Aims
To study the individual and combined contribution of catechin, protocatechuic and vanillic acids to inhibit the adhesion of uropathogenic Escherichia coli (UPEC) on the surface of silicone ...catheters.
Methods and Results
The adhesion of UPEC to silicone catheters during the exposure to nonlethal concentrations of phenolic compounds was measured, as well as changes in motility, presence of fimbriae, extra‐cellular polymeric substances, surface charge, hydrophobicity and membrane fluidity. The phenolic combination reduced 26–51% of motility, 1 log CFU per cm2 of adhered bacteria and 20–40% the carbohydrate and protein content in the biofilm matrix. Curli fimbriae, surface charge and cell hydrophobicity were affected to a greater extent by the phenolic combination. In the mixture, vanillic acid was the most effective for reducing bacterial adhesion, extra‐polymeric substance production, motility, curli fimbriae and biofilm structure. Notwithstanding, protocatechuic acid caused major changes in the bacterial cell surface properties, whereas catechin affected the cell membrane functionality.
Conclusion
Catechin, protocatechuic and vanillic acids have different bacterial cell targets, explaining the synergistic effect of their combination against uropathogenic E. coli.
Significance and Impact of Study
This study shows the contribution of catechin, protocatechuic and vanillic acids in producing a synergistic mixture against the adhesion of uropathogenic E. coli on silicone catheters. The action of catechin, vanillic and protocatechuic acids included specific contributions of each compound against the E. coli membrane’s integrity, motility, surface properties and production of extracellular polymeric substances. Therefore, the studied mixture of phenolic compounds could be used as an antibiotic alternative to reduce urinary tract infections associated with silicone catheters.
The present study explored the effect of quercetin on the expression of virulence genes actA, inlA, inlC, and their regulatory components, sigB and prfA, in L. monocytogenes. Furthermore, the ...physicochemical changes on the surface, membrane permeability, and biofilm formation of quercetin-treated bacteria were evaluated. An inhibitory dose-dependent effect of quercetin (0.1–0.8 mM) was observed on the cell attachment on stainless steel at 2 and 6 h at 37 °C. Quercetin at 0.8 mM prevented the biofilm formation on stainless steel surfaces after 6 h of incubation at 37 °C, while the untreated bacteria formed biofilms with a cell density of 5.1 Log CFU/cm2. The microscopic analysis evidenced that quercetin at 0.2 mM decreased the biovolume and covered area of the attached micro-colonies. Also, sigB, prfA, inlA, inlC, and actA genes were downregulated by 7–29 times lower compared to untreated bacteria. In addition, quercetin decreased the superficial cell charge, increased the membrane permeability, and its surface hydrophobicity. These results demonstrated that quercetin prevented biofilm formation, repressed the genes of stress and virulence of L. monocytogenes and also altered the physicochemical cell properties.
•Quercetin increased the membrane permeability and affected the physicochemical properties.•Virulence genes and their regulatory components were downregulated by quercetin.•Quercetin inhibited the biofilm development of L. monocytogenes.
Abstract
We present the first results from the Mapping Obscuration to Reionization with ALMA (MORA) survey, the largest Atacama Large Millimeter/submillimeter Array (ALMA) blank-field contiguous ...survey to date (184 arcmin
2
) and the only at 2 mm to search for dusty star-forming galaxies (DSFGs). We use the 13 sources detected above 5
σ
to estimate the first ALMA galaxy number counts at this wavelength. These number counts are then combined with the state-of-the-art galaxy number counts at 1.2 and 3 mm and with a backward evolution model to place constraints on the evolution of the IR luminosity function and dust-obscured star formation in the past 13 billion years. Our results suggest a steep redshift evolution on the space density of DSFGs and confirm the flattening of the IR luminosity function at faint luminosities, with a slope of
. We conclude that the dust-obscured component, which peaks at
z
≈ 2–2.5, has dominated the cosmic history of star formation for the past ∼12 billion years, back to
z
∼ 4. At
z
= 5, the dust-obscured star formation is estimated to be ∼35% of the total star formation rate density and decreases to 25%–20% at
z
= 6–7, implying a minor contribution of dust-enshrouded star formation in the first billion years of the universe. With the dust-obscured star formation history constrained up to the end of the epoch of reionization, our results provide a benchmark to test galaxy formation models, to study the galaxy mass assembly history, and to understand the dust and metal enrichment of the universe at early times.
Aims: To analyse the production of different metabolites by dark‐grown Euglena gracilis under conditions found to render high cell growth. Methods and Results: The combination of glutamate (5 g l⁻¹), ...malate (2 g l⁻¹) and ethanol (10 ml l⁻¹) (GM + EtOH); glutamate (7·15 g l⁻¹) and ethanol (10 ml l⁻¹); or malate (8·16 g l⁻¹), glucose (10·6 g l⁻¹) and NH₄Cl (1·8 g l⁻¹) as carbon and nitrogen sources, promoted an increase of 5·6, 3·7 and 2·6‐fold, respectively, in biomass concentration in comparison with glutamate and malate (GM). In turn, the production of α‐tocopherol after 120 h identified by LC‐MS was 3·7 ± 0·2, 2·4 ± 0·1 and 2 ± 0·1 mg g dry weight (DW)⁻¹, respectively, while in the control medium (GM) it was 0·72 ± 0·1 mg (g DW)⁻¹. For paramylon synthesis, the addition of EtOH or glucose induced a higher production. Amino acids were assayed by RP‐HPLC; Tyr a tocopherol precursor and Ala an amino acid with antioxidant activity were the amino acids synthesized at higher concentration. Conclusions: Dark‐grown E. gracilis Z is a suitable source for the generation of the biotechnologically relevant metabolites tyrosine, α‐tocopherol and paramylon. Significance and Impact of the Study: By combining different carbon and nitrogen sources and inducing a tolerable stress to the cell by adding ethanol, it was possible to increase the production of biomass, paramylon, α‐tocopherol and some amino acids. The concentrations of α‐tocopherol achieved in this study are higher than others reported previously for Euglena, plant and algal systems. This work helps to understand the effect of different carbon sources on the synthesis of bio‐molecules by E. gracilis and can be used as a basis for future works to improve the production of different metabolites of biotechnological importance by this organism.
The aim of the present study was to investigate the inhibitory mechanisms of quercetin against L. monocytogenes biofilm formation, by affecting secretion of polymeric substances (EPS) and ...spatio-temporal organization. The minimum concentration of quercetin inhibiting the establishment of bacterial biofilm was determined to be 0.8 mM; therefore, a lower concentration of the flavonoid (0.2 mM) was used in order to investigate its effect on cell attachment and EPS production on stainless steel and the spatio-temporal organization on glass, while avoiding bias of loss of cellular viability. In applying this concentration, reductions of 1.32 and 1.94 Log10 CFU/cm2 of initial adhesion and maximum cell density on stainless steel were observed on the test surfaces at 2 h (initial adhesion) and 24 h (maximum cell density), respectively. EPS on mature biofilms (24 h) was mainly composed by proteins (97.83%), followed by polysaccharides (2.03%) and DNA (0.14%). In addition, quercetin reduced total extracellular protein content by 41% compared with control; while, DNA and polysaccharide contents in biofilms were not affected. Also, relative to control, quercetin impaired surface colonization, early stages of biofilm formation and the development of a more complex architecture during its formation. This proved that quercetin inhibited the formation of L. monocytogenes biofilms by reducing initial attachment, the amount of extracellular proteins found in the EPS matrix and the overall spatio-temporal organization of L. monocytogenes.
•Quercetin inhibits biofilm formation of L. monocytogenes on stainless steel surfaces.•Spatio-temporal organization of L. monocytogenes biofilms was impaired by quercetin.•Anti-biofilm activity of quercetin can be related to inhibition of extracellular proteins secretion.
Live donor kidney transplantation is the best treatment option for most patients with late‐stage chronic kidney disease; however, the rate of living kidney donation has declined in the United States. ...A consensus conference was held June 5–6, 2014 to identify best practices and knowledge gaps pertaining to live donor kidney transplantation and living kidney donation. Transplant professionals, patients, and other key stakeholders discussed processes for educating transplant candidates and potential living donors about living kidney donation; efficiencies in the living donor evaluation process; disparities in living donation; and financial and systemic barriers to living donation. We summarize the consensus recommendations for best practices in these educational and clinical domains, future research priorities, and possible public policy initiatives to remove barriers to living kidney donation.
This article summarizes the proceedings of the June 2014 Consensus Conference on Best Practices in Live Kidney Donation, which include recommendations for educating transplant candidates and potential living donors, improving efficiencies in the living donor evaluation process, reducing disparities in living kidney donation, and steering future research and policy priorities to remove barriers to donation.
We present Early Science observations with the Large Millimeter Telescope, AzTEC 1.1 mm continuum images and wide bandwidth spectra (73–111 GHz) acquired with the Redshift Search Receiver, towards ...four bright lensed submillimetre galaxies identified through the Herschel Lensing Survey-snapshot and the Submillimetre Common-User Bolometer Array-2 Cluster Snapshot Survey. This pilot project studies the star formation history and the physical properties of the molecular gas and dust content of the highest redshift galaxies identified through the benefits of gravitational magnification. We robustly detect dust continuum emission for the full sample and CO emission lines for three of the targets. We find that one source shows spectroscopic multiplicity and is a blend of three galaxies at different redshifts (z = 2.040, 3.252, and 4.680), reminiscent of previous high-resolution imaging follow-up of unlensed submillimetre galaxies, but with a completely different search method, that confirm recent theoretical predictions of physically unassociated blended galaxies. Identifying the detected lines as 12CO (J
up = 2–5) we derive spectroscopic redshifts, molecular gas masses, and dust masses from the continuum emission. The mean H2 gas mass of the full sample is (2.0 ± 0.2) × 1011 M⊙/μ, and the mean dust mass is (2.0 ± 0.2) × 109 M⊙/μ, where μ ≈ 2–5 is the expected lens amplification. Using these independent estimations we infer a gas-to-dust ratio of δGDR ≈ 55–75, in agreement with other measurements of submillimetre galaxies. Our magnified high-luminosity galaxies fall on the same locus as other high-redshift submillimetre galaxies, extending the
$L^{\prime }_{\rm CO}$
–L
FIR correlation observed for local luminous and ultraluminous infrared galaxies to higher far-infrared and CO luminosities.
European forests have a prominent role in the global carbon cycle and an increase in carbon storage has been consistently reported during the twentieth century. Any further increase in forest carbon ...storage, however, could be hampered by increases in aridity and extreme climatic events. Here, we use forest inventory data to identify the relative importance of stand structure (stand basal area and mean d.b.h.), mean climate (water availability), and recent climate change (temperature and precipitation anomalies) on forest basal area change during the late twentieth century in three major European biomes. Using linear mixed-effects models we observed that stand structure, mean climate, and recent climatic change strongly interact to modulate basal area change. Although we observed a net increment in stand basal area during the late twentieth century, we found the highest basal area increments in forests with medium stand basal areas and small to medium-sized trees. Stand basal area increases correlated positively with water availability and were enhanced in warmer areas. Recent climatic warming caused an increase in stand basal area, but this increase was offset by water availability. Based on recent trends in basal area change, we conclude that the potential rate of aboveground carbon accumulation in European forests strongly depends on both stand structure and concomitant climate warming, adding weight to suggestions that European carbon stocks may saturate in the near future.
Seed predation and dispersal can critically influence plant community structure and dynamics. Inter-specific differences arising at these early stages play a crucial role on tree recruitment ...patterns, which in turn could influence forest dynamics and species segregation in heterogeneous environments such as Mediterranean forests. We investigated removal rates from acorns set onto the ground in two coexisting Mediterranean oak species -Quercus canariensis and Q. suber- in southern Spain. We developed maximum likelihood estimators to investigate the main factors controlling probabilities of seed removal and to describe species-specific functional responses. To account for inter-specific differences in seed-drop timing, two experiments were established: a simultaneous exposure of acorns of the two species (synchronous experiments) and a seed exposure following their natural seed-drop phenology (diachronic experiments). A total of 1536 acorns were experimentally distributed along a wide and natural gradient of plant cover, and removal was periodically monitored for three months at two consecutive years (with contrasting differences in seed production and thus seed availability on the ground). The probability of seed removal increased with plant cover (leaf area index, LAI) for the two oak species. Inter-specific differences in acorn removal were higher in open areas and disappeared in closed microhabitats, especially during a non-mast year. Despite later seed-drop, Q. suber acorns were removed faster and at a higher proportion than those of Q. canariensis. The higher probability of seed removal for this species could be attributed to its larger seed size compared to Q. canariensis, as inter-specific differences were less pronounced when similar sized acorns were exposed. Inter-specific differences in seed removal, arising from seed size variability and microsite heterogeneity, could be of paramount importance in oak species niche separation, driving stand dynamics and composition along environmental gradients.
ABSTRACT
We present long-slit intermediate-dispersion spectroscopic observations and narrow-band direct imaging of four classical nova shells, namely T Aur, HR Del, DQ Her, and QU Vul, and the ...nova-like source CK Vul. These are used to construct models of their nebular remnants using the morphokinematic modelling tool shape to reveal their 3D shape. All these nova remnants but CK Vul can be described by prolate ellipsoidal shells with different eccentricity degree, from the spherical QU Vul to the highly elongated shell with an equatorial component HR Del. On the other hand, CK Vul shows a more complex structure, with two pairs of nested bipolar lobes. The spatiokinematic properties of the ellipsoidal nova shells derived from our models include their true axial ratios. This parameter is expected to correlate with the expansion velocity and decline time t3 (i.e. their speed class) of a nova as the result the interaction of the ejecta with the circumstellar material and rotation speed and magnetic field of the white dwarf. We have compared these three parameters including data available in the literature for another two nova shells, V533 Her and FH Ser. There is an anticorrelation between the expansion velocity and the axial ratio and decline time t3 for nova remnants with ellipsoidal morphology, and a correlation between their axial ratios and decline times t3, confirming theoretical expectations that the fastest expanding novae have the smallest axial ratios. We note that the high expansion velocity of the nova shell HR Del of 615 km s−1 is inconsistent with its long decline time t3 of 250 d.
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