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  • 1975-1979  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 18 (1975), S. 1-16 
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die gebräuchlichen Techniken zur Zucht von pflanzensaugenden Insekten an künstlichen Diäten können nur relativ kleine Populationen liefern. Darüber hinaus hat der manuelle Aufwand, der für die Unterhaltung laufender Kulturen verschiedener Versuchsgruppen erforderlich ist, Ernährungsversuche mit pflanzensaugenden Insekten begrenzt. Zur Verbesserung dieser Situation wurde ein automatisches Zuchtsystem für laufende Zuchten der Erbsenlaus an holidischen Diäten konstruiert. Dieses System besteht aus Gefrierkammern, Diätflaschen, Verteilernetz, Pumpen und Diätkammern. Diese letzteren sind Teflonscheiben mit Rinnen, die als Doppelspiralmuster in eine der Oberflächen eingegraben sind. Daraus wird ein membranbedeckter Kanal durch Überziehen der Doppelspirale mit Parafilm. Durch diese Kanäle wird dreimal die Woche Diät gepumpt. Ein programmierbarer Zeitgeber regelt das System über längere Zeit hin. Dabei lassen sich Eintritt, Dauer und Reihenfolge der Abläufe leicht programmieren. Nur einmal in zwei Wochen müssen leere Flaschen durch volle ersetzt und alte Diätkammern durch neue ausgetauscht werden. Blattläuse können an den im System angeschlossenen Diätkammern leicht beobachtet werden; ebenso gut können diese Kammern, wenn nötig, für eine Inspektion vom System abgenommen werden. Das hier beschriebene automatische Zuchtsystem besitzt grosse technische Vorteile für die Massenproduktion von saugenden Insekten. Der hier entwickelte Zeitgeber ist verwendbar für die Automation von Systemen, die zu komplex für konventionelle Zeitgeber sind, aber auch nicht die Kapazitäten eines Prozessrechners erfordern.
    Notes: Abstract Current techniques for rearing plant-sucking insects on artificial diets can support only relatively small populations. Moreover, the manual effort required to maintain continuous cultures of several experimental groups has limited nutritional research on plant-sucking insects. To alleviate these problems, an automated-rearing system was devised to maintain continuous cultures of the pea aphid, Acyrthosiphon pisum, on holidic diets. The automated system is comprised of freezers, diet bottles, distribution networks, pumps, and diet chambers. The latter are Teflon® discs with grooves cut in a double-spiral pattern on one face. A membrane-covered channel is formed by bonding Parafilm® over the double spiral. Diet is pumped through the channels of the diet chambers three times a week. A programmable sequence timer controls the system for extended periods of time. The occurrence, duration, and order of the sequences may be easily reprogrammed. Once every 2 weeks, the system requires replacing empty bottles of diet with full ones and exchanging new diet chambers for old ones. Aphids are easily inspected with the diet chambers connected to the system or, if desired, the diet chambers can be disconnected for inspection away from the rearing facility. The automated-rearing system described here should be a great technological asset for the mass production of haustellate insects. The timer developed for the system is applicable for the automation of systems that are too complex for conventional timers but do not require the capabilities of process-control computers.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 103 (1975), S. 227-245 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The Photoperiodic Determination Model proposed earlier (I, II) is further elaborated, and its applicability to nondiel photoperiods tested. Model-generated predictions of diapause incidences were in good agreement with observed incidences among larvae of the European corn borer,Ostrinia nubilalis, reared under photoperiods from 15 to 50 hrs duration with scotophases of from 9 to 18 hrs.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 107 (1976), S. 97-111 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The Dual System Theory of photoperiodic time measurement is shown to provide a satisfactory basis for the interpretation of: (1) photoperiodic determination of diapause; (2) effects of different photoperiodic regimes on circadian rhythms of adult eclosion; and (3) the phase response curve. A fundamental unity of photoperiodic time measurement in a wide variety of organisms is strongly suggested by the Dual System Theory.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 105 (1976), S. 267-277 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The Dual System Theory of photoperiodic determination was found to be consistent with experimental data on diapause induction in response to skeleton photoperiods. Symmetrical and asymmetrical skeleton photoperiods of both diel and nondiel durations were investigated. The theoretical model was shown to predict accurately the incidence of diapause among larvae of the European corn borer,Ostrinia nubilalis, that had been reared under the different photoperiodic regimes.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0878
    Keywords: Blood-brain barrier ; Moth ; Diapause ; ATPase ; Peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural examination of diapause and nondiapause larval brains of the European corn borer disclosed anatomical differences that may be related to the insect's “blood-brain barrier.” The perineurial type I cells are quite closely appressed in the diapause brain, but thrown into extensive folds with large intercellular spaces in the nondiapause brain. The perineurial type II cells of diapause and nondiapause larvae are basically similar in general ultrastructure, and most likely form the basis for the “blood-brain barrier.” Horseradish peroxidase penetration studies indicated that the outer margin of the perineurial type II cells constitute the limits of infiltration into the brain. An enzymatic component of the “blood-brain barrier” is postulated in this insect. The localization of ATPase in the perineurial type II cells indicates that energy-requiring regulatory mechanisms may be localized here. Metabolic studies with isolated insect brains, coupled with recent evidence from mammalian systems, suggest that glial cells may be of importance in an enzymatic “blood-brain barrier.”
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0878
    Keywords: Cholesterol ; Symbiotes ; Aphids ; Digitonin ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pea aphid primary symbiotes have previously been shown to synthesize cholesterol in vitro. Two electron microscopic techniques were used here to determine whether the symbiotes also synthesize cholesterol in vivo and whether this cholesterol is made available to the aphid. We also inquired into a possible role of secondary symbiotes in cholesterol biosynthesis. Treatment of aphids with digitonin resulted in significant alteration of ultrastructural sites in primary and secondary symbiote membranes. We concluded that these sites are areas of high cholesterol concentration in the symbiotes. Electron microscopic autoradiography with 3H-mevalonate precursor indicated that both primary and secondary symbiotes synthesize cholesterol; in both cases, the majority of grains were associated with the symbiote membranes. While the frequency of grains on the symbiotes remained constant, irrespective of incubation time in labelled media, the frequency of grains over surrounding tissues increased exponentially as the time of incubation was increased from 30 min to 8 h, indicating that symbiote cholesterol is transported to other tissues. High voltage electron microscopic autoradiography permitted thick section autoradiography, reducing the time of emulsion exposure from 54 days (thin section) to 12 days (0.5 μm sections).
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0878
    Keywords: OsO4 ; Cholesterol ; Symbiotes ; Aphids ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pea aphids left for 48 h in unbuffered osmium tetroxide show heavy staining of many organelles in the symbiote-containing cells (mycetocytes and sheath), embryos and oenocytes very similar to that characteristic of mammalian sterol-synthesizing cells. However, the staining of the pea-aphid cells is, to a large extent, dependent on the presence of cholesterol benzoate, or free cholesterol, in the aphid's diet. In aphids cultured in vitro with 3H mevalonate in the presence of added cholesterol, the incorporation of label into the cholesterol and lanosterol fractions is significantly reduced. If the dietary cholesterol effects a similar inhibition in vivo, the cholesterol-dependent osmium staining could be due to precursors(s) of cholesterol accumulating in the intracellular sites described. There is also osmium staining of large (normally electron-transparent) vacuoles in mycetocytes, gut and fat body, irrespective of dietary cholesterol.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 159 (1975), S. 351-367 
    ISSN: 1432-0878
    Keywords: Symbiotes ; Aphids ; Vesicles ; Organelles ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A detailed investigation into the ultrastructure of the pea aphid mycetocytes and their contained symbiotes and organelles was carried out with the transmission electron microscope. The most striking observation was the presence of small vesicles in the space between the primary symbiote cell wall and membrane envelope (outer membrane space). The vesicles appear to form by a budding process at the outer cell wall layer. Subsequently, the vesicles, we suggest, may move out into the mycetocyte cytoplasm via a similar budding of the membrane envelope. The Golgi apparatus was found to be an important structural component of the primary mycetocyte; it is continuous with the rough endoplasmic reticulum and the latter, in turn, appears to be closely connected to the primary symbiote membrane envelope. This may be of functional significance. A number of other organelles not previously described in mycetocytes were found, including transparent vacuoles, granular bodies, multivesicular bodies and microfilaments. The chemical composition of the various vesicles and organelles is unknown at present.
    Type of Medium: Electronic Resource
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