67 research outputs found

    Interactions of PatA with the divisome during heterocyst differentiation in anabaena

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    The Anabaena organismic unit is a filament of communicating cells. Under conditions of nitrogen scarcity, some cells along the filament differentiate into heterocysts, which are specialized in the fixation of atmospheric N2 and provide the vegetative cells with N2 fixation products. At a certain stage, the differentiation process becomes irreversible, so that even when nitrogen is replenished, no return to the vegetative cell state takes place, possibly as a consequence of loss of cell division capacity. Upon N-stepdown, midcell FtsZ-rings were detected in vegetative cells, but not in differentiating cells, and this was also the case for ZipN, an essential protein that participates in FtsZ tethering to the cytoplasmic membrane and divisome organization. Later, expression of ftsZ was arrested in mature heterocysts. PatA is a protein required for the differentiation of intercalary heterocysts in Anabaena. The expression level of the patA gene was increased in differentiating cells, and a mutant strain lacking PatA exhibited enhanced FtsZ-rings. PatA was capable of direct interactions with ZipN and SepF, another essential component of the Anabaena Z-ring. Thus, PatA appears to promote inhibition of cell division in the differentiating cells, allowing progress of the differentiation process. PatA, which in mature heterocysts was detected at the cell poles, could interact also with SepJ, a protein involved in production of the septal junctions that provide cell-cell adhesion and intercellular communication in the filament, hinting at a further role of PatA in the formation or stability of the intercellular structures that are at the basis of the multicellular character of Anabaena

    SepT, a novel protein specific to multicellular cyanobacteria, influences peptidoglycan growth and septal nanopore formation in Anabaena sp. PCC 7120

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    Anabaena sp. PCC 7120 grows by forming filaments of communicating cells and is considered a paradigm of bacterial multicellularity. Molecular exchanges between contiguous cells in the filament take place through multiprotein channels that traverse the septal peptidoglycan through nanopores connecting their cytoplasms. Besides, the septal-junction complexes contribute to strengthen the filament. In search for proteins with coiled-coil domains that could provide for cytoskeletal functions in Anabaena, we identified SepT (All2460). SepT is characteristic of the phylogenetic clade of filamentous cyanobacteria with the ability to undergo cell differentiation. SepT-GFP fusions indicate that the protein is located at the cell periphery and, conspicuously, in the intercellular septa. During cell division, the protein is found at midcell resembling the position of the divisome. The bacterial adenylate cyclase two-hybrid analysis shows SepT interactions with itself and putative elongasome (MreB, RodA), divisome (FtsW, SepF, ZipN), and septal-junction (SepJ)-related proteins. Thus, SepT appears to rely on the divisome for localization at mature intercellular septa to form part of intercellular protein complexes. Two independently obtained mutants lacking SepT showed alterations in cell size and impaired septal and peripheral peptidoglycan incorporation during cell growth and division. Notably, both mutants showed conspicuous alterations in the array of nanopores present in the intercellular peptidoglycan disks, including aberrant nanopore morphology, number, and distribution. SepT appears, therefore, to be involved in the control of peptidoglycan growth and the formation of cell-cell communication structures that are at the basis of the multicellular character of this group of cyanobacteria

    5to. Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad. Memoria académica

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    El V Congreso Internacional de Ciencia, TecnologĂ­a e InnovaciĂłn para la Sociedad, CITIS 2019, realizado del 6 al 8 de febrero de 2019 y organizado por la Universidad PolitĂ©cnica Salesiana, ofreciĂł a la comunidad acadĂ©mica nacional e internacional una plataforma de comunicaciĂłn unificada, dirigida a cubrir los problemas teĂłricos y prĂĄcticos de mayor impacto en la sociedad moderna desde la ingenierĂ­a. En esta ediciĂłn, dedicada a los 25 años de vida de la UPS, los ejes temĂĄticos estuvieron relacionados con la aplicaciĂłn de la ciencia, el desarrollo tecnolĂłgico y la innovaciĂłn en cinco pilares fundamentales de nuestra sociedad: la industria, la movilidad, la sostenibilidad ambiental, la informaciĂłn y las telecomunicaciones. El comitĂ© cientĂ­fico estuvo conformado formado por 48 investigadores procedentes de diez paĂ­ses: España, Reino Unido, Italia, BĂ©lgica, MĂ©xico, Venezuela, Colombia, Brasil, Estados Unidos y Ecuador. Fueron recibidas un centenar de contribuciones, de las cuales 39 fueron aprobadas en forma de ponencias y 15 en formato poster. Estas contribuciones fueron presentadas de forma oral ante toda la comunidad acadĂ©mica que se dio cita en el Congreso, quienes desde el aula magna, el auditorio y la sala de usos mĂșltiples de la Universidad PolitĂ©cnica Salesiana, cumplieron respetuosamente la responsabilidad de representar a toda la sociedad en la revisiĂłn, aceptaciĂłn y validaciĂłn del conocimiento nuevo que fue presentado en cada exposiciĂłn por los investigadores. Paralelo a las sesiones tĂ©cnicas, el Congreso contĂł con espacios de presentaciĂłn de posters cientĂ­ficos y cinco workshops en temĂĄticas de vanguardia que cautivaron la atenciĂłn de nuestros docentes y estudiantes. TambiĂ©n en el marco del evento se impartieron un total de ocho conferencias magistrales en temas tan actuales como la gestiĂłn del conocimiento en la universidad-ecosistema, los retos y oportunidades de la industria 4.0, los avances de la investigaciĂłn bĂĄsica y aplicada en mecatrĂłnica para el estudio de robots de nueva generaciĂłn, la optimizaciĂłn en ingenierĂ­a con tĂ©cnicas multi-objetivo, el desarrollo de las redes avanzadas en LatinoamĂ©rica y los mundos, la contaminaciĂłn del aire debido al trĂĄnsito vehicular, el radĂłn y los riesgos que representa este gas radiactivo para la salud humana, entre otros

    Métodos y técnicas de monitoreo y predicción temprana en los escenarios de riesgos socionaturales

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    Esta obra concentra los mĂ©todos y las tĂ©cnicas fundamentales para el seguimiento y monitoreo de las dinĂĄmicas de los escenarios de riesgos socionaturales (geolĂłgicos e hidrometeorolĂłgicos) y tiene como objetivo general orientar, apoyar y acompañar a los directivos y operativos de protecciĂłn civil en aterrizar las acciones y polĂ­ticas pĂșblicas enfocadas a la gestiĂłn del riesgo local de desastre

    Ciencia OdontolĂłgica 2.0

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    Libro que muestra avances de la Investigación Odontológica en MéxicoEs para los integrantes de la Red de Investigación en Estomatología (RIE) una enorme alegría presentar el segundo de una serie de 6 libros sobre casos clínicos, revisiones de la literatura e investigaciones. La RIE estå integrada por cuerpos académicos de la UAEH, UAEM, UAC y UdeG

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

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    Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    Regulation of cell size and cell division in the filamentous cyanobacterium Anabaena: a paradigm of bacterial multicellularity

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    La forma y el tamaño celular son caracteres codificados en el genoma bacteriano y, por tanto, hereditarios. En cada especie bacteriana, estos rasgos son constantes, aunque pueden sufrir modificaciones a lo largo del ciclo celular o bajo ciertas condiciones ambientales. En bacterias, la forma celular es crucial para la interacciĂłn con el medio ambiente y, como tal, un carĂĄcter seleccionado evolutivamente. La pared celular de peptidoglicano (PG) que rodea a las cĂ©lulas bacterianas es la estructura que determina su morfologĂ­a. En bacterias con morfologĂ­a bacilar, la sĂ­ntesis de PG se lleva a cabo por dos complejos enzimĂĄticos conocidos como el elongasoma y el divisoma, que permiten respectivamente el crecimiento y la divisiĂłn celular. Estos procesos se han caracterizado, sobre todo, en bacterias unicelulares. Sin embargo, en bacterias multicelulares la informaciĂłn disponible acerca de la sĂ­ntesis de PG es escasa. En este trabajo se ha estudiado el efecto de algunas condiciones ambientales en la morfologĂ­a y el tamaño celular, asĂ­ como en la longitud de los filamentos de Anabaena sp. PCC 7120, un modelo paradigmĂĄtico de multicelularidad bacteriana. Esta cianobacteria crece como filamentos uniseriados en los cuales cada cĂ©lula se comunica con las cĂ©lulas adyacentes mediante unas estructuras proteicas llamadas septal junctions. Las caracterĂ­sticas peculiares de su envuelta celular, incluyendo la presencia de una membrana externa que alberga a todas las cĂ©lulas del filamento y un periplasma continuo, que alberga un sĂĄculo de PG tambiĂ©n continuo, hacen de Anabaena un modelo atractivo para el estudio de la sĂ­ntesis del PG. AdemĂĄs, en ausencia de compuestos nitrogenados, algunas cĂ©lulas del filamento de Anabaena pueden diferenciarse en cĂ©lulas especializadas en la fijaciĂłn del nitrĂłgeno atmosfĂ©rico, llamadas heterocistos, que presentan una morfologĂ­a distintiva y unas caracterĂ­sticas peculiares en su pared celular. Los resultados de este trabajo han mostrado que la fuente de nitrĂłgeno y de carbono, asĂ­ como las distintas fases del ciclo celular, impactan tanto en la forma y el tamaño de las cĂ©lulas como en el nĂșmero de cĂ©lulas que componen el filamento. Al igual que sucede en las bacterias unicelulares, Anabaena muestra sĂ­ntesis de PG lateral y divisional y, ademĂĄs, una sĂ­ntesis permanente en los septos intercelulares que no se ha observado en otras estirpes bacterianas. Por otro lado, este trabajo ha desvelado que, ademĂĄs de su funciĂłn en la sĂ­ntesis de PG perifĂ©rico, los factores Mre del elongasoma tienen un papel adicional en el correcto posicionamiento del divisoma, asĂ­ como en la diferenciaciĂłn de la pared celular de los heterocistos. TambiĂ©n, estos estudios han revelado un papel del divisoma en la sĂ­ntesis perifĂ©rica de PG que se requiere para el alargamiento de las cĂ©lulas. En resumen, este trabajo ha puesto de manifiesto la influencia de las condiciones ambientales en la morfologĂ­a de Anabaena, su peculiar patrĂłn de crecimiento de PG y el papel de las proteĂ­nas Mre en la elongaciĂłn celular, la divisiĂłn y la diferenciaciĂłn de heterocistos

    The Inorganic Nutrient Regime and the mre Genes Regulate Cell and Filament Size and Morphology in the Phototrophic Multicellular Bacterium Anabaena

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    The model cyanobacterium Anabaena sp. PCC 7120 exhibits a phototrophic metabolism relying on oxygenic photosynthesis and a complex morphology. The organismic unit is a filament of communicated cells that may include cells specialized in different nutritional tasks, thus representing a paradigm of multicellular bacteria. In Anabaena, the inorganic carbon and nitrogen regime influenced not only growth, but also cell size, cell shape, and filament length, which also varied through the growth cycle. When using combined nitrogen, especially with abundant carbon, cells enlarged and elongated during active growth. When fixing N2, which imposed lower growth rates, shorter and smaller cells were maintained. In Anabaena, gene homologs to mreB, mreC, and mreD form an operon that was expressed at higher levels during the phase of fastest growth. In an ntcA mutant, mre transcript levels were higher than in the wild type and, consistently, cells were longer. Negative regulation by NtcA can explain that Anabaena cells were longer in the presence of combined nitrogen than in diazotrophic cultures, in which the levels of NtcA are higher. mreB, mreC, and mreD mutants could grow with combined nitrogen, but only the latter mutant could grow diazotrophically. Cells were always larger and shorter than wild-type cells, and their orientation in the filament was inverted. Consistent with increased peptidoglycan width and incorporation in the intercellular septa, filaments were longer in the mutants, suggesting a role for MreB, MreC, and MreD in the construction of septal peptidoglycan that could affect intercellular communication required for diazotrophic growth.Peer reviewe

    The Role of MreB, MreC and MreD in the Morphology of the Diazotrophic Filament of Anabaena sp. PCC 7120

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    The cyanobacterium Anabaena sp. PCC 7120 forms filaments of communicating cells. Under conditions of nitrogen scarcity, some cells differentiate into heterocysts, allowing the oxygen-sensitive N2-reduction system to be expressed and operated in oxic environments. The key to diazotrophic growth is the exchange of molecules with nutritional and signaling functions between the two types of cells of the filament. During heterocyst differentiation, the peptidoglycan sacculus grows to allow cell enlargement, and the intercellular septa are rebuilt to narrow the contact surface with neighboring cells and to hold specific transport systems, including the septal junction complexes for intercellular molecular transfer, which traverse the periplasm between heterocysts and neighboring vegetative cells through peptidoglycan nanopores. Here we have followed the spatiotemporal pattern of peptidoglycan incorporation during heterocyst differentiation by Van-FL labeling and the localization and role of proteins MreB, MreC and MreD. We observed strong transitory incorporation of peptidoglycan in the periphery and septa of proheterocysts and a maintained focal activity in the center of mature septa. During differentiation, MreB, MreC and MreD localized throughout the cell periphery and at the cell poles. In mreB, mreC or mreD mutants, instances of strongly increased peripheral and septal peptidoglycan incorporation were detected, as were also heterocysts with aberrant polar morphology, even producing filament breakage, frequently lacking the septal protein SepJ. These results suggest a role of Mre proteins in the regulation of peptidoglycan growth and the formation of the heterocyst neck during differentiation, as well as in the maintenance of polar structures for intercellular communication in the mature heterocyst. Finally, as previously observed in filaments growing with combined nitrogen, in the vegetative cells of diazotrophic filaments, the lack of MreB, MreC or MreD led to altered localization of septal peptidoglycan-growth bands reproducing an altered localization of FtsZ and ZipN rings during cell division
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