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排序方式: 共有350条查询结果,搜索用时 31 毫秒
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Sean Dunne 《Ethnic and racial studies》2014,37(10):1916-1919
135.
Aisling Dunne Jodi Maple‐Grødem Daniela Gargano Richard P. Haslam Johnathan A. Napier Nam‐Hai Chua Rosalind Russell Simon Geir Møller 《The Plant journal : for cell and molecular biology》2014,80(6):1131-1138
The widespread use of herbicides and antibiotics for selection of transgenic plants has not been very successful with regard to commercialization and public acceptance. Hence, alternative selection systems are required. In this study, we describe the use of ipt, the bacterial gene encoding the enzyme isopentenyl transferase from Agrobacterium tumefaciens, as a positive selectable marker for plastid transformation. A comparison between the traditional spectinomycin‐based aadA selection system and the ipt selection system demonstrated that selection of transplastomic plants on medium lacking cytokinin was as effective as selection on medium containing spectinomycin. Proof of principle was demonstrated by transformation of the kasIII gene encoding 3‐ketoacyl acyl carrier protein synthase III into tobacco plastids. Transplastomic tobacco plants were readily obtained using the ipt selection system, and were phenotypically normal despite over‐expression of isopentenyl transferase. Over‐expression of KASIII resulted in a significant increase in 16:0 fatty acid levels, and a significant decrease in the levels of 18:0 and 18:1 fatty acids. Our study demonstrates use of a novel positive plastid transformation system that may be used for selection of transplastomic plants without affecting the expression of transgenes within the integrated vector cassette or the resulting activity of the encoded protein. This system has the potential to be applied to monocots, which are typically not amenable to traditional antibiotic‐based selection systems, and may be used in combination with a negative selectable marker as part of a two‐step selection system to obtain homoplasmic plant lines. 相似文献
136.
Jennifer A. Dunne Conrad C. Labandeira Richard J. Williams 《Proceedings. Biological sciences / The Royal Society》2014,281(1782)
Generalities of food web structure have been identified for extant ecosystems. However, the trophic organization of ancient ecosystems is unresolved, as prior studies of fossil webs have been limited by low-resolution, high-uncertainty data. We compiled highly resolved, well-documented feeding interaction data for 700 taxa from the 48 million-year-old latest early Eocene Messel Shale, which contains a species assemblage that developed after an interval of protracted environmental and biotal change during and following the end-Cretaceous extinction. We compared the network structure of Messel lake and forest food webs to extant webs using analyses that account for scale dependence of structure with diversity and complexity. The Messel lake web, with 94 taxa, displays unambiguous similarities in structure to extant webs. While the Messel forest web, with 630 taxa, displays differences compared to extant webs, they appear to result from high diversity and resolution of insect–plant interactions, rather than substantive differences in structure. The evidence presented here suggests that modern trophic organization developed along with the modern Messel biota during an 18 Myr interval of dramatic post-extinction change. Our study also has methodological implications, as the Messel forest web analysis highlights limitations of current food web data and models. 相似文献
137.
Christopher R. Dunne Anthony R. Cillo Danielle R. Glick Katherine John Cody Johnson Jaspinder Kanwal Brian T. Malik Kristina Mammano Stefan Petrovic William Pfister Alexander S. Rascoe Diane Schrom Scott Shapiro Jeffrey W. Simkins David Strauss Rene Talai John P. Tomtishen III Josephine Vargas Tony Veloz Thomas O. Vogler Michael E. Clenshaw Devin T. Gordon-Hamm Kathryn L. Lee Elizabeth C. Marin 《PLoS biology》2014,12(12)
138.
Aims: This study investigates the antimicrobial activity and mode of action of novel carbohydrate fatty acid (CFA) derivatives against Staphylococcus aureus and methicillin‐resistant Staph. aureus (MRSA). Methods and Results: Minimum inhibitory concentrations (MICs) and the effect of CFA derivatives on lag phase were determined using a broth microdilution method. Lauric acid carbohydrate esters and corresponding ether analogues showed the greatest antimicrobial activity with MIC values between 0·04 and 0·16 mmol l?1. Leakage studies at 260 nm following exposure to CFA derivatives at 4× MIC showed a significant increase in membrane permeability for all compounds, after c. 15 min exposure except for the lauric beta ether CFA derivative. Further assessment using both BacLight and luminescence ATP assays confirmed that an increase in membrane permeability and reduced metabolic activity was associated with CFA treatment. Conclusions: All strains were significantly inhibited by the novel compounds studied, and efficacy was related to specific structural features. Cell‐membrane permeabilization was associated with CFA treatment and may account for at least a component of the mode of action of these compounds. Significance and Impact of the Study: This study reports the antimicrobial action of CFA compounds against a range of Staph. aureus and MRSA strains, and provides insights into their mode of action. 相似文献
139.
Valdovinos FS Ramos-Jiliberto R Garay-Narváez L Urbani P Dunne JA 《Ecology letters》2010,13(12):1546-1559
Species coexistence within ecosystems and the stability of patterns of temporal changes in population sizes are central topics in ecological theory. In the last decade, adaptive behaviour has been proposed as a mechanism of population stabilization. In particular, widely distributed adaptive trophic behaviour (ATB), the fitness-enhancing changes in individuals' feeding-related traits due to variation in their trophic environment, may play a key role in modulating the dynamics of feeding relationships within natural communities. In this article, we review and synthesize models and results from theoretical research dealing with the consequences of ATB on the structure and dynamics of complex food webs. We discuss current approaches, point out limitations, and consider questions ripe for future research. In spite of some differences in the modelling and analytic approaches, there are points of convergence: (1) ATB promotes the complex structure of ecological networks, (2) ATB increases the stability of their dynamics, (3) ATB reverses May's negative complexity-stability relationship, and (4) ATB provides resilience and resistance of networks against perturbations. Current knowledge supports ATB as an essential ingredient for models of community dynamics, and future research that incorporates ATB will be well positioned to address questions important for basic ecological research and its applications. 相似文献
140.
Wuhrer M Balog CI Catalina MI Jones FM Schramm G Haas H Doenhoff MJ Dunne DW Deelder AM Hokke CH 《The FEBS journal》2006,273(10):2276-2292
Schistosomes are parasitic flatworms that infect millions of people in (sub)tropical areas around the world. Glycoconjugates of schistosomes play a critical role in the interaction of the different developmental stages of the parasite with the host. In particular, glycosylated components of the eggs produced by the adult worm pairs living in the bloodstream are strongly immunogenic. We have investigated the glycosylation of interleukin-4-inducing factor from schistosome eggs (IPSE/alpha-1), a major secretory egg antigen from Schistosoma mansoni that triggers interleukin-4 production in human basophils, by MS analysis of tryptic glycopeptides. Nanoscale LC-MS(/MS) and MALDI-TOF(/TOF)-MS studies combined with enzymatic degradations showed that monomeric IPSE/alpha-1 contains two N-glycosylation sites, which are each occupied for a large proportion with core-difucosylated diantennary glycans that carry one or more Lewis X motifs. Lewis X has been reported as a major immunogenic glycan element of schistosomes. This is the first report both on the expression of Lewis X on a specific schistosome egg protein and on a protein-specific glycosylation analysis of schistosome eggs. 相似文献