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191.
The anti-algal activity of five macrophyte extracts on the cyanobacterium Microcystis aeruginosa in Egypt was investigated in 2013. Extract activity varied according to plant type, extracting solvent and its concentration. The highest inhibitory activity was achieved with ethanol extract at a concentration of 80 mg l?1, followed by chloroformic extracts, at 60 mg l?1. Methanolic extracts of Eichhornia crassipes and Polygonum tomentosum inhibited growth of Microcystis aeruginosa at all concentrations. Acetonic extracts inhibited algal growth at 60 mg l?1, except for the extract of Ceratophyllum subdemersum, which showed stimulation of M. aeruginosa growth. Eichhornia crassipes ethanolic extract exerted the most powerful inhibition by more than five-fold, 570.17%, followed by those of P. tomentosum, Saccharum spontaneum, Ceratophyllum demersum and C. subdemersum, 559.48, 553.99, 544.11 and 366.51%, respectively. Phytochemical screening for the tested plant extracts revealed the presence of biologically active substances of different concentrations, with P. tomentosum having the highest polyphenols, 1.95% of dry weight. 相似文献
192.
Visualization of cytosolic ribosomes on the surface of mitochondria by electron cryo‐tomography 下载免费PDF全文
We employed electron cryo‐tomography to visualize cytosolic ribosomes on the surface of mitochondria. Translation‐arrested ribosomes reveal the clustered organization of the TOM complex, corroborating earlier reports of localized translation. Ribosomes are shown to interact specifically with the TOM complex, and nascent chain binding is crucial for ribosome recruitment and stabilization. Ribosomes are bound to the membrane in discrete clusters, often in the vicinity of the crista junctions. This interaction highlights how protein synthesis may be coupled with transport. Our work provides unique insights into the spatial organization of cytosolic ribosomes on mitochondria. 相似文献
193.
Colin?AM?SempleEmail author Alison?Maxwell Philippe?Gautier Fiona?M?Kilanowski Hayden?Eastwood Perdita?E?Barran Julia?R?Dorin 《BMC evolutionary biology》2005,5(1):32
Background
We have examined the evolution of the genes at the major human β-defensin locus and the orthologous loci in a range of other primates and mouse. For the first time these data allow us to examine selective episodes in the more recent evolutionary history of this locus as well as the ancient past. We have used a combination of maximum likelihood based tests and a maximum parsimony based sliding window approach to give a detailed view of the varying modes of selection operating at this locus. 相似文献194.
Kinetoplastida are protozoan organisms that probably diverged early in evolution from other eukaryotes. They are characterized
by a number of unique features with respect to their energy and carbohydrate metabolism. These organisms possess peculiar
peroxisomes, called glycosomes, which play a central role in this metabolism; the organelles harbour enzymes of several catabolic
and anabolic routes, including major parts of the glycolytic and pentosephosphate pathways. The kinetoplastid mitochondrion
is also unusual with regard to both its structural and functional properties. 相似文献
195.
Background
Capillary DNA sequencing machines allow the generation of vast amounts of data with little hands-on time. With this expansion of data generation, there is a growing need for automated data processing. Most available software solutions, however, still require user intervention or provide modules that need advanced informatics skills to allow implementation in pipelines. 相似文献196.
van Bennekum AM Wei S Gamble MV Vogel S Piantedosi R Gottesman M Episkopou V Blaner WS 《The Journal of biological chemistry》2001,276(2):1107-1113
Transthyretin (TTR) acts physiologically in the transport of retinol in the circulation. We previously reported the generation and partial characterization of TTR-deficient (TTR(-)) mice. TTR(-) mice have very low circulating levels of retinol and its specific transport protein, retinol-binding protein (RBP). We have examined the biochemical basis for the low plasma retinol-RBP levels. Cultured primary hepatocytes isolated from wild type (WT) and TTR(-) mice accumulated RBP in their media to an identical degree, suggesting that RBP was being secreted from the hepatocytes at the same rate. In vivo experiments support this conclusion. For the first 11 h after complete nephrectomy, the levels retinol and RBP rose in the circulations of WT and TTR(-) mice at nearly identical rates. However, human retinol-RBP injected intravenously was more rapidly cleared from the circulation (t(12) = 0.5 h for TTR(-) versus t(12) >6 h for WT) and accumulated faster in the kidneys of TTR(-) compared with WT mice. The rate of infiltration of the retinol-RBP complex from the circulation to tissue interstitial fluids was identical in both strains. Taken together, these data indicate that low circulating retinol-RBP levels in TTR(-) mice arise from increased renal filtration of the retinol-RBP complex. 相似文献
197.
Albsoul-Younes AM Sternweis PM Zhao P Nakata H Nakajima S Nakajima Y Kozasa T 《The Journal of biological chemistry》2001,276(16):12712-12717
G protein-coupled inward rectifier K(+) channels (GIRK channels) are activated directly by the G protein betagamma subunit. The crystal structure of the G protein betagamma subunits reveals that the beta subunit consists of an N-terminal alpha helix followed by a symmetrical seven-bladed propeller structure. Each blade is made up of four antiparallel beta strands. The top surface of the propeller structure interacts with the Galpha subunit. The outer surface of the betagamma torus is largely made from outer beta strands of the propeller. We analyzed the interaction between the beta subunit and brain GIRK channels by mutating the outer surface of the betagamma torus. Mutants of the outer surface of the beta(1) subunit were generated by replacing the sequences at the outer beta strands of each blade with corresponding sequences of the yeast beta subunit, STE4. The mutant beta(1)gamma(2) subunits were expressed in and purified from Sf9 cells. They were applied to inside-out patches of cultured locus coeruleus neurons. The wild type beta(1)gamma(2) induced robust GIRK channel activity with an EC(50) of about 4 nm. Among the eight outer surface mutants tested, blade 1 and blade 2 mutants (D1 and CD2) were far less active than the wild type in stimulating GIRK channels. However, the ability of D1 and CD2 to regulate type I and type II adenylyl cyclases was not very different from that of the wild type beta(1)gamma(2). As to the activities to stimulate phospholipase Cbeta(2), D1 was more potent and CD2 was less potent than the wild type beta(1)gamma(2). Additionally we tested four beta(1) mutants in which mutated residues are located in the top Galpha/beta interacting surface. Among them, mutant W332A showed far less ability than the wild type to activate GIRK channels. These results suggest that the outer surface of blade 1 and blade 2 of the beta subunit might specifically interact with GIRK and that the beta subunit interacts with GIRK both over the outer surface and over the top Galpha interacting surface. 相似文献
198.
Cannibals and their victims often share common resources and thus potentially compete. Smaller individuals are often competitively superior to larger ones because of size-dependent scaling of foraging and metabolic rates, while larger ones may use cannibalism to counter this competition. We study the interplay between cannibalism and competition using a size-structured population model in which all individuals consume a shared resource but in which larger ones may cannibalize smaller conspecifics. In this model, intercohort competition causes single-cohort cycles when cannibalism is absent. Moderate levels of cannibalism reduce intercohort competition, enabling coexistence of many cohorts. More voracious cannibalism, in combination with competition, produces large-amplitude cycles and a bimodal population size distribution with many small and few giant individuals. These coexisting "dwarfs" and "giants" have very different life histories, resulting from a reversal in importance of cannibalism and competition. The population structure at time of birth determines whether individuals suffer severe cannibalism, with the few survivors reaching giant sizes, or whether they suffer intense intracohort competition, with all individuals remaining small. These model results agree remarkably well with empirical data on perch population dynamics. We argue that the induction of cannibalistic giants in piscivorous fish is a population-dynamic emergent phenomenon that requires a combination of size-dependent cannibalism and competition. 相似文献
199.
Lidwien AM Smit Manolis Kogevinas Josep M Ant�� Emmanuelle Bouzigon Juan Ram��n Gonz��lez Nicole Le Moual Hans Kromhout Anne-Elie Carsin Isabelle Pin Deborah Jarvis Roel Vermeulen Christer Janson Joachim Heinrich Ivo Gut Mark Lathrop Miguel A Valverde Florence Demenais Francine Kauffmann 《Respiratory research》2012,13(1):26
Background
Transient receptor potential (TRP) vanilloid and ankyrin cation channels are activated by various noxious chemicals and may play an important role in the pathogenesis of cough. The aim was to study the influence of single nucleotide polymorphisms (SNPs) in TRP genes and irritant exposures on cough.Methods
Nocturnal, usual, and chronic cough, smoking, and job history were obtained by questionnaire in 844 asthmatic and 2046 non-asthmatic adults from the Epidemiological study on the Genetics and Environment of Asthma (EGEA) and the European Community Respiratory Health Survey (ECRHS). Occupational exposures to vapors, gases, dusts, and/or fumes were assessed by a job-exposure matrix. Fifty-eight tagging SNPs in TRPV1, TRPV4, and TRPA1 were tested under an additive model.Results
Statistically significant associations of 6 TRPV1 SNPs with cough symptoms were found in non-asthmatics after correction for multiple comparisons. Results were consistent across the eight countries examined. Haplotype-based association analysis confirmed the single SNP analyses for nocturnal cough (7-SNP haplotype: p-global = 4.8 × 10-6) and usual cough (9-SNP haplotype: p-global = 4.5 × 10-6). Cough symptoms were associated with exposure to irritants such as cigarette smoke and occupational exposures (p < 0.05). Four polymorphisms in TRPV1 further increased the risk of cough symptoms from irritant exposures in asthmatics and non-asthmatics (interaction p < 0.05).Conclusions
TRPV1 SNPs were associated with cough among subjects without asthma from two independent studies in eight European countries. TRPV1 SNPs may enhance susceptibility to cough in current smokers and in subjects with a history of workplace exposures. 相似文献200.
Bjorn Kloosterman AM Anithakumari Pierre-Yves Chibon Marian Oortwijn Gerard C van der Linden Richard GF Visser Christian WB Bachem 《BMC plant biology》2012,12(1):17