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ABSTRACT Streptococcus pneumoniae acquires genes for resistance to antibiotics such as streptomycin (Str) or trimethoprim (Tmp) by recombination via transformation of DNA released by other pneumococci and closely related species. Using naturally transformable pneumococci, including strain D39 serotype 2 (S2) and TIGR4 (S4), we studied whether pneumococcal nasopharyngeal transformation was symmetrical, asymmetrical, or unidirectional. Incubation of S2Tet and S4Str in a bioreactor simulating the human nasopharynx led to the generation of SpnTet/Str recombinants. Double-resistant pneumococci emerged soon after 4 h postinoculation at a recombination frequency (rF) of 2.5 × 10−4 while peaking after 8 h at a rF of 1.1 × 10−3. Acquisition of antibiotic resistance genes by transformation was confirmed by treatment with DNase I. A high-throughput serotyping method demonstrated that all double-resistant pneumococci belonged to one serotype lineage (S2Tet/Str) and therefore that unidirectional transformation had occurred. Neither heterolysis nor availability of DNA for transformation was a factor for unidirectional transformation given that the density of each strain and extracellular DNA (eDNA) released from both strains were similar. Unidirectional transformation occurred regardless of the antibiotic-resistant gene carried by donors or acquired by recipients and regardless of whether competence-stimulating peptide-receptor cross talk was allowed. Moreover, unidirectional transformation occurred when two donor strains (e.g., S4Str and S19FTmp) were incubated together, leading to S19FStr/Tmp but at a rF 3 orders of magnitude lower (4.9 × 10−6). We finally demonstrated that the mechanism leading to unidirectional transformation was due to inhibition of transformation of the donor by the recipient. IMPORTANCE Pneumococcal transformation in the human nasopharynx may lead to the acquisition of antibiotic resistance genes or genes encoding new capsular variants. Antibiotics and vaccines are currently putting pressure on a number of strains, leading to an increase in antibiotic resistance and serotype replacement. These pneumococcal strains are also acquiring virulence traits from vaccine types via transformation. In this study, we recapitulated multiple-strain colonization with strains carrying a resistance marker and selected for those acquiring resistance to two or three antibiotics, such as would occur in the human nasopharynx. Strains acquiring dual and triple resistance originated from one progenitor, demonstrating that transformation was unidirectional. Unidirectional transformation was the result of inhibition of transformation of donor strains. Unidirectional transformation has implications for the understanding of acquisition patterns of resistance determinants or capsule-switching events.

ABSTRACT The Mylodontidae Scelidotheriinae (Mammalia, Xenarthra, Tardigrada) are a diversified clade of South American fossil ground sloths, with a wide geographic distribution, especially in high and middle latitudes. According to the last revision, the Quaternary diversity includes the genera Scelidotherium, Catonyx, and Valgipes. The clade Scelidotheriinae is well represented in the Pleistocene of the Tarija-Padcaya basin, and the first mention of these ground sloths correspond to the middle of the XIX Century. Since then, several species (i.e., Scelidotherium tarijensis, Scelidodon tarijensis, Scelidotherium capellini) have been reported as inhabiting the Tarija-Padcaya basin during the Pleistocene. Despite the abundance of fossil records of Scelidotheriinae in this area, no modern taxonomic revisions are available. In consequence, in this contribution a revision of the remains assigned to Scelidotheriinae from the Tarija-Padcaya basin is accomplished, and some biostratigraphic and geographic implications are discussed. Our results show that one single species (Catonyx tarijensis) can be recognized in the studied area, whereas a supposed smaller one (Scelidotherium patrium) actually corresponds to juvenile specimens of C. tarijensis.

Selection pressures exerted on Staphylococcus aureus by host factors may lead to the emergence of mutants better adapted to the evolving conditions at the infection site. This study was aimed at identifying the changes that occur in S. aureus exposed to the host defense mechanisms during chronic osteomyelitis and evaluating whether these changes affect the virulence of the organism. Genome assessment of two S. aureus isolates collected 13 months apart (HU-85a and HU-85c) from a host with chronic osteomyelitis was made by whole genome sequencing. Agr functionality was assessed by qRT-PCR. Isolates were tested in a rat model of osteomyelitis and the bacterial load (CFU/tibia) and the morphometric osteomyelitic index (OI) were determined. The ability of the isolates to trigger the release of proinflammatory cytokines was determined on macrophages in culture. Persistence of S. aureus within the host resulted in an agrC frameshift mutation that likely led to the observed phenotype. The capacity to cause bone tissue damage and trigger proinflammatory cytokines by macrophages of the agr-deficient, unencapsulated derivative (HU-85c) was decreased when compared with those of the isogenic CP8-capsulated parental strain (HU-85a). By comparison, no significant differences were found in the bacterial load or the OI from rats challenged with isogenic Reynolds strains [CP5, CP8, and non-typeable (NT)], indicating that lack of CP expression alone was not likely responsible for the reduced capacity to cause tissue damage in HU-85c compared with HU-85a. The production of biofilm was significantly increased in the isogenic derivative HU-85c. Lack of agr-dependent factors makes S. aureus less virulent during chronic osteomyelitis and alteration of the agr functionality seems to permit better adaptation of S. aureus to the chronically infected host.

Colares Marta N.; Santiago M. Martínez Alonso; Etile Spegazzini; Marcelo P. Hernández; Vanesa G. Perrotta; María C. Novoa; Ana M. Arambarri. 2017. “Anatomía e histoquímica de los órganos subterráneos de plantas trepadoras medicinales rioplatenses (Ar- gentina)”. Lilloa 54 (2). El objetivo de este estudio fue caracterizar los rizomas y raíces por sus atributos histológico-estructurales y determinar la presencia de compuestos químicos que faciliten la identificación de los taxones de muestras enteras o fragmentadas de los mismos. Se analizó material fresco recolectado en el área de estudio y ejemplares de herbario (LPAG). Para las preparaciones anatómicas se procedió con técnicas usuales para microscopía óptica. Se realizaron reacciones histoquímicas para identificar almidón, mucílagos, lípidos y taninos. Los principales rasgos micrográficos resultaron: las características de las células y número de estratos celulares de la rizodermis y exodermis; el desarrollo de la peridermis; las pecu- liaridades del parénquima cortical y de la estela; el engrosamiento de las paredes celulares de las células corticales adyacentes a la endodermis y de la endodermis; la presencia de reservorios secretores y tipos de cristales. Sobre la base de los datos obtenidos se generaron tablas comparativas con los grupos químicos identificados y construyeron claves dicotómicas de las especies que constituyen una herramienta de valor en el control de calidad botánica.

Este artículo propone la necesidad de realizar una revisión teórica sobre la actual asunción epistemológica que establece a la dicotomía naturaleza-sociedad como piedra angular de una cosmovisión amplia para contextos occidentales. Se rebaten aquellas perspectivas antropológicas que dan por sentado que, en estos espacios, de manera genérica y sin matices, la práctica social y las ideas no se construyen de forma vinculada al medio, cayendo bajo la creencia de que la naturaleza existe ajena a la voluntad humana. Discutiremos el ingenuo esencialismo etnológico que posiciona al naturalismo como modelo central de la cosmovisión socio-europea, el cual es caracterizado por patrones dualistas que han permitido configurar, al mismo tiempo y por contraposición a este, paradigmas monistas de relaciones socioecológicas en otras partes del mundo.

Reseña de Ariel Petruccelli, Ciencia y utopía. En Marx y en la tradición marxista, Buenos Aires: Herramienta, 2016, 287 pgs.

Este artículo ofrece diversos elementos legales, filosóficos y económicos para una teoría general del derecho de propiedad y libertad económica, que permita explicar por qué es un derecho fundamental. En primer lugar, plantea una visión unificada del derecho de propiedad privada y libertad económica, el que debe distinguirse analíticamente de los distintos derechos de propiedad susceptibles de reglamentación y expropiación estatal. En segundo lugar, explica, desde la teoría tomista del derecho natural, en qué sentido este derecho es un derecho natural secundario. En tercer lugar, señala, desde la teoría austríaca del proceso de mercado, cómo la protección del derecho de propiedad privada y libertad económica da lugar a un proceso virtuoso que genera mayor desarrollo, reducción de la pobreza y paz social. Y finalmente, explica también cómo la violación de dicho derecho genera los efectos contrarios: subdesarrollo, pobreza y conflicto social.

Direct Laser Interference Patterning (DLIP) technique has been used to generate a line pattern on the surface of WO3 thin films, due to the interference of two coherent laser beams, modifying its surface morphology and physical properties. Gas sensing devices based on WO3 thin films annealed at 600 °C and nanostructured by DLIP have been fabricated and compared to samples simply annealed at the same temperature. The sensors processed by DLIP present a great enhancement on the response in NO2 atmospheres indicating possible modifications on the composition, aside from the morphological one.

El objetivo del estudio fue comprobar el efecto en el plátano de las capturas masivas de adultos con feromonas y de la aplicación de hongos entomopatógenos sobre Cosmopolites sordidus. La investigación se realizó en el Carmen, Manabí, Ecuador, de diciembre 2013 a octubre 2014 en una parcela de nueva plantación de plátano Barraganete y se valoró el efecto de la eliminación de restos vegetales de las parcelas. El diseño experimental fue al azar con tres repeticiones. En laboratorio se comprobó la infectividad de la cepa de Beauveria bassiana sobre adultos del picudo negro y del picudo café (Metamasius hemipterus) (92,80 y 100% en M. hemipterus frente a 46,70 y 16,20% en C. sordidus). Las capturas de adultos fueron continuas a lo largo del ensayo, con una media de 0,37 adultos/trampa/día. Los datos agronómicos indicaron una diferencia positiva y significativa (análisis de la varianza) de los tratamientos frente al control en el perímetro del pseudotallo (F de 4,982) y en el peso de los racimos entre las parcelas limpias con feromonas y con hongos limpias frente al control (F= 3,994). Al comparar los tratamientos el peso del racimo y la longitud de los dedos fueron significativamente mayores en las parcelas de feromonas frente a las de hongos (F = 4,508). Las capturas de adultos con feromonas no estuvieron condicionadas por la limpieza de las parcelas, aunque esta sí incidió en la altura de las plantas (F= 4,245).

This paper argues that taking the economy seriously in histories of science could not only extend the range of activities studied but also change, often quite radically our understanding of well-known cases and instances about the scientific novelty generation in twentieth-century science. It shows how scientific intellectuals and historians of science have followed the money as a means of critique of particular forms of science, as a critique of particular conceptions of science. It suggests the need to go further, to a much broader implicit definition of what constitutes science, one which implies a criticism of much history of twentieth-century science, for defining it implicitly and inappropriately in very restrictive ways.

Ecología Austral, 24:64-74 (2014) Volcanic eruptions are natural phenomena with the most diverse and varied consequences, and have important effects on both terrestrial and aquatic environments. On June 4th, 2011 the volcanic Puyehue Cordón-Caulle complex (2.236 MASL, 40º 32´ S-72º 2´ W, Chile) erupted explosively ejecting on the first day, 950 million metric tons of ashes into the atmosphere. Due to predominant westerly winds, 24 million hectares of Argentinian Patagonia were covered by the ashfall. We studied three streams in northwestern Patagonia in order to explore the ash fall impact and possible recovery processes in water quality and macroinvertebrate communities. We selected three streams representing maximum, intermediate and minimum ash deposition levels. For each stream, we selected two sampling sites to measure pH, conductivity, total dissolved solids (TDS), turbidity (NTU) and to take three macroinvertebrate samples during summer 2012 and 2013. After the eruption of the Puyehue-Cordón Caulle complex, substantial environmental changes were observed in association with the large amount of ash ejected by the volcano and deposited on the nearest areas. Low benthic fauna densities, as well as low values of Ephemeroptera, Plecoptera and Trichoptera (EPT) and Biotic Monitoring Patagonian Streams (BMPS) indexes, reflected changes in water quality due to ash fall, mainly in the two streams closer to the volcano. After eighteen months, the streams had not reached the density, taxa composition and structure of trophic webs comparable to other streams previously studied in the region. The exploratory analysis suggests that the main impact was a consequence of ash fall in terms of the amount and particle size proportions.

Se analizaron datos de producción de biomasa de un pastizal bajo distintas estructuras de dosel de Pinus taeda L. en un ensayo localizado en Sto. Tomé, Corrientes, Argentina, para establecer relaciones con dichas estructuras del rodal y el ambiente. Debido al efecto de la canopia el estrato herbáceo fue subdivido en tres estratos, con predominancia de Paspalum paniculatum y con o sin predominancia de Axonopus compresuss. Modelos vinculando la producción de biomasa forrajera anual y una variable independiente que relaciona la precipitación anual y el producto de la longitud de copa verde con el volumen cilindrométrico promedio, fueron ajustados para los tres estratos. No se encontraron diferencias entre los modelos con presencia de Axonopus compresuss. Por ese motivo se ajustó un modelo único, para esos dos estratos, con el cual se obtuvo un R2 de 68 %. Ajustados los datos por año de observación pudo verificarse la existencia de niveles de producción de biomasa forrajera en función de las precipitaciones. Fue posible comprobar que para longitudes de copa similares, la biomasa forrajera disminuye sensiblemente en los años en que las precipitaciones son inferiores a las normales de la región. Este hecho refleja la competencia por agua entre el estrato arbóreo y el herbáceo

Resumen Objetivos. Determinar las características de la adaptación de postes no metálicos de diferentes diseños a las paredes de preparaciones realizadas mediante un sistema de tratamiento endodóntico mecanizado y otro manual (con acceso facilitado). Materiales y métodos. Se analizó la superficie resultante entre la generada por la preparación endodóntica (sumada al pasaje de los instrumentos calibradores) y aquella ocupada por la sección del poste empleado. Para ello se seleccionaron treinta y seis piezas unirradiculares inferiores. Dieciocho fueron instrumentadas en forma mecanizada con la técnica crown down con el sistema ProFile y las restantes, con una técnica mixta: primero generando un acceso facilitado mediante el uso de fresas de Gattes–Glidden y posteriormente empleando limas K en forma manual. Se obturaron con conos de gutapercha y luego se prepararon con las fresas piloto correspondientes a los sistemas de postes Parapost Fiber White, Postec Plus FRC y Cosmopost. Se fijaron a las piezas de manera adhesiva y las muestras fueron incluidas en resina epoxi para ser cortadas a cuatro niveles. Cada espécimen fue visualizado bajo estero microscopía y, con un software específico, se realizaron las mediciones de la adaptación de los postes a las preparaciones. Mediante análisis de variancia multifactorial se evaluó la significación estadística (P

Staphylococcus aureus nasal carriage is a risk factor for individuals suffering from trauma, surgical procedures, invasive devices, and/or decreased immunity. Recently, we demonstrated that artificial nasal colonization with an attenuated S. aureus mutant reduced by bacterial interference with the colonization of pathogenic strains of S. aureus. This could be an optional tool to diminish the rate of S. aureus infections in hospitalized patients. The aim of this study was to construct a safe ΔaroA mutant of S. aureus and to discriminate it from nasal colonizing and osteomyelitis S. aureus isolates by SmaI pulsed-field gel electrophoresis (PFGE) typing. The ΔaroA mutant, named RD17, exhibited an LD50 (3.2 × 106 colony-forming unit (CFU)) significantly higher than that of the parental strain (2.2 × 103 CFU). The colony number of the RD17 mutants recovered from nares of leukopenic mice was similar to that observed in the animals of the control group. Therefore, the ΔaroA mutant was demonstrated to be safe due to maintaining low growth levels in the nares regardless of immune status of the animals. PFGE typing allowed the unequivocal identification of the S. aureus and differentiation of aroA mutants in nasal colonizing and osteomyelitis isolates. This information could be important to discriminate endogenous infections from laboratory strains of S. aureus.