87,288 research outputs found
Cytochrome oxidase subunit VI of Trypanosoma brucei is imported without a cleaved presequence and is developmentally regulated at both RNA and protein levels
Get PDFMitochondrial respiration in the African trypanosome undergoes dramatic developmental stage regulation. This requires co-ordinated control of components encoded by both the nuclear genome and the kinetoplast, the unusual mitochondrial genome of these parasites. As a model for understanding the co-ordination of these genomes, we have examined the regulation and mitochondrial import of a nuclear-encoded component of the cytochrome oxidase complex, cytochrome oxidase subunit VI (COXVI). By generating transgenic trypanosomes expressing intact or mutant forms of this protein, we demonstrate that COXVI is not imported using a conventional cleaved presequence and show that sequences at the N-terminus of the protein are necessary for correct mitochondrial sorting. Analyses of endogenous and transgenic COXVI mRNA and protein expression in parasites undergoing developmental stage differentiation demonstrates a temporal order of control involving regulation in the abundance of, first, mRNA and then protein. This represents the first dissection of the regulation and import of a nuclear-encoded protein into the cytochrome oxidase complex in these organisms, which were among the earliest eukaryotes to possess a mitochondrion
11.03.010: Letter to F. E. Rabbitts Esq., District Grand Secretary, from H. K. Pike, Secretary, Lodge Tasker No. 454
No full textLetter to F. E. Rabbitts Esq., District Grand Secretary, from H. K. Pike, Secretary, Lodge Tasker No. 454; 27.6 x 21.0 cm, February 24, 193
Ballistics : course of instruction for artillery gunners
No full textPrecede al título: Artillery Circular F, April 25, 1893Precede ó tít.: Artillery Circular F, April 25, 189
Highly Regioselective Indoline Synthesis under Nickel/Photoredox Dual Catalysis
Get PDFNickel/photoredox catalysis is used to synthesize indolines in one step from iodoacetanilides and alkenes. Very high regioselectivity for 3-substituted indoline products is obtained for both aliphatic and styrenyl olefins. Mechanistic investigations indicate that oxidation to Ni(III) is necessary to perform the difficult C–N bond-forming reductive elimination, producing a Ni(I) complex, which in turn is reduced to Ni(0). This process serves to further demonstrate the utility of photoredox catalysts as controlled single electron transfer agents in multioxidation state nickel catalysis.National Institute of General Medical Sciences (U.S.) (GM63755
Diets of seabirds and consequences of changes in food supply
No full textResearch conducted by members of the Working Group on Seabird Ecology, on issues most likely to be raised within the ICES community concerning the foraging ecology of seabirds and waders, and the potential interactions between these groups of birds and fisheries.
A review of issues related to seabird consumption of fish and shellfish stocks, discards and mariculture as well as the trophic role and ecology of seabirds and waders: G. L. Hunt, W. A. Montevecchi, and M. F. Leopold.
Consumption of pre-recruit fish by seabirds and the possible use of this as an indicator of fish stock recruitment: S. P. R. Greenstreet, P. H. Becker, R. T. Barrett, P. Fossum, and M. F. Leopold.
Variation in prey taken by seabirds: M. L. Tasker, C. J. Camphuysen, and P.Fossum.
Evaluation of the role of discards in supporting bird populations and their effects on the species composition of seabirds in the North Sea: S. Garthe, U. Walter, M. L. Tasker, P. H. Becker, G. Chapdelaine, and R. W. Furness.
Exploration of the short-and medium-term consequences of a reduction in the amounts of fish discarded: M. L. Tasker, P. H. Becker, and G. Chapdelaine
Evidence for decadal scale variations in seabird population ecology and links with the North Atlantic oscillation: J. B. Reid, P. H. Becker, and R. W. Furness.
A review of the causes, and consequences at the population level, of mass mortalities of seabirds : C. J. Camphuysen, P. J. Wright, M. Leopold, O. Hüppop, and J. B. Reid.
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Nickel-Catalyzed Mizoroki-Heck Reaction of Aryl Sulfonates and Chlorides with Electronically Unbiased Terminal Olefins: High Selectivity for Branched Products
Get PDFAchieving high selectivity in the Heck reaction of electronically unbiased alkenes has been a longstanding challenge. Using a nickel-catalyzed cationic Heck reaction, we were able to achieve excellent selectivity for branched products (≥19:1 in all cases) over a wide range of aryl electrophiles and aliphatic olefins. A bidentate ligand with a suitable bite angle and steric profile was key to obtaining high branched/linear selectivity, whereas the appropriate base suppressed alkene isomerization of the product. Although aryl triflates are traditionally used to access the cationic Heck pathway, we have shown that, by using triethylsilyl trifluoromethanesulfonate, we can effect a counterion exchange of the catalytic nickel complex, such that cheaper and more stable aryl chlorides, mesylates, tosylates, and sulfamates can be used to yield the same branched products with high selectivity.National Institute of General Medical Sciences (U.S.) (NIGMS (GM62755))National Institutes of Health (U.S.) (NIH Postdoctoral Fellowship)National Science Foundation (U.S.) (NSF Graduate Research Fellowship
Recent advances in homogeneous nickel catalysis
No full textTremendous advances have been made in nickel catalysis over the past decade. Several key properties of nickel, such as facile oxidative addition and ready access to multiple oxidation states, have allowed the development of a broad range of innovative reactions. In recent years, these properties have been increasingly understood and used to perform transformations long considered exceptionally challenging. Here we discuss some of the most recent and significant developments in homogeneous nickel catalysis, with an emphasis on both synthetic outcome and mechanism.National Science Foundation (U.S.) (Graduate Research Fellowship)National Institute of General Medical Sciences (U.S.) (NIGMS (GM62755)
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
METAL NON-METAL AND OTHER INTERFACES - THE ROLE OF IMAGE INTERACTIONS
No full textThe authors argue that many phenomena associated with metal/nonmetal interfaces and similar situations with a large dielectric constant mismatch can be understood in terms of the image interactions due to charges in the nonmetal. The effects are additional to the traditional interactions, and are especially significant when no reactions between the phases occur. The image-charge concept allows one to rationalise much apparently unrelated information concerning: (a) the systematics of wetting and nonwetting of oxides by liquid metals; (b) the systematics of strong metal-support interaction in catalysis; (c) the spatial variation of stoichiometry in oxides grown on metals; (d) the dependence on thickness of the observed changes in the wetting by water of oxide grown on silicon; (e) some features of radiation-enhanced adhesion; and (f) a number of correlations of behaviour with nonmetal properties in which the precise choice of metal is not critical
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