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  • 1
    Electronic Resource
    Electronic Resource
    Temporal snychrony and patterns in an exotic host-parasitoid community (1994)
    Springer
    Oecologia 100 (1994), S. 196-199 
    Details
    ISSN: 1432-1939
    Keywords: Braconidae ; Tephritidae ; Temporal ; Synchrony
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied an imported host-parasitoid community in Hawaii, asking to what extent the species covaried in a systematic fashion even though all species were exotic to Hawaii, and occurred in an artificial agroecosystem (a commercial guava, Psidium guajava L., orchard). Using knock-down pyrethrin sprays we were able to accurately quantify numbers of the host, [oriental fruit fly, Bactrocera dorsalis (Hendel)] and its four major parasitoid species [Biosteres arisanus (Sonan), Diachasmimorpha longicaudata (Ashmead), Psyttalia incisi (Silvestri), and Bi. vandenboschi (Fullaway)] at hourly intervals. We found that the parasitoids' activity and abundance was well correlated with the activity and abundance of their host, and that all four parasitoid species covaried in concert with one another. In fact, the magnitude of correlation between the different species in this system was greater than the correlation with temperature. This show clearly that an entirely exotic community, reassembled piecemeal as a result of biocontrol efforts, can end up with patterns of temporal covariation that are highly coincident. One other interesting result concerns the speed with which sprayed trees were recolonized by the fruit fly and its parasitoids. The time that it took each species to reach its mean density prior to removal by the first pyrethrin spray at 0600 hours varied. It took 2 h for female B. dorsalis to recolonize guava trees to pre-spray levels. It took 3 h for Bi. arisanus, 4 h for D. longicaudata, 7 h for Bi. vandenboschi and 14 h for P. incisi to reach pre-spray levels. The fact that Bi. arisanus recolonized vacant trees almost as rapidly as did the fruit fly pest suggest that there is little opportunity for the fruit fly to escape in space and time by “staying one step ahead of its enemies”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317147
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics of ion transport in lipid membranes induced by lysine-valinomycin and derivatives (1979)
    Springer
    European biophysics journal 6 (1979), S. 39-56 
    Details
    ISSN: 1432-1017
    Keywords: Lipid membranes ; Valinomycin ; Ion transport ; Fast kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary Lysine-valinomycin and two N∈-acyl derivatives are compared with respect to their potency to transport Rb+ ions across thin lipid membranes. Lysine-valinomycin acts as a neutral ion carrier only above a pH of about 7 of the aqueous solutions, while at lower pH the molecules seem to be positively charged due to a protonation of the ε-NH2 group of the lysine residue. A kinetic analysis based on voltage jump relaxation experiments and on the nonlinearity of the current-voltage characteristics showed that the conductance increment λ per carrier molecule for uncharged lysine-valinomycin is similar to that of natural valinomycin. The attachment of a rather bulky side group such as the dansyl or para-nitrobenzyloxycarbonyl group reduced λ by approximately one order of magnitude. Some of the relaxation data of the valinomycin analogues were influenced by an unspedfic relaxation of the pure lipid membrane. This structural relaxation represents a limitation to the possibility of analyzing specific transport systems in thin lipid membranes by the voltage jump or charge pulse techniques. It is shown that the time dependence of this structural relaxation — which was first published by Sargent (1975) — is at variance with a three capacitor equivalent circuit of the membrane, which was suggested by Coster and Smith (1974) on the basis of a.c. measurements. A modified equivalent circuit has been found to represent a satisfactory analogue for the current relaxation in the presence of valinomycin. It turned out, however, that such an equivalent circuit provides little insight into the molecular mechanism of transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00537594
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  • 3
    Electronic Resource
    Electronic Resource
    Optical and electrical studies on dansyllysine-valinomycin in thin lipid membranes (1976)
    Springer
    European biophysics journal 2 (1976), S. 119-137 
    Details
    ISSN: 1432-1017
    Keywords: Valinomycin ; Lipid membranes ; Fluorescence ; Relaxation methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Summary Dansyllysine-valinomycin, a fluorescent analogue of the ionophore valinomycin was synthesized and incorporated into black lipid membranes. Its concentration inside the membrane was measured fluorometrically and was also determined from electrical relaxation experiments, which were analyzed on the basis of a previously proposed carrier model. The results of both methods agreed within less than one order of magnitude. This appears satisfactory in view of the sources of error inherent in both procedures. A conductance increment per carrier molecule of about 3 · 10−17 Ω−1 was obtained for dansyllysine-valinomycin in diphytanoyllecithin membranes at 25
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00863705
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  • 4
    Electronic Resource
    Electronic Resource
    Attraction of Female Oriental Fruit Fly, Bactrocera dorsalis, to Volatile Semiochemicals from Leaves and Extracts of a Nonhost Plant, Panax (Polyscias guilfoylei) in Laboratory and Olfactometer Assays (1997)
    Springer
    Journal of chemical ecology 23 (1997), S. 1389-1401 
    Details
    ISSN: 1573-1561
    Keywords: Oriental fruit fly ; Bactrocera dorsalis ; female attractant ; panax ; fruit fly control ; semiochemicals ; kairomones ; Tephritidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Fresh whole leaves and solvent–water leaf extracts of the hedgerow plant panax, Polyscias guilfoylei (Bull), were tested for their attractiveness to male and female Oriental fruit flies, Bactrocera dorsalis, in laboratory flight tunnel and cage olfactometer bioassays. Fresh mature whole panax leaves were found to be attractive to mated female oriental fruit flies in the flight tunnel. Response of males and virgin females was low and in most instances not significantly different from controls. Attraction of mated female flies to the layers resulting from a methylene chloride–water partition or a hexane–water partition of freshly ground leaves using small McPhail traps was greatest in the methylene chloride fraction. When methylene chloride and water layers were tested competitively in a multiple-choice rotating olfactometer, the methylene chloride fraction was more attractive. Tests involving the methylene chloride–water interface (an emulsion of the two partitioned layers) with and without a standard attractant NuLure, showed the emulsion layer to be significantly more attractive than the other fractions or NuLure. In outdoor cage olfactometer assays of methylene chloride and water fractions, activity was greatest in the methylene chloride fraction. The results suggests that volatile semiochemicals from this nonhost plant are attractive to mated female Oriental fruit flies. The results are discussed in relation to the chemical ecology of B. dorsalis and the potential use of this nonhost plant for detection and control of female Oriental fruit flies in the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:JOEC.0000006471.46161.8d
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure of the compound eye and first optic neuropile of the photoreceptor mutant ora JK84 of Drosophila (1983)
    Springer
    Cell & tissue research 233 (1983), S. 305-317 
    Details
    ISSN: 1432-0878
    Keywords: Freeze fracture ; HVEM ; Retina ; Optic neuropile ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The developmental mutant of Drosophila (ora JK84) is characterized by nonfunctional photoreceptor cells (R1–6), while the R7/R8 cells are normal. A fundamental question is: Does the near absence of photosensitive membranes inhibit development of the Rl-6 axons and their synapses at the other end of the cell? The retina and first optic neuropile (lamina ganglionaris) were examined with freeze-fracture technique and high voltage electron microscopy. R1–6 have reduced rhabdomere caps; rhabdomeric microvilli have about 50% of the normal diameter and 20% of the normal length. Affected cells exhibit prominent vacuoles which appear to communicate with some highly convoluted microvillar membranes. Almost no P-face particles (putative rhodopsin molecules) are present in the R1–6 rhabdomeres, and particle densities are lower in R7 than previously reported. Near the rhabdomere caps, microvilli of R1–6 are fairly normal, but at more proximal levels they are greatly diminished in length and changed in orientation, while at still more proximal levels they are lost. R1–6, R7, and R8 axons from each ommatidium are bundled into normal pseudocartridges beneath the basement membrane. No abnormalities are found in the lamina ganglionaris, and all synaptic associations as well as the presumed “virgin” synapses (of R1–6) appear normal. No glial anomalies are present, and R7/R8 axons project through the lamina in the usual fashion. These fine structural findings are correlated with known electrophysiological, biochemical, and behavioral correlates of both sets of photoreceptors (R1–6, and R7/R8).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238298
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  • 6
    Electronic Resource
    Electronic Resource
    Ultrastructural pathology of the compound eye and optic neuropiles of the retinal degeneration mutant (w rdgB KS222) Drosophila melanogaster (1982)
    Springer
    Cell & tissue research 225 (1982), S. 11-22 
    Details
    ISSN: 1432-0878
    Keywords: Transmission and high voltage electron microscopy ; Drosophila ; Degeneration ; Retinular cells ; Optic neuropiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The compound eye and the two most distal optic neuropils (lamina ganglionaris and medulla externa) of the Drosophila mutant w rdgB KS222were examined with transmission electron microscopes at conventional (60 kV) and high (0.8–1 MV) voltages. Eye tissue was sampled in the newly emerged and at 3, 7, and 21 days following eclosion. This mutant is known to show a light-induced degeneration of the peripheral retinular cells (R 1–6); the spectral sensitivity is altered and the threshold is increased reflecting the function of the central cells (R7, 8) which do not degenerate. A totally normal appearing visual system (peripheral retina and optic neuropiles) was found in newly emerged adults. After 3 days the somata of some of the peripheral retinal cells are affected and all of their axons show degeneration. At one week the R 1–6 pathology is well advanced in both somal and axonal regions. In affected cells the cytoplasm is more or less uniformly electron dense and contains liposomes, lysosome-like bodies, myeloid figures and vacuoles suggesting autophagy. Such cytoplasm (noted at 3 and 7 days post-eclosion) exhibits an electron dense reticulum and degenerate mitochondria. Microvilli become more electron dense. Retinular axon terminals are electron opaque and lack synaptic vesicles with few if any presynaptic structures. Mitochondrial remains are barely recognizable. Transsynaptic degeneration was not found. After 3 weeks, the structure of R 1–6 in the peripheral retina (somata and rhabdomeres) is greatly reduced or lost while R7 and R8 and higher order neurons are not affected. The debris from cell bodies and axon terminals of R 1–6 seems diminished, so that some phagocytosis probably takes place along with gliosis in the lamina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216214
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