Bacterial adhesion efficiency on implant abutments: a comparative study

The attachment of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 28213 onto six different materials used to manufacture dental implant abutments was quantitatively determined after 2 and 24 h of contact between the materials and the bacterial cultures. The materials were topographically characterized and their wettability determined, with both parameters subsequently related to bacterial adhesion. Atomic force microscopy, interferometry, and contact angle measurement were used to characterize the materials" surfaces. The results showed that neither roughness nor nano-roughness greatly influenced bacterial attachment whereas wettability strongly correlated with adhesion. After 2 h the degree of E. coli attachment markedly differed depending on the material whereas similar differences were not observed for S. aureus, which yielded consistently higher counts of adhered cells. Nevertheless, after 24 h the adhesion of the two species to the different test materials no longer significantly differed, although on all surfaces the numbers of finally adhered E. coli were higher than those of S. aureus

Asociación de síndrome de boca ardiente con xerostomía y medicamentos

Objetivo: Identificar factores de riesgo para el síndrome de boca ardiente (SBA) a través de estudio de casos y controles. Material y métodos: Se realizó análisis cuantitativo del flujo salival total en reposo y estimulado; se registraron la xerostomía subjetiva, el consumo de medicamentos y los estados psicológicos de ansiedad y depresión en 40 pacientes con SBA y 40 controles. Resultados: El análisis ANOVA mostró diferencias significativas en las medias del número de medicamentos/día, número de medicamentos xerostomizantes/día, xerostomía subjetiva, ansiedad y depresión, entre los grupos estudiados. No se observaron diferencias significativas en las tasas de flujo salival en reposo y estimulado. El análisis de asociación Odds ratio determinó asociación del SBA con xerostomía y con el consumo de hipotensores y diuréticos. Conclusiones: Según los resultados de este estudio, se puede afirmar que el consumo de hipotensores y diuréticos fue un factor de riesgo para el padecimiento del SBA. La función de las glándulas salivales en los pacientes con SBA no está deteriorada.

Soybean (Glycine max. L.) and bacteroid glyoxylate cycle activities during nodular senescence

Soybean (Glycine max. L.) nodular senescence results in the dismantling of the peribacteroid membrane (PBM) and in an increase of soybean isocitrate lyase (ICL; EC 4.1.3.1) and malate synthase (MS; EC 4.1.3.2) mRNA and protein levels. This suggests that in senescing soybean nodular cells, the specific glyoxylate cycle enzyme activities might be induced to reallocate carbon obtained from the PBM degradation. In order to evaluate as well the carbon metabolism of the nitrogen-fixing Bradyrhizobium japonicum endosymbiotic bacteroids during nodular senescence, their glyoxylate cycle activities were also investigated. To this end, partial DNA sequences were isolated from their icl and ms genes, but the corresponding mRNAs were not detected in the microorganisms. It was also observed that the bacteroid ICL and MS activities were negligible during nodular senescence. This suggests that glyoxylate cycle activities are not reinitiated in the bacteroids under these physiological conditions. In case the microorganisms nevertheless feed on the PBM degradation products, this might occur via the citric acid cycle exclusively.

Candida albicans Inhibits Pseudomonas aeruginosa Virulence through Suppression of Pyochelin and Pyoverdine Biosynthesis.

Bacterial-fungal interactions have important physiologic and medical ramifications, but the mechanisms of these interactions are poorly understood. The gut is host to trillions of microorganisms, and bacterial-fungal interactions are likely to be important. Using a neutropenic mouse model of microbial gastrointestinal colonization and dissemination, we show that the fungus Candida albicans inhibits the virulence of the bacterium Pseudomonas aeruginosa by inhibiting P. aeruginosa pyochelin and pyoverdine gene expression, which plays a critical role in iron acquisition and virulence. Accordingly, deletion of both P. aeruginosa pyochelin and pyoverdine genes attenuates P. aeruginosa virulence. Heat-killed C. albicans has no effect on P. aeruginosa, whereas C. albicans secreted proteins directly suppress P. aeruginosa pyoverdine and pyochelin expression and inhibit P. aeruginosa virulence in mice. Interestingly, suppression or deletion of pyochelin and pyoverdine genes has no effect on P. aeruginosa's ability to colonize the GI tract but does decrease P. aeruginosa's cytotoxic effect on cultured colonocytes. Finally, oral iron supplementation restores P. aeruginosa virulence in P. aeruginosa and C. albicans colonized mice. Together, our findings provide insight into how a bacterial-fungal interaction can modulate bacterial virulence in the intestine. Previously described bacterial-fungal antagonistic interactions have focused on growth inhibition or colonization inhibition/modulation, yet here we describe a novel observation of fungal-inhibition of bacterial effectors critical for virulence but not important for colonization. These findings validate the use of a mammalian model system to explore the complexities of polymicrobial, polykingdom infections in order to identify new therapeutic targets for preventing microbial disease.

Embryonic gene expression of Coregonus palaea (whitefish) under pathogen stress as analyzed by high-throughput RNA-sequencing.

Most fishes produce free-living embryos that are exposed to environmental stressors immediately following fertilization, including pathogenic microorganisms. Initial immune protection of embryos involves the chorion, as a protective barrier, and maternally-allocated antimicrobial compounds. At later developmental stages, host-genetic effects influence susceptibility and tolerance, suggesting a direct interaction between embryo genes and pathogens. So far, only a few host genes could be identified that correlate with embryonic survival under pathogen stress in salmonids. Here, we utilized high-throughput RNA-sequencing in order to describe the transcriptional response of a non-model fish, the Alpine whitefish Coregonus palaea, to infection, both in terms of host genes that are likely manipulated by the pathogen, and those involved in an early putative immune response. Embryos were produced in vitro, raised individually, and exposed at the late-eyed stage to a virulent strain of the opportunistic fish pathogen Pseudomonas fluorescens. The pseudomonad increased embryonic mortality and affected gene expression substantially. For example, essential, upregulated metabolic pathways in embryos under pathogen stress included ion binding pathways, aminoacyl-tRNA-biosynthesis, and the production of arginine and proline, most probably mediated by the pathogen for its proliferation. Most prominently downregulated transcripts comprised the biosynthesis of unsaturated fatty acids, the citrate cycle, and various isoforms of b-cell transcription factors. These factors have been shown to play a significant role in host blood cell differentiation and renewal. With regard to specific immune functions, differentially expressed transcripts mapped to the complement cascade, MHC class I and II, TNF-alpha, and T-cell differentiation proteins. The results of this study reveal insights into how P. fluorescens impairs the development of whitefish embryos and set a foundation for future studies investigating host pathogen interactions in fish embryos.

Sanitary quality of edible bivalve mollusks in Southeastern Brazil using an UV based depuration system

The increase in seafood production, especially in mariculture worldwide, has brought out the need of continued monitoring of shellfish production areas in order to ensure safety to human consumption. The purpose of this research was to evaluate pathogenic protozoa, viruses and bacteria contamination in oysters before and after UV depuration procedure, in brackish waters at all stages of cultivation and treatment steps and to enumerate microbiological indicators of fecal contamination from production site up to depuration site in an oyster cooperative located at the Southeastern estuarine area of Brazil. Oysters and brackish water were collected monthly from September 2009 to November 2010. Four sampling sites were selected for enteropathogens analysis: site 1- oyster growth, site 2- catchment water (before UV depuration procedure), site 3 - filtration stage of water treatment (only for protozoa analysis) and site 4- oyster's depuration tank. Three microbiological indicators ! were examined at sites 1, 2 and 4. The following pathogenic microorganisms were searched: Giardia cysts, Cryptosporidium oocysts, Human Adenovirus (HAdV), Hepatitis A virus (HAV), Human Norovirus (HnoV) (genogroups I and II), JC strain Polyomavirus (JCPyV) and Salmonella sp. Analysis consisted of molecular detection (qPCR) for viruses (oysters and water samples); immunomagnetic separation followed by direct immunofluorescence assay for Cryptosporidium oocysts and Giardia cysts and also molecular detection (PCR) for the latter (oysters and water samples); commercial kit (Reveal-Neogee (R)) for Salmonella analysis (oysters). Giardia was the most prevalent pathogen in all sites where it was detected: 36.3%, 18.1%, 36.3% and 27.2% of water from sites 1, 2, 3 and 4 respectively; 36.3% of oysters from site 1 and 54.5% of depurated oysters were harboring Giardia cysts. The huge majority of contaminated samples were classified as Giardia duodenalis. HAdv was detected in water and o! ysters from growth site and HnoV GI in two batches of oysters ! (site 1) in huge concentrations (2.11 x 10(13), 3.10 x 10(12) gc/g). In depuration tank site, Salmonella sp., HAV (4.84 x 10(3)) and HnoV GII (7.97 x 10(14)) were detected once in different batches of oysters. Cryptosporidium spp. oocysts were present in 9.0% of water samples from site four. These results reflect the contamination of oysters even when UV depuration procedures are employed in this shellfish treatment plant. Moreover, the molecular comprehension of the sources of contamination is necessary to develop an efficient management strategy allied to shellfish treatment improvement to prevent foodborne illnesses. (C) 2011 Elsevier Ltd. All rights reserved.

The awr gene family encodes a novel class of Ralstonia solanacearum type III effectors displaying virulence and avirulence activities

We present here the characterization of a new gene family, awr, found in all sequenced Ralstonia solanacearum strains and in other bacterial pathogens. We demonstrate that the five paralogues in strain GMI1000 encode type III-secreted effectors and that deletion of all awr genes severely impairs its capacity to multiply in natural host plants. Complementation studies show that the AWR (alanine-tryptophanarginine tryad) effectors display some functional redundancy, although AWR2 is the major contributor to virulence. In contrast, the strain devoid of all awr genes (¿awr1-5) exhibits enhanced pathogenicity on Arabidopsis plants. A gain-of-function approach expressing AWR in Pseudomonas syringae pv. tomato DC3000 proves that this is likely due to effector recognition, because AWR5 and AWR4 restrict growth of this bacterium in Arabidopsis. Transient overexpression of AWR in nonhost tobacco species caused macroscopic cell death to varying extents, which, in the case of AWR5, shows characteristics of a typical hypersensitive response. Our work demonstrates that AWR, which show no similarity to any protein with known function, can specify either virulence or avirulence in the interaction of R. solanacearum with its plant hosts.

Mycorrhization between Cistus ladanifer L. and Boletus edulis Bull is enhanced by the mycorrhiza helper bacteria Pseudomonas fluorescens Migula.

Boletus edulis Bull. is one of the most economically and gastronomically valuable fungi worldwide. Sporocarp production normally occurs when symbiotically associated with a number of tree species in stands over 40 years old, but it has also been reported in 3-year-old Cistus ladanifer L. shrubs. Efforts toward the domestication of B. edulis have thus focused on successfully generating C. ladanifer seedlings associated with B. edulis under controlled conditions. Microorganisms have an important role mediating mycorrhizal symbiosis, such as some bacteria species which enhance mycorrhiza formation (mycorrhiza helper bacteria). Thus, in this study, we explored the effect that mycorrhiza helper bacteria have on the efficiency and intensity of the ectomycorrhizal symbiosis between C. ladanifer and B. edulis. The aim of this work was to optimize an in vitro protocol for the mycorrhizal synthesis of B. edulis with C. ladanifer by testing the effects of fungal culture time and coinoculation with the helper bacteria Pseudomonas fluorescens Migula. The results confirmed successful mycorrhizal synthesis between C. ladanifer and B. edulis. Coinoculation of B. edulis with P. fluorescens doubled within-plant mycorrhization levels although it did not result in an increased number of seedlings colonized with B. edulis mycorrhizae. B. edulis mycelium culture time also increased mycorrhization levels but not the presence of mycorrhizae. These findings bring us closer to controlled B. edulis sporocarp production in plantations.

Ocean surface winds drive dynamics of transoceanic aerial movements

Global wind patterns influence dispersal and migration processes of aerial organisms, propagules and particles, which ultimately could determine the dynamics of colonizations, invasions or spread of pathogens. However, studying how wind-mediated movements actually happen has been hampered so far by the lack of high resolution global wind data as well as the impossibility to track aerial movements. Using concurrent data on winds and actual pathways of a tracked seabird, here we show that oceanic winds define spatiotemporal pathways and barriers for large-scale aerial movements. We obtained wind data from NASA SeaWinds scatterometer to calculate wind cost (impedance) models reflecting the resistance to the aerial movement near the ocean surface. We also tracked the movements of a model organism, the Cory's shearwater (Calonectris diomedea), a pelagic bird known to perform long distance migrations. Cost models revealed that distant areas can be connected through"wind highways" that do not match the shortest great circle routes. Bird routes closely followed the low-cost"wind-highways" linking breeding and wintering areas. In addition, we found that a potential barrier, the near surface westerlies in the Atlantic sector of the Intertropical Convergence Zone (ITCZ), temporally hindered meridional trans-equatorial movements. Once the westerlies vanished, birds crossed the ITCZ to their winter quarters. This study provides a novel approach to investigate wind-mediated movements in oceanic environments and shows that large-scale migration and dispersal processes over the oceans can be largely driven by spatiotemporal wind patterns.

Signaling in the Rhizosphere.

Signaling studies in the rhizosphere have focused on close interactions between plants and symbiotic microorganisms. However, this focus is likely to expand to other microorganisms because the rhizomicrobiome is important for plant health and is able to influence the structure of the microbial community. We discuss here the shaping of the rhizomicrobiome and define which aspects can be considered signaling. We divide signaling in the rhizosphere into three categories: (i) between microbes, (ii) from plants to microorganisms, and (iii) from microorganisms to plants. Signals act on diverse organisms including the plant. Mycorrhizal and rhizobial interkingdom signaling has revealed its pivotal role in establishing associations, and the recent discovery of signaling with non-symbiotic microorganisms indicates the important role of communication in shaping the rhizomicrobiome.

Identification of metabolites and thermal transformation products of quinolones in raw cow milk by liquid chromatography coupled to high resolution mass spectrometry

The presence of residues of antibiotics, metabolites, and thermal transformation products (TPs), produced during thermal treatment to eliminate pathogenic microorganisms in milk, could represent a risk for people. Cow"s milk samples spiked with enrofloxacin (ENR), ciprofloxacin (CIP), difloxacin (DIF), and sarafloxacin (SAR) and milk samples from cows medicated with ENR were submitted to several thermal treatments. The milk samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to find and identify TPs and metabolites. In this work, 27 TPs of 4 quinolones and 24 metabolites of ENR were found. Some of these compounds had been reported previously, but others were characterized for the first time, including lactose-conjugated CIP, the formamidation reaction for CIP and SAR, and hydroxylation or ketone formation to produce three different isomers for all quinolones studied.

Eletrólise de resíduos poluidores: I - Efluente de uma indústria liofilizadora de condimentos

Wastewater from a seasoning freeze-drying industry was electrolysed to increase its biodegradability. Stainless-steel electrodes were used at 9.09 A/m², for up to 80 min. Conductivity, pH, biochemical (BOD) and chemical (COD) oxygen demands, Daphnia similis acute toxicity bioassays, and bacteria counting through the plate count agar method were determined after different times of electrolysis. The results (e.g. higher BOD and lower COD) showed that the biodegradability of the wastewater was significantly increased; furthermore, Fe2+ ions liberated by the electrodes cause microorganisms to die and, when oxidised to Fe3+, contribute for the flocculation and sedimentation of solid residues.

The lipopolysaccharide of Aeromonas spp: structure-activity relationships.

Marine microorganisms, including Aeromonas, are a source of compounds for drug development that have generated great expectations in the last decades. Aeromonas infections produce septicaemia, and ulcerative and haemorrhagic diseases in fish. Among the pathogenic factors associated with Aeromonas, the lipopolysaccharides (LPS), a surface glyconconjugate unique to Gram-negative bacteria consisting of lipid A (lipid anchor of the molecule), core oligosaccharide and O-specific polysaccharide (O antigen), are key elicitors of innate immune responses. The chemical structure of these three parts has been characterized in Aeromonas. Based on the high variability of repeated units of O-polysaccharides, a total of 97 O-serogroups have been described in Aeromonas species, of which four of them (O:11; O:16; O:18 and O:34) account for more than 60% of the septicemia cases. The core of LPS is subdivided into two regions, the inner (highly conserved) and the outer core. The inner core of Aeromonas LPS is characterized by the presence of 3-deoxy-D-manno-oct-2-ulosonic (ketodeoxyoctonic) acid (Kdo) and L-glycero-D-manno-Heptoses (L,D-Hep), which are linked to the outer core, characterized by the presence of Glc, GlcN, Gal, and GalNAc (in Aeromonas salmonicida), D,D-Hep (in Aeromonas salmonicida), and L,D-Hep (in Aeromonas hydrophila). The biological relevance of these differences in the distal part of the outer core among these species has not been fully assessed to date. The inner core is attached to the lipid A, a highly conserved structure that confers endotoxic properties to the LPS when the molecule is released in blood from lysed bacteria, thus inducing a major systemic inflammatory response known as septic or endotoxic shock. In Aeromonas salmonicida subsp. salmonicida the Lipid A components contain three major lipid A molecules, differing in acylation patterns corresponding to tetra-, penta- and hexaacylated lipid A species and comprising of 4′-monophosphorylated β-2-amino-2-deoxy-D-glucopyranose-(1→6)-2-amino-2-deoxy-D-glucopyranose disaccharide. In the present review, we discuss the structure-activity relationships of Aeromonas LPS, focusing on its role in bacterial pathogenesis and its possible applications.

O uso de calorimetria em ecologia

The macroscopic effects caused by sun radiation and the mankind-nature interactions in a ecosystem are firstly presented. However, the importance of calorimetric determinations to clarify some phenomena related to the living microorganism populations and their interactions with the food additive or inhibitor agents are reported. The collect values illustrate the occurence a great deal of effects in this microscopic world. For this subject, the reachest Latosol soil was selected due to the content of organic matter and consequently in microorganisms. Microbial activity was stimulated by addition of glucose, which showed to be the best nutrient source. Inhibitory effect was detected with many compounds used in the agriculture like some herbicides and fungicides. Although the assays are based on the use of the microcalorimetry, other techniques like respirometry contributes strongly to the understanding of the ecosystem. The main objective in this exposition is to stimulate by means of many interesting examples, the importance of preserving the environment in order to establish direct analogies by using the Chemistry in the daily life.

DAI-DEPUR: an integrated and distributed architecture for wastewater treatment plants supervision

The activated sludge process - the main biological technology usually applied towastewater treatment plants (WWTP) - directly depends on live beings (microorganisms), and therefore on unforeseen changes produced by them. It could be possible to get a good plant operation if the supervisory control system is able to react to the changes and deviations in the system and can take thenecessary actions to restore the system’s performance. These decisions are oftenbased both on physical, chemical, microbiological principles (suitable to bemodelled by conventional control algorithms) and on some knowledge (suitable to be modelled by knowledge-based systems). But one of the key problems in knowledge-based control systems design is the development of an architecture able to manage efficiently the different elements of the process (integrated architecture), to learn from previous cases (spec@c experimental knowledge) and to acquire the domain knowledge (general expert knowledge). These problems increase when the process belongs to an ill-structured domain and is composed of several complex operational units. Therefore, an integrated and distributed AIarchitecture seems to be a good choice. This paper proposes an integrated and distributed supervisory multi-level architecture for the supervision of WWTP, that overcomes some of the main troubles of classical control techniques and those of knowledge-based systems applied to real world systems