1,992 research outputs found
Dual endothelin-converting enzyme/neutral endopeptidase blockade in rats with D-galactosamine-induced liver failure
Secondary activation of the endothelin system is thought to be involved in toxic liver injury. This study tested the hypothesis that dual endothelin-converting enzyme / neutral endopeptidase blockade might be able to attenuate acute toxic liver injury
Amplification of phosphoglycerate dehydrogenase diverts glycolytic flux and contributes to oncogenesis
Aquatic adaptation of a laterally acquired pectin degradation pathway in marine gammaproteobacteria
Mobile genomic islands distribute functional traits between microbes and habitats, yet it remains unclear how their proteins adapt to new environments. Here we used a comparative phylogenomic and proteomic approach to show that the marine bacterium Pseudoalteromonas haloplanktis ANT/505 acquired a genomic island with a functional pathway for pectin catabolism. Bioinformatics and biochemical experiments revealed that this pathway encodes a series of carbohydrate-active enzymes including two multimodular pectate lyases, PelA and PelB. PelA is a large enzyme with a polysaccharide lyase family 1 (PL1) domain and a carbohydrate esterase family 8 domain, and PelB contains a PL1 domain and two carbohydrate-binding domains of family 13. Comparative phylogenomic analyses indicate that the pathway was most likely acquired from terrestrial microbes, yet we observed multi-modular orthologues only in marine bacteria. Proteomic experiments showed that P. haloplanktis ANT/505 secretes both pectate lyases into the environment in the presence of pectin. These multi-modular enzymes may therefore represent a marine innovation that enhances physical interaction with pectins to reduce loss of substrate and enzymes by diffusion. Our results revealed that marine bacteria can catabolize pectin, and highlight enzyme fusion as a potential adaptation that may facilitate microbial consumption of polymeric substrates in aquatic environments
Cultura alimentar associada às plantas alimentícias não convencionais (PANC): uso e preparo por agricultores familiares agroecológicos ou em transição agroambiental.
A fim de resgatar e valorizar o conhecimento sobre a agrobiodiversidade que integra os espaços rurais, o objetivo deste trabalho foi investigar as formas de uso e preparo de plantas alimentícias não convencionais (PANC) conhecidas e/ou utilizadas por agricultores familiares agroecológicos ou em transição agroambiental, no sul do Brasil. Foram selecionadas 14 famílias no município de São Lourenço do Sul, RS, e realizadas entrevistas guiadas por um roteiro semiestruturado. Após a análise dos dados, foram estabelecidas categorias para os modos de uso e preparo das PANC. Foi constatado um amplo conhecimento, destacando-se o consumo in natura, seguido do processamento em geleia e schmier (doce em pasta). Muitas espécies ainda são subutilizadas, porém, a gradativa valorização das PANC, especialmente pelo público consumidor e pesquisadores, tem resultado em crescente interesse por parte dos (as) agricultores (as) para consumo e comércio nas feiras livres.Edição dos Anais do XI Congresso Brasileiro de Agroecologia, São Cristóvão, Sergipe, 2019. Ecologia de Saberes: Ciência, Cultura e Arte na Democratização dos Sistemas Agroalimentares
Chemical Composition and Anti-Inflammatory Activity of the Essential Oil from the Leaves of Male and Female Specimens of Baccharis punctulata DC.
Vortex microavalanches in superconducting Pb thin films
Local magnetization measurements on 100 nm type-II superconducting Pb thin
films show that flux penetration changes qualitatively with temperature. Small
flux jumps at the lowest temperatures gradually increase in size, then
disappear near T = 0.7Tc. Comparison with other experiments suggests that the
avalanches correspond to dendritic flux protrusions. Reproducibility of the
first flux jumps in a decreasing magnetic field indicates a role for defect
structure in determining avalanches. We also find a temperature-independent
final magnetization after flux jumps, analogous to the angle of repose of a
sandpile.Comment: 6 pages, 5 figure
Exploring structural and electronic effects in three isomers of tris{bis(trifluoromethyl)phenyl}borane: Towards the combined electrochemical-frustrated Lewis pair activation of H2
Three structural isomers of tris{bis(trifluoromethyl)phenyl}borane have been studied as the acidic com- ponent of frustrated Lewis pairs. While the 3,5-substituted isomer is already known to heterolytically cleave H2 to generate a bridging-hydride; ortho-substituents in the 2,4- and 2,5-isomers quench such reactivity through electron donation into the vacant boron pz orbital and steric blocking of the boron centre; as shown by electrochemical, structural and computational studies. Electrochemical studies of the corresponding borohydrides identify that the two-electron oxidation of terminal-hydrides occurs at more positive potentials than observed for [HB(C6F5)3]−, while the bridging-hydride oxidizes at a higher poten- tial still, comparable to that of free H2
Winner-take-all selection in a neural system with delayed feedback
We consider the effects of temporal delay in a neural feedback system with
excitation and inhibition. The topology of our model system reflects the
anatomy of the avian isthmic circuitry, a feedback structure found in all
classes of vertebrates. We show that the system is capable of performing a
`winner-take-all' selection rule for certain combinations of excitatory and
inhibitory feedback. In particular, we show that when the time delays are
sufficiently large a system with local inhibition and global excitation can
function as a `winner-take-all' network and exhibit oscillatory dynamics. We
demonstrate how the origin of the oscillations can be attributed to the finite
delays through a linear stability analysis.Comment: 8 pages, 6 figure
Internal avalanches in a pile of superconducting vortices
Using an array of miniature Hall probes, we monitored the spatiotemporal
variation of the internal magnetic induction in a superconducting niobium
sample during a slow sweep of external magnetic field. We found that a sizable
fraction of the increase in the local vortex population occurs in abrupt jumps.
The size distribution of these avalanches presents a power-law collapse on a
limited range. In contrast, at low temperatures and low fields, huge avalanches
with a typical size occur and the system does not display a well-defined
macroscopic critical current.Comment: 5 pages including 5 figure
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