273 research outputs found
Two mini-preparation protocols to DNA extraction from plants with high polysaccharide and secondary metabolites
Were standardized two previously reported standard plant DNA extraction methods, but improved them on mini preparations to use the samples for population genetic analysis. The combination of CTAB lysis procedure-solvent extraction and DNA column purification (DNeasy plant mini kit modification) enables a faster and reliable DNA extraction from all samples tested:Â Piper, Quercus, Zea and cacti species (considered âhardâ extraction species), and this protocol uses smaller tissue samples than other mini or midi-prep protocols. We obtained high quality and DNA yields in all samples tested. This alternative protocol (CTAB lysis-solvent extraction based) is an excellent option if there are many samples to process and it is also a non expensive protocol. This method also produces good DNA quality but fewer yields. Both two protocols produce reproducible PCR pattern-bands amplification with all the genetic markers tested (RAPDâs and microsatellites). The DNA obtained was used in other molecular biology standard analysis methods, like enzymptic restriction patterns, ligation, sequencing and cloning with good results too
H^+_2$ in a strong magnetic field described via a solvable model
We consider the hydrogen molecular ion in the presence of a strong
homogeneous magnetic field. In this regime, the effective Hamiltonian is almost
one dimensional with a potential energy which looks like a sum of two Dirac
delta functions. This model is solvable, but not close enough to our exact
Hamiltonian for relevant strenght of the magnnetic field. However we show that
the correct values of the equilibrium distance as well as the binding energy of
the ground state of the ion, can be obtained when incorporating perturbative
corrections up to second order. Finally, we show that exists for
sufficiently large magnetic fields
Opportunities at the interface of network science and metabolic modeling
Metabolism plays a central role in cell physiology because it provides the molecular machinery for growth. At the genome-scale, metabolism is made up of thousands of reactions interacting with one another. Untangling this complexity is key to understand how cells respond to genetic, environmental, or therapeutic perturbations. Here we discuss the roles of two complementary strategies for the analysis of genome-scale metabolic models: Flux Balance Analysis (FBA) and network science. While FBA estimates metabolic flux on the basis of an optimization principle, network approaches reveal emergent properties of the global metabolic connectivity. We highlight how the integration of both approaches promises to deliver insights on the structure and function of metabolic systems with wide-ranging implications in discovery science, precision medicine and industrial biotechnology
Dry deposition of nitrogen to passive samplers in grassland and forest canopies in the central depression of southern Chile
The Proteome of Biologically Active Membrane Vesicles from Piscirickettsia salmonis LF-89 Type Strain Identifies Plasmid-Encoded Putative Toxins
IndexaciĂłn: Scopus.Piscirickettsia salmonis is the predominant bacterial pathogen affecting the Chilean salmonid industry. This bacterium is the etiological agent of piscirickettsiosis, a significant fish disease. Membrane vesicles (MVs) released by P. salmonis deliver several virulence factors to host cells. To improve on existing knowledge for the pathogenicity-associated functions of P. salmonis MVs, we studied the proteome of purified MVs from the P. salmonis LF-89 type strain using multidimensional protein identification technology. Initially, the cytotoxicity of different MV concentration purified from P. salmonis LF-89 was confirmed in an in vivo adult zebrafish infection model. The cumulative mortality of zebrafish injected with MVs showed a dose-dependent pattern. Analyses identified 452 proteins of different subcellular origins; most of them were associated with the cytoplasmic compartment and were mainly related to key functions for pathogen survival. Interestingly, previously unidentified putative virulence-related proteins were identified in P. salmonis MVs, such as outer membrane porin F and hemolysin. Additionally, five amino acid sequences corresponding to the Bordetella pertussis toxin subunit 1 and two amino acid sequences corresponding to the heat-labile enterotoxin alpha chain of Escherichia coli were located in the P. salmonis MV proteome. Curiously, these putative toxins were located in a plasmid region of P. salmonis LF-89. Based on the identified proteins, we propose that the protein composition of P. salmonis LF-89 MVs could reflect total protein characteristics of this P. salmonis type strain. © 2017 Oliver, HernĂĄndez, Tandberg, Valenzuela, Lagos, Haro, SĂĄnchez, Ruiz, Sanhueza-OyarzĂșn, CortĂ©s, Villar, Artigues, Winther-Larsen, Avendaño-Herrera and Yåñez.https://www.frontiersin.org/articles/10.3389/fcimb.2017.00420/ful
Burdigalian deposits of the Santa Cruz Formation in the Sierra Baguales, Austral (Magallanes) Basin: Age, depositional environment and vertebrate fossils
IndexaciĂłn: Web of Science; Scielo.ABSTRACT. A succession of marine and continental strata on the southern flank of Cerro Cono in the Sierra Baguales,
northeast of Torres del Paine, can be correlated with stratigraphic units exposed along the southern border of the Lago
Argentino region in Santa Cruz Province, Argentina. These include the Estancia 25 de Mayo Formation and the basal
part of the Santa Cruz Formation. The lithological correlation is also confirmed by detrital zircon ages (maximum age
of 18.23±0.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a postColhuehuapian,
pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to
17.8 Ma. Similar ages have been obtained from the basal part of the Santa Cruz Formation at Estancia Quién Sabe
in southwestern Argentina, supporting the assumption of a regional continuity between these deposits. A measured
lithostratigraphic column is presented and the depositional environment is interpreted as a coastal plain with small,
meandering rivers and ephemeral floodplain lakes. The sedimentation coincides with intensified uplift of the Patagonian
Andes during the âQuechua Phaseâ of Andean tectonism, which is reflected by a change in paleocurrent directions from
northwest to east-northeast.
Keywords: Burdigalian, Santa Cruz Formation, Santacrucian SALMA, âNotohippidianâ fauna, Meandering rivers.RESUMEN. Una sucesiĂłn de estratos marinos y continentales en el flanco meridional del cerro Cono, en la sierra Baguales, al noreste de Torres del Paine, se correlaciona con estratos al sur de la regiĂłn de lago Argentino en la Provincia de Santa Cruz, RepĂșblica Argentina. Estas unidades incluyen la FormaciĂłn Estancia 25 de Mayo y la parte basal de la FormaciĂłn Santa Cruz. La correlaciĂłn litolĂłgica es, ademĂĄs, confirmada por dataciĂłn de circones detrĂticos (edad mĂĄxima de 18,23±0,26 Ma) y un variado ensamble de vertebrados fĂłsiles terrestres de edad post-Colhuehuapense a pre-Santacrucense en la escala de Edades MamĂfero Sudamericanas (EMAS), con un rango temporal de entre 19 a 17,8 Ma. Edades similares han sido reportadas para la parte basal de la FormaciĂłn Santa Cruz, en estancia QuiĂ©n Sabe, en el suroeste de Argentina, ratificando la continuidad regional entre estos depĂłsitos. Se presenta una columna estratigrĂĄfica y se interpreta el ambiente de depositaciĂłn como una llanura costera con pequeños rĂos sinuosos y lagos efĂmeros. La edad de sedimentaciĂłn coincide con el solevantamiento de los Andes PatagĂłnicos durante la 'Fase Quechua', lo que se ve reflejado por un cambio en la direcciĂłn de las paleocorrientes desde el noroeste hacia el este-noreste.http://ref.scielo.org/csxwd
Indigenous higher education in Mexico and Brazil: between redistribution and recognition
Indigenous groups in Latin America face a double exclusion from higher education, with low levels of access to institutions and little acknowledgement of their distinctive cultural and epistemological traditions within the curriculum. This article assesses current policies in Mexico and Brazil towards indigenous populations in higher education, considering the various responses to the challenge, including affirmative action programmes in mainstream universities, intercultural courses and autonomous institutions. These policies and initiatives are analysed using the theoretical frames of redistribution and recognition, focusing on demands for formal equality and material wellbeing on the one hand, and a distinctive cultural and educational space on the other. While state-sponsored policies focus primarily on the redistributive element, initiatives based on recognition come largely from autonomous organisations, raising a series of dilemmas and tensions around educational justice for indigenous populations in the region
Poly(N,N-dimethylaminoethyl methacrylate) for removing chromium (VI) through polymer-enhanced ultrafiltration technique
This work is focused on the removal of Cr(VI) ions from aqueous solution using polymer-enhanced ultrafiltration (PEUF) techniques with water-soluble poly(N,N-dimethylaminoethyl methacrylate), PDMAEMA, used as sorbent. The polymer was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization at different reaction times, characterized by size exclusion chromatography (SEC) and proton nuclear magnetic resonance (1H NMR). The sorption of Cr(VI) was studied by PEUF as a function of pH, the polymer:Cr(VI) molar ratio, and the presence of interfering ions. The PEUF-enrichment mode was used to saturate the polymer and further determine the release of Cr(VI) and regeneration of the polymer using sorption-desorption process. The RAFT polymerization showed a yield in the range 46% to 79% (determined by 1H NMR) for polymers with molecular weight (Mn) between 28 and 195âŻkgâŻmolâ1. The polydispersity estimated by SEC was between 1.1 and 1.8. The capacity of PDMAEMA as sorbent of Cr(VI), by the PEUF technique showed an efficient removal of Cr(VI) (100%, 25âŻmgâŻLâ1 in the feed) at pHâŻ4 using polymer:Cr molar ratio of 40:1. The presence of interfering ions does not significantly decrease the retention capacity of PDMAEMA. Finally the results indicated that PDMAEMA can release Cr(VI) and be regenerated.Peer reviewe
Synthesis and morphological characterization of nanocomposite based on anodic TiO2 nanotubes and poly(N-maleoyl Glycine-CO-Acrylic acid)
IndexaciĂłn: Scopus.In this study, we examined the synthesis, and characterization of TiO2/poly(N-maleoylglycine-co-acrylic acid) (TiO2/poly(MG-co-AA)) nanocomposite. The nanocomposite was prepared by the dispersion of TiO2 nanotubes in a water solution of the polymer (3% w/w) and then it was lyophilized. The nanocomposite was characterized by FTIR and Raman spectroscopies. The incorporation of TiO2 nanotubes to the polymeric matrix was determined by transmission electron microscopy (TEM) from which TiO2 nanotubes in the inner of copolymer with diameters ranging between 90 and 100 nm were observed. The overall morphology of the previously synthetized nanotubes was determined by scanning electron microscopy (SEM). For the nanocomposite system, the morphology was studied by atomic force microscopy (AFM) from which a grain shape structure was observed. This process resulted in a new nanocompsite material with an average grain diameter estimated by SEM and AFM ranging between 210-240 nm. It was observed that the nanotubes were homogeneously dispersed within the polymeric matrix. The prepared material could be suitable in the design of electronic devices and additionally could have potential applications as biomaterial.https://scielo.conicyt.cl/pdf/jcchems/v62n3/0717-9324-jcchems-62-03-3634.pd
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