Heterologous expression of genes from a cyanobacterial endosymbiont highlights substrate exchanges with its diatom host.

A few genera of diatoms are widespread and thrive in low-nutrient waters of the open ocean due to their close association with N2-fixing, filamentous heterocyst-forming cyanobacteria. In one of these symbioses, the symbiont, Richelia euintracellularis, has penetrated the cell envelope of the host, Hemiaulus hauckii, and lives inside the host cytoplasm. How the partners interact, including how the symbiont sustains high rates of N2 fixation, is unstudied. Since R. euintracellularis has evaded isolation, heterologous expression of genes in model laboratory organisms was performed to identify the function of proteins from the endosymbiont. Gene complementation of a cyanobacterial invertase mutant and expression of the protein in Escherichia coli showed that R. euintracellularis HH01 possesses a neutral invertase that splits sucrose producing glucose and fructose. Several solute-binding proteins (SBPs) of ABC transporters encoded in the genome of R. euintracellularis HH01 were expressed in E. coli, and their substrates were characterized. The selected SBPs directly linked the host as the source of several substrates, e.g. sugars (sucrose and galactose), amino acids (glutamate and phenylalanine), and a polyamine (spermidine), to support the cyanobacterial symbiont. Finally, transcripts of genes encoding the invertase and SBPs were consistently detected in wild populations of H. hauckii collected from multiple stations and depths in the western tropical North Atlantic. Our results support the idea that the diatom host provides the endosymbiotic cyanobacterium with organic carbon to fuel N2 fixation. This knowledge is key to understanding the physiology of the globally significant H. hauckii-R. euintracellularis symbiosis.

Effect of oral exposure on chemical, physical, mechanical, and morphologic properties of clear orthodontic aligners.

INTRODUCTION: The dental industry is heavily committed to developing more esthetic solutions for orthodontic treatments. Invisalign is a system of transparent orthodontic aligners introduced as an alternative to conventional orthodontic fittings with brackets and metal wires. This study aimed to assess the chemical, physical, mechanical and morphologic changes in these polymeric aligners after exposure to the oral environment. METHODS: Twenty-four Invisalign orthodontic aligners were equally divided into 2 groups: an in vivo aged group in which patients used aligners for 14 days and the reference group, unexposed to the oral environment. Different experimental techniques were used to study the chemical structure, the color changes and translucency, the density and subsequent volume of the aligners, mechanical properties, surface roughness, morphology and elemental composition. The data were subjected to several statistical analyses. RESULTS: Clear orthodontic aligners exhibit chemical stability but undergo a statistically significant optical change in color and translucency. There was a gradual increase in the water absorption rate and the dimensional variation of the polymer, indicating a strong correlation among these factors. The mechanical properties of the polymer showed a statistically significant decrease in its elastic modulus and hardness. There was a slight tendency toward increased surface roughness of the material, but no statistical differences were found between reference and aged groups. The surface morphology of the used aligners demonstrates microcracks, distortions and biofilm formation. CONCLUSION: Intraoral aging adversely affected the physical, mechanical, and morphologic properties of the Invisalign appliance.

Spotted Fever and Typhus Group Rickettsiae in Dogs and Humans, Mexico, 2022.

We found serologic evidence of spotted fever group Rickettsia in humans and dogs and typhus group Rickettsia in dogs in Reynosa, Mexico. Our investigation revealed serologic samples reactive to spotted fever group Rickettsia in 5 community members, which highlights a potential rickettsial transmission scenario in this region.

Percepción de madres sobre la atención de enfermería en el servicio de crecimiento y desarrollo / Mothers' perception of nursing care in the growth and development service / Percepção das mães sobre os cuidados de enfermagem no serviço de crescimento e desenvolvimento

Introducción: El programa de crecimiento y desarrollo es una estrategia que permite identificar la evolución adecuada de los menores de 5 años a través de la valoración de los profesionales de enfermería. Objetivo: Determinar el grado de satisfacción de madres sobre la atención recibida por enfermería en el servicio de control de crecimiento y desarrollo. Cartagena 2022. Materiales y métodos: estudio cuantitativo descriptivo de tipo transversal. La muestra correspondió a 604 madres con hijos menores de 1 año que asisten al Control de Crecimiento y Desarrollo y que desearan participar en el estudio, para la recolección de la información se aplicó el instrumento tipo escala de Likert denominado: Satisfacción de la madre. Resultados: En general, la satisfacción global de las madres fue alta 77%, dadas las habilidades del profesional de Enfermería durante la atención brindad al menor en la consulta de crecimiento y desarrollo. Datos consistentes con la valoración de cada una de las dimensiones de la satisfacción: humana 76%, oportuna 78%, continua 72% y segura 71%. Conclusión: Influye el comportamiento y las habilidades del profesional en enfermería para garantizar la adherencia al programa y a las sugerencias que se puedan derivar de la valoración del menor en cada control.

Introduction: The growth and development program is a strategy that allows to identify the adequate evolution of children under 5 years of age through the assessment of nursing professionals. Objective: To evaluate the degree of satisfaction of mothers on the quality of care received by nurses in the growth and development control service. Cartagena 2022. Materials and methods: cross-sectional descriptive quantitative study. The sample consisted of 610 mothers with children under 1 year of age who attended the Growth and Development Control Service and who wished to participate in the study. For the collection of information, a Likert scale type instrument was applied called: Mother's Satisfaction. Results: In general, the overall satisfaction of the mothers was high 77%, given the skills of the nursing professional during the care provided to the child in the growth and development consultation. Data consistent with the evaluation of each of the dimensions of satisfaction: humane 76%, timely 78%, continuous 72% and safe 71%. Conclusion: The behavior and skills of the nursing professional to ensure adherence to the program and the suggestions that can be derived from the assessment of the child in each control influences the behavior and skills of the professional in nursing to ensure adherence to the program and the suggestions that can be derived from the assessment of the child in each control.

Introdução: O programa de crescimento e desenvolvimento é uma estratégia para identificar a evolução adequada das crianças menores de 5 anos de idade através da avaliação dos profissionais de enfermagem. Objetivo: Avaliar o grau de satisfação das mães com a qualidade dos cuidados recebidos pelas enfermeiras do serviço de acompanhamento do crescimento e desenvolvimento. Cartagena 2022. Materiais e métodos: estudo quantitativo descritivo de corte transversal. A amostra foi constituída por 610 mães com filhos menores de 1 ano de idade que frequentaram a Consulta de Crescimento e Desenvolvimento e que desejaram participar no estudo. Para a recolha de informação foi utilizado um instrumento do tipo escala de Likert denominado: Satisfação da Mãe Resultados: De um modo geral, a satisfação global das mães foi elevada 77%, tendo em conta as competências do profissional de enfermagem durante os cuidados prestados à criança na consulta de crescimento e desenvolvimento. Dados coerentes com a avaliação de cada uma das dimensões da satisfação: humanizado 76%, atempado 78%, contínuo 72% e seguro 71%. Conclusão: O comportamento e as habilidades do profissional de enfermagem influenciam para garantir a adesão ao programa e as sugestões que podem ser derivadas da avaliação da criança em cada consulta de controle.

Robust, coherent, and synchronized circadian clock-controlled oscillations along Anabaena filaments.

Circadian clocks display remarkable reliability despite significant stochasticity in biomolecular reactions. We study the dynamics of a circadian clock-controlled gene at the individual cell level in Anabaena sp. PCC 7120, a multicellular filamentous cyanobacterium. We found significant synchronization and spatial coherence along filaments, clock coupling due to cell-cell communication, and gating of the cell cycle. Furthermore, we observed low-amplitude circadian oscillatory transcription of kai genes encoding the post-transcriptional core oscillatory circuit and high-amplitude oscillations of rpaA coding for the master regulator transducing the core clock output. Transcriptional oscillations of rpaA suggest an additional level of regulation. A stochastic one-dimensional toy model of coupled clock cores and their phosphorylation states shows that demographic noise can seed stochastic oscillations outside the region where deterministic limit cycles with circadian periods occur. The model reproduces the observed spatio-temporal coherence along filaments and provides a robust description of coupled circadian clocks in a multicellular organism.

Impaired cell-cell communication in the multicellular cyanobacterium Anabaena affects carbon uptake, photosynthesis, and the cell wall.

Cell-cell communication is an essential attribute of multicellular organisms. The effects of perturbed communication were studied in septal protein mutants of the heterocyst-forming filamentous cyanobacterium Anabaena sp. PCC 7120 model organism. Strains bearing sepJ and sepJ/fraC/fraD deletions showed differences in growth, pigment absorption spectra, and spatial patterns of expression of the hetR gene encoding a heterocyst differentiation master regulator. Global changes in gene expression resulting from deletion of those genes were mapped by RNA sequencing analysis of wild-type and mutant strains, both under nitrogen-replete and nitrogen-poor conditions. The effects of sepJ and fraC/fraD deletions were non-additive, and perturbed cell-cell communication led to significant changes in global gene expression. Most significant effects, related to carbon metabolism, included increased expression of genes encoding carbon uptake systems and components of the photosynthetic apparatus, as well as decreased expression of genes encoding cell wall components related to heterocyst differentiation and to polysaccharide export.

Effect of different home-bleaching techniques for a regular or an extended time on enamel properties.

CONTEXT: The side effects of bleaching products are still incompletely known. AIMS: This work aims to evaluate the effects of bleaching regimens on colour variation, microstructure, roughness, composition and nanohardness of human dental enamel until 8 weeks. SETTINGS AND DESIGN: : Twenty teeth were cross-sectioned to obtain eighty enamel fragments (50 × 50 mm) divided into four groups: CN (control Negative-artificial saliva), CP10 (10% carbamide peroxide), HP10 (10% hydrogen peroxide), and WS (whitening strips-10% hydrogen peroxide). METHODS AND MATERIAL: Roughness (atomic force microscopy-AFM and 3-D surface scanning), morphology (confocal laser scanning microscopy-CLSM and AFM), hardness and elastic modulus (nanoindentation), and composition (Raman microspectroscopy) were analysed before the therapy and after 4 and 8 weeks. Colour measures were performed weekly. STATISTICAL ANALYSIS USED: : Two-way ANOVA with repeated measures (P < 0.05). RESULTS: Bleaching stabilizes after 3 weeks for HP10 and after 4 weeks for CP10 and WS. Roughness evaluation showed statistical difference for HP10 after 8 weeks for Sa and Sq, for HP10 and WS after 4 weeks and for CP10 after 8 weeks. The same occurred for hardness and elastic modulus. The morphological evaluation demonstrated the most significant effects after 8 weeks of treatment for HP10 and WS. Composition analysis revealed modifications in peaks related to the organic content spectra (protein) with an increase in detection after 4 weeks, followed by a decrease after 8 weeks. CONCLUSIONS: H2O2-based products caused morphological and compositional alterations on enamel.

ZipN is an essential FtsZ membrane tether and contributes to the septal localization of SepJ in the filamentous cyanobacterium Anabaena.

The organismic unit of heterocyst-forming cyanobacteria is a filament of communicating cells connected by septal junctions, proteinaceous structures bridging the cytoplasms of contiguous cells. This distinct bacterial organization is preserved during cell division. In Anabaena, deletion of the zipN gene could not be segregated. We generated strain CSL109 that expresses zipN from a synthetic regulatable promoter. Under conditions of ZipN depletion, cells progressively enlarged, reflecting restricted cell division, and showed drastic morphological alterations including cell detachment from the filaments, to finish lysing. In contrast to the wild-type localization in midcell Z-rings, FtsZ was found in delocalized aggregates in strain CSL109. Consistently, the proportion of membrane-associated to soluble FtsZ in fractionated cell extracts was lower in CSL109. Bacterial two-hybrid analysis showed that ZipN interacts with FtsZ and other cell-division proteins including cytoplasmic Ftn6 and SepF, and polytopic FtsW, FtsX, FtsQ and FtsI. Additionally, ZipN interacted with the septal protein SepJ, and in CSL109 depletion of ZipN was concomitant with a progressive loss of septal specificity of SepJ. Thus, in Anabaena ZipN represents an essential FtsZ membrane tether and an organizer of the divisome, and it contributes to the conformation of septal structures for filament integrity and intercellular communication.

FtsZ of Filamentous, Heterocyst-Forming Cyanobacteria Has a Conserved N-Terminal Peptide Required for Normal FtsZ Polymerization and Cell Division.

Filamentous cyanobacteria grow by intercalary cell division, which should involve distinct steps compared to those producing separate daughter cells. The N-terminal region of FtsZ is highly conserved in the clade of filamentous cyanobacteria capable of cell differentiation. A derivative of the model strain Anabaena sp. PCC 7120 expressing only an FtsZ lacking the amino acids 2-51 of the N-terminal peptide (ΔN-FtsZ) could not be segregated. Strain CSL110 expresses both ΔN-FtsZ, from the endogenous ftsZ gene promoter, and the native FtsZ from a synthetic regulated promoter. Under conditions of ΔN-FtsZ predominance, cells of strain CSL110 progressively enlarge, reflecting reduced cell division, and show instances of asymmetric cell division and aberrant Z-structures notably differing from the Z-ring formed by FtsZ in the wild type. In bacterial 2-hybrid assays FtsZ interacted with ΔN-FtsZ. However, ΔN-FtsZ-GFP appeared impaired for incorporation into Z-rings when expressed together with FtsZ. FtsZ, but not ΔN-FtsZ, interacted with the essential protein SepF. Both FtsZ and ΔN-FtsZ polymerize in vitro exhibiting comparable GTPase activities. However, filaments of FtsZ show a distinct curling forming toroids, whereas ΔN-FtsZ form thick bundles of straight filaments. Thus, the N-terminal FtsZ sequence appears to contribute to a distinct FtsZ polymerization mode that is essential for cell division and division plane location in Anabaena.

Judicialização nas políticas de saúde no Brasil: fundamentos éticos, jurídicos, econômicos e políticos / Judicialization on health policies in Brazil: ethical, legal, economic and political foundations

Resumo: O acesso aos bens e serviços de saúde, constitucionalmente definidos como direito de todos e dever do Estado, tem demandado crescente intervenção do poder judiciário, o que caracteriza o fenômeno da judicialização da política e da saúde; especificamente, este estudo tem como objeto a Judicialização das Políticas de Saúde no Sistema Único de Saúde (SUS). Seu objetivo geral é investigar quais os fundamentos Éticos, jurídicos, econômicos e políticos associados ao tema. A metodologia do estudo associa estas categorias da razão prática grega ¿ Ética, política, direito e economia - à teoria do agir comunicativo de Habermas, que identifica o uso pragmático, ético e moral da razão prática. Trata-se de um ensaio teórico composto por quatro capítulos. O primeiro aborda a responsabilidade sanitária do estado baseado na Ética de Responsabilidade de Hans Jonas; o segundo capítulo relaciona com o direito e aborda a judicialização da política como medicalização da vida social e política através da comparação entre médicos e juízes; o terceiro capítulo analisa os determinantes econômicos da judicialização das políticas de saúde; o quarto capítulo aborda a judicialização da saúde por meio da análise política. A presente investigação identifica três possibilidades de judicialização da saúde: judicialização-equidade, judicialização-desigualdade e judicialização-iniquidade(AU)

Abstract: Access to health goods and services, constitutionally defined as the right of everyone and the duty of the State, has demanded increasing intervention by the judiciary, which characterizes the phenomenon of judicialization of politics and health; specifically, this study aims at the Judicialization of Health Policies in the Unified Health System (SUS). Its general objective is to investigate the Ethical, legal, economic and political foundations associated to the subject. The methodology of the study associates these categories of Greek practical reason - Ethics, politics, law and economics - with Habermas' theory of communicative action, which identifies the pragmatic, ethical and moral use of practical reason. This is a theoretical essay consisting of four chapters. The first addresses the state's health responsibility based on Hans Jonas's Ethics of Responsibility; the second chapter relates to law and addresses the judicialization of politics as the medicalization of social and political life by comparing between physicians and judges; the third chapter analyzes the economic determinants of the judicialization of health policies; the fourth chapter deals with the judicialization of health through political analysis. The present research identifies three possibilities for judicialization of health: judicialization-equity, judicialization-inequality, and judicialization-iniquity(AU)

An International Urogynecological Association (IUGA)/International Continence Society (ICS) joint report on the terminology for female pelvic organ prolapse (POP).

INTRODUCTION: The terminology for female pelvic floor prolapse (POP) should be defined and organized in a clinically-based consensus Report. METHODS: This Report combines the input of members of two International Organizations, the International Urogynecological Association (IUGA) and the International Continence Society (ICS), assisted at intervals by external referees. Appropriate core clinical categories and a sub-classification were developed to give a coding to definitions. An extensive process of fourteen rounds of internal and external review was involved to exhaustively examine each definition, with decision-making by collective opinion (consensus). RESULTS: A Terminology Report for female POP, encompassing over 230 separate definitions, has been developed. It is clinically-based with the most common diagnoses defined. Clarity and user-friendliness have been key aims to make it interpretable by practitioners and trainees in all the different specialty groups involved in female pelvic floor dysfunction and POP. Female-specific imaging (ultrasound, radiology and MRI) and conservative and surgical managements are major additions and appropriate figures have been included to supplement and clarify the text. Emerging concepts and measurements, in use in the literature and offering further research potential, but requiring further validation, have been included as an appendix. Interval (5-10 year) review is anticipated to keep the document updated and as widely acceptable as possible. CONCLUSION: A consensus-based Terminology Report for female POP has been produced to aid clinical practice and research.

An International Urogynecological Association (IUGA) / International Continence Society (ICS) joint report on the terminology for female pelvic organ prolapse (POP).

INTRODUCTION: The terminology for female pelvic floor prolapse (POP) should be defined and organized in a clinically-based consensus Report. METHODS: This Report combines the input of members of two International Organizations, the International Urogynecological Association (IUGA) and the International Continence Society (ICS), assisted at intervals by external referees. Appropriate core clinical categories and a sub-classification were developed to give a coding to definitions. An extensive process of fourteen rounds of internal and external review was involved to exhaustively examine each definition, with decision-making by collective opinion (consensus). RESULTS: A Terminology Report for female POP, encompassing over 230 separate definitions, has been developed. It is clinically-based with the most common diagnoses defined. Clarity and user-friendliness have been key aims to make it interpretable by practitioners and trainees in all the different specialty groups involved in female pelvic floor dysfunction and POP. Female-specific imaging (ultrasound, radiology and MRI) and conservative and surgical managements are major additions and appropriate figures have been included to supplement and clarify the text. Emerging concepts and measurements, in use in the literature and offering further research potential, but requiring further validation, have been included as an appendix. Interval (5-10 year) review is anticipated to keep the document updated and as widely acceptable as possible. CONCLUSION: A consensus-based Terminology Report for female POP has been produced to aid clinical practice and research.

An International Urogynecological Association (IUGA) / International Continence Society (ICS) Joint Report on the Terminology for Female Pelvic Organ Prolapse (POP).

INTRODUCTION: The terminology for female pelvic floor prolapse (POP) should be defined and organized in a clinically-based consensus Report. METHODS: This Report combines the input of members of two International Organizations, the International Urogynecological Association (IUGA) and the International Continence Society (ICS), assisted at intervals by external referees. Appropriate core clinical categories and a sub-classification were developed to give a coding to definitions. An extensive process of fourteen rounds of internal and external review was involved to exhaustively examine each definition, with decision-making by collective opinion (consensus). RESULTS: A Terminology Report for female POP, encompassing over 230 separate definitions, has been developed. It is clinically-based with the most common diagnoses defined. Clarity and user-friendliness have been key aims to make it interpretable by practitioners and trainees in all the different specialty groups involved in female pelvic floor dysfunction and POP. Female-specific imaging (ultrasound, radiology and MRI) and conservative and surgical managements are major additions and appropriate figures have been included to supplement and clarify the text. Emerging concepts and measurements, in use in the literature and offering further research potential, but requiring further validation, have been included as an appendix. Interval (5-10 year) review is anticipated to keep the document updated and as widely acceptable as possible. CONCLUSION: A consensus-based Terminology Report for female POP has been produced to aid clinical practice and research.

Infrared spectroscopy, nano-mechanical properties, and scratch resistance of esthetic orthodontic coated archwires.

OBJECTIVE: To evaluate the material composition, mechanical properties (hardness and elastic modulus), and scratch resistance of the coating of four commercialized esthetic orthodontic archwires. MATERIALS AND METHODS: The coating composition of esthetic archwires was assessed by Fourier-transform infrared spectroscopy (FTIR). Coating hardness and elastic modulus were analyzed with instrumented nano-indentation tests. Scratch resistance of coatings was evaluated by scratch test. Coating micromorphologic characteristics after scratch tests were observed in a scanning electron microscope. Statistical differences were investigated using analysis of variance and Tukey post hoc test. RESULTS: The FTIR results indicate that all analyzed coatings were markedly characterized by the benzene peak at about 1500 cm(-1). The coating hardness and elastic modulus average values ranged from 0.17 to 0.23 GPa and from 5.0 to 7.6 GPa, respectively. Scratch test showed a high coating elasticity after load removal with elastic recoveries >60%, but different failure features could be observed along the scratches. CONCLUSION: The coatings of esthetic archwires evaluated are probably a composite of polyester and polytetrafluoroethylene. Delamination, crack propagation, and debris generation could be observed along the coating scratches and could influence its durability in the oral environment.

Effects of PipX on NtcA-dependent promoters and characterization of the cox3 promoter region in the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120.

In Anabaena, the pipX gene is induced in the cells differentiating into heterocysts, being the PipX factor required for full expression of late heterocyst-specific genes. Here we show that PipX has a positive effect on in vitro binding of the transcription factor NtcA to DNA, as well as on transcript production, in different NtcA-dependent promoters. We found that the cox3 operon, encoding a heterocyst-specific terminal respiratory oxidase, is expressed from three nitrogen-regulated promoters to which NtcA binds. At the three sites, NtcA binding is potentiated by PipX. Thus, PipX has a direct effect on gene expression influencing the activity of NtcA.

Effect of resin infiltration on the nanomechanical properties of demineralized bovine enamel.

OBJECTIVE: The aim of the present study was to evaluate the efficacy of resin infiltration in preventing in vitro lesion progression. MATERIALS AND METHODS: Buccal surfaces of bovine incisors were divided into mesial and distal regions and, at the center, nail varnish was applied (1.0 mm width) to protect the enamel surface against any further treatment. In order to create artificial enamel lesions in the unprotected areas, each specimen was soaked in a demineralizing solution. After that, specimens had two enamel lesions. One lesion in each sample was etched with 15% HCl for 120 s and infiltrated with a commercial infiltrating resin for 3 min, while the other lesion was not treated (control). Each specimen was cross-sectionally halved and randomly allocated to two groups: Group 1 was immediately processed and Group 2 was submitted to a new demineralization process. The samples were analyzed by means of cross-sectional hardness measurements using a nanoindenter equipment. Hardness data were statistically analyzed by non-parametric Kruskal-Wallis and MannWhitney tests (α = 0.05). RESULTS: The findings showed statistical difference between treatments at the same analyzed distance range from the outer surface of the enamel (P < 0.05). CONCLUSION: The untreated lesion showed lower hardness values for distances near the outer surface of the enamel. The resin infiltration was efficient in preventing further in vitro demineralization of bovine enamel lesions.

Avaliação da resistência adesiva após colagem ortodôntica com resina e sistema hidrofílicos com ou sem contaminação / Evaluation of adhesive strengh after orthodontics bonding with hydrophilic resin and system with or without contamination

A contaminação salivar deve ser evitada para obter-se adequada adesão dos braquetes no esmalte. Entretanto, a colagem de braquetes e acessórios em dentes impactados, superfícies dentárias linguais, segundos molares e dentes parcialmente irrompidos torna mais difícil o procedimento de colagem sem contaminação. Dessa forma, materiais têm sido desenvolvidos com a intenção de obter-se boa resistência adesiva dos braquetes frente à contaminação por água e/ou saliva. O objetivo desse trabalho foi avaliar, in vitro, a resistência adesiva ao cisalhamento após a colagem de braquetes metálicos com a resina Transbond Color Change® (TCC) e sistema adesivo Transbond Plus Self-Etching Primer® (TPSEP) na presença ou ausência de contaminação por saliva. Foram utilizados 100 incisivos inferiores bovinos, divididos em 4 grupos (Grupo 1: TPSEP + Transbond XT e ausência de contaminação; Grupo 2: TPSEP + Transbond XT e presença de contaminação; Grupo 3: TPSEP + TCC e ausência de contaminação; Grupo 4: TPSEP + TCC e presença de contaminação). Os corpos de prova foram submetidos ao teste de cisalhamento na máquina de ensaio universal DL 500 (EMIC). Os valores obtidos foram analisados estatisticamente através do método de ANOVA a dois critérios, modelo fatorial completo, e evidenciaram que a presença de contaminação por saliva diminuiu a resistência adesiva nos dois grupos estudados (p < 0,05). Conclui-se que a resistência adesiva ao cisalhamento diminui na presença de contaminação por saliva ao se utilizar um sistema adesivo e resina hidrofílicos.

Regulation of internal promoters in a zinc-responsive operon is influenced by transcription from upstream promoters.

In the cyanobacterium Anabaena sp. strain PCC 7120 (also known as Nostoc sp. strain PCC 7120), a zinc-responsive operon (all4725-all4721) has been described, which contains 4 distinct promoters. The two most upstream ones bind Zur with high affinity, whereas the other two do not or do so with a very low affinity. In this paper, a detailed characterization of the four promoters is presented, showing that all four were induced by metal depletion, and they were constitutively derepressed in a zur mutant, despite the two downstream promoters not being direct targets for this regulator. Crucially, induction by metal depletion of the two downstream promoters was abrogated when transcription initiated at the upstream promoters was interrupted by a polar insertion midway in the operon. In contrast, insertion of a nitrogen-responsive promoter at a roughly similar position provoked the two downstream promoters to adopt a regulatory pattern mimicking that of the inserted promoter. Thus, regulation of the two downstream promoters is apparently influenced by transcription from promoters upstream. Evidence is presented indicating that the activity of the two downstream promoters is kept basal in Anabaena by repression. A regulatory model compatible with these results is proposed, where promoters controlled by repression in bacterial operons may be subjected to a hierarchical regulation depending on their position in the operon. According to this model, internal promoters may respond to stimuli governing the activity of promoters upstream by an indirect regulation and to specific stimuli by a direct regulation.

Transcription activation by NtcA in the absence of consensus NtcA-binding sites in an anabaena heterocyst differentiation gene promoter.

Heterocyst differentiation is orchestrated by the N control transcriptional regulator NtcA and the differentiation-specific factor HetR. In Anabaena sp. strain PCC 7120, the devBCA operon is expressed from two different promoters activated upon N stepdown. The distal devB promoter (transcription start point [TSP] located at position -704) represents a canonical class II NtcA-activated promoter, including a consensus NtcA-binding site centered 39.5 nucleotides upstream from the TSP. Transcription activation from a second TSP (-454) requires NtcA and is impaired in hetR mutants. In a wild-type background, three different DNA fragments, including both or each individual promoter, directed gfp expression localized mainly to proheterocysts and heterocysts. Expression was undetectable in an ntcA background and, for the fragment including the proximal promoter alone, also in a hetR background. In spite of the absence of consensus NtcA-binding sequences between the two TSPs, NtcA was shown to interact with this DNA region, and NtcA and its effector, 2-oxoglutarate, were necessary and sufficient for in vitro transcription from the -454 TSP. No HetR binding to the DNA or in vitro transcription from the proximal devB TSP promoted by HetR alone were detected. However, a moderate positive effect of HetR on NtcA binding to the DNA between the two devB TSPs was observed. The proximal devB promoter appears to represent a suboptimal NtcA-activated promoter for which HetR may act as a coactivator, with the physiological effect of restricting gene activation to conditions of prevalence of high NtcA and HetR levels, such as those taking place during heterocyst differentiation.