摘要:

AbstractSinusoidally modulated and discrete light pulses, the parameters of which approximated natural light conditions, were used to determine the response characteristics of ocellar first‐order interneurons of the worker honeybee (Apis mellifera carnica). Large ocellar interneurons which terminate within the brain (LBneurons) were recorded from intracellularly and were identified visually after dye injection.Absolute sensitivity of LBneurons to light flashes ranges from 4 × 109quanta/cm2s (Q) for MOC1,7 neurons to 1 × 1012Q for MOC3,4. The slope of the response‐intensity (R/I) functions, which were calculated for intensities between 2 × 109and 4 × 1013Q, varies in different types of LBneurons. The strongest response is given by one group of median ocellar neurons. With constant light around 1013Q, most LBneurons exhibit oscillatory hyperpolarizations which, upon increasing the stimulus to even higher intensities (1014–1015Q), gradually evolve to a hyperpolarized plateau. The frequency of these oscillatory voltage fluctuations increases with the rate of modulation of the stimulating light and reaches maximum values at 5–15 Hz modulation frequency. Two groups of MOC neurons follow sinusoidally modulated light up to 32 ± 8 Hz (n= 5) and 29 ± 6 Hz (n= 3), respectively, whereas lateral ocellar neurons cut off at 17 ± 5 Hz (n= 4).The possible role of LBneurons is discussed. They may be inactivated when the bee is flying in b

ISSN:0022-3034    

DOI:10.1002/neu.480200602

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe biosynthetic capabilities of individual neurons of the abdominal ganglion of the marine molluscAplysia californicahave been analyzed after intrasomatic injection of3H‐monosaccharides. Glycopeptides prepared from the metabolically labeled cells were fractionated using serial lectin affinity and gel filtration chromatography. The fractionation procedure yielded eight populations of glycopeptides, and comparison of two different neurons (R2 and R14) showed that the quantity of the individual species produced is cell‐dependent. Structural analysis indicated that the glycoconjugates produced by theAplysianeuron constitute both O‐ and N‐linked structures as well as an unusual class of oligosaccharide whose linkage to protein is unknown. The O‐linked units are small and consist only ofN‐acetylglucosamine orN‐acetylgalactosamine attached to protein. High‐mannose‐type asparagine‐linked units are produced by the neurons, and some of these appear to be processed to biantennary complex‐type units that bind to lentil lectin‐agarose. Overall, although theAplysianeurons produce oligosaccharides of a nature similar to that produced by higher eucaryotes, the N‐ and O‐linked structures produced by the neurons do not achieve the complexity of the comparable structures produced by mammalian cells. The results provide a basis for further studies aimed at understanding the role of glycoconjugates in the develo

ISSN:0022-3034    

DOI:10.1002/neu.480200603

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

年代:1989

数据来源: WILEY

摘要:

AbstractIn the accompanying paper (Gabel, Den, and Ambron, in press) it was shown that eight populations of glycopeptides are synthesized by single neurons ofAplysia californica. To see which glycopeptides might mediate interactions with target cells, we first identified glycopeptides that are transported selectively to synapses and growth cones. The giant neuron R2 was injected intrasomatically with3H‐glucosamine. Twenty‐four hours later,3H‐glycopeptides in the axon and cell body were isolated and resolved by serial lectin affinity chromatography. Of the eight populations, the biantennary‐type glycopeptides (GPbi) and those that bind to WGA (GPwga) were preferentially associated with rapidly transported glycoproteins. In contrast, the glycopeptide that consists ofN‐acetylglucosamine O‐linked to ser/thr was mostly retained in the cell body. GPbi and GPwga were also preferentially transported to growth cones. Analyses of RUQ cells, exposed to3H‐glucosaminein vitrofor 36 h showed an enrichment of GPbi and GPwga at the growth cone relative to the cell body. The disposition of the various glycopeptides in growing neurons was also examined using FITC lectins. FITC‐coupled WGA,Vicia vellosa, and lentil lectin showed extensive staining of the cell body, but only WGA stained the growth cones.To investigate if GPwga interacts specifically with target cells, these glycopeptides were isolated from the neurons of 180 abdominal ganglia. GPwga, otherAplysiaglycopeptides, and glycopeptides prepared from ovalbumin were coupled separately to fluorescent spheres. The spheres were then added to muscle cells isolated from the auricle of the heart, which is innervated by many neurons from the ganglion. While spheres coupled to GPwga bound to the muscle cell surface, the other glycopeptides did not. These results indicate that glycopeptide class GPwga, found among rapidly transported glycoproteins and on the growth cone surface, is able to bind to muscle cells and may therefore play some role in neuron‐ta

ISSN:0022-3034    

DOI:10.1002/neu.480200604

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

年代:1989

数据来源: WILEY

摘要:

AbstractThe principal locomotory appendages of theManduca sextacaterpillar, the prolegs, are present on the third through sixth abdominal segments (anal prolegs located on the terminal segment were not included in this study). Previous studies have characterized some of the proleg retractor muscles and their motoneurons. In the present study we identified additional proleg motoneurons and their putative homologs in the non‐proleg‐bearing segments. One of the motoneurons present in the proleg‐bearing segments is absent in the non‐proleg‐bearing segments. At pupation the prolegs are lost, their muscles degenerate, and some of their motoneurons regress structurally. Subsequently, subsets of the proleg motoneurons and their homologs in other segments die in a segment‐specific pattern. This is the first report of segment‐specific motoneurons, and of segment‐specific death of identified motoneurons, inManduca. During adult development the surviving proleg motoneurons innervate the tergosternal muscle (TSM) and grow bilateral dendritic arbors. Dendritic growth is completed by about the 12th of the 18 days of adult development. Following adult emergence all but one of the respecified proleg motoneurons dies. The hormonal dependence of dendritic outgrowth was tested by isolating abdomens to eliminate the ecdysteroid‐secreting glands in the thorax. Between the second and fifth days after pupation the motoneurons became progressively more competent to undergo dendritic outgrowth following abdomen isolation. The extent of dendritic outgrowth paralleled the degree of morphological development attained by isolated abdomens. It is concluded that ecdysteroids are required for motoneuron outgrowth, but our findings suggest that, unless an abdominal source of ecdysteroids exists in pupae, a relatively small exposure

ISSN:0022-3034    

DOI:10.1002/neu.480200605

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

年代:1989

数据来源: WILEY

摘要:

AbstractInDrosophila, brain stimulation of the giant fiber pathway brings about highly stereotyped electrical responses in target muscles involved in the escape response. Both the order of muscle response and the latency of that response are predictable in wild‐type flies. The neuronal circuit to the targets is well defined and has been used in the analysis of a number of mutant phenotypes, including induced anomalies in temperature‐sensitive (ts) mutations such asshibire (shi). It has been assumed that the stereotyped response includes simultaneous activation of all six fibers of the wing depressor muscle, DLM, resulting in equal latencies for all fibers. We report here a small, but distinct, inherent difference in latency between two sets of DLM fibers in a proportion of two wild‐type strains as well as in a strain carrying the ts mutationshi. This difference may occur on one or both sides of an individual, is stable over time, and persists when the motor axon is stimulated peripherally. These results, due to the circuit leading to the target, suggest that the difference in latency arises peripherally. In flies reared at theshipermissive temperature (22°C), the difference is more common inshithan in wild‐type flies; however, inshiflies reared at 18°C, the prevalence resembles that of wild‐type flies. This indicates a subtle expression of theshidefect even at the presumed permissive temperature of 22°C. The difference in latency is similar to that induced inshiflies whose development is affected by pupal heat pulse. Thus, correct interpretation of differences in latency, e.g., inshi/wild‐type mosaic flies or in flies with mutations affecting the GF pathway, requires recognition of the inherent asynchrony that can occur betw

ISSN:0022-3034    

DOI:10.1002/neu.480200606

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

年代:1989

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480200607

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

年代:1989

数据来源: WILEY

ISSN:0022-3034    

DOI:10.1002/neu.480200601

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

年代:1989

数据来源: WILEY