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301.
Classical heart-rate conditioning and differentiation of visual CS with an appetitive UCS in pigeons
A tachycardic response was classically conditioned in thirsty pigeons using water as an unconditioned stimulus and localized lights as conditioned stimuli. This was successful in 6 out of 9 birds. In one experiment the subjects had their heads immobilized so that the positions of the stimuli within the visual field could be precisely specified. When the stimuli were shifted from the binocular to the monocular field and vice versa there was no initial transfer of a conditioned differentiation between a white and a green light. 相似文献
302.
I. Maye A. de Fraissinette L.M. Cruz-Orive E. Andersen C. Niederlander W. Bueb C. Froehlich M. Schreier J. Vonderscher F. Richter A. Cordier P. Gehr 《Cell biology and toxicology》1998,14(6):411-418
The aim of this study was to compare two types of cyclosporin (Cs) particles, SDZ OXL 400 and SDZ IMM 125, the latter being more hydrophilic, to understand their uptake by airway macrophages. Alveolar macrophages (AM), harvested by bronchoalveolar lavage (BAL) of hamster lungs, were cultured with two different doses (0.1 mg and 0.5 mg) for 1 h, 6 h, and 24 h. Control incubations without Cs particles or with latex particles were carried out simultaneously. Cell viability, cell activation (i.e., respiratory burst, interleukin-6 (IL-6) synthesis) and mean volume of particles phagocytosed per macrophage were measured. Both types of Cs particles did not modify the AM viability, and failed to induce IL-6 synthesis during phagocytosis but slightly decreased the cell oxidative respiratory burst. The comparison between SDZ OXL 400 and SDZ IMM 125 showed that for the lower dose the mean volume of both Cs types phagocytosed was similar at 1 h and 6 h. At 24 h an increase of the mean volume phagocytosed was seen for SDZ IMM 125 but not for SDZ OXL 400. For the higher dose the mean volume of SDZ IMM 125 phagocytosed was higher than SDZ OXL 400 at 1 h and 6 h and comparable for both types at 24 h. SDZ IMM 125 particles were phagocytosed more rapidly than SDZ OXL 400. The mean volume of phagocytosed latex particles increased with time and dose and was higher than for both Cs particle types. In conclusion, AM were seen to phagocytose particles of different physical properties (i.e., form, size, and shape), chemical properties (i.e., inert or peptidic) and degrees of hydrophilicity in a different manner. 相似文献
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Affinity purification of histidine-tagged proteins 总被引:11,自引:0,他引:11
Expression of recombinant proteins is a standard technique in molecular biology and a wide variety of prokaryotic as well as eukaryotic expression systems are currently in use. A limiting step is often the purification of the expressed recombinant protein, particularly if mammalian expression systems that yield low expression levels are employed. Here, we discuss the advantages and restrictions of tagging recombinant proteins with histidines and purifying them by Ni2+-NTA chromatography.Abbreviations GST
glutathione S-transferase
- NTA
nitrilotriacetic acid
- His
histidine
- PAGE
polyacrylamide gel electrophoresis 相似文献
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Gérard Marigo Jean-Paul Peltier Jacky Girel Guy Pautou 《Trees - Structure and Function》2000,15(1):1-13
This review examines the ecological traits and ecophysiological characteristics of the common ash (Fraxinus excelsior L.) that help to explain the current spread of ash communities in Europe. As a consequence of anthropogenic disturbance, the common ash has experienced new environmental conditions and the frequency of the species has fluctuated over space and time. Owing to its ubiquity, over the last few decades the common ash has been greatly favoured in areas abandoned by agriculture and also along impounded rivers. F. excelsior is a mesophilic species that usually thrives on alluvial soils and can also survive the strong water deficit on hillslopes. Drought tolerance in ash trees is related to stomatal regulation, a decrease in osmotic potential and also an increase in the elastic modulus ). Malic acid plays a central role in drought tolerance, first as one of the major solutes involved in osmotic adjustment, and second as an effector for stomatal regulation through a drought-induced increase in its xylem concentration. 相似文献