The Combined Effect of Hg(II) Speciation, Thiol Metabolism, and Cell Physiology on Methylmercury Formation by Geobacter sulfurreducens

The chemical and biological factors controlling microbial formation of methylmercury (MeHg) are widely studied separately, but the combined effects of these factors are largely unknown. We examined how the chemical speciation of divalent, inorganic mercury (Hg(II)), as controlled by low-molecular-mass thiols, and cell physiology govern MeHg formation by Geobacter sulfurreducens. We compared MeHg formation with and without addition of exogenous cysteine (Cys) to experimental assays with varying nutrient and bacterial metabolite concentrations. Cysteine additions initially (0-2 h) enhanced MeHg formation by two mechanisms: (i) altering the Hg(II) partitioning from the cellular to the dissolved phase and/or (ii) shifting the chemical speciation of dissolved Hg(II) in favor of the Hg(Cys)2 complex. Nutrient additions increased MeHg formation by enhancing cell metabolism. These two effects were, however, not additive since cysteine was largely metabolized to penicillamine (PEN) over time at a rate that increased with nutrient addition. These processes shifted the speciation of dissolved Hg(II) from complexes with relatively high availability, Hg(Cys)2, to complexes with lower availability, Hg(PEN)2, for methylation. This thiol conversion by the cells thereby contributed to stalled MeHg formation after 2-6 h Hg(II) exposure. Overall, our results showed a complex influence of thiol metabolism on microbial MeHg formation and suggest that the conversion of cysteine to penicillamine may partly suppress MeHg formation in cysteine-rich environments like natural biofilms

Evaluation of the Degree of Knowledge About Quervain's Tenosynovitis and its Labor Influence in Dental Students Who Perform Internships at the Dental Care Unit of the Regional Autonomous University of Los Andes, Ecuador

Musculoskeletal diseases have experienced a progressive increase in recent years due to excessive workload, which has generated a series of health problems that have become one of the main causes of absenteeism and decreased productivity. Repetitive occupational trauma of the hand, in particular dorsal flexion of the wrist has been identified as one of the main reasons underlying these conditions. In order to assess the level of preventive knowledge about musculoskeletal diseases related to cumulative trauma, a study was conducted with tenth semester students of UNIANDES. An evaluation format was designed to measure variables such as pain, sensitivity and functional assessment. The objective was to provide students with the necessary knowledge about this syndrome, the probability of developing such pathology and preventive methods to counteract it in the future. Data collection made it possible to identify the factors that influence quality care and how they affect long-term job performance. For this purpose, a 12-item structured questionnaire was developed to assess the level of knowledge about Quervain's Tenosynovitis

Release and stability of aluminum metal nanoparticles in surface water: effects of particle loading

При определении экотоксичности наночастиц важную роль играют условия пробоподготовки суспензий. В работе с помощью фотонной кросскорреляционной и атомной абсорбционной спектроскопии показано влияние концентрации суспензии (10 и 100 мг/л) на степень растворения и агрегацию электровзрывных наночастиц алюминия в растворе, моделирующем поверхностную воду пресного водоема

Neutralization profiles of HIV-1 viruses from the VRC01 Antibody Mediated Prevention (AMP) trials

The VRC01 Antibody Mediated Prevention (AMP) efficacy trials conducted between 2016 and 2020 showed for the first time that passively administered broadly neutralizing antibodies (bnAbs) could prevent HIV-1 acquisition against bnAb-sensitive viruses. HIV-1 viruses isolated from AMP participants who acquired infection during the study in the sub-Saharan African (HVTN 703/HPTN 081) and the Americas/European (HVTN 704/HPTN 085) trials represent a panel of currently circulating strains of HIV-1 and offer a unique opportunity to investigate the sensitivity of the virus to broadly neutralizing antibodies (bnAbs) being considered for clinical development. Pseudoviruses were constructed using envelope sequences from 218 individuals. The majority of viruses identified were clade B and C; with clades A, D, F and G and recombinants AC and BF detected at lower frequencies. We tested eight bnAbs in clinical development (VRC01, VRC07-523LS, 3BNC117, CAP256.25, PGDM1400, PGT121, 10–1074 and 10E8v4) for neutralization against all AMP placebo viruses (n = 76). Compared to older clade C viruses (1998–2010), the HVTN703/HPTN081 clade C viruses showed increased resistance to VRC07-523LS and CAP256.25. At a concentration of 1μg/ml (IC80), predictive modeling identified the triple combination of V3/V2-glycan/CD4bs-targeting bnAbs (10-1074/PGDM1400/VRC07-523LS) as the best against clade C viruses and a combination of MPER/V3/CD4bs-targeting bnAbs (10E8v4/10-1074/VRC07-523LS) as the best against clade B viruses, due to low coverage of V2-glycan directed bnAbs against clade B viruses. Overall, the AMP placebo viruses represent a valuable resource for defining the sensitivity of contemporaneous circulating viral strains to bnAbs and highlight the need to update reference panels regularly. Our data also suggests that combining bnAbs in passive immunization trials would improve coverage of global viruses

4to. Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad. Memoria académica

Este volumen acoge la memoria académica de la Cuarta edición del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad, CITIS 2017, desarrollado entre el 29 de noviembre y el 1 de diciembre de 2017 y organizado por la Universidad Politécnica Salesiana (UPS) en su sede de Guayaquil. El Congreso ofreció un espacio para la presentación, difusión e intercambio de importantes investigaciones nacionales e internacionales ante la comunidad universitaria que se dio cita en el encuentro. El uso de herramientas tecnológicas para la gestión de los trabajos de investigación como la plataforma Open Conference Systems y la web de presentación del Congreso http://citis.blog.ups.edu.ec/, hicieron de CITIS 2017 un verdadero referente entre los congresos que se desarrollaron en el país. La preocupación de nuestra Universidad, de presentar espacios que ayuden a generar nuevos y mejores cambios en la dimensión humana y social de nuestro entorno, hace que se persiga en cada edición del evento la presentación de trabajos con calidad creciente en cuanto a su producción científica. Quienes estuvimos al frente de la organización, dejamos plasmado en estas memorias académicas el intenso y prolífico trabajo de los días de realización del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad al alcance de todos y todas

Conception of chemical structured surfaces for the study of the bacterial adhesion and the controlled development of bacterial biofilms

La formation de biofilms bactériens pathogènes est un problème important, particulièrement dans les secteurs médicaux et agro-alimentaires. La formation contrôlée de biofilms de la bactérie probiotique Lactobacillus rhamnosus GG (LGG) est sélectionnée ici comme méthode potentielle pour prévenir la contamination de surfaces par des bactéries pathogènes. Nous avons étudié le développement de biofilms de LGG ainsi que leur possible contrôle en combinant des approches physico-chimiques et de fonctionnalisation de surface. L’impact des conditions environnementales sur la cinétique de croissance des biofilms et sur leur composition biochimique a été analysé par des mesures in situ et en temps réel par spectroscopie infrarouge à transformée de Fourier en réflexion totale atténuée (ATR-FTIR) sous conditions de flux. Ces données ont été complétées par des images de microscopie en épifluorescence permettant d’obtenir des informations sur la distribution et la forme des cellules bactériennes sur la surface à des étapes clé du développement du biofilm. Compatible avec les mesures ATR-FTIR, un cristal de séléniure de zinc a été choisi comme substrat, nu ou fonctionnalisé avec des monocouches auto-assemblées d’alcane-thiols (SAMs). Différents groupes fonctionnels ont été étudiés : méthyl (-CH3), hydroxyle (-OH) ou amine (-NH2) pour obtenir respectivement des substrats hydrophobe, hydrophile ou chargé positivement. La cinétique d’auto-assemblage des SAMs, leur organisation et l’énergie de surface ont été étudiées en combinant ATR-FTIR, spectroscopie de rétrodiffusion de Rutherford à hautes énergies et mesures d’angles de contact. L’analyse des spectres ATR-FTIR des biofilms de LGG enregistrés in situ et en temps réel pendant 24 heures a montré un rôle important du milieu nutritif sur la composition biochimique et le métabolisme bactériens. Les propriétés du substrat ont un impact faible sur la composition biochimique des biofilms, mais ont un rôle crucial sur leur force d’attachement à la surface. Ce travail pluridisciplinaire a fourni des informations sur l’influence de l’environnement, et particulièrement des caractéristiques du support, sur les propriétés des biofilms aux échelles moléculaire et cellulaire. La méthodologie développée dans ce travail peut notamment être utilisée dans la recherche des conditions les plus favorables à la croissance des biofilms de bactéries probiotiques.Biofilm formation by pathogenic bacteria brings concerns, particularly in food and medical sectors, and is associated with high sanitary risks and economic losses. Biofilms of probiotic bacteria can potentially be used to prevent the surface contamination by pathogenic species. This work was focused on the investigation of the development of biofilms of probiotic Lactobacillus rhamnosus GG (LGG) and the possible control of their formation by combining surface functionalisation and physico-chemical approaches. The effect of different environmental conditions on the kinetics of the biofilm growth and on its biochemical composition was analysed by in situ and real time measurements with infrared spectroscopy in attenuated total reflection mode (ATR-FTIR) under flow conditions. These data were complemented by epifluorescence images providing information on the surface distribution and the shape of the bacterial cells at specific stages of the biofilm development. Compatible with ATR-FTIR measurements, a zinc selenide (ZnSe) crystal was chosen as a substrate, bare or functionalised with self-assembled monolayers (SAMs). SAMs were formed from alkanethiols terminated by methyl (-CH3), hydroxyl (-OH) or amine (-NH2) groups to obtain hydrophobic, hydrophilic and positively charged substrates, respectively. The kinetics of self-assembly of the alkanethiols onto ZnSe, the organisation of the molecules, their areal density and the surface energy of thus obtained surfaces were studied preliminarily to the biofilm cultivation by means of ATR-FTIR spectroscopy, high energy Rutherford backscattering spectrometry, and contact angle measurements. The analysis of the ATR-FTIR spectra of LGG biofilms recorded in situ and in real time during 24 hours revealed an important role of the nutritive medium in the biosynthesis of nucleic acids, phospholipids, polysaccharides and lactic acid. Substrate properties had low impact on the biochemical composition of LGG biofilms, but had a critical role in the strength of attachment of cultivated biofilms. The findings of this multidisciplinary work provide a fundamental understanding of how the direct environment, including a support surface, influences the properties of bacterial biofilms at the molecular and cellular scales, based on which favourable conditions for the enhancement of probiotic biofilm growth and its mechanical stability can be chosen

Conception de surfaces chimio-structurées pour l'étude de l'adhésion bactérienne et la formation contrôlée des biofilms bactériens

Texte intégral accessible uniquement aux membres de l'Université de LorraineBiofilm formation by pathogenic bacteria brings concerns, particularly in food and medical sectors, and is associated with high sanitary risks and economic losses. Biofilms of probiotic bacteria can potentially be used to prevent the surface contamination by pathogenic species. This work was focused on the investigation of the development of biofilms of probiotic Lactobacillus rhamnosus GG (LGG) and the possible control of their formation by combining surface functionalisation and physico-chemical approaches. The effect of different environmental conditions on the kinetics of the biofilm growth and on its biochemical composition was analysed by in situ and real time measurements with infrared spectroscopy in attenuated total reflection mode (ATR-FTIR) under flow conditions. These data were complemented by epifluorescence images providing information on the surface distribution and the shape of the bacterial cells at specific stages of the biofilm development. Compatible with ATR-FTIR measurements, a zinc selenide (ZnSe) crystal was chosen as a substrate, bare or functionalised with self-assembled monolayers (SAMs). SAMs were formed from alkanethiols terminated by methyl (-CH3), hydroxyl (-OH) or amine (-NH2) groups to obtain hydrophobic, hydrophilic and positively charged substrates, respectively. The kinetics of self-assembly of the alkanethiols onto ZnSe, the organisation of the molecules, their areal density and the surface energy of thus obtained surfaces were studied preliminarily to the biofilm cultivation by means of ATR-FTIR spectroscopy, high energy Rutherford backscattering spectrometry, and contact angle measurements. The analysis of the ATR-FTIR spectra of LGG biofilms recorded in situ and in real time during 24 hours revealed an important role of the nutritive medium in the biosynthesis of nucleic acids, phospholipids, polysaccharides and lactic acid. Substrate properties had low impact on the biochemical composition of LGG biofilms, but had a critical role in the strength of attachment of cultivated biofilms. The findings of this multidisciplinary work provide a fundamental understanding of how the direct environment, including a support surface, influences the properties of bacterial biofilms at the molecular and cellular scales, based on which favourable conditions for the enhancement of probiotic biofilm growth and its mechanical stability can be chosen.La formation de biofilms bactériens pathogènes est un problème important, particulièrement dans les secteurs médicaux et agro-alimentaires. La formation contrôlée de biofilms de la bactérie probiotique Lactobacillus rhamnosus GG (LGG) est sélectionnée ici comme méthode potentielle pour prévenir la contamination de surfaces par des bactéries pathogènes. Nous avons étudié le développement de biofilms de LGG ainsi que leur possible contrôle en combinant des approches physico-chimiques et de fonctionnalisation de surface. L’impact des conditions environnementales sur la cinétique de croissance des biofilms et sur leur composition biochimique a été analysé par des mesures in situ et en temps réel par spectroscopie infrarouge à transformée de Fourier en réflexion totale atténuée (ATR-FTIR) sous conditions de flux. Ces données ont été complétées par des images de microscopie en épifluorescence permettant d’obtenir des informations sur la distribution et la forme des cellules bactériennes sur la surface à des étapes clé du développement du biofilm. Compatible avec les mesures ATR-FTIR, un cristal de séléniure de zinc a été choisi comme substrat, nu ou fonctionnalisé avec des monocouches auto-assemblées d’alcane-thiols (SAMs). Différents groupes fonctionnels ont été étudiés : méthyl (-CH3), hydroxyle (-OH) ou amine (-NH2) pour obtenir respectivement des substrats hydrophobe, hydrophile ou chargé positivement. La cinétique d’auto-assemblage des SAMs, leur organisation et l’énergie de surface ont été étudiées en combinant ATR-FTIR, spectroscopie de rétrodiffusion de Rutherford à hautes énergies et mesures d’angles de contact. L’analyse des spectres ATR-FTIR des biofilms de LGG enregistrés in situ et en temps réel pendant 24 heures a montré un rôle important du milieu nutritif sur la composition biochimique et le métabolisme bactériens. Les propriétés du substrat ont un impact faible sur la composition biochimique des biofilms, mais ont un rôle crucial sur leur force d’attachement à la surface. Ce travail pluridisciplinaire a fourni des informations sur l’influence de l’environnement, et particulièrement des caractéristiques du support, sur les propriétés des biofilms aux échelles moléculaire et cellulaire. La méthodologie développée dans ce travail peut notamment être utilisée dans la recherche des conditions les plus favorables à la croissance des biofilms de bactéries probiotiques

Effect of the nutritive medium choice on the formation of Lactobacillus rhamnosus GG biofilms on an abiotic surface

International audienc

In situ spectroscopic analysis of Lactobacillus rhamnosus GG flow on an abiotic surface reveals a role for nutrients in biofilm development

International audienceIn this work, infrared spectroscopy was used to monitor the changes in the biochemical composition of biofilms of the probiotic bacterium Lactobacillus rhamnosus GG (LGG) in three nutritive media (10-fold diluted MRS, AOAC, and mTSB), in situ and under flow conditions. Epifluorescence microscopy was used to observe the shape of LGG cells and their distribution on the surface. Spectroscopic fingerprints recorded as a function of time revealed a medium-dependent content of nucleic acids, phospholipids and polysaccharides in the biofilms. In addition, time-dependent synthesis of lactic acid was observed in MRS/10 and AOAC/10. Polysaccharides were produced to the highest extent in mTSB/10, and the biofilms obtained were the densest in this medium. The rod shape of the cells was preserved in MRS/10, whereas acidic stress induced in AOAC/10 and the nutritional quality of mTSB/10 led to strong morphological changes. These alterations due to the nutritive environment are important to consider in research and use of LGG biofilms