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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 62 (1992), S. 293-300 
    ISSN: 1570-7458
    Keywords: Aphids ; Brachycaudus helichrysi ; Drepanosiphum platanoidis ; electrical penetration graphs ; potato virus Y ; stylet activities ; vector efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stylet penetration activities of two aphid species were recorded electrically and compared with their efficiency of potato virus Y transmission. B. helichrysi (Kltb.) acquired the virus during 15% of single penetrations on infected leaves. These acquisitions were associated with the occurrence of cell membrane puncture by stylets, recorded during 44% of the penetrations. D. platanoidis (Schrank) punctured membranes during only 8% of penetrations, and its acquisition efficiency was less than 1%. The frequency with which aphids puncture cell membranes appears to partially determine their vector efficiency.
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  • 2
    ISSN: 1871-4528
    Keywords: Brachycaudus helichrysi ; Myzus persicae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Zusammenfassung Im Abwind einer Parzelle mit PVY-infizierten Kartoffelpflanzen (7% PVYO, 4% PVYN, 89% beide) wurden fliegende Blattläuse in zwei vertikalen Netzen (4,4 m × 1,4 m mit hexagonalen Löchern mit 1,5 mm Durchmesser) gefangen und anschliessend auf Tabaksämlinge überführt, um zu prüfen, ob sie PVY übertragen. Die Blattläuse wurden vom 8. Juni bis zum 8. August 1984 normalerweise an einem Tag pro Woche von 10 bis 17 Uhr gefangen. Im Laufe von 12 Fangtagen wurden 6769 sachte 52% der Übertragungen bei nur 15% der totalen Fangzahl (Tab. 3).B. helichrysi mitMyzus persicae, Phorodon humuli und Species des GenusAphis ergaben sich als 90% der übertragenden Individuen bei nur 32% der gefangenen Proben. Acht Prozent der gefangenenB. helichrysi waren Überträger, dagegen nur 4,7% vonM. persicae. B. helichrysi könnte als Vektor besonders wichtig sein, weil sie in der Vegetationszeit Blattläuse von 119 Species oder Speciesgruppen gefangen, von denen 165 (2,44%) Tabak mit PVY inokulierten (Tab. 1). 133 Blattläuse übertrugen PVYO und 32 übertrugen PVYN (und möglicherweise auch PVYO). 20 Species oder Speciesgruppen waren Vektoren, von denen 9 (Cryptomyzus ballotae, Hyperomyzus lactucae, Metopolophium festucae, Myzus ligustri, M. myosotidis, Myzaphis rosarum, Sitobion avenae, S. fragariae undUroleucon spp.) erstmalig beschriebene Vektoren sind.Brachycaudus helichrysi verurfrüh auftritt (Tab. 2), wenn die Pflanzen am anfälligsten sind und die Virus-Translokation zu den Knollen am schnellsten stattfindet. Die Aussichten zum Gebrauch dieser Information zur Abschätzung des Aufbaues von Virusbefall im Bestand und die Aussichten für eine Vorhersage der Menge der wichtigsten Vektoren werden diskutiert. Es ist dringend erforderlich, die Biologie vonB. helichrysi zu untersuchen.
    Abstract: Résumé Deux filets verticaux (4,40 m × 1,40 m à mailles héxagonales de 1,5 mm de diamètre) sont placés face au vent pour la capture des pucerons dans une parcelle de plants de pommes de terre contaminés par PVY (7% PVYO, 4% PVYN, 89% par les deux) puis les pucerons sont transferrés sur des plantules de tabac en milieu clos pour tester la transmission de PVY. Les captures de pucerons ont eu lieu du 8 juin au 8 août 1984, en général à raison d'un journée par semaine, de 10 heures à 17 heures. Pendant les 12 premiers jours, 6769 pucerons de 119 espèces ou groupes d'espèces ont été capturés, les plantules de tabac ayant été inoculées par PVY avec 165 pucerons (2,44%) (tabl. 1). 133 pucerons étaient vecteurs de PVYO et 32 de PVYN (et probablement PVYO). 20 espèces ou groupes d'espèces étaient des vecteurs dont 9 récemment enregistrés (Cryptomyzus ballotae, Hyperomyzus lactucae, Metopolophium festucae, Myzus ligustri, M. myosotidis, Myzaphis rosarum, Sitobion avenae, S. fragariae etUroleucon spp.).Brachycaudus helichrysi représentait 52% des transmissions mais seulement 15% du total capturé (tabl. 3).B. helichrysi, Myzus persicae, Phorodon humuli et les espèces du gèneAphis représentaient 90% des transmissions et 32% des captures seulement. 8,0% deB. helichrysi capturé a transmis le virus contre, 4,7% pourM. persicae. B. helichrysi peut être particulièrement important comme vecteur dans la mesure ou il apparaît tôt en saison (tabl. 2) lorsque les plantes sont très sensibles et la translocation di virus aux tubercules la plus rapide. Les perspectives à partir de cette connaissance sont discutées en vue d'analyser l'évolution du virus dans une culture et les prévisions de l'abondance des plus importants vecteurs. Une plus grande connaissance de la biologie deB. helichrysi devient urgente.
    Notes: Summary Flying aphids were trapped throughout the summer on a vertical net downwind of a plot of PVY-infected potato plants. Of 6769 individuals caught, 165 transmitted PVY to tobacco test seedlings. Of 119 species or species groups caught, 20 were found to be vectors of which nine had not been recorded previously.Brachycaudus helichrysi, Myzus persicae, Phorodon humuli andAphis species accounted for 90% of transmissions andB. helichrysi alone for 52% of transmissions. The prospects of using this information to assess the amount of virus spread in a potato crop and of forecasting the timing and abundance of the main vectors are discussed.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 9 (1970), S. 141-157 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Instrumentation and associated techniques are described for the measurement of flow birefringence and extinction angles of high molecular weight polymer systems at extremely low velocity gradients. Precision of less than one degree in the extinction angles is obtained for birefringence smaller than 10-11, based upon studies of very dilute high molecular weight DNA solutions over a range of velocity gradients from 0.1 to 3 sec-1. Extinction angles approaching 44° are also observed with at least this degree of reliability for these systems. A relatively simple method of data reduction is outlined which permits explicit correction for solvent effects and for residual instrument birefringence and background; only the latter are found to be necessary at the shear rates reported in this communication. Applicability of the techniques to other macromolecules of biological interest is discussed.
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2167-2188 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The flow birefringence and extinction angle over a velocity gradient range of approximately 5-100 sec-1, and the zero shear-viscosity have been obtained from human umbilical cord hyaluronic acid at concentrations of 0.25, 0.125 and 0.0625%, and pHs 6.0, 6.5, 7.0, 7.5, 8.0, and 8.5 and constant ionic strength 0.1. The data indicate a large change in optical anisotropy as a function of pH, with most of the transition in the pH range 7.0-7.5, i.e., across the physiological range. The sign of the anisotropy changes between pH 8.0 and 8.5. These results, together with changes in the extinction angle and intrinsic viscosity as a function of pH, suggest a pH-dependent structural change in the system. Due to the abruptness of the transition, as evidenced by the intrinsic viscosity and flow birefringence, it is probable that the structural transition is cooperative. If the data are interpreted in terms of the Rouse-Zimm Gaussian subchain theory, a modification of the model in terms of the Haller-Cerf concept of internal viscosity is required. Thus, the demonstrated properties of hyaluronate solutions indicate a system with memory of stress. Due to the presence of large concentration effects discernible in the extinction angle measurements, hyaluronic acid probably exists as a network in solution. The results are discussed with respect to the mechanoelectrical transducing properties of hyaluronates and stress-dependent changes in ORD already reported.
    Additional Material: 3 Ill.
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  • 5
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The degradation and biocompatibility of seveal commercially available glasses, glass-ceramics, and ceramics have been evaluated in soft tissue. Tissue compatibility was investigated by histological and toxicological determinations. Materials degration was evaluated by weight loss and surface replica electron microscopic techniques. High lead and arsenic-selenium-sulfur glasses are found to be unsuitable materials for implantation due to high corrosion and toxicity. Certain borosilicate glasses are also found unacceptable because of severe corrosion. Fused quartz, aluminosilicates, certain borosilicates, alkali resistant glass, soda-lime glass, titania frit, arsenic trisulfide, lithium and magnesium aluminosilicate, glass-ceramics, and calcium-fluorapatite all appear to be well tolerated and seem acceptable for soft tissue implantation on the basis of the present data. Because of the lack of sensitivity of weight change as a parameter to measure low corrosion rates, we have no data on which to estimate the actual corrosion rate. The detailed changes in surface structurte produced during the corrosion process only provide information about the corrosion mechanism and may not be correlated with the corrosion rate. A more sensitive method to study low corrosion rates in glasses may be to use radioactive tracer techniques to measure the loss in radioactivity of glasses when implanted in the peritoneal cavity rather than subcutaneously.
    Additional Material: 20 Ill.
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