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61.
The odour of acids has a distinct quality that is perceived as sharp, pungent and often irritating. How acidity is sensed and translated into an appropriate behavioural response is poorly understood. Here we describe a functionally segregated population of olfactory sensory neurons in the fruitfly, Drosophila melanogaster, that are highly selective for acidity. These olfactory sensory neurons express IR64a, a member of the recently identified ionotropic receptor (IR) family of putative olfactory receptors. In vivo calcium imaging showed that IR64a+ neurons projecting to the DC4 glomerulus in the antennal lobe are specifically activated by acids. Flies in which the function of IR64a+ neurons or the IR64a gene is disrupted had defects in acid-evoked physiological and behavioural responses, but their responses to non-acidic odorants remained unaffected. Furthermore, artificial stimulation of IR64a+ neurons elicited avoidance responses. Taken together, these results identify cellular and molecular substrates for acid detection in the Drosophila olfactory system and support a labelled-line mode of acidity coding at the periphery. 相似文献
62.
Dispersed human immunoglobulin kappa light-chain genes 总被引:11,自引:0,他引:11
E L?tscher K H Grzeschik H G Bauer H D Pohlenz B Straubinger H G Zachau 《Nature》1986,320(6061):456-458
The gene segments encoding the constant and variable regions of human immunoglobulin light chains of the kappa type (C kappa, V kappa) have been localized to chromosome 2. The distance between the C kappa and V kappa genes and the number of germline V kappa genes are unknown. As part of our work on the human V kappa locus, we have now mapped two solitary V kappa gene and a cluster of three V kappa genes to chromosomes 1, 15 and 22, respectively. The three genes that have been sequenced are nonprocessed pseudogenes, and the same may be true for the other two genes. This is the first time that V-gene segments have been found outside the C-gene-containing chromosomes. Our finding is relevant to current estimates of the size of the V kappa-gene repertoire. Furthermore, the dispersed gene regions have some unusual characteristics which may help to clarify the mechanism of dispersion. 相似文献
63.
Mary F. Argus Charlotte J. Leutze Judith F. Kane 《Cellular and molecular life sciences : CMLS》1961,17(8):357-359
Résumé Les auteurs montrent que les composés cancérogènes hydrosolubles, l'acide tannique, le phénol, la diéthyl-et diméthylnitrosamine, la thioacétamide, le carbamate d'éthyl et la thiourée sont des agents puissants de dénaturation de protéines. La précipitation produite par ces agents peut être inhibée, inversée ou accrue par divers réactifs de groupes sulfhydryles. Ces recoupements, ainsi que d'autres expériences sur l'effet de l'urée sur la précipitation par la diméthylnitrosamine, indiquent que le mécanisme de la formation des aggrégats moléculaires consiste dans l'établissement de ponts -S-S- intermoléculaires, probablement renforcés par des liaisons intermoléculaires d'hydrogène.
This work was supported by USPHS Grant CY-4939 at the University of Florida, and by USPHS Grant C-5431 and a Grant-in-aid from the Greater New Orleans Cancer Association and the Cancer Society of Greater Baton Rouge, at Tulane University.
Presented at the Fifty-second Annual Meeting of the American Association for Cancer Research, Atlantic City, N.J., April, 1961 (Abstr., Proc. Amer. Assoc. Cancer Research3, 206 (1961)). 相似文献
This work was supported by USPHS Grant CY-4939 at the University of Florida, and by USPHS Grant C-5431 and a Grant-in-aid from the Greater New Orleans Cancer Association and the Cancer Society of Greater Baton Rouge, at Tulane University.
Presented at the Fifty-second Annual Meeting of the American Association for Cancer Research, Atlantic City, N.J., April, 1961 (Abstr., Proc. Amer. Assoc. Cancer Research3, 206 (1961)). 相似文献
64.
Summary The influence of DTPA on the chromosome aberration rate of Chinese hamster cells in culture was studied. No increase of the aberration rate was observed after treatment with 10–2 and 10–3
M concentrations. 相似文献
65.
Curro NJ Caldwell T Bauer ED Morales LA Graf MJ Bang Y Balatsky AV Thompson JD Sarrao JL 《Nature》2005,434(7033):622-625
In the Bardeen-Cooper-Schrieffer theory of superconductivity, electrons form (Cooper) pairs through an interaction mediated by vibrations in the underlying crystal structure. Like lattice vibrations, antiferromagnetic fluctuations can also produce an attractive interaction creating Cooper pairs, though with spin and angular momentum properties different from those of conventional superconductors. Such interactions have been implicated for two disparate classes of materials--the copper oxides and a set of Ce- and U-based compounds. But because their transition temperatures differ by nearly two orders of magnitude, this raises the question of whether a common pairing mechanism applies. PuCoGa5 has a transition temperature intermediate between those classes and therefore may bridge these extremes. Here we report measurements of the nuclear spin-lattice relaxation rate and Knight shift in PuCoGa5, which demonstrate that it is an unconventional superconductor with properties as expected for antiferromagnetically mediated superconductivity. Scaling of the relaxation rates among all of these materials (a feature not exhibited by their Knight shifts) establishes antiferromagnetic fluctuations as a likely mechanism for their unconventional superconductivity and suggests that related classes of exotic superconductors may yet be discovered. 相似文献
66.
Israël G Szopa C Raulin F Cabane M Niemann HB Atreya SK Bauer SJ Brun JF Chassefière E Coll P Condé E Coscia D Hauchecorne A Millian P Nguyen MJ Owen T Riedler W Samuelson RE Siguier JM Steller M Sternberg R Vidal-Madjar C 《Nature》2005,438(7069):796-799
Aerosols in Titan's atmosphere play an important role in determining its thermal structure. They also serve as sinks for organic vapours and can act as condensation nuclei for the formation of clouds, where the condensation efficiency will depend on the chemical composition of the aerosols. So far, however, no direct information has been available on the chemical composition of these particles. Here we report an in situ chemical analysis of Titan's aerosols by pyrolysis at 600 degrees C. Ammonia (NH3) and hydrogen cyanide (HCN) have been identified as the main pyrolysis products. This clearly shows that the aerosol particles include a solid organic refractory core. NH3 and HCN are gaseous chemical fingerprints of the complex organics that constitute this core, and their presence demonstrates that carbon and nitrogen are in the aerosols. 相似文献
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70.
Pressure to ban the hunting of foxes with hounds in Britain has fuelled debate about its contribution to the control of fox populations. We took advantage of a nationwide one-year ban on fox-hunting during the outbreak of foot-and-mouth disease (FMD) in 2001 to examine this issue and found that the ban had no measurable impact on fox numbers in randomly selected areas. Our results argue against suggestions that fox populations would increase markedly in the event of a permanent ban on hunting. 相似文献