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31.
Nidia Obscura Acosta Veli Mäkinen Alexandru I. Tomescu 《Algorithms for molecular biology : AMB》2018,13(1):3
Background
Reconstructing the genome of a species from short fragments is one of the oldest bioinformatics problems. Metagenomic assembly is a variant of the problem asking to reconstruct the circular genomes of all bacterial species present in a sequencing sample. This problem can be naturally formulated as finding a collection of circular walks of a directed graph G that together cover all nodes, or edges, of G.Approach
We address this problem with the “safe and complete” framework of Tomescu and Medvedev (Research in computational Molecular biology—20th annual conference, RECOMB 9649:152–163, 2016). An algorithm is called safe if it returns only those walks (also called safe) that appear as subwalk in all metagenomic assembly solutions for G. A safe algorithm is called complete if it returns all safe walks of G.Results
We give graph-theoretic characterizations of the safe walks of G, and a safe and complete algorithm finding all safe walks of G. In the node-covering case, our algorithm runs in time \(O(m^2 + n^3)\), and in the edge-covering case it runs in time \(O(m^2n)\); n and m denote the number of nodes and edges, respectively, of G. This algorithm constitutes the first theoretical tight upper bound on what can be safely assembled from metagenomic reads using this problem formulation.32.
33.
Preventing and eradicating biofilms remains a challenge in clinical and industrial settings. Recently, the present authors demonstrated that silver oxynitrate (Ag7NO11) prevented and eradicated single-species planktonic and biofilm populations of numerous microbes at lower concentrations than other silver (Ag) compounds. Here, the antimicrobial and anti-biofilm efficacy of Ag7NO11 is elaborated by testing its in vitro activity against combinations of dual-species, planktonic and biofilm populations of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. As further evidence emerges that multispecies bacterial communities are more common in the environment than their single-species counterparts, this study reinforces the diverse applicability of the minimal biofilm eradication concentration (MBEC?) assay for testing antimicrobial compounds against biofilms. Furthermore, this study demonstrated that Ag7NO11 had enhanced antimicrobial and anti-biofilm activity compared to copper sulfate (CuSO4) and silver nitrate (AgNO3) against the tested bacterial species. 相似文献
34.
Florin G. Horhat Fuat Gundogdu Laurentiu V. David Eugen S. Boia Laurentiu Pirtea Razvan Horhat Alexandru Cucui-Cozma Ioana Ciuca Mircea Diaconu Razvan Nitu Monica Licker Delia I. Horhat Alexandru F. Rogobete Marius L. Moise Calin Tataru 《Biochemical genetics》2017,55(3):204-211
A high percentage of critical patients are found to develop acute respiratory distress syndrome (ARDS). Several studies have reported high mortality rates in these cases which are most frequently associated with multiple organ dysfunctions syndrome. Lately, many efforts have been made to evaluate and monitor ARDS in critical patients. In this regard, the assessment of genetic polymorphisms responsible for developing ARDS present as a challenge and are considered future biomarkers. Early detection of the specific polymorphic gene responsible for ARDS in critically ill patients can prove to be a useful tool in the future, able to help decrease the mortality rates in these cases. Moreover, identifying the genetic polymorphism in these patients can help in the implementation of a personalized intensive therapy scheme for every type of patient, based on its genotype. 相似文献
35.
Endogenous circadian rhythms in pigment composition induce changes in photochemical efficiency in plant canopies 下载免费PDF全文
José Ignacio García‐Plazaola Beatriz Fernández‐Marín Juan Pedro Ferrio Josu G. Alday Günter Hoch Damien Landais Alexandru Milcu David T. Tissue Jordi Voltas Arthur Gessler Jacques Roy Víctor Resco de Dios 《Plant, cell & environment》2017,40(7):1153-1162
There is increasing evidence that the circadian clock is a significant driver of photosynthesis that becomes apparent when environmental cues are experimentally held constant. We studied whether the composition of photosynthetic pigments is under circadian regulation, and whether pigment oscillations lead to rhythmic changes in photochemical efficiency. To address these questions, we maintained canopies of bean and cotton, after an entrainment phase, under constant (light or darkness) conditions for 30–48 h. Photosynthesis and quantum yield peaked at subjective noon, and non‐photochemical quenching peaked at night. These oscillations were not associated with parallel changes in carbohydrate content or xanthophyll cycle activity. We observed robust oscillations of Chl a/b during constant light in both species, and also under constant darkness in bean, peaking when it would have been night during the entrainment (subjective nights). These oscillations could be attributed to the synthesis and/or degradation of trimeric light‐harvesting complex II (reflected by the rhythmic changes in Chl a/b), with the antenna size minimal at night and maximal around subjective noon. Considering together the oscillations of pigments and photochemistry, the observed pattern of changes is counterintuitive if we assume that the plant strategy is to avoid photodamage, but consistent with a strategy where non‐stressed plants maximize photosynthesis. 相似文献
36.
37.
Joachim Müller Carmen Limban Britta Stadelmann Alexandru Vasile Missir Ileana Cornelia Chirita Mariana Carmen Chifiriuc George Mihai Nitulescu Andrew Hemphill 《Parasitology international》2009,58(2):128-135
Fifty members of a novel class of antimicrobial compounds, 2-(4-R-phenoxymethyl)benzoic acid thioureides, were synthesized and characterized with respect to their activities against three parasites of human relevance, namely the protozoa Giardia lamblia and Toxoplasma gondii, and the larval (metacestode) stage of the tapeworm Echinococcus multilocularis. To determine the selective toxicity of these compounds, the human colon cancer cell line Caco2 and primary cultures of human foreskin fibroblasts (HFF) were also investigated. The new thioureides were obtained in a three-step-reaction process and subsequently characterized by their physical constants (melting point, solubility). The chemical structures were elucidated by 1H NMR, 13C NMR, IR spectral methods and elemental analysis. The analyses confirmed the final and intermediate compound structures and the synthesis. The compounds were then tested on the parasites in vitro. All thioureides, except two compounds with a nitro group, were totally ineffective against Giardia lamblia. 23 compounds inhibited the proliferation of T. gondii, three of them with an IC50 of approximately 1 μM. The structural integrity of E. multilocularis metacestodes was affected by 22 compounds. In contrast, HFF were not susceptible to any of these thioureides, while Caco2 cells were affected by 17 compounds, two of them inhibiting proliferation with an IC50 in the micromolar range. Thioureides may thus present a promising class of anti-infective agents. 相似文献
38.
Patterns of contemporary hybridization inferred from paternity analysis in a four-oak-species forest
Background
Few studies address the issue of hybridization in a more than two-species context. The species-rich Quercus complex is one of the systems which can offer such an opportunity. To investigate the contemporary pattern of hybridization we sampled and genotyped 320 offspring from a natural mixed forest comprising four species of the European white oak complex: Quercus robur, Q. petraea, Q. pubescens, and Q. frainetto. 相似文献39.
40.
Lemieux M Bouchard F Gosselin P Paquin J Mateescu MA 《Biochemical and biophysical research communications》2011,(3):429-434
The objective of this study was to evaluate the human NCI-N87 cell line as a model for gastric permeability drug studies under pH conditions of the stomach. The optimal conditions that led NCI-N87 cells to form a typical differentiated gastric epithelial barrier were a seeding density of 2.5 × 105 cells/cm2 on porous inserts and growth in serum-complemented RPMI-1640 medium until 18–27 days post-confluency. The resulting cell monolayers showed moderately high transepithelial electrical resistance (TEER) values of about 500 Ω cm2, cells of polygonal morphology expressing E-cadherin and ZO-1 proteins at their contact surfaces, and production of mucus clusters. The monolayers withstood apical pH of 7.4 down to 3.0 with the basal pH fixed at 7.4. The apparent permeability coefficients (Papp) of model compounds were evaluated in the apical-to-basolateral and basolateral-to-apical directions under different pH gradients. The monolayers were impermeable to the integrity marker Lucifer Yellow (low Papp of 0.3–1.1 × 10−6 cm/s). The furosemide Papp (0.4–1.5 × 10−5 cm/s) were slightly dependent on pH but remained moderate. The caffeine Papp (4.2–5.0 × 10−5 cm/s) were higher and insensitive to pH changes. The NCI-N87 cell line provides a useful in vitro tool to assess gastric drug permeability and absorption under physiologic conditions prevailing in the human stomach. 相似文献