Paper-based chromatic toxicity bioassay by analysis of bacterial ferricyanide reduction

Water quality assessment requires a continuous and strict analysis of samples to guarantee compliance with established standards. Nowadays, the increasing number of pollutants and their synergistic effects lead to the development general toxicity bioassays capable to analyse water pollution as a whole. Current general toxicity methods, e.g. Microtox®, rely on long operation protocols, the use of complex and expensive instrumentation and sample pre-treatment, which should be transported to the laboratory for analysis. These requirements delay sample analysis and hence, the response to avoid an environmental catastrophe. In an attempt to solve it, a fast (15 min) and low-cost toxicity bioassay based on the chromatic changes associated to bacterial ferricyanide reduction is here presented. E. coli cells (used as model bacteria) were stably trapped on low-cost paper matrices (cellulose-based paper discs, PDs) and remained viable for long times (1 month at -20 °C). Apart from bacterial carrier, paper matrices also acted as a fluidic element, allowing fluid management without the need of external pumps. Bioassay evaluation was performed using copper as model toxic agent. Chromatic changes associated to bacterial ferricyanide reduction were determined by three different transduction methods, i.e. (i) optical reflectometry (as reference method), (ii) image analysis and (iii) visual inspection. In all cases, bioassay results (in terms of half maximal effective concentrations, EC50) were in agreement with already reported data, confirming the good performance of the bioassay. The validation of the bioassay was performed by analysis of real samples from natural sources, which were analysed and compared with a reference method (i.e. Microtox). Obtained results showed agreement for about 70% of toxic samples and 80% of non-toxic samples, which may validate the use of this simple and quick protocol in the determination of general toxicity. The minimum instrumentation requirements and the simplicity of the bioassay open the possibility of in-situ water toxicity assessment with a fast and low-cost protocolPostprint (author's final draft

Fast fabrication of reusable polyethersulfone microbial biosensors through biocompatible phase separation

In biosensors fabrication, entrapment in polymeric matrices allows efficient immobilization of the biorecognition elements without compromising their structure and activity. When considering living cells, the biocompatibility of both the matrix and the polymerization procedure are additional critical factors. Bio-polymeric gels (e.g. alginate) are biocompatible and polymerize under mild conditions, but they have poor stability. Most synthetic polymers (e.g. PVA), on the other hand, present improved stability at the expense of complex protocols involving chemical/physical treatments that decrease their biological compatibility. In an attempt to explore new solutions to this problem we have developed a procedure for the immobilization of bacterial cells in polyethersulfone (PES) using phase separation. The technology has been tested successfully in the construction of a bacterial biosensor for toxicity assessment. Biosensors were coated with a 300 μm bacteria-containing PES membrane, using non-solvent induced phase separation (membrane thickness≈300 μm). With this method, up to 2.3×106 cells were immobilized in the electrode surface with an entrapment efficiency of 8.2%, without compromising cell integrity or viability. Biosensing was performed electrochemically through ferricyanide respirometry, with metabolically-active entrapped bacteria reducing ferricyanide in the presence of glucose. PES biosensors showed good stability and reusability during dry frozen storage for up to 1 month. The analytical performance of the sensors was assessed carrying out a toxicity assay in which 3,5-dichlorophenol (DCP) was used as a model toxic compound. The biosensor provided a concentration-dependent response to DCP with half-maximal effective concentration (EC50) of 9.2 ppm, well in agreement with reported values. This entrapment methodology is susceptible of mass production and allows easy and repetitive production of robust and sensitive bacterial biosensorsPostprint (author's final draft

Global study of 9 Be + p at 2.72 A MeV

Background: In our recent experiment, 9 Be + p at 5.67 A MeV, the breakup decay rates to the three configurations, α + α + n , 8 Be ∗ + n and 5 He + 4 He of 9 Be , were observed and quantified in the proton recoil spectra, in a full kinematics approach. Unfolding step by step the accessibility to the above configurations, it will require similar experiments at lower or/and higher energies. It will also require the interpretation of the data in a theoretical framework. Three-body models for the structure of 9 Be have been developed and applied to reactions with heavy targets. Further research on lighter targets is required for the best establishment of the model. Such models are relevant for the calculation of the corresponding radiative capture reaction rate, α ( α , γ ) 9 Be followed by 9 Be ( α , n ) 12 C . The last is essential for the r -process abundance predictions. Purpose: Investigate the breakup decay rate of 9 Be + p at 2.72 A MeV, where the direct configuration α + α + n is mainly accessible. Compare and interpret data at this low energy and at the higher energy of 5.67 A MeV into a four-body continuum discretized coupled-channel formalism. Point out and discuss couplings to continuum. Methods: Our experimental method includes an exclusive breakup measurement in a full kinematic approach of 9 Be incident on a proton target at 24.5 MeV ( 2.72 A MeV). Complementary the elastic scattering is measured and other reaction channels are evaluated from previous measurements under the same experimental conditions. The interpretation of present data at 2.72 A MeV and previous data at 5.67 A MeV, are considered in a four-body continuum discretized coupled channel (CDCC) approach, using the transformed harmonic oscillator method for the three-body projectile. Results: An elastic scattering angular distribution at 2.72 A MeV is measured, which compares very well with CDCC calculations, indicating a strong coupling to continuum. At the same energy, the breakup and total reaction cross sections are measured as σ break = 2.5 ± 1 mb and σ tot = 510 ± L 90 mb , in good agreement with the calculated values of 3.7 and 433 mb, respectively. Further on, into the same theoretical framework, the elastic scattering and breakup cross section data at 5.67 A MeV are found in very good agreement with the CDCC calculations. Conclusions: It was confirmed in a global experimental framework that four-body CDCC calculations can describe very well the data even at low energies. Coupling to continuum is very strong despite the small measured breakup cross section. Moreover, the present results support further our three-body model for the structure of 9 Be , validating relevant radiative reaction rates obtained previously.Programa de investigación e innovación de la Unión Europea HORIZON2020 No. 654002-ENSAR2European Research Council (ERC) 714625Ministerio de Ciencia, Innovación y Universidades de España. PGC2018-095640-B-I00Ministerio de España de Economía y Competitividad y Fondo de Desarrollo de la Unión Europea (FEDER) FIS2017- 88410-PFondos SID 2019 (Università degli Studi di Padua, Italia) CASA_SID19_0

Molecular testing of the São Francisco River as an ecological filter for the Brazilian large-eyed stingray Hypanus marianae (Dasyatidae, Myliobatiformes)

Ecological niche modeling (ENM) provides information on the potential environmental barriers to a species that can be tested in phylogeographic studies. A previous ENM analysis of the benthic coastal stingray Hypanus marianae revealed a low suitability area for its occurrence at the São Francisco River (SFR) mouth, the fourth largest river flowing into Southwestern Atlantic. Hence, phylogeographic analyses were used to test the hypothesis of two populations: one north and another south of SFR outflow. We sampled 109 specimens in six localities throughout the species’ geographic distribution and sequenced mitochondrial (cytb) and nuclear (rag1) markers. Our analyses corroborated the existence of two groups (ΦST = 0.68, P < 0.0001) within H. marianae, partially agreeing with the ENM results. The commonest mitochondrial haplotype (H2) was shared among almost all localities, except Salvador, where all individuals shared the same and unique haplotype. This group is restricted to a shallow bay area close to SFR, as predicted by the ENM. However, its plume was not effective in isolating a continental island 55 km off the Brazilian coast. While the broad north group is protected in a few Marine Protected Areas, our results suggest that the restricted southern one deserves to be managed specifically.Fil: Costa, Tiego L. A.. Universidade Federal do Rio Grande; BrasilFil: de Figueiredo Petean, Flávia. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; Argentina. Universidade Federal do Rio Grande; BrasilFil: Berbel Filho, Waldir M.. Universidade Federal do Rio Grande; BrasilFil: Solé Cava, Antonio M.. Universidade Federal do Rio de Janeiro; BrasilFil: Mendes, Liana F.. Universidade Federal do Rio Grande do Norte; BrasilFil: Lima, Sergio M. Q.. Universidade Federal do Rio Grande; Brasi

Diagenetic Fate of Biogenic Soft and Hard Magnetite in Chemically Stratified Sedimentary Environments of Mamanguá Ría, Brazil

Magnetotactic bacteria (MTB) synthesize magnetite and greigite crystals under low oxygen conditions in the water column or uppermost sediment (greigite‐producing bacteria are found below the oxic‐anoxic transition). Dissolved iron and oxygen contents in local environments are known to be limiting factors for the production and preservation of biogenic magnetite. Understanding the processes that link MTB to their living environments is fundamental to reconstructing past chemical variations in the water column and sediment, and for using the magnetic properties of biogenic magnetite as environmental proxy indicators. Previous studies have suggested that the frequently identified biogenic soft (BS) and biogenic hard (BH) magnetite types are associated with equant and more elongated morphologies, respectively, and that their abundance varies in accordance with sedimentary oxygen content, where MTB that produce the BH component live in less oxygenated environments. We test this hypothesis in a high‐resolution integrated environmental magnetic and geochemical study of surface sediments from Mamanguá Ría, SE Brazil. Based on magnetic and pore water profiles, we demonstrate that both the BS and BH components occur within microaerobic environments and that as sediment oxygen content decreases with depth, the BS component disappears before the BH component. With continued burial into the sulfidic diagenetic zone, both components undergo progressive dissolution, but the BH component is more resistant to dissolution than the BS component. Our observations confirm previous inferences about the relative stability of these phases and provide a firmer basis for use of these two types of biogenic magnetite as paleoenvironmental proxies.D. R. and L. J. acknowledge funding from FAPESP grants 2012/212123 and 2011/22018‐3, respectively. F. A. acknowledges funding from FAPERJ, CNPq, and CAPES. A. P. R. acknowledges funding from the Australian Research Council (grants DP140104544 and DP160100805)

Desacidificación por destilación mediante arrastre con nitrógeno. Posible aplicación a la refinación de grasas comestibles

The possibility of substituting direct steam by nitrogen as stripper in the deodorizing or neutralizing distillation of oils and fats has been the subject of research in recent years. Although this is a practical possibility, it implies a greater cost due to the higher price of nitrogen, and the need to adapt the technology in order to maintain the deodorizer head pressure (as nitrogen does not condensate). These disadvantages would be compensated by a better quality of the oils and condensates, and a decrease in pollution. The tests carried out indicate that the efficiency calculated in each of the operations is within the theoretical values, and that using from 1 to 1.5 times the theoretical amount of nitrogen, the refined oils are graded physically as good and very good by an expert. The condensates obtained have been of good quality.En los últimos años se está investigando la posibilidad de sustituir por nitrógeno el vapor de agua directo utilizado en la desodorización o la destilación neutralizante de aceites y grasas. Dicha posibilidad es factible, sin embargo implica un mayor costo debido al mayor precio del nitrógeno, y una necesidad de adecuar la tecnología para mantener la presión en cabeza del desodorizador (al no condensar el nitrógeno). Estos inconvenientes deben ser solventados por una mejor calidad de los aceites, de los condensados y por una disminución de la contaminación. Los ensayos realizados indican que la "eficacia" calculada en cada una de las operaciones realizadas está dentro de los valores teóricos; y que los aceites refinados físicamente, mediante el paso de 1 a 1,5 veces la cantidad teórica de nitrógeno, tienen calificaciones de bueno y muy bueno dadas por un experto. Los condensados obtenidos han sido de buena calidad

Detection of blaCTX-M-15 in an integrative and conjugative element in four extensively drug-resistant Haemophilus parainfluenzae strains causing urethritis

Haemophilus parainfluenzae is a commensal organism with rising numbers of multidrug-resistant (MDR) strains. This pathogen is of increasing clinical relevance in urogenital infection. The aim of this work was to identify and characterise the molecular mechanisms of resistance associated with four cephalosporin-resistant H. parainfluenzae strains collected from patients with urethritis. Antimicrobial resistance was determined by microdilution following European Committee on Antimicrobial Susceptibility Testing cri-teria. Strains were then analysed by whole-genome sequencing to determine clonal relationship and the molecular basis of antimicrobial resistance. Finally, a phylogenetic analysis was performed on all urogen-ital MDR strains of H. parainfluenzae previously isolated in our hospital. All strains were resistant to ,B- lactams, macrolides, tetracycline, fluoroquinolones, chloramphenicol, cotrimoxazole, and aminoglycosides. The resistance profile was compatible with the presence of an extended-spectrum ,B-lactamase (ESBL). Whole-genome sequencing detected blaCTX-M-15 that conferred high minimum inhibitory concentrations to cephalosporins in two novel integrative and conjugative elements (ICEHpaHUB6 and ICEHpaHUB7) that also harboured a blaTEM-1 ,B-lactamase. This study shows a novel bla CTX-M-15 ESBL carried in an integrative conjugative element in four extensively drug-resistant H. parainfluenzae strains. This resistance determi-nant could be transmitted to other sexually transmitted pathogens and this is a cause for concern. (c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/

Three to Tango: Inhibitory Effect of Quercetin and Apigenin on Acetylcholinesterase, Amyloid-β Aggregation and Acetylcholinesterase-Amyloid Interaction

One of the pathological hallmarks of Alzheimer's disease (AD) is the formation of amyloid-β plaques. Since acetylcholinesterase (AChE) promotes the formation of such plaques, the inhibition of this enzyme could slow down the progression of amyloid-β aggregation, hence being complementary to the palliative treatment of cholinergic decline. Anti-aggregation assays performed for apigenin and quercetin, which are polyphenolic compounds that exhibit inhibitory properties against the formation of amyloid plaques, reveal distinct inhibitory effects of these compounds on Aβ40 aggregation in the presence and absence of AChE. Furthermore, the analysis of the amyloid fibers formed in the presence of these flavonoids suggests that the Aβ40 aggregates present different quaternary structures, viz., smaller molecular assemblies are generated. In agreement with a non-competitive inhibition of AChE, molecular modeling studies indicate that these effects may be due to the binding of apigenin and quercetin at the peripheral binding site of AChE. Since apigenin and quercetin can also reduce the generation of reactive oxygen species, the data achieved suggest that multitarget catechol-type compounds may be used for the simultaneous treatment of various biological hallmarks of AD