Involvement of the histone-like nucleoid structuring protein (H-ns) in acinetobacter baumannii’s natural transformation

Most Acinetobacter baumannii strains are naturally competent. Although some information is available about factors that enhance or reduce the frequency of the transformation of this bacterium, the regulatory elements and mechanisms are barely understood. In this article, we describe studies on the role of the histone-like nucleoid structuring protein, H-NS, in the regulation of the expression of genes related to natural competency and the ability to uptake foreign DNA. The expression levels of the natural transformation-related genes pilA, pilT, pilQ, comEA, comEC, comF, and drpA significantly increased in a ∆hns derivative of A. baumannii A118. The complementation of the mutant with a recombinant plasmid harboring hns restored the expression levels of six of these genes (pilT remained expressed at high levels) to those of the wild-type strain. The transformation frequency of the A. baumannii A118 ∆hns strain was significantly higher than that of the wild-type. Similar, albeit not identical, there were consequences when hns was deleted from the hypervirulent A. baumannii AB5075 strain. In the AB5075 complemented strain, the reduction in gene expression in a few cases was not so pronounced that it reached wild-type levels, and the expression of comEA was enhanced further. In conclusion, the expression of all seven transformation-related genes was enhanced after deleting hns in A. baumannii A118 and AB5075, and these modifications were accompanied by an increase in the cells’ transformability. The results highlight a role of H-NS in A. baumannii’s natural competence.Fil: Le, Casin. California State University; Estados UnidosFil: Pimentel, Camila. California State University; Estados UnidosFil: Tuttobene, Marisel Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Subils, Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Procesos Biotecnológicos y Químicos Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Procesos Biotecnológicos y Químicos Rosario; ArgentinaFil: Escalante, Jenny. California State University; Estados UnidosFil: Nishimura, Brent. California State University; Estados UnidosFil: Arriaga, Susana. California State University; Estados UnidosFil: Rodgers, Deja. California State University; Estados UnidosFil: Bonomo, Robert A.. Center for Antimicrobial Resistance and Epidemiology; Estados Unidos. Veterans Affairs Medical Center; Estados Unidos. Case Western Reserve University School of Medicine; Estados UnidosFil: Sieira, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Tolmasky, Marcelo E.. California State University; Estados UnidosFil: Ramírez, María Soledad. California State University; Estados Unido

México y Jalisco en la coyuntura : primer semestre de 1998

Análisis de coyuntura sobre los principales sucesos del primer semestre de 1997 en Jalisco, a nivel político, económico y social: la situación en el estado de los tres principales partidos políticos (PAN, PRI y PRD), la cuestión laboral, los derechos humanos y el problema de abastecimiento de agua en la zona metropolitana de Guadalajara.ITESO, A.C

Broadband tuning of a long-cavity all-fiber mode locked Thulium-doped fiber laser using an acousto-optic bandpass filter

A long-cavity passively mode-locked thulium-doped all-fiber laser is reported incorporating a tapered acousto-optic tunable bandpass filter (AOTBF). The operation of the AOTBF relies on the intermodal coupling between core and cladding modes when a flexural acoustic wave propagates along an 80-microm tapered fiber. The filter works in transmission and exhibits a 3-dB bandwidth of 9.02 nm with an insertion loss of 3.4 dB. The laser supports ultrashort pulse generation at a low repetition rate of 784.93 kHz. Optical pulses with 2.43 nm of optical bandwidth and 2.1 ps pulse duration were obtained in a broad tuning range from 1824.77 to 1905.16 nm

The Antiquity and Evolutionary History of Social Behavior in Bees

A long-standing controversy in bee social evolution concerns whether highly eusocial behavior has evolved once or twice within the corbiculate Apidae. Corbiculate bees include the highly eusocial honey bees and stingless bees, the primitively eusocial bumble bees, and the predominantly solitary or communal orchid bees. Here we use a model-based approach to reconstruct the evolutionary history of eusociality and date the antiquity of eusocial behavior in apid bees, using a recent molecular phylogeny of the Apidae. We conclude that eusociality evolved once in the common ancestor of the corbiculate Apidae, advanced eusociality evolved independently in the honey and stingless bees, and that eusociality was lost in the orchid bees. Fossil-calibrated divergence time estimates reveal that eusociality first evolved at least 87 Mya (78 to 95 Mya) in the corbiculates, much earlier than in other groups of bees with less complex social behavior. These results provide a robust new evolutionary framework for studies of the organization and genetic basis of social behavior in honey bees and their relatives

Diseño para el desarrollo sustentable y la habitabilidad segura e incluyente

Este libro se divide en dos partes que permiten permear en el campo de la enseñanza del diseño; la primera se enfoca en temáticas que se desprenden del diseño en la educación para la sustentabilidad; en la segunda, se identifican las tendencias del diseño como un modo de verlo y sentirlo: va desde el diseño emocional hacia uno de conservación, reúso y reparación de objetos para reducir el consumo de recursos materiales

Palaeocene–Eocene miospores from the Chicxulub impact crater, Mexico. Part 1:spores and gymnosperm pollen

In the summer of 2016, the International Ocean Discovery Program (IODP) Expedition 364 coredthrough the post-impact strata of the end-Cretaceous Chicxulub impact crater, Mexico. Core sampleswere collected from the post-impact successions for terrestrial palynological analysis, yielding a rareDanian to Ypresian high-resolution palynological assemblage. This record constitutes one of the firstPalaeocene and Ypresian palynological assemblages from Central America or Mexico, representing amore coastal lowland palaeoenvironment than previous studies from mainland Mexico. Although theabundance of pollen and spores is very low in the Palaeocene carbonates, abundance increases in themore organic-rich shale layers representing the Palaeocene–Eocene Thermal Maximum (PETM) andlater Ypresian. The spores and gymnosperm pollen identified from IODP 364, although rare comparedto the angiosperm pollen, are a diverse mix of cosmopolitan taxa, as well as some characteristic of fossilCentral American assemblages (e.g. Selaginellaceae), and others previously identified from thePaleogene northern Gulf of Mexico coastal plain. The assemblage generally indicates the presence ofnearby moist to seasonally dry lowland tropical forest, with some taxa suggestive of higher elevationforests. Ephedroid pollen grains may be indicative of the presence of more arid conditions

OPTICAL FEEDBACK INTERFEROMETRY: FROM BASICS TO APPLICATIONS OF LASER FLOWMETRY

International audienceOptical feedback interferometry (OFI) is a contactless technique that is employed for measuring parameters related to object's motion. The light emitted by a laser is backreflected or scattered from a moving object and a small portion of the scattered waves re-enters the laser cavity and impacts the laser's emission properties. We review the theoretical basics of optical feedback interferometry and explain the physical principles in the frame of laser Doppler flowmetry. We present a model derived from the Lang and Kobayashi rate equations to show the particular features of the optical feedback signal in temporal and frequency domain. In addition, we present experimental measurements relative to the detection of flowing particles in a microchannel, the measurement of unsteady flows and the quantification of blood perfusion in skin, which demonstrate the potential use of OFI sensors in the assessment of fluidic systems of interest in chemical and biomedical engineering.La interferometría de retroinyeccí onópticaon´onóptica (IRO) constituye una t ´ ecnica de no contacto utilizada para la medicí on de parámetrospar´parámetros del movimiento. La luz emitida por un l ´ aser es esparcida por un objeto en movimiento y una pequeñapeque˜pequeña parte de las ondas producto de esa dispersí on entran en la cavidad del l ´ aser, impactando sus propiedades espectrales. Se presenta una revisí on de las bases té oricas del efecto de la retroinyeccí onópticaon´onóptica y se exponen sus principios físicos en el marco de la flujometría. Se presenta un modelo derivado de las ecuaciones de Lang y Kobayashi para mostrar las características principales de la señalse˜señal de retroinyeccí onóptica on´onóptica en dominio temporal y frecuencial. Adicionalmente, se presentan resultados experimentales relativos a la medicí on de partículas fluyendo dentro de un microcanal, la medicí on de flujos no estacionarios y la cuantificací on de la perfusí on sanguínea en la piel, los cuales demuestran los usos potenciales de los sensores IRO para el análisisan´análisis de sistemas fluídicos de interésinter´interés para la ingeniería química y biomédicabiom´biomédica

Palynological Evidence for Middle Miocene Vegetation in the Tehuacán Formation of Puebla, Mexico

Palynological assemblages from the Tehuacán Formation (TF), geochronologically dated as Middle Miocene (15.6 ± 0.4 Ma), provide evidence of a highly diverse flora that, at the generic level, is similar to the extant flora in the Tehuacán Valley. We propose that, during Miocene times, plant communities may have been formed of similar botanical elements to those seen today in the region, with some taxa adapted to semiarid conditions. While major temperate floristic elements of Pinus, Quercus, Juniperus, cloud forest and mexical vegetation can be recognized, components of tropical deciduous forests, such as Burseraceae, Leguminosae and Cactaceae, are also present, indicating semiarid conditions. Semiarid local conditions are also inferred from the geological record, consisting of lacustrine and alluvial fan deposits, which contain abundant evaporites beds. This lithology was formed under high evaporation and moderate precipitation conditions, as usually occurs in small basins fed by a seasonal input of water in semiarid environments. Important differences in the vegetation from the TF palynoflora as compared to older associations from south-central Mexico can be inferred, such as an increase in the diversity of semiarid taxa, belonging to Leguminosae and Burseraceae, and the oldest abundant occurrence of the Cactaceae.Fil: Ramírez Arriaga, E.. Universidad Nacional Autónoma de México. Instituto de Geología; MéxicoFil: Pramparo, Mercedes Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Nieto Samaniego, A. F.. Universidad Nacional Autónoma de México. Centro de Geociencias; MéxicoFil: Martínez Hernández, E.. Universidad Nacional Autónoma de México. Instituto de Geología; MéxicoFil: Valiente Banuet, A.. Instituto de Ecología; México. Universidad Nacional Autónoma de México; MéxicoFil: Macías Romo, C.. Universidad Nacional Autónoma de México. Instituto de Geología; MéxicoFil: Dávalos Álvarez, O. G.. Universidad Nacional Autónoma de México. Centro de Geociencias; Méxic

Human Serum Proteins and Susceptibility of Acinetobacter baumannii to Cefiderocol: Role of Iron Transport

Cefiderocol, a recently introduced antibiotic, has a chemical structure that includes a cephalosporin that targets cell wall synthesis and a chlorocatechol siderophore moiety that facilitates cell penetration by active iron transporters. Analysis of the effect that human serum, human serum albumin, and human pleural fluid had on growing Acinetobacter baumannii showed that genes related to iron uptake were down-regulated. At the same time, β-lactamase genes were expressed at higher levels. The minimum inhibitory concentrations of this antimicrobial in A. baumannii cells growing in the presence of human serum, human serum albumin, or human pleural fluid were higher than those measured when these fluids were absent from the culture medium. These results correlate with increased expression levels of β-lactamase genes and the down-regulation of iron uptake-related genes in cultures containing human serum, human serum albumin, or human pleural fluid. These modifications in gene expression could explain the less-than-ideal clinical response observed in patients with pulmonary or bloodstream A. baumannii infections. The exposure of the infecting cells to the host’s fluids could cause reduced cefiderocol transport capabilities and increased resistance to β-lactams. The regulation of genes that could impact the A. baumannii susceptibility to cefiderocol, or other antibacterials, is an understudied phenomenon that merits further investigation.Fil: Le, Casin. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.Fil: Pimentel, Camila. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.Fil: Pasteran, Fernando. National/Regional Reference Laboratory for Antimicrobial Resistance. Instituto Nacional de Enfermedades Infecciosas. Servicio Antimicrobianos; Argentina.Fil: Tuttobene, Marisel Romina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Biología Molecular; Argentina.Fil: Tuttobene, Marisel Romina. Instituto de Biología Molecular y Celular de Rosario (IBR); Argentina.Fil: Subils, Tomás. Instituto de Procesos Biotecnológicos y Químicos de Rosario; Argentina.Fil: Escalante, Jenny. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.Fil: Nishimura, Brent. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.Fil: Arriaga, Susana. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.Fil: Carranza, Aimee. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.Fil: Mezcord, Vyanka. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.Fil: Vila, Alejandro J. Instituto de Biología Molecular y Celular de Rosario; Argentina.Fil: Vila, Alejandro J. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Área Biofísica; Argentina.Fil: Corso, Alejandra. National/Regional Reference Laboratory for Antimicrobial Resistance. Instituto Nacional de Enfermedades Infecciosas. Servicio Antimicrobianos; Argentina.Fil: Actis, Luis A. Miami University. Department of Microbiology; United Kingdom.Fil: Tolmasky, Marcelo E. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States.Fil: Bonomo, Robert A. Case Western Reserve University. School of Medicine. Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics; United States.Fil: Bonomo, Robert A. Research Service and GRECC. Louis Stokes Cleveland Department of Veterans Affairs Medical Center; United States.Fil: Bonomo, Robert A. CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES); United States.Fil: Ramírez, María Soledad. California State University Fullerton. College of Natural Sciences and Mathematics. Department of Biological Science. Center for Applied Biotechnology Studies; United States