The alternative complex III of Rhodothermus marinus and its structural and functional association with caa3 oxygen reductase

AbstractAn alternative complex III (ACIII) is a respiratory complex with quinol:electron acceptor oxidoreductase activity. It is the only example of an enzyme performing complex III function that does not belong to bc1 complex family. ACIII from Rhodothermus (R.) marinus was the first enzyme of this type to be isolated and characterized, and in this work we deepen its characterization. We addressed its interaction with quinol substrate and with the caa3 oxygen reductase, whose coding gene cluster follows that of the ACIII. There is at least, one quinone binding site present in R. marinus ACIII as observed by fluorescence quenching titration of HQNO, a quinone analogue inhibitor. Furthermore, electrophoretic and spectroscopic evidences, taken together with mass spectrometry revealed a structural association between ACIII and caa3 oxygen reductase. The association was also shown to be functional, since quinol:oxygen oxidoreductase activity was observed when the two isolated complexes were put together. This work is thus a step forward in the recognition of the structural and functional diversities of prokaryotic respiratory chains

Differences between Pseudomonas aeruginosa non-adapted and adapted to benzalkonium chloride : comparison of adhesion capacity, and susceptibility of biofilms to removal and surfactant attack

Bacteria adhesion, and consequent biofilm formation, in vitro and in vivo, are phenomena that often occur naturally but are also bacteria´s strategies to protect themselves from stress factors, playing probably an important role in virulence. Furthermore, bacteria growing in biofilms are less susceptible to many antibacterial agents than their suspended counterparts. These factors emphasize the need of suitable and efficient surface disinfection procedures in order to reduce the overgrowth of resistant microorganisms in response to an ineffective course of antimicrobials. In this study, we examined the effect of adaptation of P. aeruginosa to a surfactant, benzalkonium chloride (BZK), on the adherence of bacterial cells to PET, conditioned and non-conditioned with BZK, and on their ability to resist to removal and BZK aggression. The assays were carried out in a PPFC. Bacterial adaptation was attained by exposing P. aeruginosa to gradual increasing concentrations of BZK, and selected in TSA supplemented with 4.0 mM BZK. The results show that adapted P. aeruginosa adhered in a more extent than the non-adapted counterpart. For both strains, the pre-conditioning of the PET surfaces significantly favored bacterial adhesion. The higher adhesion was observed with the adapted bacteria onto the conditioned PET coupons. These results highlight that the extent of adhesion is greater the higher are the stress factors. The strength of adhesion is also higher in the case of adapted bacteria since detachment only occurs with P. aeruginosa non-adapted. BZK application did not cause significant removal except for P.aeruginosa non-adapted adhered to non-conditioned PET. Nevertheless, BZK attack causes loss of viability of the cells that remained adhered to the surfaces, this loss being more notorious in the case of non adapted cells adhered in the conditioned surfaces. Based on the results it can be said that the presence of BZK residues on the adhesion surfaces did not impair the bacterial adhesion capacity though affects the viability of the adhered cells. It can also be concluded that resistant bacteria that survived to a simple adaptation step to a common antimicrobial agent increased its adherence ability and insusceptibility to removal and antimicrobial treatment. In a disinfection point of view, these results can represent additional problems for the eradication of pathogenic bacteria with increased virulence from equipment and surfaces in the medical arenas

Behavior of single and mixed biofilms subjected to benzalkonium chloride : the impact of using chemical-adapted bacteria

The majority of lab‐scale studies involves a single species to form biofilms and to later evaluate the effect of the antimicrobials against these biofilms. However, in real systems, biofilms can be found as a complex consortium of species where the biofilm behaviour is the sum of the synergistic and antagonistic interactions between the different species. It is not surprising that disinfection protocols developed with a single species biofilm can fail when applied to a real system. The central query of this study was to understand the behaviour of binary biofilms when exposed to high doses of benzalkonium chloride (BZK), a general disinfectant in health care facilities. P. aeruginosa (ATCC 10145), P. aeruginosa adapted to 4.0 mM of BZK (PA4) and Escherichia coli k12 were the strains used to form single and binary biofilms. The mixed‐species biofilms were obtained by a combination of 50% of suspended inocula of each specie: E. coli with P. aeruginosa and E. coli with PA4. The role of surface preconditioning with BZK on biofilm properties was also investigated. Biofilms where formed for 24 h in 96 plates (non‐ and conditioned with 0.7 mM of BZK for 30 min), being then treated with 1.0 mM of BZK. Crystal violet (CV) together with XTT, were used to assess, respectively, total attached biomass and respiratory activity. The number of CFU/cm2 was also determined. The data emphasised that the characteristics of the binary biofilms depend on the strains that formed them. In fact, when the adapted strain is involved, the resulting biofilms have less mass, activity and cells. It is also observed that, for both single‐ and dual‐species biofilms, surface preconditioning significantly favoured biofilm formation. Although the BZK preconditioning of the surfaces increased biomass, it simultaneous appeared to weak bacterial adhesion, since BZK attack reduced significantly the amount of biofilm comparing to the clear surfaces, for both single‐ and mixed‐species. Concerning the data related with BZK attack, for both non‐ and conditioned surfaces, there was a notorious reduction of the bacterial activity and number of cells, in both single and mixed biofilms. But, the PA4 and E. coli binary biofilms seemed to reveal recalcitrant behaviour since the CFU still unaltered after BZK attack. These data suggest that when biofims are formed by the PA4 and E. coli, it seems to exist an competitive behaviour between the bacteria that give rise to a mixed biofilm with fewer mass and cells. However, these biofilms are less susceptible to the action of BZK, sign of a possible protective effect of one species to another. Since few reports specifically address interactions within multi‐species biofilms, these results highlight the importance of understanding the multiple behaviours of biofilms as a community and a complex web of interactions.Universidade do Minho. Centro de Engenharia Biológica. Instituto de Biotecnologia e Bioengenharia (IBB-CEB) e Fundação para a Ciência e a Tecnologia (FCT) - PTDC/SAU‐ESA/64609/2006, SFRH/BD/31065/200

Role of planktonic and sessile extracellular signals on interspecies relationships

Universidade do Minho. Centro de Engenharia Biológica. Instituto de Biotecnologia e Bioengenharia (IBB-CEB) e Fundação para a Ciência e a Tecnologia (FCT) - PTDC/SAU-ESA/64609/2006; SFRH/BD/31065/200

Agricultural land systems importance for supporting food security and sustainable development goals: a systematic review

Agriculture provides the largest share of food supplies and ensures a critical number of ecosystem services (e.g., food provisioning). Therefore, agriculture is vital for food security and supports the Sustainable Development Goal (SDGs) 2 (SDG 2 - zero hunger) as others SDG's. Several studies have been published in different world areas with different research directions focused on increasing food and nutritional security from an agricultural land system perspective. The heterogeneity of the agricultural research studies calls for an interdisciplinary and comprehensive systematization of the different research directions and the plethora of approaches, scales of analysis, and reference data used. Thus, this work aims to systematically review the contributions of the different agricultural research studies by systematizing the main research fields and present a synthesis of the diversity and scope of research and knowledge. From an initial search of 1151 articles, 260 meet the criteria to be used in the review. Our analysis revealed that most articles were published between 2015 and 2019 (59%), and most of the case studies were carried out in Asia (36%) and Africa (20%). The number of studies carried out in the other continents was lower. In the last 30 years, most of the research was centred in six main research fields: land-use changes (28%), agricultural efficiency (27%), climate change (16%), farmer's motivation (12%), urban and peri-urban agriculture (11%), and land suitability (7%). Overall, the research fields identified are directly or indirectly linked to 11 of the 17 SDGs. There are essential differences in the number of articles among research fields, and future efforts are needed in the ones that are less represented to support food security and the SDGs.info:eu-repo/semantics/publishedVersio

Magnetic carbon composites as recycling electron shuttles on anaerobic biotransformations

Book of Abstracts of CEB Annual Meeting 2017[Excerpt] The unique properties of magnetic nanoparticles (MNP), such as high surface area, magnetic, sorption and catalytic characteristics, make them very versatile for many applications in different areas including environmental remediation, as catalysts, adsorbents, immobilising agents for microorganisms and enzymes, and as supports for biofilm growth and water disinfectants. In order to improve their stability and to introduce additional surface properties and functionalities, MNP can be coated with carbon materials (CM) due to their chemical stability, biocompatibility and possibility of tailoring their textural and surface chemical properties for specific applications [1]. We have previously proved that various CM, including activated carbon, carbon xerogels and carbon nanotubes (CNT), can be used as redox mediators (RM) in anaerobic biotransformation, accelerating the electron transfer and, consequently, the reduction rates of organic compounds [1,2]. The combination of CM with MNP offers the possibility of creating magnetic carbon composites with synergistic properties: the adsorptive and catalytic properties of both and the magnetic character of MNP, improving the material performance and rendering it easier to be retained and recovered, by applying a magnetic field. [...]info:eu-repo/semantics/publishedVersio

The teas of Portuguese centenarians

Copyright © 2019 Elsevier Inc. All rights reserved.Introduction: Medicinal plants traditional consumption habits, can contribute to longevity. Methods: A sample of 253 centenarian individuals in Portugal, both sexes, median age 100 years, was studied, to verify past habits in relation to medicinal-interest plants use. It was compared with a control group median age 67 year, with a reduced theoretical probability of reaching 100 years. Results: Among the 8 most cited plants, in decreasing frequency order, in centenarian's group: Lemon-balm, barley, lemon-verbena, orange (leaf-flower), linden, whig-plant, pennyroyal and mount-carqueja (Pterospartum-tridentatum); in the control group: Lemon-balm, lemonverbena, chamomile, linden, prince-herb, green-tea, lemon-tea and minttea. Whereas 28% of the control subjects reported not using infusion plants, in the centennial group, only 9.1% reported not routinely use them (χ2¼30,42, po0.001). Among the 8 plants most marked by the centenarians that were not mentioned by the controls, they include barley, whig-plant, pennyroyal and mount-carqueja. Conclusion: the high antioxidant power associated with the use of plants by centenarian individuals, determined by anti-free radical's activity, lipoperoxidation inhibition and antitumor potential, may have contributed to their exceptional longevity.info:eu-repo/semantics/publishedVersio

PET and optical imaging of caveolin-1 in gastric tumors

Previous studies have suggested tumoral caveolin-1 (CAV1) as a predictive biomarker for the response to anti-HER2 antibody drug therapies in gastric tumors. In this study, radiolabeled and fluorescently labeled anti-CAV1 antibodies were developed and tested as an immunoPET or optical imaging agent to detect CAV1 in HER2-positive/CAV1-high NCIN87 gastric tumors. The expression of CAV1 receptors in NCIN87 gastric tumors and nontumor murine organs was determined by Western blot. Binding assays were performed to validate the anti-CAV1 antibody specificity for CAV1-expressing NCIN87 cancer cells. Subcutaneous and orthotopic NCIN87 xenografts were used for PET imaging an

Spatial distribution of citizen science casuistic observations for different taxonomic groups

PT acknowledges support from the Portuguese Foundation for Science and Technology (FCT/MCTES) (SFRH/BD/89543/2012). ACH acknowledges support from the Portuguese Foundation for Science and Technology (FCT/MCTES) (UID/BIA/50027/2013) and from FEDER through the Operational Programme for Competitiveness Factors – COMPETE (POCI-01-0145-FEDER-006821). TAM thanks partial support by CEAUL (funded by FCT - Fundação para a Ciência e a Tecnologia, Portugal, through the project UID/MAT/00006/2013). CC acknowledges support from the Portuguese Foundation for Science and Technology (FCT) FCT for funds to GHTM - UID/Multi/04413/2013. We thank all volunteers who participate in BioDiversity4All project.Opportunistic citizen science databases are becoming an important way of gathering information on species distributions. These data are temporally and spatially dispersed and could have limitations regarding biases in the distribution of the observations in space and/or time. In this work, we test the influence of landscape variables in the distribution of citizen science observations for eight taxonomic groups. We use data collected through a Portuguese citizen science database (biodiversity4all.org). We use a zero-inflated negative binomial regression to model the distribution of observations as a function of a set of variables representing the landscape features plausibly influencing the spatial distribution of the records. Results suggest that the density of paths is the most important variable, having a statistically significant positive relationship with number of observations for seven of the eight taxa considered. Wetland coverage was also identified as having a significant, positive relationship, for birds, amphibians and reptiles, and mammals. Our results highlight that the distribution of species observations, in citizen science projects, is spatially biased. Higher frequency of observations is driven largely by accessibility and by the presence of water bodies. We conclude that efforts are required to increase the spatial evenness of sampling effort from volunteers.Publisher PDFPeer reviewe

Cation-exchange resin applied to paralytic Shellfish toxins depuration from Bivalves exposed to Gymnodinium catenatum

The accumulation of marine biotoxins in shellfish and their consumption causes serious food safety problems, threatening human health and compromising the availability of protein-based food. It is thus urgent to develop methodologies for the detoxification of live bivalves, avoiding their economic and nutritional devaluation. In this context, we tested an adsorption mechanism of paralytic shellfish toxins (PST) based on a cation-exchange resin. The first studies using cultures of Gymnodinium catenatum (natural producers of PST) showed a decrease of about 80% in overall toxicity after 48 h. Interestingly, we found that the toxins are adsorbed differently, with toxins’ structural features playing a part in the adsorption capacity via steric hindrance, electronic effects, or the extent of positive charge density (e.g., dcSTX). The positive effect of the resin in accelerating PST clearance from live mussels (Mytilus edulis) is not evident when compared to resin-free clearance; nevertheless, relevant information could be gathered that will facilitate further in vivo studies. Several factors appear to be at play, namely the competition of natural substances (e.g., salts, organic matter) for the same binding sites, the blocking of pores due to interactions between molecules, and/or difficulties in resin absorption by mussels. Additionally, the present work revealed the ability of mussels to neutralize pH and proposes bioconversion reactions among the PST molecules.LA/P/0101/2020MAR-01.03.01-FEAMP0049info:eu-repo/semantics/publishedVersio