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  • Ultrastructure  (41)
  • pheromone  (16)
  • Springer  (57)
  • International Union of Crystallography
  • PANGAEA
  • 2000-2004  (3)
  • 1975-1979  (54)
  • 1960-1964
  • 1945-1949
  • 1935-1939
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  • Springer  (57)
  • International Union of Crystallography
  • PANGAEA
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  • 1
    Electronic Resource
    Electronic Resource
    The need for speed. II. Myelin in calanoid copepods (2000)
    Springer
    Journal of comparative physiology 186 (2000), S. 347-357 
    Details
    ISSN: 1432-1351
    Keywords: Key words Crustacean ; Sensorimotor ; Ultrastructure ; Multilamellar sheath ; Myelinated axons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Speed of nerve impulse conduction is greatly increased by myelin, a multi-layered membranous sheath surrounding axons. Myelinated axons are ubiquitous among the vertebrates, but relatively rare among invertebrates. Electron microscopy of calanoid copepods using rapid cryofixation techniques revealed the widespread presence of myelinated axons. Myelin sheaths of up to 60 layers were found around both sensory and motor axons of the first antenna and interneurons of the ventral nerve cord. Except at nodes, individual lamellae appeared to be continuous and circular, without seams, as opposed to the spiral structure of vertebrate and annelid myelin. The highly organized myelin was characterized by the complete exclusion of cytoplasm from the intracellular spaces of the cell generating it. In regions of compaction, extracytoplasmic space was also eliminated. Focal or fenestration nodes, rather than circumferential ones, were locally common. Myelin lamellae terminated in stepwise fashion at these nodes, appearing to fuse with the axolemma or adjacent myelin lamellae. As with vertebrate myelin, copepod sheaths are designed to minimize both resistive and capacitive current flow through the internodal membrane, greatly speeding nerve impulse conduction. Copepod myelin differs from that of any other group described, while sharing features of every group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050435
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  • 2
    Electronic Resource
    Electronic Resource
    Female pheromone in the black molly fish (Mollinenesia latipinna): A possible metabolic correlate (1977)
    Springer
    Journal of chemical ecology 3 (1977), S. 207-217 
    Details
    ISSN: 1573-1561
    Keywords: Black molly fish ; Mollinenesia latipinna ; pheromone ; thyroxine ; thiouracil ; general activity stimulus ; social contact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The female black mollyMollinenesia latipinna emits a water-borne pheromone which increases general activity and social contacts among males. Two hormones, thyroxine and thiouracil, administered to the females increase these behaviors in males. Apparently the hormones do not functionally compete in this species, and both seem to elevate the emission of the male stimulant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00994147
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  • 3
    Electronic Resource
    Electronic Resource
    The general ultrastructure of the carotid body of the domestic fowl (1975)
    Springer
    Cell & tissue research 162 (1975), S. 483-497 
    Details
    ISSN: 1432-0878
    Keywords: Carotid body ; Domestic fowl ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic studies of the carotid body of the domestic fowl (Gallus gallus domesticus) have shown Type I and Type II cells combined with axons into compact groups. The many Type I cells in the depths of the organ had a body, containing the nucleus, and an elongated, flared process. Some of the Type I cells in the superficial regions tended to be spindle-shaped. Type I cells were characterised by membrane-bound, dense-cored vesicles about 120 nm in diameter. Type II cells invested the Type I cells and had axons embedded in them as in Schwann cells. The fine structure of the carotid body in the domestic fowl resembles that of the Lovebird (Uroloncha domestica) and of various amphibia and mammals. The possibility is discussed that the Type I cells may have a chemoreceptor or a general secretory function, or even both pathway for functions together. The main role of the Type II cells seems to be to provide a of these axons leading to or from Type I cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209348
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  • 4
    Electronic Resource
    Electronic Resource
    Synaptic morphology of the carotid body of the domestic fowl (1975)
    Springer
    Cell & tissue research 162 (1975), S. 459-473 
    Details
    ISSN: 1432-0878
    Keywords: Carotid body ; Domestic fowl ; Reciprocal synapses ; Afferent axons ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Efferent and reciprocal synapses have been demonstrated in the carotid body of the domestic fowl (Gallus gallus domesticus). Synapses were also found with purely afferent morphology, but were probably components of reciprocal synapses. The general morphology of the endings suggested the presence of two types of axon, afferent axons making reciprocal and perhaps afferent synapses with Type I cells, and efferent axons making efferent synapses with Type I cells. A few axo-dendritic synapses were also found. The dense-cored vesicles associated with the afferent components of reciprocal synapses and with the possible true afferent synapses varied in diameter and core but could belong to one population of presynaptic vesicles. These observations are consistent with a new theory for the carotid body receptor mechanism. This proposes a spontaneously discharging afferent axon inhibited by an inhibitory transmitter substance released by the Type I cell via the “afferent” component of its reciprocal synapse, the “efferent” component inhibiting this release. Besides this chemoreceptor modulation of its afferent axon, the Type I cell may also have a general secretory function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209346
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of the compound eye of the diploid female beetle, Xyleborus ferrugineus (1975)
    Springer
    Cell & tissue research 165 (1975), S. 23-36 
    Details
    ISSN: 1432-0878
    Keywords: Sensory receptor ; Compound eye ; Insect ; Ultrastructure ; Scanning and transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The compound eye of female (diploid) Xyleborus ferrugineus beetles was examined with scanning and transmission electron microscopy. The eye is emarginate, and externally consists of roughly 70–100 facets. Each ommatidium is composed of a thickly biconvex lenslet with about 50 electron dense and rare layers. The lens facet overlies a crystalline cone of the acone type which is roughly hourglass-shaped. Pigment cells envelop the entire ommatidium, and pigment granules also are abundant throughout the cytoplasm of the 8 retinular cells. The rhabdomeres of 2 centrally situated photoreceptor cells effectively fuse into a rhabdom that extends from the base of the crystalline cone deeply into the ommatidium. Six distal peripheral retinular cells encircle the 2 central cells, and their rhabdomeres join laterally to form a rhabdomeric ring around the central rhabdom. The rhabdom and rhabdomeric ring are effectively separated by the cytoplasm of the two central retinular cells which contains the usual organelles and an abundance of shielding pigment granules. Eight axons per ommatidium gather in a tracheae-less fascicle before exiting the eye through the fenestrate basement membrane. No tracheation was observed among the retinular cells. Each Semper cell of each observed crystalline cone contained an abundance of virus-like particles near the cell nucleus. The insect is laboratory reared, and the visual system seems very amenable to photoreceptor investigations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222797
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  • 6
    Electronic Resource
    Electronic Resource
    Electron-microscopic observations of normal coelomocytes from the earthworm, Lumbricus terrestris (1977)
    Springer
    Cell & tissue research 185 (1977), S. 315-330 
    Details
    ISSN: 1432-0878
    Keywords: Leukocytes ; Coelomocytes ; Earthworms ; Immunity ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Coelomocytes of the earthworm, Lumbricus terrestris, were studied by transmission electron microscopy. Four morphological cell types are distinguishable: lymphocytic coelomocytes, granulocytic coelomocytes, eleocytes (chloragogen cells), and inclusion-containing coelomocytes. Within these major categories, several distinct cell types differ and may represent developmental stages. The two types of lymphocytic coelomocytes are small with central nuclei and scanty cytoplasms. Two types of granulocytic coelomocytes differ greatly in shape and content; both have small dark-staining granules that resemble lysosomes. Electrocytes, derived from chloragogen tissue, contain a variety of granules, inclusions and vacuoles. Inclusion-containing coelomocytes appear as two types which may be immature and mature forms. Although these cells resemble those that have been referred to as erythroid cells in other invertebrates, the large inclusion bodies are apparently unrelated to hemoglobin; they can undergo morphologic transformation and be extruded by exocytosis. This information on lymphocytic, granulocytic and inclusion-containing coelomocytes is crucial to understanding more about cellular immunity in the earthworm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220292
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  • 7
    Electronic Resource
    Electronic Resource
    Quantitative estimates of the western pine beetle attractive pheromone components,exo-brevicomin, frontalin, and myrcene in nature (1979)
    Springer
    Journal of chemical ecology 5 (1979), S. 397-414 
    Details
    ISSN: 1573-1561
    Keywords: Dendroctonus brevicomis ; exo-brevicomin ; frontalin ; myrcene ; attractant ; pheromone ; pheromone production ; pest management ; bark beetle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Three parameters are described for estimating the natural occurrence of chemically defined insect pheromones: (1) the rate and duration of release by the insect, (2) the density of the pheromone-emitting insect population in both time and space, and (3) dispersal and degradation rates of the chemicals. Each of these parameters, except dispersal, was estimated for a population ofDendroctonus brevicomis LeC, and its three component attractive pheromones. A single generation of 610,000 beetles, believed to comprise the entire population in a 65-km2 forest, was estimated to have released 0.78, 3.7, and 370.5 g of frontalin,exo-brevicomin, and myrcene, respectively, within a 30-day period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987925
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  • 8
    Electronic Resource
    Electronic Resource
    Trapping the western pine beetle at and near a source of synthetic attractive pheromone Effects of trap size and position (1979)
    Springer
    Journal of chemical ecology 5 (1979), S. 519-531 
    Details
    ISSN: 1573-1561
    Keywords: Pinus ponderosa ; Dendroctonus brevicomis ; western pine beetle ; attractant ; pheromone ; behavior ; traps ; Coleoptera ; Scolytidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Western pine beetles were caught on unbaited sticky traps placed near a source ofexo-brevicomin, frontalin, and myrcene. Size of trap, distance and direction from the source of attractant, and height from the ground were varied. Significant differences in trap catch were observed in relation to each of the variables. Traps close to the source of attractant caught more beetles than traps farther from the source. Traps downwind of the source of attractant caught more beetles than did upwind traps. More males than females were trapped close to the source of attractant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00987837
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  • 9
    Electronic Resource
    Electronic Resource
    Synthesis and field testing of 4,6,6-lineatin, the aggregation pheromone ofTrypodendron lineatum (Coleoptera: Scolytidae) (1979)
    Springer
    Journal of chemical ecology 5 (1979), S. 681-689 
    Details
    ISSN: 1573-1561
    Keywords: Trypodendron lineatum ; 4,6,6-lineatin ; 3,3,7-trimethyl-2,9-dioxatricyclo[3.3.1.04,7]nonane ; pheromone ; attractant ; tricyclic acetal ; Scolytidae ; aggregation pheromone ; ambrosia beetle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Authentic 4,6,6-lineatin (3,3,7-trimethyl-2,9-dioxatricyclo-[3.3.1.04,7]nonane) (I) was produced in low yield via three synthetic pathways. In field tests, microgram amounts of the product from all three syntheses attracted large numbers ofTrypodendron lineatum of both sexes. These results confirm that 4,6,6-lineatin (I) is a population aggregation pheromone forT. lineatum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00986553
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  • 10
    Electronic Resource
    Electronic Resource
    Has the Attraction of Predatory Coccinellids to Cornicle Droplets Constrained Aphid Alarm Signaling Behavior? (2000)
    Springer
    Journal of insect behavior 13 (2000), S. 321-329 
    Details
    ISSN: 1572-8889
    Keywords: kairomone ; searching ; predator–prey interactions ; pheromone ; E-B-farnesene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When attacked by a predator, aphids of many species secrete cornicle droplets, containing an alarm pheromone, that results in the dispersal of nearby conspecifics. As females are parthenogenetic, alarm signaling functions to enhance the survival of clone-mates. Enigmatically, however, aphids are physically able to, but usually do not emit alarm pheromone when initially detecting a predator, but rather signal only when captured by a predator. We hypothesized that cornicle droplets may be attractive to natural enemies and result in an increased risk of predation for the signaler, thereby selecting for prudent alarm signalers. We tested this hypothesis by investigating the olfactory cues that the multicolored Asian ladybird beetle, Harmonia axyridis Pallas, uses to locate pea aphids, Acyrthosiphon pisum. In choice tests, H. axyridis were attracted to odors from pea aphid colonies, whether feeding or not feeding on a host plant leaf, but were not attracted to cornicle droplets containing alarm pheromone. Further, individual pea aphids emitting cornicle droplets were not located more often or in a shorter period of time by beetles than aphids not emitting cornicle droplets. Thus, the cost of emitting early alarm signals is not prohibitively high in regards to the attraction of predators such as H. axyridis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007754000862
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