Community of thermoacidophilic and arsenic resistant microorganisms isolated from a deep profile of mine heaps

"Soluble arsenic (As) in acidic feed solution may inhibit the copper (Cu) bioleaching process within mine heaps. To clarify the effect of soluble arsenic on the live biomass and bioxidative activity in heaps, toxicological assays were performed using a synthetic feed solution given by a mine company. The microorganisms had previously been isolated from two heap samples at up to 66 m depth, and cultured using specific media for chemolithotrophic acidophiles (pH 1-2) and moderate thermophiles (48 degrees C), for arsenic tolerance assay. The four media with the highest biomass were selected to assay As-resistance; one culture (Q63h) was chosen to assay biooxidative activity, using a heap sample that contained chalcopyrite and covellite. We found that 0.5 g/L of As does not affect living biomass or biooxidative activity on Cu sulfides, but it dissolves Cu, while As precipitates as arsenic acid (H3AsO4 center dot 1/2H(2)O). The arsenic tolerant community, as identified by 16S rDNA gene sequence analysis, was composed of three main metabolic groups: chemolithotrophs (Leptospirillum, Sulfobacillus); chemolithoheterotrophs and organoheterotrophs as Acidovorax temperans, Pseudomonas alcaligenes, P. mendocina and Sphingomonas spp. Leptospirillum spp. and S. thermosulfidooxidans were the dominant taxa in the Q63-66 cultures from the deepest sample of the oldest, highest-temperature heap. The results indicated arsenic resistance in the microbial community, therefore specific primers were used to amplify ars (arsenic resistance system), aio (arsenite oxidase), or arr (arsenate respiratory reduction) genes from total sample DNA. Presence of arsB genes in S. thermosulfidooxidans in the Q63-66 cultures permits H3AsO4-As(V) detoxification and strengthens the community's response to As.

Usos de los recursos digitales y las tic en el proceso educativo de nivel superior

Las TIC han generado nuevos escenarios comunicativos y de interacción. Las tendencias globales promueven la incorporación de estos recursos, Internet y la Web, redimensionan los procesos de la educación, propiciando la generación e intercambio del conocimiento. Ante esta perspectiva se han implementado políticas públicas en beneficio de la educación y la incorporación de estas tecnologías en esta área. En la República Mexicana mediante el Programa Sectorial de educación 2013-2018, establece como prioridades educativas asegurar la calidad de la educación, fortalecer la calidad y permanencia de la educación, asegurar mayor cobertura

Recent evidences of Domvs in Ilipa (Alcalá del Río, Seville): Old mosaics in new urban context

En el presente trabajo se presentan los resultados preliminares de una intervención arqueológica preventiva llevada a cabo muy recientemente en el área urbana de Alcalá del Río, antigua Ilipa. La excavación, a pesar de ser limitada en extensión, ha permitido contextualizar los ambientes domésticos propios de un mosaico conocido ya de antiguo. De esta forma, lo que era un dato aislado cobra así sentido, sumándose al actual y creciente conocimiento de la ciudad romana, proporcionando nuevos y valiosos datos sobre aspectos urbanísticos, tecnológicos, constructivos o socioeconómicos, entre otros.Preliminary results of a preventive archaeological intervention carried out recently in the urban area of Alcalá del Rio, former Ilipa, are presented in this paper. The excavation, despite being of limited surface, has allowed characterizing the domestic contexts related to a mosaic that was already known more than two decades ago. In this way an isolate item starts to be meaningful and the new information increases the current and growing knowledge of the Roman city, providing valuable new data on urban, technological, constructive or socioeconomic aspects, among others

Densidad y tallas de Plicopurpura patula pansa relacionadas con el sustrato y oleaje en la costa rocosa de Guerrero, México

The relationship was analyzed between the density and sizes average of the snail Plicopurpura patula pansa with the shock wave and substratum type in nine rocky beaches of Guerrero State, Mexico. The relative density was 4.7 snails/m2 and the size average 21.7 mm. The correlation between density and sizes average it was negative. The one-way analysis of variance found significant differences in the sizes average of the snail among the study places. The multiple comparisons established three groups that were integrated for beaches that presented similarity in certain characteristics of the substratum and shock wave action. A hierarchical analysis formed eight groups. The most similar groups were integrated by beaches that presented similar characteristics in the substratum type, but not in shock wave action. The density obtained by this study is the biggest to those registered in other States of the Mexican Pacific. The substratum type presented the greater association with densities and sizes average of P. p pansa.Se analizó la relación entre la densidad y tallas promedio del caracol Plicopurpura patula pansa con la exposición al oleaje y tipo de sustrato en nueve playas rocosas del Estado de Guerrero, México. La densidad relativa fue 4.7 caracoles/m2 y la talla promedio 21.7 mm. La correlación entre densidad y tallas promedio fue negativa. El análisis de varianza encontró diferencias significativas en las tallas promedio del caracol entre los sitios de estudio. La comparación múltiple de medias estableció tres grupos, que se integraron por playas que presentaron similitud en ciertas características del sustrato y exposición al oleaje. El análisis jerárquico formó ocho grupos, dentro de los cuales, las playas que integraron los grupos con mayor similitud en cuanto a densidad y tallas promedio de los organismos, presentaron características afines en el tipo de sustrato, no así en cuanto a la intensidad del oleaje. La densidad obtenida en este estudio es superior a las registradas en otros Estados del Pacífico Mexicano. El tipo de sustrato presentó la mayor asociación con densidades y tallas promedio de P. p pans

Composition of Prosobranchia-Pulmonata (Mollusca: Gastropoda) in rocky intertidal zone in the Marine Priority Region 32, Guerrero, Mexico

Resumen.- El objetivo de esta investigación fue la descripción de la taxocenosis de las subclases Prosobranchia y Pulmonata (clase Gastropoda), asociados a la zona intermareal rocosa de la Región Marina Prioritaria 32, Guerrero, México. Basada en la riqueza de especies, la composición de la comunidad a partir de la representación de las familias, se evaluó la abundancia, distribución geográfica de las especies, se estimó los estadísticos descriptivos de las tallas (en largo) de las poblaciones y la diversidad. El muestreo se llevó a cabo en 7 sitios, la unidad de muestreo fue de 1 m-2 y el área de muestreo de 10 m-2. Se identificaron 104 especies de prosobranquios y 4 de pulmonados. Las familias Columbellidae y Muricidae fueron las mejores representadas en riqueza de especies y la familia Muricidae en abundancia. Acanthais triangularis se consideró como la representativa de la zona, la especie Macrocypraea cervinetta mostró la mayor talla. Además, 23 especies presentaron amplia distribución, 27 distribución regular y 54 distribución restringida. Veintiocho especies estuvieron representadas por un único organismo, y 6 especies por 2 organismos, estas especies son consideradas raras. Las especies raras se encontraron en las estaciones cuya característica de exposición del oleaje es de bajo a medio. La riqueza de especies fue alta y corresponde a lo esperado en una zona tropical. Palabras clave: Gastropoda, riqueza, distribución geográfica, tallas, Guerrero Abstract.- The aim of this research was the description of the taxocoenosis of Prosobranchia and Pulmonata subclasses (Gastropoda) associated with the rocky intertidal zone of the Marine Priority Region 32, Guerrero, Mexico. Based on known species richness, we examine the composition of the community based on the representation of families, assess abundance, the geographic distribution of species, estimate descriptive statistics of size, and estimate diversity. Sampling was conducted at 7 sites, the sampling unit was 1 m-2 and the sampling area was 10 m-2. One hundred and four species of subclass Prosobranchia and 4 species of subclass Pulmonata were identified. Columbellidae and Muricidae families showed higher species richness, meanwhile family Muricidae was the most abundant. Acanthais triangularis was the most representative species of the study area, and Macrocypraea cervinetta showed the greatest size. Twenty three species were found with broad distribution, 27 taxa with frequent distribution and 54 taxa with restricted distribution. Twenty eight species were represented by a single organism and 6 species with 2 organisms, these species were considered rare and were found in sites whose characteristic wave exposure is low to medium. Species richness was high and corresponds to that expected in the tropics. Key words: Gastropoda, species richness, geographic distribution, size, Guerrer

Matas de microalgas termófilas que crecen sobre la estructura de madera de una torre de enfriamiento de una central termoeléctrica en el centro de México

"The aims of this research are to identify and describe a periphyton community of thermophilic microalgae in order to expand our knowledge on biodiversity of a particular environment. Conspicuous biomass of thermophilic microalgae (48 °C) inhabits the cooling towers of the thermoelectric power plant of Villa de Reyes (Central Mexico). Aggregate samples or microalgal mats were taken in three different areas of the top of a cooling tower, for identification. According to the sequencing analysis of 16S and 18S rDNA genes, the community is dominated by 3 species of Cyanoprokaryota: Chlorogloeopsis fritschii, Arthronema africanum and Chroococcidiopsis sp., previously reported as thermophiles. Also, 2 species of the Chlorophyte or green algae Scenedesmus. Finally, 12 species of diatoms comprise the microalgal community; diatoms were only microscopically identified within the mats, suggesting that the mats constitute a suitable microenvironment in thermal ambiences. The identified species are of particular interest because their habitat represents an extreme and an artificial biotope. To the best of our knowledge, this is the first report of thermophilic communities of microalgae in Mexico from a power plant; also, this is the first report of A. africanum for the country.""Esta investigación tiene por objetivo identificar y describir la comunidad perifítica de microalgas termófilas, para expandir nuestro conocimiento de la biodiversidad en ambientes particulares, como las microalgas termófilas (48 °C) que crecen de manera conspicua en la zona superior de la torre de enfriamiento de la central termoeléctrica de Villa de Reyes (centro de México). Se tomaron muestras de agregados o tapetes microalgales en 3 zonas distintas de la parte superior de una torre de enfriamiento, para su identificación. Una vez realizada la amplificación, la clonación y el análisis de los genes que codifican para las subunidades 16S y 18S del rDNA, se observó el predominio de 3 especies de Cyanoprokaryota: Chlorogloeopsis fritschii, Arthronema africanum y Chroococcidiopsis sp., especies descritas como termófilas en trabajos previos. Además, se identificaron 2 especies de Chlorophyta (algas verdes) del género Scenedesmus y 12 especies de diatomeas; la identificación de diatomeas se realizó a partir de observaciones por microscopia electrónica de barrido. Característicamente, las diatomeas solo se observaron dentro los densos tapetes algales que se conforman, sugiriendo que estos tapetes constituyen un microambiente conveniente en ambientes térmicos. Las especies identificadas son de particular interés, ya que su hábitat representa un biotopo extremo y artificial. Por lo que sabemos, este trabajo constituye el primer registro de microalgas termófilas que habitan en torres de enfriamiento y Arthronema africanum se documenta por primera vez para México.

La clase Bivalvia en sitios rocosos de las Regiones Marinas Prioritarias en Guerrero, México: riqueza de especies, abundancia y distribución

Background. Bivalves are part of the fauna that inhabit the coast of the state of Guerrero. Many species are of commercial importance and few studies exist of this class in the state. The National Commission for the Use and Conservation of Diversity acknowledges the lack of studies regarding the diversity that exists in the Priority Marine Regions (PMRs) located in Guerrero. This study focused on the Bivalves and its Goals were to document species richness by analyzing the composition of the community based on the representation of families, estimate the density, and establish the geographical distribution of species. Methods. Sampling was conducted at 21 sites, the area was 10 m2 and the unit was 1 m2. Results. 5962 specimens were analyzed and 40 species were identified. Mytilidae and Arcidae families were the best represented in species richness and Mytilidae and Isognomonidae families were the best represented in abundance. The density was 18.63 organisms / m2 and Choromytilus palliopunctatus (4.5 organisms / m2) and Isognomon janus (4.0 organisms / m2) showed the highest densities. We determined that three species have wide distribution, one species has frequent distribution, eight species have limited distribution, and 32 species have restricted distribution. This study registered five new additions to bivalve fauna in the Mexican Pacific Transition, one for the state of Guerrero, five for PMR 30, six for PmR 31, and 17 for PMR 33. Conclusions. Results from this study significantly advance our understanding of biodiversity and ecology of Bivalves in the state of Guerrero.Antecedentes. Los bivalvos son parte de la fauna que habita en las costas del estado de Guerrero, muchos tienen importancia comercial, sin embargo, hay muy pocos estudios acerca de esta clase. La Comisión Nacional para el Uso y Conservación de la Biodiversidad refirió la falta de conocimiento sobre la variedad de especies que existe en las regiones marinas prioritarias (RMPs) que se ubican en esta región. Objetivos. Conocer la riqueza de especies de la clase Bivalvia, analizar la composición de la comunidad con base en la representación de las familias, estimar la densidad y conocer la distribución geográfica de los ejemplares. Métodos. El muestreo se realizó en 21 sitios, el área de muestreo fue de 10 m2 y la unidad de muestreo fue de 1 m2. Resultados. Se analizaron 5962 especímenes y se identificaron 40 especies. Las familias Myitilidae y Arcidae presentaron una mayor riqueza de especies y Mytilidae e Isognomonidae, una mayor abundancia. La densidad fue de 18.63 organismos/m2. Choromytilus palliopunctatus (4.5 organismos/m2) e Isognomon janus (4.0 organismos/m2) mostraron una densidad superior. Tres especies tuvieron distribución amplia, una frecuente, ocho limitada y 32 restringida. Se reportaron cinco nuevas adiciones a la fauna de bivalvos en el Pacífico Transicional Mexicano, una para Guerrero, cinco para la RMP 30, seis para la RMP 31 y diecisiete para la RMP 33. Conclusiones. Con los resultados de este análisis, se logró avanzar en el conocimiento de la biodiversidad y ecología de los bivalvos en las RMP en el estado de Guerrero

The separation between the 5′-3′ ends in long RNA molecules is short and nearly constant

"RNA molecules play different roles in coding, decoding and gene expression regulation. Such roles are often associated to the RNA secondary or tertiary structures. The folding dynamics lead to multiple secondary structures of long RNA molecules, since an RNA molecule might fold into multiple distinct native states. Despite an ensemble of different structures, it has been theoretically proposed that the separation between the 5 ' and 3 ' ends of long single-stranded RNA molecules (ssRNA) remains constant, independent of their base content and length. Here, we present the first experimental measurements of the end-to-end separation in long ssRNA molecules. To determine this separation, we use single molecule Fluorescence Resonance Energy Transfer of fluorescently end-labeled ssRNA molecules ranging from 500 to 5500 nucleotides in length, obtained from two viruses and a fungus. We found that the end-to-end separation is indeed short, within 5-9 nm. It is remarkable that the separation of the ends of all RNA molecules studied remains small and similar, despite the origin, length and differences in their secondary structure. This implies that the ssRNA molecules are 'effectively circularized' something that might be a general feature of RNAs, and could result in finetuning for translation and gene expression regulation.

Ir-Sn-Sb-O Electrocatalyst for Oxygen Evolution Reaction: Physicochemical Characterization and Performance in Water Electrolysis Single Cell with Solid Polymer Electrolyte

Mixed oxide Ir-Sn-Sb-O electrocatalyst was synthesized using thermal decomposition from chloride precursors in ethanol. Our previous results showed that Ir-Sn-Sb-O possesses electrocatalytic activity for an oxygen evolution reaction (OER) in acidic media. In the present work, the physicochemical characterization and performance of Ir-Sn-Sb-O in an electrolysis cell are reported. IrO2 supported on antimony doped tin oxide (ATO) was also considered in this study as a reference catalyst. Scanning electron microscopy (SEM) images indicated that Ir-Sn-Sb-O has a mixed morphology with nanometric size. Energy dispersive X-ray spectroscopy (EDS) showed a heterogeneous atomic distribution. Transmission electron microscopy (TEM) analysis resulted in particle sizes of IrO2 and ATO between 3 to >10 nm, while the Ir-Sn-Sb-O catalyst presented non-uniform particle sizes from 3 to 50 nm. X-ray diffraction (XRD) measurements indicated that synthesized mixed oxide consists of IrO2, IrOx, doped SnO2 phases and metallic Ir. The Ir-Sn-Sb-O mixed composition was corroborated by temperature programmed reduction (TPR) measurements. The performance of Ir-Sn-Sb-O in a single cell electrolyser showed better results for hydrogen production than IrO2/ATO using a mechanical mixture. Ir-Sn-Sb-O demonstrated an onset potential for water electrolysis close to 1.45 V on Ir-Sn-Sb-O and a current density near to 260 mA mg−1 at 1.8 V. The results suggest that the mixed oxide Ir-Sn-Sb-O has favorable properties for further applications in water electrolysers