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1.
1.  The effects of three barbiturates and the local anesthetic procaine on the ion channel function of mouse nicotinic acetylcholine receptor (nAChR) muscle subtype expressed inXenopus laevis oocytes were examined by whole-cell voltage-clamp technique.
2.  A concentration-response curve for the specific nicotinic agonist dimethylphenylpiperazinium iodide (DMPP) was first determined. This agonist produced increasing whole-cell currents up to a concentration of 100µM (EC50 = 13µM), then decreased responses at higher concentrations.
3.  The barbiturates (amobarbital, secobarbital, pentobarbital) and procaine produced reversible inhibition of DMPP-induced currents at clinically used concentrations. The two classes of drugs differed in the voltage dependence of the inhibition: procaine-induced inhibition was increased at more negative transmembrane holding potentials (-90 vs. -45 mV); whereas amobarbital-induced inhibition did not vary at different transmembrane potentials.
4.  Mutant forms of the nAChR, containing single amino acid changes in the M2 regions of and subunits, showed increased sensitivity to procaine but no change in sensitivity to amobarbital-induced inhibition.
5.  These electrophysiologic studies provide further evidence that barbiturates and local anesthetics produce inhibition of the nAChR at different sites.
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2.
1.  Interspecific diversity in the visual pigments of stomatopod crustaceans was characterized using microspectrophotometry. We examined the 10 visual pigments in main rhabdoms in retinas of 3 species of each of two genera of stomatopod crustaceans of the superfamily Gonodactyloidea, Gonodactylus (G. oerstedii, G. aloha, and G. curacaoensis) and Odontodactylus (O. scyllarus, O. brevirostris, and O. havanensis). Species were selected to provide a matched diversity of habitats.
2.  In each genus, visual pigments varied in max in several regions of the retina, as revealed by analysis of variance. The variation within closely related species of the same genus implies that visual pigments can evolve rapidly in stomatopods.
3.  In photoreceptors of the peripheral retina, which are devoted to spatial vision, visual pigment max decreased as the depth range of the various species increased, a typical pattern for marine animals. In contrast, visual pigment max in photoreceptors of retinal regions devoted to polarization vision (midband Rows 5 and 6) is not obviously correlated with the spectral environment, implying that polarization information may be confined to particular spectral ranges. Visual pigments of the tiered rows of the midband, which are committed to spectral analysis, span a larger spectral range in shallow-water than deepwater species.
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3.
1.  The dependence of dark-adapted fly (Calliphora vicina) photoreceptors on oxygen was investigated by measuring the electroretinogram (ERG), the receptor potential, and the redox states of the mitochondrial cytochromes. The redox states were determined via reflection microspectrophotometry on white-eyed fly mutants.
2.  The light sensitivity of the photoreceptors at oxygen fractions above 2% is identical to that in the normal (air) environment, as judged from both ERG and receptor potential. Light sensitivity is rather abruptly and strongly reduced at oxygen fractions lower than 1% and vanishes at anoxia (0%).
3.  The redox state of the mitochondrial cytochromes also changes around oxygen fractions of 1–2%, but the dependence on oxygen fraction is less abrupt than that of ERG and receptor potential.
4.  The mitochondrial activity of dark-adapted fly photoreceptors appears to be well-buffered, to warrant ample supply of metabolic energy for unimpaired photoreceptor function down to extremely low oxygen levels.
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4.
1.  To determine the specificity of the goldfish (Carassius auratus) olfactory system to the reproductive pheromone 17,20-dihydroxy-4-pregnen-3-one (17,20P), and to determine if related sex steroids might also function as pheromones, electro-olfactogram (EOG) responses were recorded from mature male goldfish.
2.  Of the 24 steroids tested, 17,20P was the most stimulatory. It had a detection threshold of 10–12 M and at a concentration of 10–8 M elicited an EOG response 3 times that elicited by 10–5 M L-serine
3.  17,20,21-triol-4-pregnen-3-one, a metabolite of 17,20P, was the only other highly stimulatory steroid. Its threshold was 10–11 M.
4.  In cross-adaptation experiments EOG responses to all 21-carbon steroids were inhibited during adaptation to 17,20P: responses to this pheromone are transduced by a single receptor/transduction mechanism.
5.  To verify the biological relevance of EOG recording whole animal responsiveness was determined by measuring blood gonadotropin. When goldfish were placed into homogeneous steroid solutions endocrine responsiveness strongly correlated with EOG recording. However, when steroids were added to aquaria containing fish, responses were less specific indicating that transient wisps of steroids trigger endocrine responses.
6.  Although the extreme sensitivity and specificity of the goldfish olfactory system to 17,20P gives it the potential to serve as a highly specific cue, realization of this potential is probably determined by the dynamics of pheromone exposure.
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5.
1.  The action of melatonin was investigated in a colonial anthozoan, the sea pansy Renilla koellikeri, in which rhythmic contractions underlying peristalsis were previously shown to be potentiated by serotonin (5-HT) and cAMP analogues (Anctil 1989).
2.  Melatonin (2–1000 mol·1-1) consistently and reversibly depressed the amplitude of rhythmic contractions, the latter all but vanishing at the most effective concentration (10 mol·1-1). In addition, the frequency of rhythmic contractions incurred a 25% reduction in some preparations exposed to melatonin (10–20 mol·1-1). Vaseline gap experiments showed that this response was restricted to tissues directly exposed to melatonin.
3.  The potentiating effect of 5-HT on rhythmic contractions was eliminated in a reversible manner in the presence of melatonin. The latter also caused a 50% reduction of the amplitude of contractions elicited by field electrical stimulation.
4.  Dibutyryl or 8-bromo cGMP, as well as the phosphodiesterase inhibitor IBMX, mimicked the melatonin-induced response and the effects of melatonin on the 5-HT potentiation or contractile response to electrical stimulation. cGMP levels, measured by radio-immunoassay (RIA) in rachidial tissues, increased 3-fold above basal levels in the presence of melatonin (0.01 mmol·1-1) and 2-fold with IBMX (1 mmol·1-1). In contrast, RIA measurements of cAMP levels showed the latter to fall to 50 and 40% of control values in the presence of melatonin (0.01 mmol·1-1) and IBMX (0.1 mmol·1-1), respectively. These results and other findings suggest that a cGMP-mediated melatonergic mechanism participates in an antagonistic fashion with 5-HT in the modulation of rhythmic contractions and peristalsis of the sea pansy.
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6.
1.  Action potentials of the mesothoracic tympanic organ's two receptor units (Al and A2) were recorded extracellularly. The impulse activity of both receptor units rises beyond resting activity when stimulated by airborne sound.
2.  The time course of the excitation of both receptor units appears to be phasic-tonic (Fig. 4).
3.  The influence of stimulus intensity and its time course on the excitation of both receptor units was studied (Figs. 5–8).
4.  The threshold curves of the receptor units Al and A2 for airborne sound were determined in the frequency range between 0.3 to 20 kHz. The two receptor units differ. Receptor unit Al shows a distinct threshold minimum, whereas the threshold curve of the less sensitive receptor units A2 appears more flat (Fig. 9).
5.  The threshold curves of the receptor units on the left body side differ from those on the right. The threshold minimum of unit Al left is absolutely lower than that of Al right and lies at higher frequencies (Fig. 10).
6.  As observed under the light microscope, vibrations of the organ's base and bulb differ from one side of the body to the other (Fig. 11).
7.  Removing the bulb influences the mode of oscillation of the base as well as the threshold curves of the receptor units.
8.  A hypothesis is proposed regarding the function of integumentary structures on the membrane in stimulus transformation.
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7.
Somatic embryos and adult plants were regenerated from mesophyll protoplasts of a clone of chicory 474 (Cichorium intybus L. x Cichorium endivia L.). Embryos were obtained in three different ways:
–  - plating of 7-day-old protoplast cultures on PM-3 solid induction medium with 2.5 M 2-isopentenyladenine (2-iP) and 0.5 M naphthaleneacetic acid (NAA);
–  - transfer of 1–2 mm microcolonies into liquid M-17 induction medium with 2.5 M (2-iP) and 0.1 M (NAA);
–  - transfer of well-established protoplast-derived calluses onto M-17.
Development of embryos was accomplished in agitated liquid Heller medium with 0.15 M gibberellic acid and germination on solid Heller medium without growth regulators. The total time for plantlet (4-leaves stage) recovery, following protoplast isolation, was 13 to 15 weeks. After acclimatization all protoplast-derived plants of Cichorium 474 were phenotypically normal and fertile.  相似文献   

8.
Stinging behavior has been extensively studied in honey bees at the level of the individual, that is, in terms of stimuli that release stinging in adult bees, and in terms of integration of individual behavior into colony defense. Yet very little is known about the physiological basis for this behavior. Using an isolated abdominal preparation factors that influence peripheral control of the sting extension response are analyzed. Results show that:
1.  Electromyogram activity released by severing the ventral nerve cord changed during the first few days of adult life but not later. Abdomens from older bees (nurses, guards, foragers) showed significantly higher EMG activity than newly emerged or 24 h-old bees.
2.  The reflex matured over 5–7 days after emergence as an adult.
3.  Younger bees (24h) had a lower threshold for initiating sting extension than older bees. However, the threshold for initiating the full sting response, i.e., extension and venom pumping, did not differ due to age.
4.  Caste status was not correlated to any of the parameters of sting extension, indicating that any effect of caste on stinging behavior must arise in more anterior ganglia and/or in the brain.
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9.
1.  Activity of individual eighth nerve fibers in the bullfrog, Rana catesbeiana, was measured in response to complex, multiple-frequency stimuli differing in both frequency composition and harmonic structure. Stimuli were chosen to parallel types of stimuli producing pitch-shift effects in humans.
2.  The fundamental frequency of harmonic stimuli can be extracted from the autocorrelation of fiber firing, whether the fundamental is physically present in the stimulus or is a missing fundamental. The spectral fine-structure of harmonic stimuli is not robustly represented in fiber temporal response. These effects are seen in both AP and BP fibers.
3.  The pseudoperiod of inharmonic stimuli is represented by synchronization to successive high-amplitude peaks in the stimulus envelope. Temporal responses to stimuli with high center frequencies are similar regardless of whether their frequency components are harmonically or inharmonically related. Responses remain dominated by the envelope periodicity, and no pitch-shift is signaled. In response to stimuli with low center frequencies, temporal responses signal a pitch-shift between harmonic and inharmonic complexes. Both AP and BP fibers show these effects.
4.  These data suggest that bullfrog peripheral fibers extract the periodicity of complex stimuli by time-domain rather than frequency-domain coding.
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10.
1.  The neurons of the pyloric network of the lobster (Panulirus interruptus) stomatogastric ganglion organize their rhythmic motor output using both chemical and electrical synapses. The 6 electrical synapses within this network help set the firing phases of the pyloric neurons during each rhythmic cycle. We examined the modulatory effects of the amines dopamine (DA), serotonin (5HT) and octopamine (Oct) on coupling at all the electrical synapses of the pyloric network.
2.  Electrical coupling within the pacemaker group [anterior burster (AB) to pyloric dilator (PD), and PD-
3.  Dopamine decreased or increased the coupling strength of all the pyloric electrical synapses: the sign of the effect depended upon which neuron was the target of current injection. For example, DA decreased AB PD coupling (i.e., when current was injected into the AB) but increased coupling in the other direction, PD AB. Dopamine decreased AB to VD coupling when current was injected into either neuron. Serotonin also had mixed effects; it enhanced PDAB coupling but decreased AB to VD and PD to VD coupling in both directions. Octopamine's only effect was to reduce PD VD coupling. li]4.
5.  The characteristic modulation of electrical coupling by each amine may contribute to the unique motor pattern that DA, 5HT and Oct each elicit from the pyloric motor network.
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11.
1.  The specificity and sensitivity of the olfactory organ of adult zebrafish, Danio rerio, to selected amino acid, bile acid, and steroid odorants were characterized using the electro-olfactogram recording technique. The olfactory organ was responsive to 28 of the 29 odorants tested.
2.  All of the 100 M amino acid and bile acid stimulants elicited a negative-going response that was significantly greater than the response to the artificial freshwater control. The general pattern of relative stimulatory effectiveness established for the amino acid stimuli was neutral amino acids > basic amino acids > acidic amino acids > imino acids. The general pattern of relative stimulatory effectiveness of 100 M bile acid stimuli was taurine-conjugated bile acids > glycineconjugated bile acids non-conjugated bile acids. The responses to the most stimulatory bile acid odorants were up to 40% larger than the responses to the most stimulatory amino acid odorants.
3.  The response threshold for cysteine and taurocholic acid, the most stimulatory of the amino acid and bile acid stimuli tested, was approximately 10-8 M. Females are significantly more sensitive to these odorants than males.
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12.
The content of neuraminic acid (NA) of different developmental stages of trout eggs was determined.
1.  The total NA increases from about 13 g NA per egg (6–8 weeks before spawning) to 50 g directly before spawning until hatching.
2.  In freshly hatched fish larvae the NA-content is decreased to about 40 per cent as compared with stages before hatching.
3.  The ratio of bound to free NA decreases from values of about 13.5 (6–8 weeks before spawning) to 0.85–1.2 at the hatching-stage.
4.  The bound NA is almost entirely bound to sialo-glycoproteins.
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13.
1.  The effects of the odorant compounds adenosine-5-monophosphate (5AMP), ammonium, betaine, L-cysteine, L-glutamate, DL-succinate, and taurine and of mixtures of these comounds on binding of taurine and 5AMP to dendritic membrane from the olfactory organ of spiny lobsters (Panulirus argus) were quantified to evaluate the contribution of inhibition of odorant-receptor binding to the generation of physiological responses to mixtures.
2.  Taurine binding sites belong to two affinity classes, while 5AMP binding sites belong to a single affinity class. Binding of either taurine or 5AMP was partially inhibited in an apparently noncompetitive, concentration dependent fashion by most odorant compounds, with 25–40 % inhibition by 1 mM of odorant. Mixtures of two or more odorant compounds also inhibited binding of taurine or 5AMP to its sites. However, the inhibition by mixtures was often significantly less than expected from the inhibition produced by a mixture's components assuming either a noncompetitive or competitive mechanism.
3.  By including this binding inhibition between compounds into models for predicting physiological responses to mixtures from the responses to the components, the predictive power of the models is significantly improved. This result strongly suggests that binding inhibition can influence the physiological responsiveness of chemoreceptor cells to mixtures.
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14.
1.  Several larval diets (Table 1) were developed for rearing the tobacco hornworm mothManduca sexta in an effort to control the synthesis of adult visual pigments (generically, rhodopsins) through the availability of their chromophore, retinaldehyde or, more likely, 3-hydroxyretinaldehyde.
2.  Rhodopsin was measured in difference spectra from detergent extracts of adult retinas. Opsin was identified and measured on SDS gels after electrophoretic separation of retinal proteins reduced with cyanoborohydride to convert rhodopsin to fluorescent N-retinyl opsin. The density of P-face particles in photoreceptor membranes was measured in freeze-fracture preparations. Visual sensitivity of compound eyes was measured from the electroretinogram (ERG).
3.  One diet containing corn meal and soy flour, rich sources of potential carotenoid precursors of the chromophore, producedfortified animals with the highest level of rhodopsin: 60 pM/retina. The addition of spinach leaves to the fortified diet did not increase the amount of rhodopsin. A second diet containing wheat germ producedintermediate moths with about 25% of the visual pigment of the fortified group. A third diet containing potato starch and lacking all sources of carotenoids except for a small amount of yeast produceddeprived animals whose visual pigment could not be measured but must have been less than 0.6 pM/retina (Fig. 1B).
4.  A band at 35–38 kDa on SDS gels prepared from cyanoborohydride-reduced extracts of fortified retinas was identified as n-retinyl opsin from its intense fluorescence. The fluorescence of the band was less intense in preparations from intermediate retinas. No fluorescence was detected in preparations of deprived retinas. However, this relatively insensitive assay would not allow detection of rhodopsin levels less than 6 pM/retina. When the gels were stained for protein, the density of the 35 kDa band from intermediate and deprived retinas was about 45% and 6%, respectively, of that from fortified retinas. Thus the relative density of the band from preparations of deprived retinas is about 6 times greater than the estimated maximum amount of rhodopsin present in extracts. Either there is excess opsin in the deprived retinas, or another minor protein runs at the same position on the gel as opsin (Fig. 2).
5.  P-face particle densities of rhabdomeric membrane ranged from 104/m2 in the fortified animals to 4×103/m2 in intermediate animals to 5×102/m2 in deprived moths (Figs. 3, 4 and Table 2).
6.  The sensitivity of the intermediate and deprived animals averaged 55% and 0.06%, respectively, of that of the fortified animals (Fig. 1 A). Measurement of the ERG proved to be the simplest and most sensitive method for measuring visual impairment. If sensitivity remains linear with rhodopsin content at low concentrations, deprived retinas contain about 0.04 pM of rhodopsin.
7.  Visual sensitivity increased by 10 to 40-fold following the addition of-carotene or xanthophyll to the deprived diet. Addition of either retinol or retinal did not significantly increase sensitivity (Fig. 1A).
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15.
Coxal hair-plate sensilla in the spider Cupiennius salei are described with respect to their innervation, central projection pattern, electrical response to mechanical stimulation, and putative behavioral function.
1.  Hair plates, each comprising 25–70 hairs, are situated on the ventrolateral leg coxae close to the prosomal joint; during coxal movements they are deflected by the bulging joint membrane. Each plate hair is innervated by one sensory cell.
2.  Threshold sensitivity lies at 0.5° to 1° of hair deflection. Only distalward deflection excites. During maintained deflections the spike rate declines slowly. These hairs differ from hair sensilla of insects in that we measure no standing potential, nor do we measure a receptor potential accompanying a mechanical stimulus.
3.  The central projection areas of both hair plates are limited to neuropil of the ipsilateral neuromere.
4.  Natural stimulus situation and the spike response to maintained deflection suggest that these hairs are used in proprioception and graviception. Yet behavioral changes following selective hair-plate ablations are not very pronounced. Unilateral removal of hair-plates produced significant increases in average body height in 7 of 10 animals, while the angular orientation of the long body axis with respect to gravity remained unchanged after hair-plate removal.
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16.
1.  Chronic ingestion of caffeine by male NIH strain mice alters the density of a variety of central receptors.
2.  The density of cortical A1 adenosine receptors is increased by 20%, while the density of striatal A2A adenosine receptors is unaltered.
3.  The densities of cortical 1 and cerebellar 2 adrenergic receptors are reduced byca. 25%, while the densities of cortical 1 and 2 adrenergic receptors are not significantly altered. Densities of striatal D1 and D2 dopaminergic receptors are unaltered. The densities of cortical 5 HT1 and 5 HT2 serotonergic receptors are increased by 26–30%. Densities of cortical muscarinic and nicotinic receptors are increased by 40–50%. The density of cortical benzodiazepine-binding sites associated with GABAA receptors is increased by 65%, and the affinity appears slightly decreased. The density of cortical MK-801 sites associated with NMDA-glutaminergic receptors appear unaltered.
4.  The density of cortical nitrendipine-binding sites associated with calcium channels is increased by 18%.
5.  The results indicate that chronic ingestion of caffeine equivalent to about 100 mg/kg/day in mice causes a wide range of biochemical alterations in the central nervous system.
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17.
The interactions occuring between graft and host leg epidermis at a congruent junction (non-rotated, homopleural combination of components cut perpendicular to the proximal-distal axis) were studied at the tibia level in the cockroach,Blattella germanica. Grafts were made between dark (Bl) and light (br) cuticle colour mutants.
1)  Precise boundaries could not usually be drawn between Bl and br tissue over areas of bare cuticle but spines, hairs and claws could be identified, providing a good indication of the graft or host origin of regenerated structures.
2)  When the graft tarsus remained intact, segmented structures were not regenerated from the junction. Host distal tibia and graft proximal tibia interacted to produce a reversed orientation intercalary regenerate, usually composed mainly of host cells which had become more proximal than their level of origin.
3)  When the graft tarsus was amputated (or broken off), nearly 50% of congruent junctions regenerated segmented distal structures, which were classified as autonomous or lateral. Amputation of the graft tarsus acted, not through removal of any inhibition, but by hindering healing of the junction because of the apolysis of graft tibial epidermis.
4)  Distal structures regenerated autonomously by host and graft components of the junction were either complete or partial (fused at a common level in the tarsus).
5)  Lateral regenerates were of joint origin and usually distally incomplete. They were stable and, when amputated, were regenerated to approximately the same level, in the presence or absence of the graft tarsus.
6)  It is concluded that autonomous regeneration occurred from junctions which had totally failed to heal, and that lateral regeneration occurred from an unhealed sector of a junction. Laterals were therefore regenerated from a bilaterally symmetrical, partial circumference. They are compared to other incomplete regenerates found in analogous situations. The relationship between transverse organization and distal incompleteness is obscure.
7)  Segmented structures are thus regenerated only in situations where host and graft do not heal and interact (at least initially) over all or part of the circumference of the junction: interaction results in the formation of an unsegmented intercalary regenerate comprising the levels normally lying between host and graft on the proximal-distal axis.
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18.
1.  Larval cultures of Sarcophaga argyrostoma, preconditioned for a low incidence of pupal diapause by embryonic exposure to continuous light, were transferred from sequences of diapause-inducing long nights into terminal sequences of either diapause-averting short nights or darkness. Conversely, other groups preconditioned for a high incidence of diapause by embryonic exposure to long nights were transferred from short nights into terminal long nights or darkness.
2.  The inductive effects of long nights (diapause) and short nights (non-diapause) were accumulated during the larval sensitive period which continued until puparium formation. Since the larvae in any one group formed puparia over a number of days it follows that late pupariaters experienced a greater number of inductive light cycles (or days in DD) than those that pupariated early.
3.  Analysis of diapause incidence in cultures transferred from long nights to DD at different temperatures, as a function of the day of pupariation, showed that the daily increase in diapause was a temperature-compensated process beginning after 9–10 cycles and reaching 10% after about 15 cycles. Cultures transferred from a series of short nights into DD at different temperature showed no evidence of temperature-compensation.
4.  The results are interpreted in terms of the external coincidence model for photoperiodic time measurement.
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19.
1.  Spectral-sensitivity functions of large-field movement-detecting units in the lobula plate of the dronefly Eristalis tenax L., which is a Batesian mimic of the honeybee, were measured using visual stimuli consisting of light flashes, or moving gratings. Two classes of units were studied, one class responding to inward horizontal motion in the contralateral eye (presumably the homologue of the well-known HI in other fly species), and the other class responding to vertically-down-ward motion in the contralateral eye.
2.  In both classes of units, the spectral-sensitivity function of the response to flashes is characterized by two peaks, one in the UV at ca. 350 nm and the other in the blue at ca. 475 nm (Figs. 3, 8). It resembles the spectral-sensitivity function of the R1-R6 class of receptors in other flies.
3.  In both classes of units, the spectral-sensitivity function of the response to movement is characterized by a single peak, occurring in the blue at ca. 450 nm (Figs. 7, 9).
4.  Control experiments on homologous units in the Australian Sheep Blowfly Lucilia cuprina, using identical stimulating conditions reveal that the response to flashes as well as movement possesses a dual-peaked spectral sensitivity, with one peak in the UV and the other in the blue-green region of the spectrum (Figs. 10–12).
5.  The results indicate that the pathways subserving the inputs to movement-detecting neurons in Eristalis are driven by more than one spectral class of photoreceptors. They also reveal that the spectral sensitivity of movement detection in Eristalis bears a closer resemblance to that of the honeybee, than to that of other flies. This similarity to the honeybee may arise from the fact that the dronefly and the honeybee occupy similar ecological niches, both foraging for nectar in flowers.
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20.
1.  In a concentration-dependent manner neuropeptide Y was found to be a potent inhibitor of the spontaneous activation of human granulocytes and macrophages as well asMytilus edulis immunocytes.
2.  Neuropeptide Y also inhibited the chemotaxic response of these immunocytes to the chemoattractant f-MLP.
3.  Incubation of both the human and the invertebrate immunocytes in f-MLP (10–9 M) causes activation as noted by random locomotion (chemokinesis). Neuropeptide Y also blocked f-MLP-induced chemokinesis.
4.  The results suggest that neuropeptide Y may, in addition to other functions, serve as an endogenous regulator of immunocyte function.
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