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排序方式: 共有178条查询结果,搜索用时 718 毫秒
1.
Doyle Hatt 《American anthropologist》2001,103(3):855-856
Mass Mediations: New Approaches to Popular Culture in the Middle East and Beyond. Walter Armbrust. ed. Berkeley. University of California Press, 2000. 378 pp.
New Media in the Muslim World: The Emerging Public Sphere. Dale Eickelman and Jon W. Anderson. eds. Bloomington: Indiana University Press, 1999. 213 pp. 相似文献
New Media in the Muslim World: The Emerging Public Sphere. Dale Eickelman and Jon W. Anderson. eds. Bloomington: Indiana University Press, 1999. 213 pp. 相似文献
2.
Ch. Franke H. Hatt J. Dudel 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1986,159(5):591-609
Summary Outside-out and inside-out patches of membrane were excised from different muscles of crayfish (Austropotamobius torrentium) and single channel currents elicited by synaptic transmitters and their analogues were measured with the patchclamp technique. If the Cl–-concentration was high on both sides of the membrane, glutamate even at concentrations <1 M elicited low amplitude single channel currents, which were identified to be Cl–-currents. The same channels were also activated by 10 M GABA. Glutamate and GABA showed competition in activating these inhibitory channels. Amplitude histograms of the single channel currents presented well defined peaks corresponding to 3 channel substatesI
1,I
2 andI
3, with conductances of about(I1)=22 pS in high chloride corresponding to a permeability
Cl(I1)=3.5× 10–14 cm3/s),(I2)=2(I1) and(I3)=3(I1). Glutamate activated preferably stateI
1, and GABA stateI
2, but both could activate all states at sufficient concentration. Distributions of the open times in the different states were plotted and could be fitted each with one or two exponentials described by time constants of(I1) of 1 and 6 ms,(I2) of 2 to 3 ms, and(I3) or 1 to 2 ms. The burst durations had components of 3 to 4 and of 30 to 40 ms. All these durations were approximately the same when the channels were activated by glutamate and GABA. The analogue quisqualate of glutamate, as well as the GABA analogue-guanidino propionic acid also elicited the respective patterns of states of the inhibitory channel. Quisqualate is by far the most effective agonist and glutamate is more effective than GABA at the inhibitory receptor. Picrotoxin blocked activation of the inhibitory channel by GABA more effectively than by glutamate. The importance of the activation of the inhibitory channel by glutamate as well as by GABA and their analogues is discussed. Elements of a tentative reaction schema are proposed. 相似文献
3.
P. J. Hatt M. Moriniere H. Oberlander P. Porcheron 《In vitro cellular & developmental biology. Animal》1994,30(10):717-720
Summary During postembryonic development of insects, molting cycles affect epidermal cells with alternate periods of proliferation
and differentiation. Cells of the cell line established from imaginal discs of the Indian meal moth (IAL-PID2) differentiate
under the action of the molting hormone, 20-hydroxyecdysone, in a manner that is meaningful in terms of the development of
the tissue from which they were derived. In particular, the hormone caused an accumulation of the cells in the G2 phase of
their cycle and induced the formation of epithelial-like aggregates and the synthesis of specific proteoglycans. Recent discovery
of members of the insulin superfamily in insects and the role of growth factors played by this family of molecules in vertebrates
led us to check for their potential effects on IAL-PID2 cell cycle regulation. On the one hand, our results showed that insulin
was involved in partial resumption of the cell cycle after an arrest caused by serum deprivation, but that other growth factors
present in fetal calf serum were needed for full completion of mitosis. On the other hand, the cytostatic effect of 20-hydroxyecdysone
was reversible, and, prior exposure of the cells to the hormone allowed the cells to complete one cell cycle in serum-free
medium. These results suggest that the production of autocrine growth factors induced by ecdysteroids could circumvent the
absence of serum. This cell culture model provides potential for further study of interactions between ecdysteroids and growth
factor homologs during differentiation of insect epidermal cells. 相似文献
4.
Characteristics of single chemoreceptive units sensitive to amino acids and related substances in the crayfish leg 总被引:2,自引:0,他引:2
Ulrike Bauer J. Dudel H. Hatt 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1981,142(1):67-74
Summary Impulses in single afferent fibres from amino acid receptors were recorded extracellularly. Doseresponse relations were determined for different superfused amino acids; the relations all had a slope of 1, a common saturation level, and the action of different amino acids was characterized by a specific half saturation concentration,K
M. The most effective amino acids were always L-serine, L-alanine and L-histidine, having aK
M of 10–5, 2·10–5 and 1.5·10–4 mol/l, respectively. The sequence of effective amino acids was the same for all units tested. Structural requirements for optimal stimulatory action of the amino acid molecules were concluded.Abbreviation
vH
van Harreveld solution
This work was supported by the Deutsche ForschungsgemeinschaftWe gratefully acknowledge assistance in electronics from Mr. W. Zeitz, and in mechanics from Mr. D. Beyer and Mr. L. Müller. Technical help was provided by Mrs. E. Köster, secretarial help by Mrs. L. Bauer. 相似文献
5.
M. Chabannes G. Hatt G. Thébaud I.D. Bedford & C. Lamb 《The Annals of applied biology》2009,155(2):293-296
Mechanisms underlying natural plant resistance to herbivorous invertebrates are still poorly understood in comparison with bacterial or fungal interactions. One reason is the difficulty in reliably and reproducibly assessing the effects under controlled conditions. This article describes a newly developed in vitro biological assay system that enables the interactions between sciarid larvae and plants, whose roots they feed on, to be studied under highly controlled conditions. The bioassay eliminates the problems created by the often variable environmental factors by providing an aseptic arena where experimental plants can be germinated and grown on agar within a Petri dish. Sciarid fly eggs are then collected, sterilised and added to the Petri dish. The system allows the eggs to hatch and the larvae to feed on the plant roots. A range of developmental parameters can then be recorded over time which can then be correlated with the experimental plant type. This assay system also allows a simultaneous comparison or 'choice chamber' between two (or more) different genotypes. The assay should greatly help to facilitate the identification of new components involved in insect resistance mediated pathway via the characterisation of mutant plants. 相似文献
6.
7.
Yeung Jade Jugé Lauriane Hatt Alice Bilston Lynne E. 《Biomechanics and modeling in mechanobiology》2019,18(5):1497-1505
Biomechanics and Modeling in Mechanobiology - The aim of this study is to characterise the stiffness of white and grey matter in paediatric subjects using magnetic resonance elastography (MRE) and... 相似文献
8.
Marcus Clauss Hanspeter Steinmetz Ulrike Eulenberger Pete Ossent Robert Zingg Jürgen Hummel Jean-Michel Hatt 《European Journal of Wildlife Research》2007,53(1):68-72
The digestive tract of elephants is surprisingly short compared to other herbivorous mammals. However, measurements relating
the length of the intestine to the body mass of the respective individual are rare. In this study, we report such data for
an African elephant and an Asian elephant. Our data support the hypothesis that Asian elephants have a longer intestinal tract
than their African counterparts. These findings are in accord with the observation of longer retention times and higher digestion
coefficients in Asian as compared to African elephants. This difference between the species could be the reflection of slightly
different ecological niches, with Asian elephants adapted to a natural diet with a higher proportion of grass. 相似文献
9.
Hatt H 《化学与生物多样性》2004,1(12):1857-1869
The human olfactory systems recognize and discriminate a large number of different odorant molecules. The detection of chemically distinct odorants begins with the binding of an odorant ligand to a specific receptor protein in the ciliary membrane of olfactory neurons. To address the problem of olfactory perception at a molecular level, we have cloned, functionally expressed, and characterized some of the human olfactory receptors from chromosome 17. Our results show that a receptor protein is capable of recognizing the particular chemical substructure of an odor molecule and, therefore, is able to respond only to odorants that have a defined molecular structure. These findings represent the beginning of the molecular understanding of odorant recognition in humans. In the future, this knowledge could be used for the design of synthetic ideal receptors for specific odors (biosensors), or the perfect odor molecule for a given receptor. 相似文献
10.
The human olfactory system can recognize and discriminate a large number of different odorant molecules. The detection of chemically distinct odorants starts with the binding of an odorant ligand to a specific receptor protein on the olfactory neuron cell surface. To address the problem of olfactory perception at a molecular level, we have expressed and characterized different olfactory receptors with several expression systems. Here we provide the first documentation of functional expression of odorant receptors using the Semliki Forest virus system. The human odorant OR 17-40 receptor and the rat 17 receptor were functionally expressed in vertebrate kidney cells (HEK293) using recombinant Semliki Forest viruses. Receptors were expressed as a fusion protein with the N-terminal membrane import sequence of the guinea pig serotonin receptor. Experiments employing the Ca2+-sensitive dye fura-2 revealed a fast, transient increase in the [Ca2+]i after application of the specific agonists helional and octanal to HEK293 cells infected with viruses containing RNA for the human odorant OR 17-40 receptor and the rat 17 receptor, respectively. 相似文献