摘要:

AbstractThe electroretinographic responses of regenerated eyes of snails (C. aspersa) were studied by means of suction electrodes and single or repetitive flash stimulation. The eyes were fixed and observed under light and electron microscopy. The results indicate that the electroretinographic response of regenerated eyes does not differ from control eyes after dark adaptation. However, the repetitive stimulation of the regenerated eyes induced an earlier fatigue of the response, evident after the fifth stimulus. This fatigue is a function of light intensity. Ultrastructural features of the regenerated eyes are similar to those of the control eyes but regenerated eyes show smaller rhabdomeres, fewer photic vesicles, and fewer paracrystalline bodies. It is suggested that the regenerated eye lability to the repetitive stimulation might be due to the decrease in the amount of photic vesicles and paracrystalline bodies, to the decrease in membrane surface of the rhabdomeres, or to some other metabolic failure not distinguished at electron microscopic level, like the membrane ionic regulation. The appearance of photic vesicles in the axon cones of regenerated and stimulated cells also suggests a possible failure in the mechanism of transport of vesicles.

ISSN:0022-3034    

DOI:10.1002/neu.480140302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractTo investigate whether static and dynamic sensitivities of slowly and rapidly adapting stretch receptor organs (SAO and RAO, respectively) of crayfish are different when perturbed compared with those in conventional laboratory experiments, receptors were submitted to ramplike length changes of different velocities separated by long‐duration, constant lengths of different values. They were perturbed at random by fast, small‐amplitude length variations called “jitter.” First‐order afferent discharges were recorded extracellularly. Quantifications involved the separate estimation of static and dynamic response components. In the SAO, jitter (1) augmented the static sensitivity, (2) decreased the dynamic sensitivity, (3) simplified response profiles by decreasing nonlinearities and increasing transduction fidelity in terms of coding length. In the RAO, jitter (1) changed the behavior from phasic to tonic with length sensitivity, (2) decreased the dynamic sensitivity to values close to those of the unperturbed SAO, (3) increased transduction fidelity for stimulus length and decreased nonlinearities. Perturbation effects suggest that differences between SAO and RAO are more quantitative than qualitative. Moreover, they have general implications and are relevant to other mechanoreceptors at other levels i

ISSN:0022-3034    

DOI:10.1002/neu.480140303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractNonneuronal cells complicate the study of neuronsin vitro. A pure population of viable neurons can be obtained easily using gradients of Percoll. For each experiment, 20 dorsal root ganglia (DRG) are minced, then sequentially dissociated in collagenase and trypsin, which digest all the intercellular connections. The dissociated tissue is separated first on the basis of density, creating an interphase fraction enriched in neurons and satellite cells, which are then further separated on the basis of size. The neurons, obtained in the final pellet, number approximately 50,000 (2500 per DRG), routinely exhibit a viability of over 80% initially and are of a purity of over 90%. The viability of the neurons is confirmed by the occurrence of neurite outgrowth in culture. Thus, a pure and viable neuronal population is obtained by a simple and rapid method.

ISSN:0022-3034    

DOI:10.1002/neu.480140304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe temperature‐sensitiveDrosophilamutant,shibirets1(shi), has been shown to exhibit a reversible block in synaptic transmission at 30°C. Various synaptic terminals (neuromuscular, sensory, central) of this mutant were observed by electron microscopy. At 19°C, all terminals ofshishowed essentially the same structural features as those of wild‐type (Oregon‐R) flies, while at 30°C (5 or 10 min of exposure)shiterminals exhibited various structural changes not seen in the wild type. The major structural change observed in all of the various types of terminals was the accumulation of many pitlike structures on the plasma membrane near presynaptic sites. These structures consisted of a spherical head portion, about 50–100 nm in diameter, and a cylindrical neck portion, about 20 nm long and 20–25 nm in diameter. The neck portion was surrounded by a kind of cytoplasmic dense material, about 10 nm thick, reminiscent of a “collar.” Thus, these pits are referred to as “collared pits.” Similar kinds of pits were observed, although very rarely, in wild‐type flies at 19 and 30°C and inshiflies at 19°C. In addition, various degrees of vesicle depletion, and an increase in membranous structures (infoldings and cisternalike or tubulelike structures) often accompanied pit formation. The possibility that these pits are the result of a blocked step in the endocytotic process, which in turn causes vesicle depletion as exocytosi

ISSN:0022-3034    

DOI:10.1002/neu.480140305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractProteins synthesized in the nodose ganglia of rabbits were radiolabeled with35S‐methionine and the proteins present in the vagus nerve, at various times later, were analyzed by SDS (sodium dodecyl sulfate)–polyacrylamide gel electrophoresis. Three major groups of proteins were transported as waves of radioactivity within the nerve at rates of 15–17 mm/h, 12–15 mm/day, and 25–30 mm/day. The front of the fastest wave was composed of two proteins only, of apparent molecular weights 21,000 and 24,000. These were followed after a delay by a number of proteins of higher molecular weight, traveling at the same fast rate. The 25‐mm/day wave contained several proteins including a major one of molecular weight 43,000 while the 12‐mm/day wave was composed entirely of two proteins of molecular weights 54,000 and 56,000. These groups of slowly transported proteins are therefore similar to those transported much more slowly in other mammalian nerves, with the exception that no proteins with molecular weight similar to the neurofilament proteins could be detected. We have confirmed the dependence of slow transport for both groups of proteins on contact between cell body and axon and suggest that it may be a general phenomenon in all mam

ISSN:0022-3034    

DOI:10.1002/neu.480140306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThe effect of elevated levels of CO2on the neurons of the metathoracic ganglion of the common house cricket was examined. Elevated CO2produced a profound depolarization of the neurons without a substantial change in conductance. The depolarization was not due to CO2acidification of the external solution since exposure of the neurons to a solution which was nominally CO2free, but at an acid pH, produced little effect. The effect of elevated CO2appeared to be due to intracellular acidification, since other treatments which acidified the cell interior also produced deplorization. Agents which block intracellular pH regulation also substantially enhance the effect and prevent recovery. The mechanism producing the deplorization appears to be blockage of a metabolic component of the resting potential, since the action of metabolic blockers mimics the effect of elevated CO2.

ISSN:0022-3034    

DOI:10.1002/neu.480140307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480140301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY