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21.
Vanin S Bhutani S Montelli S Menegazzi P Green EW Pegoraro M Sandrelli F Costa R Kyriacou CP 《Nature》2012,484(7394):371-375
Circadian clocks have evolved to synchronize physiology, metabolism and behaviour to the 24-h geophysical cycles of the Earth. Drosophila melanogaster's rhythmic locomotor behaviour provides the main phenotype for the identification of higher eukaryotic clock genes. Under laboratory light-dark cycles, flies show enhanced activity before lights on and off signals, and these anticipatory responses have defined the neuronal sites of the corresponding morning (M) and evening (E) oscillators. However, the natural environment provides much richer cycling environmental stimuli than the laboratory, so we sought to examine fly locomotor rhythms in the wild. Here we show that several key laboratory-based assumptions about circadian behaviour are not supported by natural observations. These include the anticipation of light transitions, the midday 'siesta', the fly's crepuscular activity, its nocturnal behaviour under moonlight, and the dominance of light stimuli over temperature. We also observe a third major locomotor component in addition to M and E, which we term 'A' (afternoon). Furthermore, we show that these natural rhythm phenotypes can be observed in the laboratory by using realistic temperature and light cycle simulations. Our results suggest that a comprehensive re-examination of circadian behaviour and its molecular readouts under simulated natural conditions will provide a more authentic interpretation of the adaptive significance of this important rhythmic phenotype. Such studies should also help to clarify the underlying molecular and neuroanatomical substrates of the clock under natural protocols. 相似文献
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Comparative stability analyses of traditional and selective room-and-pillar mining techniques for sub-horizontal tungsten veins 下载免费PDF全文
Vidal Félix Navarro Torres Carlos Dinis da Gama Matilde Costa e Silva Paula Falc?o Neves Qiang Xie 《矿物冶金与材料学报》2011,18(1):1-8
The stability and productivity concerning a modification on the traditional room and pillar for a new selective technique at the Portuguese Panasqueira Mine have been described. The traditional room-and-pillar stoping uses 5.0-m wide rooms with 3.0 m×3.0 m pillars, while the selective room-and-pillar mining technique consists in stoping with rooms of 4.0 m wide and pillars of 4 m×4 m with a subsequent selective cutting of the quartz veins at the mid pillar of approximately 0.5 m high, to obtain a pillar section with an area of 3.0 m×3.0 m. The stability and productivity analyses indicate that the selective technique obtains smaller average pillar safety factor, more rock mass displacement, more extraction and selectivity ratios, and ore grade improvement, compared with the traditional technique. These results show that the selective technique is also more convenient. This proposed selective room-and-pillar mining technique is applicable to any sub-horizontal narrow quartz veins with wolfram, gold, etc. such as the famous La Rinconada gold mine in the Peruvian Andes. 相似文献
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Foreman J Demidchik V Bothwell JH Mylona P Miedema H Torres MA Linstead P Costa S Brownlee C Jones JD Davies JM Dolan L 《Nature》2003,422(6930):442-446
Cell expansion is a central process in plant morphogenesis, and the elongation of roots and root hairs is essential for uptake of minerals and water from the soil. Ca2+ influx from the extracellular store is required for (and sets the rates of) cell elongation in roots. Arabidopsis thaliana rhd2 mutants are defective in Ca2+ uptake and consequently cell expansion is compromised--rhd2 mutants have short root hairs and stunted roots. To determine the regulation of Ca2+ acquisition in growing root cells we show here that RHD2 is an NADPH oxidase, a protein that transfers electrons from NADPH to an electron acceptor leading to the formation of reactive oxygen species (ROS). We show that ROS accumulate in growing wild-type (WT) root hairs but their levels are markedly decreased in rhd2 mutants. Blocking the activity of the NADPH oxidase with diphenylene iodonium (DPI) inhibits ROS formation and phenocopies Rhd2-. Treatment of rhd2 roots with ROS partly suppresses the mutant phenotype and stimulates the activity of plasma membrane hyperpolarization-activated Ca2+ channels, the predominant root Ca2+ acquisition system. This indicates that NADPH oxidases control development by making ROS that regulate plant cell expansion through the activation of Ca2+ channels. 相似文献
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Ghezzi D Arzuffi P Zordan M Da Re C Lamperti C Benna C D'Adamo P Diodato D Costa R Mariotti C Uziel G Smiderle C Zeviani M 《Nature genetics》2011,43(3):259-263
Although mutations in CYTB (cytochrome b) or BCS1L have been reported in isolated defects of mitochondrial respiratory chain complex III (cIII), most cIII-defective individuals remain genetically undefined. We identified a homozygous nonsense mutation in the gene encoding tetratricopeptide 19 (TTC19) in individuals from two families affected by progressive encephalopathy associated with profound cIII deficiency and accumulation of cIII-specific assembly intermediates. We later found a second homozygous nonsense mutation in a fourth affected individual. We demonstrated that TTC19 is embedded in the inner mitochondrial membrane as part of two high-molecular-weight complexes, one of which coincides with cIII. We then showed a physical interaction between TTC19 and cIII by coimmunoprecipitation. We also investigated a Drosophila melanogaster knockout model for TTC19 that showed low fertility, adult-onset locomotor impairment and bang sensitivity, associated with cIII deficiency. TTC19 is a putative cIII assembly factor whose disruption is associated with severe neurological abnormalities in humans and flies. 相似文献
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N. H. Neff R. E. Barrett E. Costa 《Cellular and molecular life sciences : CMLS》1969,25(11):1140-1141
Riassunto Scimmie scoiattolo trattate cronicamente con MnO2 presentano disturbi del sistema extrapiramidale ed una riduzione delle concentrazioni di serotonina e dopamina nel nucleo caudato. L'intensità dei disturbi extrapiramidali e la riduzione della concentrazione delle amine nel caudato appaiono correlate.
This work was supported in part by the Clinical Research Center for Parkinson's and Allied Diseases, NB 05184, and the Parkinson Information Center, a part of the National Information Network of NINDB under contract NIH-69-76. 相似文献
This work was supported in part by the Clinical Research Center for Parkinson's and Allied Diseases, NB 05184, and the Parkinson Information Center, a part of the National Information Network of NINDB under contract NIH-69-76. 相似文献
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Riassunto Le ricerche istochimiche effettuate sull'innervazione adrenergica dell'intestino hanno dimostrato che fibre adrenergiche sono presenti non solo attorno ai neuroni e nelle maglie dei plessi mienterico e sottomucoso, ma anche nello spessore stesso dello strato muscolare interno e in intimo rapporto con elementi ghiandolari della tonaca mucosa. Vi è quindi la possibilità che sugli effettori ghiandolari e muscolari le fibre adrenergiche esercitino sia un'azione diretta sia un'azione indiretta attraverso i neuroni intramurali.
This work was supported by a grant from the Consiglio Nazionle delle Ricerche (Rome). 相似文献
This work was supported by a grant from the Consiglio Nazionle delle Ricerche (Rome). 相似文献
29.
Riassunto Con il metodo in microscopia a fluorescenza diFalck eHillarp è stata studiata l'innervazione adrenergica della tonaca mucosa del canale alimentare della cavia adulta. Sono state messe in evidenza fibre adrenergiche nella lamina propria della tonaca mucosa, in intimo rapporto con le cellule epiteliali secernenti. Fibre adrenergiche sono presenti anche nello spessore della muscularis mucosae parallele ai fasci di cellule muscolari lisce. 相似文献
30.
Tuber formation and protein content in some wild cassava (Mandioca) species native of central Brazil
Summary Screening for protein content in some wild species of Manihot showed 2 of them to have a notably high percentage of protein on dry matter basis. Moreover, one of these high-protein wild species was found to be extremely sweet.This work is being carried out with the aid of a grant from the International Development Research Centre, Ottawa, Canada. 相似文献