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111.
The neurotrophin receptor TrkB is essential for normal function of the mammalian brain. It is expressed in three splice variants. Full-length receptors (TrkB(FL)) possess an intracellular tyrosine kinase domain and are considered as those TrkB receptors that mediate the crucial effects of brain-derived neurotrophic factor (BDNF) or neurotrophin 4/5 (NT-4/5). By contrast, truncated receptors (TrkB-T1 and TrkB-T2) lack tyrosine kinase activity and have not been reported to elicit rapid intracellular signalling. Here we show that astrocytes predominately express TrkB-T1 and respond to brief application of BDNF by releasing calcium from intracellular stores. The calcium transients are insensitive to the tyrosine kinase blocker K-252a and persist in mutant mice lacking TrkB(FL). By contrast, neurons produce rapid BDNF-evoked signals through TrkB(FL) and the Na(v)1.9 channel. Expression of antisense TrkB messenger RNA strongly reduces BDNF-evoked calcium signals in glia. Thus, our results show that, unexpectedly, TrkB-T1 has a direct signalling role in mediating inositol-1,4,5-trisphosphate-dependent calcium release; in addition, they identify a previously unknown mechanism of neurotrophin action in the brain. 相似文献
112.
Isolation of the closed circular form of the transposable element Tc1 in Caenorhabditis elegans 总被引:1,自引:0,他引:1
The mobilization of Tc1, a transposable element in the genome of the roundworm Caenorhabditis elegans, has been investigated. Genomic blot hybridization has shown that Tc1 exists in very different numbers in the genomes of two closely related strains of C. elegans: there are approximately 30 copies of Tc1 in the Bristol strain, whereas in the Bergerac strain there are 200-300. Most of these Tc1 elements are structurally highly conserved although there exists a second form which contains a HindIII restriction site (Tc1 (Hin) form) and comprises approximately 10% of the population. Excision of Tc1 from its chromosomal location in the Bergerac strain is indicated by the presence, on genomic blots, of a minor band corresponding to the size of the uninserted restriction fragment. Here we describe the recovery of extrachromosomal linear and closed circular copies of Tc1 from the Bergerac strain, presumably a result of Tc1 excision. 相似文献
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115.
G. P. Young M. B. Van der Weyden I. S. Rose F. J. Dudley 《Cellular and molecular life sciences : CMLS》1979,35(2):268-269
Summary The basis of peripheral blood lymphopenia observed in patients with chronic alcoholism and liver disease was investigated by examining the effect of sera of these patients on in vitro transformation of normal human peripheral blood lymphocytes. A positive correlation was demonstrated between the serum inhibition of phytohaemagglutinin- and pokeweed mitogen-induced transformation and the degree of lymphopenia. Thus serum factors may contribute to the observed lymphopenia by inhibiting lymphocyte production in vivo.This study was supported by grants from the National Health and Medical Research Council of Australia, Royal Australasian College of Physicians and Alfred Hospital Henry Laurie Scholarship Fund. 相似文献
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Résumé Dans différentes lignées de souris et de rats, on a souvent trouvé du tissu thymique d'aspect normal au voisinage ou dans la thyroide mme. Les animaux thymectomisés dovient tre examinés pour contrôler la présemce d'un tissu thymique aberrant.
Research assistant professor, supported by Bertha H. and Henry Buswell Ressearch Fellowship.
This work was supported in part by USPHS research grant No CA 05203 from the National Caucer Institute. 相似文献
Research assistant professor, supported by Bertha H. and Henry Buswell Ressearch Fellowship.
This work was supported in part by USPHS research grant No CA 05203 from the National Caucer Institute. 相似文献
118.
Temporal hyperacuity in the electric sense of fish 总被引:4,自引:0,他引:4
It has recently become evident that sensory thresholds for certain tasks are lower than those expected from the properties of individual receptors. This perceptual capacity, termed hyperacuity, reveals the impressive information-processing abilities of the central nervous system. Although much is known about spatial hyperacuity, temporal hyperacuity has received little attention. Here we demonstrate that an electric fish, Eigenmannia, can detect modulations in the timing (phase) of an electrical signal at least as small as 400 ns. Such sensitivity exceeds the temporal resolution of individual phase-coding afferents. This hyperacuity results from a nonlinear convergence of parallel afferent inputs to the central nervous system; subthreshold inputs from particular areas of the body surface accumulate to permit the detection of these extremely small temporal modulations. 相似文献
119.
Molecular mimicry, the concept that antigenic determinants of microorganisms resemble antigenic determinants of the host,
is frequently cited as a plausible mechanism to account for the association of infection and autoimmune disease. Based on
analogous sequences of amino acids or on cross-reactions of monoclonal antibodies, numerous examples of such mimicry have
been reported. There are, however, no clear examples of a human disease caused by molecular mimicry. 相似文献
120.
UTX and JMJD3 are histone H3K27 demethylases involved in HOX gene regulation and development 总被引:2,自引:0,他引:2
Agger K Cloos PA Christensen J Pasini D Rose S Rappsilber J Issaeva I Canaani E Salcini AE Helin K 《Nature》2007,449(7163):731-734