ISSN:0022-3034    

DOI:10.1002/neu.480040602

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

年代:1973

数据来源: WILEY

摘要:

AbstractHk1,Hk2,Sh5, andEagare sex‐linked behavior mutants ofDrosophilawhich shake their legs vigorously when etherized. The shaking rate increases with age to a plateau by five days after eclosion; it is decreased by increasing ether concentrations.Eagis temperature sensitive, shaking vigorously at 30°C but not at all below 20°C.Hk1andHk2have cyclic shaking patterns consisting of three to six periods of shaking per minute.Hk1stakes more, and has longer shaking periods thanHk2; the heterozygoteHk1/Hk2is intermediate. When heterozygous with a deletion for the locus, bothHk1andHk2shake more, the pattern ofHk2resembling that ofHk1. Therefore, these alleles may differ only quantitatively. The shaking pattern ofSh5is distinctly different, consisting of short bursts of shaking two or three times a second. Flies with bothHkandSh5mutations in different combinations can have a pattern which isHk‐type,Sh5‐type, or both simultaneously, depending upon the geno‐type. The shaking ofHk1is known to be a consequence of abnormally firing neurons in the thoracic ganglion. Therefore, the interactions betweenHkandSh5are probably between two different mutant effects upon the motor system, both subject to genetic man

ISSN:0022-3034    

DOI:10.1002/neu.480040603

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

年代:1973

数据来源: WILEY

摘要:

AbstractNeural tubes from Hamburger‐Hamilton Stage 14–18 (50–68 hr incubation) chick embryos were dissociated by exposure to trypsin and cultured in Maximow double coverslip assemblies for up to 155 days. Undifferentiated neural tube cells continued to differentiate into large multipolar neurons with the features characteristic of mature neurons.Choline acetyltransferase and acetylcholinesterase activity, enzymes responsible for synthesizing and catabolizing acetylcholine transmitter in neurons, were demonstrated histochemically in neurons differentiated from early neural tube cells, indicating the development of these cells into biochemically mature neurons.It is concluded that the disruption of the tissue integrity of the neural tube does not interfere with the morphological and biochemical differentiation potencies of the neural tube cells in tissue cu

ISSN:0022-3034    

DOI:10.1002/neu.480040604

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

年代:1973

数据来源: WILEY

摘要:

AbstractSkeletal muscle fibers can be reinnervated by motor cholinergic fibers, that is, functional connection can be achieved. However, functional connection implies not only the capacity of the nerve impulse to elicit a contractile response but also the capability of the reinnervating neurons to evoke particular modifications of the physiological and biological features of the muscles.In order to search for some of the modifications due to reinnervation by preganglionic sympathetic fibers, muscle contraction time was studied in three different preparations of adult cats: a) cricothyroid muscle reinnervated by preganglionic fibers; b) cricothyroideus reinnervated by its own nerve; and c) the corresponding normal neuromuscular preparation. The activities of malic dehydrogenase, of aldolase and pyruvic kinase were studied in these three preparations as well as in the denervated cricothyroid muscles.Reinnervation by preganglionic fibers prolonged the twich contraction time, whereas, self‐reinnervation did not alter it. On the other hand, the activities of the three enzymes decreased as a result of denervation. In contrast, the muscle reinnervated with sympathetic preganglionic fibers partially recovered the normal level of malic dehydrogenase and the aldolase activities; but showed no modification in the level of pyruvic kinase activity. Conversely, in the muscle fibers reinnervated by their own nerve, the activity of the three enzymes returned to normal levels. The shortening of contraction time of the preganglionic reinnervated muscle correlates well with the features of the enzymic activities found in these muscles. It can be concluded: a) preganglionic sympathetic axons are able to achieve functional connections with striated muscles and b) considering the trophic effect, preganglionic fibers resemble the motor nerve supplying slow muscle

ISSN:0022-3034    

DOI:10.1002/neu.480040605

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe transport of RNA from the ganglion cell bodies within the retina to the contralateral optic tectum has been studied in the chick following intraocular injection of radioactive uridine. By tracing the appearance of labeled RNA at the proximal end of the optic nerve as it leaves the eyeball and comparing this to the time of arrival of RNA within the optic tectum, the migratory velocity of axonal RNA has been calculated to be around 12 mm per day. The continuation of RNA migration to the optic tectum in the presence of intracerebrally injected actinomycin‐D but not in the presence of the intraocularly injected drug, suggests a retinal site of synthesis of the excess RNA found in the tectum innervated by the injected eye. A study of the rate of disppearance of radioactivity of the transported RNA in the optic lobes, suggested that this RNA turns over more rapidly than the bulk of tectal RNA. The destination of migrating RNA within the optic tectum has been autoradiographically examined. Most radioactive RNA is found in the outer tectal layers in which are found the afferent fibers of the optic tract and most of their synaptic terminations. Label is not confined to these areas however but is also present in the deeper layers of the optic tectum which are not known to contain any primary synapses of the axons from retinal ganglion cell

ISSN:0022-3034    

DOI:10.1002/neu.480040606

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

年代:1973

数据来源: WILEY

摘要:

AbstractIntact synaptic complexes were isolated from five human cerebral cortices obtained 4–20 hr after death. Synaptic complexes had a common isopycnic banding density of 1.17–1.20 in CsCl. Their banding densities and ultrastructural features were similar to those of complexes isolated from a variety of other mammalian species. The ultrastructure of the synaptic complexes isolated from different aged subjects (2, 3, 28, 76, and 78 years old) were simi

ISSN:0022-3034    

DOI:10.1002/neu.480040607

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe metabolism of glycine was studied in vitro using preparations of synaptosomes (P2) isolated from the spinal cord, medulla oblongata, telencephalon, and cerebellum of the rat. The content of aspartate, glutamate, glutamine, serine, threonine, glycine, and alanine was determined in the crude synaptosomal fraction (P2) from the four regions of the CNS. In general, the content of the amino acids in the subcellular fraction from the medulla oblongata and spinal cord resembled one another whereas the same was true for the telencephalon and cerebellum. Significantly greater amounts of glutamate, aspartate, glutamine, and serine were found in the synaptosomal fraction of the telencephalon and cerebellum than in similar P2fractions from the medulla oblongata and spinal cord. On the other hand, glycine had a higher content in the latter two preparations than in the P2fractions from the telencephalon and cerebellum. [U‐14C]‐serine and [U‐14C]‐glycine were readily taken up by the crude synaptosomal fractions. The rate of conversion of serine to glycine appeared to be 18.5, 3.9, 2.9, and 2.7 times greater than the conversion of glycine to serine in the incubated synaptosomal fractions from the cerebellum, spinal cord, medulla oblongata, and telencephalon, respectively. The conversion of serine carbons into glycine appeared to be 2.5, 1.9 and 1.6 times greater in the synaptosomal fraction from the cerebellum, spinal cord, and medulla oblongata than in similar preparations from the telencephalon. The data are discussed in terms of the possible synthesis pathway for the pool of glycine used as a tran

ISSN:0022-3034    

DOI:10.1002/neu.480040608

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

年代:1973

数据来源: WILEY

摘要:

AbstractStrychnine, bicuculline, and picrotoxin show similar effects on the membrane of the lobster giant axon. At concentrations above 5 × 10−5M these compounds cause depolarization of the resting potential and a broadening of the action potential contour. Also occurring is an increase in excitability as defined by a decrease in stimulus threshold. Repetitive firing of action potentials is sometimes observed during the depolarizing process. Drug levels of 5 × 10−4Mand higher may secondarily induce depolarizing inactivation of the spike generating mechanism. The loss in resting potential is accounted for by a shift in relative membrane selectivity away from potassium and towards sodium. Associated with this alteration in selectivity is a marked fall in total conductance and abolition of delayed rectification. The results indicate that strychnine, bicuculline, and picrotoxin cause potassium inactivation and further that this effect is manifest in both the resting and active electrogenic state of the mem

ISSN:0022-3034    

DOI:10.1002/neu.480040609

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

年代:1973

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480040610

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

年代:1973

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480040611

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

年代:1973

数据来源: WILEY