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  • 1
    Digitale Medien
    Digitale Medien
    Electrophoresis as a tool for estimating levels of hymenopterous parasitism in field populations of the cereal aphid, Sitobion avenae (1990)
    Springer
    Entomologia experimentalis et applicata 54 (1990), S. 271-279 
    Details
    ISSN: 1570-7458
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Beschreibung / Inhaltsverzeichnis: Résumé L'électrophorèse sur gel de polyacrylamide a servi à déterminer l'importance du parasitisme de populations naturelles de S. avenae F. Des clés électrophorétiques, préparées à partir de parasitoïdes élevés au laboratoire, ont été utilisées pour identifier les parasitoïdes provenant des pucerons récoltés dans la nature. Ainsi ont été décelés les parasites primaires: Aphidius rhopalosiphi De Stefani Perez, A. ervi Haliday, A. picipes Nees, Praon volucre Haliday, Ephedrus plagiator Nees et Aphelinus abdominalis Dalman. Quelques bandes non-identifiées devraient être attribuées à des hyperparasitoïdes. L'électrophorèse a été comparée aux techniques d'échantillonnage plus conventionnelles de décompte des momies et d'élevage des individus vivants utilisées pour estimer le taux de parasitisme. L'électrophorèse et les méthodes d'élevage donnent généralement des résultats semblables pour les 2 niveaux de parasitisme et la composition en espèces de parasitoïdes, tandis que le décompte des momies tend à donner des résultats inférieurs.
    Notizen: Abstract Polyacrylamide gel electrophoresis was used to monitor levels of parasitism in field populations of the cereal aphid, Sitobion avenae (F.) (Hemiptera: Aphididae). Electrophoretic keys previously prepared from laboratory-reared parasitoids were used to identify parasitoids within field-collected aphids. Using this approach, the primary parasitoids Aphidius rhopalosiphi De Stefani Perez, Aphidius ervi (Haliday), Aphidius picipes (Nees), Praon volucre Haliday, Ephedrus plagiator Nees and Aphelinus abdominalis Dalman were detected. Some unidentified banding patterns were also obtained, most of which were probably attributable to the presence of hyperparasitoids. Electrophoresis was compared with the more conventional sampling techniques of live-rearing and mummy counts as a means of estimating percentage parasitism. Electrophoresis was found to be a much quicker method than live-rearing and gave similar results for both levels of parasitism and parasitoid species composition, whereas mummy counts tended to give lower estimates than the other two methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00186796
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  • 2
    Digitale Medien
    Digitale Medien
    Electrophoretic study of enzymes from cereal aphid populations (1985)
    Springer
    Theoretical and applied genetics 70 (1985), S. 407-412 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Parthenogenetic aphid populations ; Allozymes ; Polymorphic loci ; Hidden genetic variation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A study of variation in three peptidases (PEP−3 to −5) in a parthenogenetic S. avenae field population at Rothamsted using serial one-dimensional polyacrylamide gel electrophoresis (involving changes of gel concentration and electrophoretic run-time) increased the overall number of “allozymes” (mobility variants) detected from 10 under standard conditions (6% gels, 2 h run-time) to 22, as well as revealing putative heterozygous banding patterns under some test conditions. However, an examination of another enzyme, 6-phosphogluconate dehydrogenase (6-PGD) in a sample collected at Rothamsted the following year failed, using a combination of serial methods (changes of gel concentration) and isoelectric focusing, to increase the total number of 6-PGD bands separated (seven, none of which appeared to be allelic in origin). Nevertheless, some major bands were split into several bands, whilst other infrequent bands were either gained or lost. The findings are briefly discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00273746
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  • 3
    Digitale Medien
    Digitale Medien
    Dissociation between mechanical performance and the cost of isometric tension maintenance inLethocerus flight muscle (1985)
    Springer
    Journal of muscle research and cell motility 6 (1985), S. 163-175 
    Details
    ISSN: 1573-2657
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A method for the continuous measurement of ATP hydrolysis (ATPase) by demembranated muscle fibres has been applied to isometrically held, glycerol-extracted flight muscle fibres from the water-bugLethocerus, under conditions of high MgATP, neutral pH, and varying ionic strength, Ca2+ and extension. These variables caused parallel changes in isometric tension and ATPase. The slope of ATPase upon tension (ΔATPase/ΔTension; incremental tension cost) remained the same upon extension at either different Ca2+ concentrations or different ionic strength. Isometric activation by Ca2+ gave a higher incremental tension cost. The calculated mechanical rate constant of the work-producing process, measured by the small-amplitude behaviour, was increased by either Ca2+ or ionic strength, and little changed by extension; there was therefore a dissociation between its value and that of the incremental tension cost. The results appear to exclude a two-state crossbridge model for fibrillar insect flight muscle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00713058
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  • 4
    Digitale Medien
    Digitale Medien
    Generation of tension by glycerol-extracted vertebrate skeletal muscle fibres in the absence of calcium (1983)
    Springer
    Journal of muscle research and cell motility 4 (1983), S. 543-556 
    Details
    ISSN: 1573-2657
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary When a small bundle of glycerol-extracted fibres from either frog, tortoise or rabbit skeletal muscle was first exposed to high MgATP (5mm) in the absence of Ca2+ (〈1nm) and at low ionic strength (〈0.11) at 20° C, it produced a single sharp transient contraction followed by a lower maintained isometric tension. The maintained tension was investigated further in rabbit psoas fibres. Ca2+-free tension was dependent on the ionic strength in the range 0.04–0.10, on the temperature in the range 6–20° C and the free Mg2+ in the range 0–6mm. It was promoted by low ionic strength, low Mg2+ and high temperature, and was unaffected by varying the MgATP2− in the range 0.4–4mm and by adding ATP regenerating components. A separate regime of tension generation was detected at MgATP2− concentrations of less than 0.1mm, in which MgATP2− concentration was critical. The results are interpreted on the assumption that binding of Mg2+ to some component of the regulatory system is necessary to maintain its inhibitory effect in the absence of Ca2+. Ionic strength and temperature, on the other hand, may affect actomyosin directly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00712114
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