Chromosomal and plasmid-encoded enzymes are required for assembly of the R3-type core oligosaccharide in the lipopolysaccharide of Escherichia coli O157:H7.

The type R3 core oligosaccharide predominates in the lipopolysaccharides from enterohemorrhagic Escherichia coli isolates including O157:H7. The R3 core biosynthesis (waa) genetic locus contains two genes, waaD and waaJ, that are predicted to encode glycosyltransferases involved in completion of the outer core. Through determination of the structures of the lipopolysaccharide core in precise mutants and biochemical analyses of enzyme activities, WaaJ was shown to be a UDP-glucose:(galactosyl) lipopolysaccharide alpha-1,2-glucosyltransferase, and WaaD was shown to be a UDP-glucose:(glucosyl)lipopolysaccharide alpha-1,2-glucosyltransferase. The residue added by WaaJ was identified as the ligation site for O polysaccharide, and this was confirmed by determination of the structure of the linkage region in serotype O157 lipopolysaccharide. The initial O157 repeat unit begins with an N-acetylgalactosamine residue in a beta-anomeric configuration, whereas the biological repeat unit for O157 contains alpha-linked N-acetylgalactosamine residues. With the characterization of WaaJ and WaaD, the activities of all of the enzymes encoded by the R3 waa locus are either known or predicted from homology data with a high level of confidence. However, when core oligosaccharide structure is considered, the origin of an additional alpha-1,3-linked N-acetylglucosamine residue in the outer core is unknown. The gene responsible for a nonstoichiometric alpha-1,7-linked N-acetylglucosamine substituent in the heptose (inner core) region was identified on the large virulence plasmids of E. coli O157 and Shigella flexneri serotype 2a. This is the first plasmid-encoded core oligosaccharide biosynthesis enzyme reported in E. coli

The assembly system for the lipopolysaccharide R2 core-type of Escherichia coli is a hybrid of those found in Escherichia coli K-12 and Salmonella enterica. Structure and function of the R2 WaaK and WaaL homologs.

In Escherichia coli F632, the 14-kilobase pair chromosomal region located between waaC (formerly rfaC) and waaA (kdtA) contains genes encoding enzymes required for the synthesis of the type R2 core oligosaccharide portion of lipopolysaccharide. Ten of the 13 open reading frames encode predicted products sharing greater than 90% total similarity with homologs in E. coli K-12. However, the products of waaK (rfaK) and waaL (rfaL) each resemble homologs in Salmonella enterica serovar Typhimurium but share little similarity with E. coli K-12. The F632 WaaK and WaaL proteins therefore define differences between the type R2 and K-12 outer core oligosaccharides of E. coli lipopolysaccharides. Based on the chemical structure of the core oligosaccharide of an E. coli F632 waaK::aacC1 mutant and in vitro glycosyltransferase analyses, waaK encodes UDP-N-acetylglucosamine:(glucose) lipopolysaccharide alpha1, 2-N-acetylglucosaminyltransferase. The WaaK enzyme adds a terminal GlcNAc side branch substituent that is crucial for the recognition of core oligosaccharide acceptor by the O-polysaccharide ligase, WaaL. Results of complementation analyses of E. coli K-12 and F632 waaL mutants suggest that structural differences between the WaaL proteins play a role in recognition of, and interaction with, terminal lipopolysaccharide core moieties

Involvement of waaY, waaQ, and waaP in the Modification of Escherichia coliLipopolysaccharide and Their Role in the Formation of a Stable Outer Membrane *

The waaY, waaQ, and waaP genes are located in the central operon of the waa (formerly rfa) locus on the chromosome of Escherichia coli. This locus contains genes whose products are involved in the assembly of the core region of the lipopolysaccharide molecule. In the R1 core prototype strain, E. coli F470, there are nine genes in this operon, and all but waaY, waaQ, and waaP have been assigned function. In this study, the waaY, waaQ, and waaP genes were independently mutated by insertion of a non-polar antibiotic resistance cassette, and the structures of the resulting mutant core oligosaccharides were determined by chemical analyses and phosphorus-nuclear magnetic resonance spectroscopy. All three of these mutations were shown to affect the modification of the heptose region of the core, a region whose structure is critical to outer membrane stability. Mutation of waaY resulted in a core oligosaccharide devoid of phosphate on HepII. Mutation of waaQ resulted in loss of the branch HepIII residue on HepII and impeded the activity of WaaY. Mutation of waaP resulted in loss of phosphoryl substituents on HepI and obviated WaaQ and WaaY activity. Only mutation of waaP resulted in hypersensitivity to novobiocin and sodium dodecyl sulfate, a characteristic of deep-rough mutations

Asteroseismic estimate of helium abundance of a solar analog binary system

16 Cyg A and B are among the brightest stars observed by Kepler. What makes these stars more interesting is that they are solar analogs. 16 Cyg A and B exhibit solar-like oscillations. In this work we use oscillation frequencies obtained using 2.5 years of Kepler data to determine the current helium abundance of these stars. For this we use the fact that the helium ionization zone leaves a signature on the oscillation frequencies and that this signature can be calibrated to determine the helium abundance of that layer. By calibrating the signature of the helium ionization zone against models of known helium abundance, the helium abundance in the envelope of 16 Cyg A is found to lie in the range 0.231 to 0.251 and that of 16 Cyg B lies in the range 0.218 to 0.266.Comment: Accepted for publication in Ap

Bioaccumulation of amylose-like glycans by Helicobacter pylori

Background: Helicobacter pylori cell surface is composed of lipopolysaccharides (LPSs) yielding structures homologous to mammalian Lewis O-chains blood group antigens. These structures are key mediators in the definition of host-microbial interactions and known to change their expression pattern in response to environmental pressure. Aims:  The present work is focused on the identification of new H. pylori cell-surface glycosides. Special attention is further devoted to provide insights on the impact of in vitro subcultivation on H. pylori cell-surface phenotypes. Methods:  Cell-surface glycans from H. pylori NCTC 11637 and two clinical isolates were recovered from the aqueous phase resulting from phenol:water extraction of intact bacteria. They were evaluated in relation to their sugars and glycosidic-linkages composition by CG-MS, size-exclusion chromatography, NMR, and Mass Spectrometry. H. pylori glycan profile was also monitored during subcultivation in vitro in agar and F12 liquid medium. Results:  All three studied strains produce LPS expressing Lewis epitopes and express bioaccumulate amylose-like glycans. Bioaccumulation of amylose was found to be enhanced with the subcultivation of the bacterium on agar medium and accompanied by a decrease in the expression of LPS O-chains. In contrast, during exponential growth in F12 liquid medium, an opposite behavior is observed, that is, there is an increase in the overall amount of LPS and decrease in amylose content. Conclusions:  This work shows that under specific environmental conditions, H. pylori expresses a phase-variable cell-surface α-(1→4)-glucose moiety

The effect of laser pan-retinal photocoagulation with or without intravitreal bevacizumab injections on the OCT-measured macular choroidal thickness of eyes with proliferative diabetic retinopathy

OBJECTIVES: To investigate the effect of laser pan-retinal photocoagulation with or without intravitreal bevacizumab injections on macular choroidal thickness parameters in eyes with high-risk proliferative diabetic retinopathy. METHODS: High-risk proliferative diabetic retinopathy patients undergoing laser treatment were prospectively enrolled in this study. One eye was randomly selected for laser treatment combined with bevacizumab injections, study group, whereas the corresponding eye was subjected to laser treatment alone, control group. Spectral-domain optical coherence tomography with enhanced depth imaging was used to measure the macular choroidal thickness prior to and 1 month after treatment. Measurements in both groups were compared. Clinicaltrials.gov: NCT01389505. RESULTS: Nineteen patients (38 eyes) with a mean±standard deviation age of 53.4±9.3 years were evaluated, and choroidal thickness measurements for 15 patients were used for comparison. The greatest measurement before treatment was the subfoveal choroidal thickness (341.68±67.66 μm and 345.79±83.66 μm for the study and control groups, respectively). No significant difference between groups was found in terms of macular choroidal thickness measurements at baseline or after treatment. However, within-group comparisons revealed a significant increase in choroidal thickness parameters in 10 measurements in the study group and in only 5 temporal measurements in the control group when 1-month follow-up measurements were compared to baseline values. CONCLUSIONS: The macular choroidal thickness does not appear to be significantly influenced by laser treatment alone but increases significantly when associated with bevacizumab injections in patients with proliferative diabetic retinopathy and macular edema. Because bevacizumab injections reduce short-term laser pan-retinal photocoagulation-induced macular edema, our findings suggest that the choroid participates in its pathogenesis

Thyroid nodules and differentiated thyroid cancer: Brazilian consensus

Thyroid nodules are a common manifestation of thyroid diseases. It is estimated that ~10% of adults have palpable thyroid nodules with the frequency increasing throughout life. The major concern on nodule evaluation is the risk of malignancy (5-10%). Differentiated thyroid carcinoma accounts for 90% of all thyroid malignant neoplasias. Although most patients with cancer have a favorable outcome, some individuals present an aggressive form of the disease and poor prognostic despite recent advances in diagnosis and treatment. Here, a set of clinical guidelines for the evaluation and management of patients with thyroid nodules or differentiated thyroid cancer was developed through consensus by 8 member of the Department of Thyroid, Sociedade Brasileira de Endocrinologia e Metabologia. The participants are from different reference medical centers within Brazil, to reflect different practice patterns. Each committee participant was initially assigned to write a section of the document and to submit it to the chairperson, who revised and assembled the sections into a complete draft document, which was then circulated among all committee members for further revision. All committee members further revised and refined the document. The guidelines were developed based on the expert opinion of the committee participants, as well as on previously published information.Os nódulos tireoidianos constituem a principal manifestação clínica de uma série de doenças da tireóide com uma prevalência de aproximadamente 10% na população adulta. O maior desafio é excluir o câncer da tireóide, que ocorre em 5 a 10% dos casos. Os carcinomas diferenciados respondem por 90% dos casos de todas as neoplasias malignas da tireóide. A maioria dos pacientes com carcinoma diferenciado apresenta, geralmente, um bom prognóstico quando tratada adequadamente, com índices de mortalidade similares à população geral. No entanto, alguns indivíduos apresentam doença agressiva, desafiando o conhecimento atual e ilustrando a complexidade do manejo dessa neoplasia. No presente trabalho, reunimos 8 membros do Departamento de Tireóide da Sociedade Brasileira de Endocrinologia & Metabologia, para elaborarmos, por consenso, as diretrizes brasileiras no manejo dos nódulos tireoidianos e do câncer diferenciado da tireóide. Os membros participantes representam diferentes Centros Universitários do Brasil, refletindo diferentes abordagens diagnósticas e terapêuticas. Inicialmente, cada participante ficou responsável pela redação de determinado tema a ser enviado ao Coordenador, que, após revisão editorial e elaboração da primeira versão do manuscrito, enviou ao grupo para sugestões e aperfeiçoamentos. Quando concluído, o manuscrito foi novamente enviado e revisado por todos. A elaboração dessas diretrizes foi baseada na experiência dos participantes e revisão pertinente da literatura.Sociedade Brasileira de Endocrinologia e Metabologia Departamento de TireóideUniversidade Federal do Rio Grande do Sul Hospital de Clínicas de Porto Alegre Serviço de EndocrinologiaUNICAMP Faculdade de Ciências Médicas Departamento de Clínica MédicaUniversidade Federal do Paraná Serviço de Endocrinologia e MetabologiaUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de MedicinaUniversidade de São Paulo Faculdade de Medicina de Ribeirão Preto Departamento de Clínica MédicaSanta Casa de Belo Horizonte Serviço de Endocrinologia Departamento de TireóideUniversidade Federal do Rio de Janeiro Faculdade de Medicina Hospital Universitário Clementino Fraga FilhoUNIFESP, EPM, Depto. de MedicinaSciEL

The automatic detection subsystem

Marques, M. M., Lobo, V., Aguiar, A. P., Silva, J. E., de Sousa, J. B., Nunes, M. D. F., Ribeiro, R. A., Bernardino, A., Cruz, G., & Marques, J. S. (2021). An unmanned aircraft system for maritime operations: The automatic detection subsystem. Marine Technology Society Journal, 55(1), 38-49. https://doi.org/10.4031/MTSJ.55.1.4 --- This work was funded by POFC (Programa Operacional Factores de Competitividade) within the National Strategic Reference Framework (QREN) under grant agreement 2013/034063 (SEAGULL, Project Number 34063).This paper addresses the development of an integrated system to support maritime situation awareness based on unmanned aerial vehicles (UAVs), empha-sizing the role of the automatic detection subsystem. One of the main topics of research in the SEAGULL project was the automatic detection of sea vessels from sensors onboard the UAV, to help human operators in the generation of situational awareness of maritime events such as (a) detection and geo-referencing of oil spills or hazardous and noxious substances, (b) tracking systems (e.g., vessels, ship-wrecks, lifeboats, debris), (c) recognizing behavioral patterns (e.g., vessels rendez-vous, high-speed vessels, atypical patterns of navigation), and (d) monitoring environmental parameters and indicators. We describe a system composed of optical sensors, an embedded computer, communication systems, and a vessel detection algorithm that can run in real time in the embedded UAV hardware and provide to human operators vessel detections with low latency, high precision rates (about 99%), and suitable recalls (>50%), which is comparable to other more computationally intensive state-of-the-art approaches. Field test results, including the detection of lifesavers and multiple vessels in red-green-and-blue (RGB) and thermal images, are presented and discussed.publishersversionpublishe

RNA interference in Lepidoptera: an overview of successful and unsuccessful studies and implications for experimental design

A