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41.
42.
Paxillin binds schwannomin and regulates its density-dependent localization and effect on cell morphology 总被引:22,自引:0,他引:22
Fernandez-Valle C Tang Y Ricard J Rodenas-Ruano A Taylor A Hackler E Biggerstaff J Iacovelli J 《Nature genetics》2002,31(4):354-362
Neurofibromatosis type 2 is an autosomal dominant disorder characterized by tumors, predominantly schwannomas, in the nervous system. It is caused by mutations in the gene NF2, encoding the growth regulator schwannomin (also known as merlin). Mutations occur throughout the 17-exon gene, with most resulting in protein truncation and undetectable amounts of schwannomin protein. Pathogenic mutations that result in production of defective schwannomin include in-frame deletions of exon 2 and three independent missense mutations within this same exon. Mice with conditional deletion of exon 2 in Schwann cells develop schwannomas, which confirms the crucial nature of exon 2 for growth control. Here we report that the molecular adaptor paxillin binds directly to schwannomin at residues 50-70, which are encoded by exon 2. This interaction mediates the membrane localization of schwannomin to the plasma membrane, where it associates with beta 1 integrin and erbB2. It defines a pathogenic mechanism for the development of NF2 in humans with mutations in exon 2 of NF2. 相似文献
43.
Bentley SD Chater KF Cerdeño-Tárraga AM Challis GL Thomson NR James KD Harris DE Quail MA Kieser H Harper D Bateman A Brown S Chandra G Chen CW Collins M Cronin A Fraser A Goble A Hidalgo J Hornsby T Howarth S Huang CH Kieser T Larke L Murphy L Oliver K O'Neil S Rabbinowitsch E Rajandream MA Rutherford K Rutter S Seeger K Saunders D Sharp S Squares R Squares S Taylor K Warren T Wietzorrek A Woodward J Barrell BG Parkhill J Hopwood DA 《Nature》2002,417(6885):141-147
Streptomyces coelicolor is a representative of the group of soil-dwelling, filamentous bacteria responsible for producing most natural antibiotics used in human and veterinary medicine. Here we report the 8,667,507 base pair linear chromosome of this organism, containing the largest number of genes so far discovered in a bacterium. The 7,825 predicted genes include more than 20 clusters coding for known or predicted secondary metabolites. The genome contains an unprecedented proportion of regulatory genes, predominantly those likely to be involved in responses to external stimuli and stresses, and many duplicated gene sets that may represent 'tissue-specific' isoforms operating in different phases of colonial development, a unique situation for a bacterium. An ancient synteny was revealed between the central 'core' of the chromosome and the whole chromosome of pathogens Mycobacterium tuberculosis and Corynebacterium diphtheriae. The genome sequence will greatly increase our understanding of microbial life in the soil as well as aiding the generation of new drug candidates by genetic engineering. 相似文献
44.
Although dopamine is considered the major hypothalamic controller of prolactin release from the anterior pituitary gland, there is evidence that a yet to be discovered prolactin releasing factor (PRF) also exists in brain. Recently, two peptides were isolated, products of the same prohormone, that were reported to have significant prolactin-releasing activity. These peptides, called prolactin releasing peptides, are not accepted by all investigators to be in fact PRFs. Instead, it appears that their widespread distribution in brain and the presence of receptors for the peptides in sites unrelated to neuroendocrine function are the basis for a variety of central nervous system action including activation of the autonomic nervous system. Thus, these peptides may not be PRFs, but instead neuroactive agents that are involved in many brain circuits with divergent functions. 相似文献
45.
46.
Reeves WH Skryabin DV Biancalana F Knight JC Russell PS Omenetto FG Efimov A Taylor AJ 《Nature》2003,424(6948):511-515
Photonic crystal fibres (PCFs) offer greatly enhanced design freedom compared to standard optical fibres. For example, they allow precise control of the chromatic dispersion (CD) profile--the frequency dependence of propagation speed--over a broad wavelength range. This permits studies of nonlinear pulse propagation in previously inaccessible parameter regimes. Here we report on spectral broadening of 100-fs pulses in PCFs with anomalously flat CD profiles. Maps of the spectral and spatio-temporal behaviour as a function of power show that dramatic conversion (to both longer and shorter wavelengths) can occur in remarkably short lengths of fibre, depending on the magnitude and shape of the CD profile. Because the PCFs used are single-mode at all wavelengths, the light always emerges in a fundamental guided mode. Excellent agreement is obtained between the experimental results and numerical solutions of the nonlinear wave equation, indicating that the underlying processes can be reliably modelled. These results show how, through appropriate choice of CD, nonlinearities can be efficiently harnessed to generate laser light at new wavelengths. 相似文献
47.
Elliot JL Ates A Babcock BA Bosh AS Buie MW Clancy KB Dunham EW Eikenberry SS Hall DT Kern SD Leggett SK Levine SE Moon DS Olkin CB Osip DJ Pasachoff JM Penprase BE Person MJ Qu S Rayner JT Roberts LC Salyk CV Souza SP Stone RC Taylor BW Tholen DJ Thomas-Osip JE Ticehurst DR Wasserman LH 《Nature》2003,424(6945):165-168
Stellar occultations--the passing of a relatively nearby body in front of a background star--can be used to probe the atmosphere of the closer body with a spatial resolution of a few kilometres (ref. 1). Such observations can yield the scale height, temperature profile, and other information about the structure of the occulting atmosphere. Occultation data acquired for Pluto's atmosphere in 1988 revealed a nearly isothermal atmosphere above a radius of approximately 1,215 km. Below this level, the data could be interpreted as indicating either an extinction layer or the onset of a large thermal gradient, calling into question the fundamental structure of this atmosphere. Another question is to what extent Pluto's atmosphere might be collapsing as it recedes from the Sun (passing perihelion in 1989 in its 248-year orbital period), owing to the extreme sensitivity of the equilibrium surface pressure to the surface temperature. Here we report observations at a variety of visible and infrared wavelengths of an occultation of a star by Pluto in August 2002. These data reveal evidence for extinction in Pluto's atmosphere and show that it has indeed changed, having expanded rather than collapsed, since 1988. 相似文献
48.
Loss and recovery of wings in stick insects 总被引:14,自引:0,他引:14
The evolution of wings was the central adaptation allowing insects to escape predators, exploit scattered resources, and disperse into new niches, resulting in radiations into vast numbers of species. Despite the presumed evolutionary advantages associated with full-sized wings (macroptery), nearly all pterygote (winged) orders have many partially winged (brachypterous) or wingless (apterous) lineages, and some entire orders are secondarily wingless (for example, fleas, lice, grylloblattids and mantophasmatids), with about 5% of extant pterygote species being flightless. Thousands of independent transitions from a winged form to winglessness have occurred during the course of insect evolution; however, an evolutionary reversal from a flightless to a volant form has never been demonstrated clearly for any pterygote lineage. Such a reversal is considered highly unlikely because complex interactions between nerves, muscles, sclerites and wing foils are required to accommodate flight. Here we show that stick insects (order Phasmatodea) diversified as wingless insects and that wings were derived secondarily, perhaps on many occasions. These results suggest that wing developmental pathways are conserved in wingless phasmids, and that 're-evolution' of wings has had an unrecognized role in insect diversification. 相似文献
49.
Performance monitoring by the supplementary eye field 总被引:10,自引:0,他引:10
Intelligent behaviour requires self-control based on the consequences of actions. The countermanding task is designed to study self-control; it requires subjects to withhold planned movements in response to an imperative stop signal, which they can do with varying success. In humans, the medial frontal cortex has been implicated in the supervisory control of action. In monkeys, the supplementary eye field in the dorsomedial frontal cortex is involved in producing eye movements, but its precise function has not been clarified. To investigate the role of the supplementary eye field in the control of eye movements, we recorded neural activity in macaque monkeys trained to perform an eye movement countermanding task. Distinct groups of neurons were active after errors, after successful withholding of a partially prepared movement, or in association with reinforcement. These three forms of activation could not be explained by sensory or motor factors. Our results lead us to put forward the hypothesis that the supplementary eye field contributes to monitoring the context and consequences of eye movements. 相似文献
50.
Paul D. Taylor Silviu O. Martha Dennis P. Gordon 《Journal of Natural History》2018,52(25-26):1657-1721
Genera assigned to the cheilostome bryozoan family Onychocellidae are revised based on the skeletal morphology of the type species and, when possible, the type material of these species. All genera are illustrated using scanning electron micrographs, some for the first time. Onychocellidae, which ranges from the Cenomanian stage of the Cretaceous to the Recent, has been a particularly troublesome family because of poorly defined generic concepts correlating at least in part with a paucity of morphological characters. Thirty-five genera are described in this review. Of these, two are recognised as subjective synonyms of other onychocellid genera (Rhebasia and Semieschara), one cannot be sufficiently characterised from the type material (Collura), and two are new: Aechmellina gen. nov. (type species Aechmella falcifera) and Kamilocella gen. nov. (type species Eschara latilabris). A neotype is chosen for Rhagasostoma hexagonum, the type species of Rhagasostoma. A key is provided to assist in the identification of onychocellid genera. Phylogenetic relationships between genera remain obscure and are unlikely to be fully resolved based on skeletal morphology alone. The family as an entity is loosely circumscribed and almost certainly paraphyletic, containing stem genera of other anascan familes such as Lunulitidae, Coscinopleuridae and Aspidostomatidae.
www.zoobank.org/urn:lsid:org:pub:63A31AD2-F049-42CB-A45B-557014DC286E 相似文献