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91.
Mechanisms by which Wnt pathways integrate the organization of receptors, organelles, and cytoskeletal proteins to confer cell polarity and directional cell movement are incompletely understood. We show that acute responses to Wnt5a involve recruitment of actin, myosin IIB, Frizzled 3, and melanoma cell adhesion molecule into an intracellular structure in a melanoma cell line. In the presence of a chemokine gradient, this Wnt-mediated receptor-actin-myosin polarity (W-RAMP) structure accumulates asymmetrically at the cell periphery, where it triggers membrane contractility and nuclear movement in the direction of membrane retraction. The process requires endosome trafficking, is associated with multivesicular bodies, and is regulated by Wnt5a through the small guanosine triphosphatases Rab4 and RhoB. Thus, cell-autonomous mechanisms allow Wnt5a to control cell orientation, polarity, and directional movement in response to positional cues from chemokine gradients. 相似文献
92.
Peptidoglycan glycosyltransferases (GTs) catalyze the polymerization step of cell-wall biosynthesis, are membrane-bound, and are highly conserved across all bacteria. Long considered the "holy grail" of antibiotic research, they represent an essential and easily accessible drug target for antibiotic-resistant bacteria, including methicillin-resistant Staphylococcus aureus. We have determined the 2.8 angstrom structure of a bifunctional cell-wall cross-linking enzyme, including its transpeptidase and GT domains, both unliganded and complexed with the substrate analog moenomycin. The peptidoglycan GTs adopt a fold distinct from those of other GT classes. The structures give insight into critical features of the catalytic mechanism and key interactions required for enzyme inhibition. 相似文献
93.
Galileo multispectral imaging of the north polar and eastern limb regions of the moon 总被引:1,自引:0,他引:1
Belton MJ Greeley R Greenberg R Geissler P McEwen A Klaasen KP Heffernan C Breneman H Johnson TV Head JW Pieters C Neukum G Chapman CR Anger C Carr MH Davies ME Fanale FP Gierasch PJ Thompson WR Veverka J Sagan C Ingersoll AP Pilcher CB 《Science (New York, N.Y.)》1994,264(5162):1112-1115
Multispectral images obtained during the Galileo probe's second encounter with the moon reveal the compositional nature of the north polar regions and the northeastern limb. Mare deposits in these regions are found to be primarily low to medium titanium lavas and, as on the western limb, show only slight spectral heterogeneity. The northern light plains are found to have the spectral characteristics of highlands materials, show little evidence for the presence of cryptomaria, and were most likely emplaced by impact processes regardless of their age. 相似文献
94.
Effect of thermal treatment on properties of OSB panels 总被引:2,自引:1,他引:1
Rafael Farinassi Mendes Geraldo Bortoletto Júnior Natalie Ferreira de Almeida Paula Gabriella Surdi Isabela Najm Barbeiro 《Wood Science and Technology》2013,47(2):243-256
The main objective of this study was to evaluate the effect of thermal treatment of strand particles (pre-treatment) and panels (post-treatment) on the physical and mechanical properties of OSB. The experimental design consisted of five treatments, with the evaluation of the following: two particle treatment temperatures (473.15 and 513.15 K) for a period of 60 min, thermal post-treatment of the panels produced with and without application of wax emulsion at 493.15 K for a period of 12 min, and panels without heat treatment (control). For each treatment, three panels were produced with adhesives based on phenol formaldehyde. The pressing cycle of the panels was at a pressure of 3.51 MPa, 433.15 K and 8 min. Through the analysis of the results, it was possible to draw the following conclusions: the panels produced with the particles heat-treated at 513.15 K showed the best dimensional stability. The thermal post-treatment caused a significant improvement in some of the physical properties of the panels without compromising the mechanical properties. The thermal pre-treatment provided a more pronounced effect on the panel properties than the thermal post-treatment providing improved physical properties and lower mechanical properties. 相似文献
95.
Lucy Chou Matt J. Griffin Trellor Fraites Cynthia Ware Hugh Ferguson Natalie Keirstead 《Journal of aquatic animal health》2013,25(4):263-271
AbstractStreptococcus iniae, the etiological agent of streptococcosis in fish, is an important pathogen of cultured and wild fish worldwide. During the last decade outbreaks of streptococcosis have occurred in a wide range of cultured and wild fish in the Americas and Caribbean islands. To gain a better understanding of the epizootiology of S. iniae in the western hemisphere, over 30 S. iniae isolates recovered from different fish species and geographic locations were characterized phenotypically and genetically. Species identities were determined biochemically and confirmed by amplification and sequencing of the 16S rRNA gene. Repetitive-element palindromic PCR fingerprinting as well as biochemical and antimicrobial susceptibility profiles suggest that a single strain of S. iniae was responsible for two different disease outbreaks among reef fishes in the Caribbean, one in 1999 and another in 2008. Interestingly, a majority of the isolates recovered from cultured fish in the Americas were genetically distinct from the Caribbean isolates and exhibited a trend toward higher minimal inhibitory concentration with respect to several antibiotics as well as greater genetic variability. The biological significance of this genetic variability is unclear, but it could have implications for future vaccine development and treatment.Received April 20, 2014; accepted July 7, 2014 相似文献
96.
Natalie M. Gulsrud Saskia Gooding Cecil C. Konijnendijk van den Bosch 《Urban Forestry & Urban Greening》2013,12(3):330-337
City place branding, an entrepreneurial urban development scheme, aims to differentiate cities from their national and international competitors based on strengths and competitive advantage. One such strength is quality urban green space which has been shown to make cities more attractive and liveable places, drawing people and investments to urban centres. Applying a place branding approach, this paper presents the results of a survey of Danish municipalities and their place branding in terms of crafting green city, or environmentally sustainable, profiles. Based on survey responses from both municipal green space and communication staff, an overview is presented of the status of ‘green’ municipal place branding, with emphasis on branding through green spaces such as parks. Findings show that green concepts such as environmentally sustainable policies as well as biophysical assets such as green spaces are not in focus in municipal place branding campaigns. Moreover, survey results demonstrate that creative professionals and local citizens are the main focus of those municipalities that are branding. There is great potential to emphasize green spaces in municipal placing branding campaigns building on partnerships with the private sector and citizen volunteers. 相似文献
97.
Ingrid E van Putten Soile Kulmala Olivier Thébaud Natalie Dowling Katell G Hamon Trevor Hutton Sean Pascoe 《Fish and Fisheries》2012,13(2):216-235
In the domain of decision‐support tools for the management of marine fish resources, considerable attention has been paid to the development of models explaining how fish stocks change over space and time. In most models, fishing effort is assumed to be exogenous and determined by factors such as management. Increasingly, there has been a call for bio‐economic models to also account for the dynamics of fishing fleets, recognizing that fishers respond to changing environmental, institutional and economic conditions. A growing literature has sought to explicitly model the endogenous determinants of the capacity of fishing fleets, the intensity of its use and its temporal and spatial allocation across fishing opportunities. We review this literature, focusing on empirical applications of the behavioural models that have been put forward to explain and predict observed fleet dynamics. We find that although economic factors are usually included as a dominant driver in most studies, this is often based on the use of proxy variables for the key economic drivers, for which adequate data are lacking. Also, while many studies acknowledge that social and social–psychological factors play a significant role in explaining observed fishing behaviour, their inclusion in fishing fleet dynamic models is still very limited. Progress in this domain can only be achieved via the development of multidisciplinary research programmes focusing on applied quantitative analysis of the drivers of fishing fleet dynamics. 相似文献
98.
Martin DM Hall J Keirstead N Lowe A 《The Canadian veterinary journal. La revue veterinaire canadienne》2006,47(4):360-362
A 10-year-old, spayed female, obese golden retriever, presented for immune-mediated thrombocytopenia, was successfully managed with the administration of vincristine and prednisone. However, 6 mo after discontinuing corticosteroid therapy because of suspected iatrogenic hyperglucocorticoidism, the patient was presented with multiple, firm, bilaterally symmetric, dermal masses composed histologically of differentiated cortical bone. 相似文献
99.
100.
Evan A Mulligan Natalie Ferry Lise Jouanin Jörg Romeis Angharad MR Gatehouse 《Pest management science》2010,66(3):325-336
BACKGROUND: In spite of concern regarding potential non‐target effects of GM crops, few studies have compared GM pest control with conventional methods. The impacts of cypermethrin and oilseed rape expressing oryzacystatin‐1 (OC‐1) were compared in this study on the predator Chrysoperla carnea (Stephens). RESULTS: Adults fed purified rOC‐1 showed a subtle shift in digestive protease profile, with an increasing reliance on serine proteases (chymotrypsin), increase in aspartic proteases and a slight reduction in elastase activity. Although there were no effects on mortality, onset of oviposition was delayed; however, once egg production commenced, egg laying and hatching success rates were comparable with those of controls. Oryzacystatin‐1 expressed in pollen showed no detrimental effects. Cypermethrin had no effect on mortality owing to high levels of non‐specific esterase activity resulting in partial breakdown of the insecticide. In spite of this, there was a significant delay in onset of oviposition and a significant reduction in egg production and viability. CONCLUSION: This study demonstrates the potential for pest management to impact on predators, but importantly it highlights the ability of the predator to detoxify/respond to treatments with different modes of action. In this case, exposure to an insecticide carried a greater fitness cost than exposure to a protease inhibitor expressed in transgenic crops. Copyright © 2009 Society of Chemical Industry 相似文献