ringer's, or during the no-stimuluscontrol condition. From the measured latencies and calculatedrates of stimulus diffusion to receptor cells, and signal propagationalong first order neurons, we conclude that taste receptor cellevents and not perireceptor or signal propagatiog events arethe major rate limiting steps in gustatory response latencies. 相似文献
5.
Particulate and dissolved phytoplankton production of the Patos Lagoon estuary, southern Brazil: comparison of methods and influencing factors 总被引:3,自引:0,他引:3
Abreu Paulo C.; Odebrecht Clarisse; Gonzlez Adriana 《Journal of plankton research》1994,16(7):737-753
Uptake rates of 14C (filtration and the acidification-bubblingmethodABM) were measured weekly in a shallow region ofthe Patos Lagoon estuary (3207'S, 5206'W) between March 1989and March 1990. Phytoplankton production varied seasonally,the lowest values occurring in the austral winter (JuneAugust1989) and the highest rates during spring and summer (March1989; September 1989March 1990). Particulate carbon productionvaried between 0.65 and 70.6 mg C m3 h1 and wasmostly associated with organisms <20 µm (mean = 73.4%).Dissolved organic carbon (DOC) released by phytoplankton variedbetween 0.1 and 89.3 mg C m3 h1 representing 相似文献
6.
Zooplankton fecal pellet fluxes and vertical transport of particulate organic material in the pelagic environment 总被引:3,自引:0,他引:3
Fecal pellet fluxes were determined using a series of multireplicatetraps set at 35, 65, 150, 500, 750 and 1500 m in the northeastPacific. Fecal pellets appear to be important contributors to total carbonfluxes. In near-surface waters (35150 m), pellet fluxesranged from 23 x 105 pellets m2 day1. Minimumpellet fluxes were observed at 500m({small tilde}0.4x 105 pelletsm2day1). In contrast, the 1500 m pellet flux valueincreased to approximately 0.8 x 105 pellets m2 day1relative to the 500 m depth, and is probably the result of insitu repackaging. Analyses of pellet content suggest multiplesources of "large" particle input throughout the water column.The implications of this phenomenon are discussed in terms ofthe detrital rain and ladder of migration theories. 相似文献
7.
PHILLIPS JOHN E.; MEREDITH JOAN; AUDSLEY NEIL; RICHARDSON NAOMI; MACINS ANDRIS; RING MARK 《Integrative and comparative biology》1998,38(3):461-470
SYNOPSIS. The anterior (ileum) and posterior (rectum) segmentsof the locust hindgut constitute the reabsorptive regions ofthe excretory system, which conserves or eliminates body waterand solutes as required for osmotic homeostasis. Hindgut transportmechanisms in the desert locust have previously been well describedbut the neuropeptide hormones that may naturally control theseprocesses are only now being identified. Ion Transport Peptide(ITP) has been isolated from locust corpus cardiacum (CC) andits full sequence of 72 amino acids deduced from its cDNA. NativeITP has the same actions as crude CC extracts in stimulatingCl , Na+, K+, and fluid absorption and inhibiting H+secretion (i.e., influencing pH regulation). The deduced aminoacid sequence of ITP was confirmed by showing biological activityof expressed and synthetic forms of this peptide. ITP has highsequence homology with a large family of crustacean hormonesthat include hyperglycaemic (CHH) and moult-inhibiting hormones(MIH) and is the first member reported outside crustaceans. 相似文献
8.
Do CW Peterson-Yantorno K Mitchell CH Civan MM 《American journal of physiology. Cell physiology》2004,287(4):C1003-C1011
The eyes aqueous humor is secreted by a bilayered ciliary epithelium comprising pigmented (PE) and nonpigmented (NPE) epithelial cell layers. Stromal Cl enters the PE cells and crosses gap junctions to the NPE cells for release into the aqueous humor. Maxi-Cl channels are expressed in PE cells, but their physiological significance is unclear. To address this question, excised patches and whole native bovine PE cells were patch clamped, and volume was monitored by calcein fluorescence. In symmetrical 130 mM NaCl, cAMP at the cytoplasmic surface of inside-out patches produced concentration-dependent activation of maxi-Cl channels with a unitary conductance of 272 ± 2 pS (n = 80). Voltage steps from 0 to ±80 mV, but not to ±40 mV, produced rapid channel inactivation consistent with the typical characteristics of maxi-Cl channels. cAMP also activated the maxi-Cl channels in outside-out patches. In both cases, maxi-Cl channels were reversibly inhibited by SITS and 5-nitro-2-(phenylpropylamino)benzoate (NPPB). Decreasing cytoplasmic Cl concentration reduced both open-channel probability and unitary conductance. Similarly, the membrane-permeant 8-bromo-cAMP stimulated outward and inward whole cell currents; the stimulation was larger at higher intracellular Cl concentration. As with unitary currents, cAMP-triggered whole cell currents displayed inactivation at ±80 but not at ±40 mV. Moreover, cAMP triggered NPPB-sensitive shrinkage of PE cells. The results suggest that cAMP directly activates maxi-Cl channels of native PE cells that contribute to Cl release particularly from Cl-loaded cells. These cAMP-activated channels provide a potential mechanism for reducing and modulating net aqueous humor secretion by facilitating Cl reabsorption into the ciliary stroma. cell volume; chloride secretion; aqueous humor formation 相似文献
9.
We have investigated the effects of oxidized low density lipoproteins(Ox-LDL) on aortic smooth muscle cell (SMC) proliferation andthe biosynthesis of glycosphingo-lipids. We found that Ox-LDL exerted a concentration, time, and temperaturedependent alteration of cell proliferation and the biosynthesisof lactosylceramide. At low concentrations (510 µg/mlmedium) Ox-LDL stimulated cell proliferation measured by anincrease in the incorporation of 3H-thymidine in cells and thesynthesis of lactosylceramide, but not glucosylceramide synthesis.Oxidized LDL exerted a threefold increase in the incorporationof [3H]-galactose and [3H]-serine in lactosylceramide. The activityof lactosylceramide synthetase; UDP-galactose glucosylceramideß1 相似文献
10.
Changes in the level of nicotinamide nucleotides, rate of 14CO2output from [114C] or [614 C6/C1 ratios, glucose-6-phosphatedehydrogenase, 6-phosphogluconate dehydrogenase, and NAD kinaseactivities were determined during the first 72 h of germinationof seeds of Cicer arietinum L. The level of oxidized and reducedforms of nicotinamide nucleotides, together with the activityof glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase,NAD kinase, and C6/C1 ratios, suggest that the pentose phosphatepathway is activated during early germination in cotyledonsof chick pea seeds. The results obtained in embryonic axes seemsto indicate a lower participation of the PP pathway, probablydue to the development of the activity of the glycolytic-TCApathway. 相似文献
11.
The mechanisms for generating receptor potentials and actionpotentials upon mechanical stimulation were studied in internodalcells of Chara. Receptor potentials and the subsequent actionpotentials could be generated even when the electrogenic protonpump was inhibited, indicating that the proton pump does notplay a central role in generating receptor potentials and actionpotentials. The involvement of Ca2+ and/or Cl channelsin both receptor and action potentials was suggested, basedon the equilibrium potentials of these ions across the plasmamembrane. Inhibitors of the Ca2+ channel, Cl channeland stretch-activated channel could not inhibit generation ofthe receptor potential. These findings suggested that the channelsinvolved in generating the receptor potential are insensitiveto these channel inhibitors, although all inhibitors significantlyinhibited the action potential. (Received July 26, 1996; Accepted November 19, 1996) 相似文献
12.
D. Schild 《Biological cybernetics》1986,54(1):9-19
In this paper the goldfish olfactory bulb is described from a systems theoretical point of view. A chain of nine interacting circuits, each one mitral cell and one granule cell, is modelled. Glomerular synapses are assumed to have variable strengths. The analysis of the model system leads to the following conclusions:
- The temporal input pattern of a mitral cell—granule cell circuit is either maintained by the circuit or inverted (lateral inhibition effect). This property together with available receptor data allows the theoretical explanation of experimentally recorded mitral cell patterns.
- The sensitivity of a mitral cell—granule cell circuit is a function of the input signal's frequency. This provides an explanation for mitral cell cluster activity patterns measured in experiments.
- Given a spatial input pattern to adjacent mitral cell—granule cell circuits, the output pattern depends largely upon the ratio between the feedback parameter p and the similarity β of the inputs to adjacent circuits. For appropriate p and β a local order between the responses of single neighbouring circuits is established. This local order can lead to a globally ordered mapping of odours onto mitral cell activities, thus providing a coding concept for the bulb. Some consequences of this concept coincide well with the spatial activity patterns found in 2-DOG-studies.
- Glomerular synapses endowed with plasticity could account for long term effects such as degeneration and sensitivity changes with respect to certain odours.
13.
We have investigated whether a transient increase in extracellularcalcium concentration is able to induce long-term modificationof neuronal excitability in the olfactory bulb. High-calciumartificial cerebrospinal fluid containing picrotoxin (Ca-PTXsolution) was applied locally near the mitral cell layer througha push-pull device for 10 min in anaesthetized rats. Changesin the neuronal excitability were monitored through electrically-evokedfield potentials. Application of the Ca-PTX solution induceda rapid increase in the granule cell response amplitude, whereasmitral/tufted cells response amplitude increased more progressivelyand reached its maximum within a few hours. The increase inmitral/tufted cells response and granule cells response reachedbetween 30 and 100% in experiments which lasted for 48h. Pre-application of amino-phosphonovalerate (NMDA receptorblocker) potently reduced both short- and long-term enhancementproduced by the Ca-PTX solution. Neither application of thehigh calcium solution alone nor the picrotoxin solution aloneinduced long-term changes. The results point out the possibleimportance of Ca2+ and NMDA receptors in persistent forms ofolfactory bulb plasticity. Relevance of this phenomenon in normalolfactory bulb physiology remains to be examined. Chem. Senses21: 159168, 1996.
1Present address: California Institute of Technology, Divisionof Biology 216-76, Pasadena, CA 91125, USA 相似文献
14.
Spatial and Temporal Aspects of Growth in the Primary Root of Cotton Seedlings: Effects of NaCl and CaCl2 总被引:1,自引:0,他引:1
Seedlings of cotton (Gossypium hirsutum L. cv. Acala SJ-2) weregrown in modified Hoagland nutrient solution with various combinationsof NaCl and CaCl2. Marking experiments and numerical analysiswere conducted to characterize the spatial and temporal patternsof cotton root growth at varied Na/Ca ratios. At 1 mol m3Ca, 150 mol m3 NaCl reduced overall root elongation rateto 60% of the control, while increasing Ca to 10 mol m3at the same NaCl concentration restored the elongation rateto 80% of the control. Analysis of the spatial distributionof elongation revealed that the presence of 150 mol m3NaCl in the medium shortened the growth zone by about 2 mm fromthe approximate 10 mm in the control and also reduced the relativeelemental elongation rate (i.e. the longitudinal strain rate,defined as the derivatives of displacement velocity of a cellularparticle with respect to position on root axis). Supply of 10mol m3 Ca at the high salt condition restored partiallythe relative elemental elongation rate, but not the length ofthe growth zone. Compared to the control, the growth trajectoriesshowed that at 1 mol m3 CaCl2 it took more time for acellular particle to move through the growth zone at 150 molm3 NaCl, while at 10 mol m3 CaCl it took lesstime and there was no difference between the NaCl treatments Key words: Gossypium hirsutum, salinity stress, root growth kinematics 相似文献
15.
Both the frequency and the temporal pattern of action potentialproduction in an insect olfactory receptor neuron are stronglyaffected by odorant composition and the time course over whichstimulus concentration varies. To investigate the temporal characteristicsof the neurophysiological responses of these neurons, we deviseda stimulus delivery system that allows us to repeatedly presentwell-mixed, constant concentration odor pulses with relativelysharp onsets and offsets. Here we compare neurophysiologicalresponses to several different stimulation regimens, includingpulses of different durations and repetition rates. During stimulationwith high concentrations of pheromone, the temporal patternof neural activity from olfactory receptor neurons on the antennaof Trichoplusia ni (Hübner) is characterized by an initialphasic period (100200 ms), followed by a tonic periodwhich is typically maintained for the remaining duration ofthe stimulus. Different olfactory receptor neurons appear tovary among themselves in the relative distribution between thephasic and tonic portions of the overall discharge. During stimulationregimens involving rapid repeated pulses of odorants, a portionof the phasic response levels is preserved during each pulse.Consequently, T. ni males probably detect much of the fluctuationin concentration of pheromone that may normally occur downwindfrom the site of pheromone release. 相似文献
16.
Effects of Ions and Membrane Potential on the Elongation of the Unicellular Green Alga Closterium 总被引:1,自引:0,他引:1
Cells of the unicellular green alga Closterium ehrenbergii elongatedexclusively at septa and for 45 hours after cell division.Cell elongation was strongly inhibited by a decrease in eitherthe external concentration of Ca2+ or pH, and was also inhibitedby several competitive Ca2+ channel blockers. Changes in concentrationsof other external ions had no effect on the elongation. Theaverage concentrations of ions in the intracellular fluid ofthe interphase cell before cell division was as follows (inmM): K+=56.5, Na+=4.8, Ca2+=2.4, Mg2+=1.3, Cl=59.5; thepH was 7.4. The levels of K+, Na+ and Cl ions decreasedsignificantly with cell elongation, suggesting that this process,which proceeds with water uptake, surpasses ion absorption.The plasma membrane potential (Vm) in both the interphase cellsand in the elongating cells was in the range of 90 to105 mV (interior negative). The Vm was entirely determinedby the simple diffusion of K+. A decrease in the external concentrationof Ca2+ caused depolarization, probably by an indirect effectof low Ca2+. Changes in the extracellular level of H+ and othercations barely affected Vm. Thus, external Ca2+ and H+ are concludedto affect cell elongation but not via a change in the Vm acrossthe plasma membrane. (Received February 29, 1988; Accepted June 8, 1988) 相似文献
17.
The Interrelations of Cell Turgor Pressure, Gas-vacuolation, and Buoyancy in a Blue-green Alga 总被引:5,自引:0,他引:5
The increase in pressure required to collapse gas vacuoles onsuspending the cells of the blue-green alga Anabaena flos-aquaein hypertonic sucrose solutions shows the turgor pressure tovary over the range of 265 to 459 KN m2 under differentculture conditions. The cell turgor increased at a rate of upto KN m2 h1 on transferring the alga from lowto high light intensity. This rise appears to be a result ofthe accumulation of photosynthate, as it is dependent on thepresence of carbon dioxide in the gas phase and is inhibitedby DCMU. Experiments using 14CO2 indicate that the increasedrate of photosynthesis during the high light exposure is easilysufficient to account for the observed turgor rise. The rise in turgor can bring about collapse of sufficient ofthe alga's gas vacuoles to destroy its buoyancy. Higher turgorpressures, and consequently a lower degree of gas vacuolationand buoyancy, were maintained when the alga was kept at highlight intensitives for a week and more. The significance ofthis behaviour is discussed in relation to stratification ofplanktonic blue-green algae in natural habitats. 相似文献
18.
The Location of the Transporting System for Inorganic Carbon and the Nature of the Form Translocated in Chlamydomonas reinhardtii 总被引:4,自引:0,他引:4
The permeability of the plasmalemma of Chlamydomonas reinhardtiicells was increased by treatment with poly-L-lysine or dimethylsulphoxideas indicated by 3-phosphoglyceric acid dependent O2 evolution.These treatments decreased the ability of the cells to accumulateinorganic carbon internally and hence their photosynthetic affinityfor inorganic carbon in the medium. With saturating light andinorganic carbon, the photosynthetic rate was less affectedby the poly-L-lysine and dimethylsulphoxide treatments. Thusthe poly-L-lysine and dimethylsulphoxide did not alter the activityof the chloroplasts but rather made the intracellular inorganiccarbon pool more freely exchangeable with the medium. It isconcluded that the transporting system for inorganic carbonis located at the plasmalemma. Treatment with Diamox, an inhibitor of carbonic anhydrase, didnot affect photosynthetic rate and accumulation of inorganiccarbon when CO2 was supplied but strongly inhibited both parameterswhen HCO3 was supplied. In a mutant of Chlamydomonasreinhardtii lacking a cell wall, carbonic anhydrase leaks tothe medium and uptake of inorganic carbon is much faster whenCO2 is supplied than when HCO3 is supplied. These resultssuggest that CO2 rather than HCO3 is the inorganic carbonspecies that is actively translocated across the plasmalemma. Key words: Chlamydomonas, Inorganic carbon uptake 相似文献
19.
The purpose of the investigation is the determination of thevolumes and numbers of cells of the meristematic dome and ofeach of the first 7 primordia and internodes at the apex ofthe shoot of Lupinui albus. This system occupies a zone whichis about 0·4 mm. in length. Techniques are describedfor dissecting the region in which the observations are made,for determining the numbers of cells and the volumes of theseveral fragments. From the number of cells and the volume ofeach fragment an average cell volume it calculated. It is shown that in the midphase of the plastochron the domecontains 3,500 cells and has a volume of 1·6 x103mm.3,the first primordium contains 1,630 cells and has a volume of0·38 x103 mm.3, and the first intemode containsabout 700 cells and has a volume of about 1·4 x103mm3The number of cells and the volume of the primordium increaseexponentially with increasing plastochron age, and the seventhprimordium contains 26,000 cells and has a volume of 20·9x 103mm3 The seventh intemode contains about 5,000 cellsand has a volume of 8·6x103mm3 The average cell volume in the dome is 4·7 x 107mm.3in the first primorndium it is 2·3 x 107mm.3 andin the first internode it is 20·9x 107mm.3 Inthe seventh primordium the average cell volume increases to7·9 x 107mm.3 In the internodes there is little,if. any, change in cell volume from the first to the seventhof the series. The significance of these changes is discussed. 相似文献
20.
Ion and saccharide concentrations in the upper and lower partsof the laminar pulvinus of the primary leaf of Phaseolus vulgariswere measured in relation to the circadian movement. Concentrations of K+, Na+, Ca2+, Mg2+, Cl, organic acid,NO3, H2PO4, fructose and fructose-yielding saccharidesin the pulvinus were 75120, 0.30.7, 58,612, 4060, 6073, 1935, 29and 15 mM, respectively, and the osmotic pressure ofthe pulvinus was considered to be due to these ions. The cell volume in the expanding part was larger than that inthe contracting part. The change of the cell volume alteredthe molar concentration in the cell sap and therefore the amountof solutes actually transported from the upper to the lowerpart and vice versa was estimated from the concentration expressedin moles per gram of dry weight. Results showed that K+, Cl, organic acid (or H+) andNO3 moved from the upper to lower parts or vice versain the pulvinus in relation to its deformation, keeping theelectroneutrality among those ions, whereas Ca2+ and Mg2+ didnot move. The difference in the K+ concentration between theupper and lower parts when the leaf was up or down amountedto 30% of the whole osmotic pressure. This lead to the conclusionthat the endogenous clock-controlled unequal distribution ofK+, Cl, organic acid (or H+) and NO3 in the pulvinuscould be the force for the circadian leaf movement. (Received August 7, 1979; ) 相似文献