Patterns of in situ Mineral Colonization by Microorganisms in a ~60°C Deep Continental Subsurface Aquifer

The microbial ecology of the deep biosphere is difficult to characterize, owing in part to sampling challenges and poorly understood response mechanisms to environmental change. Pre-drilled wells, including oil wells or boreholes, offer convenient access, but sampling is frequently limited to the water alone, which may provide only a partial view of the native diversity. Mineral heterogeneity demonstrably affects colonization by deep biosphere microorganisms, but the connections between the mineral-associated and planktonic communities remain unclear. To understand the substrate effects on microbial colonization and the community response to changes in organic carbon, we conducted an 18-month series of in situ experiments in a warm (57°C), anoxic, fractured carbonate aquifer at 752 m depth using replicate open, screened cartridges containing different solid substrates, with a proteinaceous organic matter perturbation halfway through this series. Samples from these cartridges were analyzed microscopically and by Illumina (iTag) 16S rRNA gene libraries to characterize changes in mineralogy and the diversity of the colonizing microbial community. The substrate-attached and planktonic communities were significantly different in our data, with some taxa (e.g., Candidate Division KB-1) rare or undetectable in the first fraction and abundant in the other. The substrate-attached community composition also varied significantly with mineralogy, such as with two Rhodocyclaceae OTUs, one of which was abundant on carbonate minerals and the other on silicic substrates. Secondary sulfide mineral formation, including iron sulfide framboids, was observed on two sets of incubated carbonates. Notably, microorganisms were attached to the framboids, which were correlated with abundant Sulfurovum and Desulfotomaculum sp. sequences in our analysis. Upon organic matter perturbation, mineral-associated microbial diversity differences were temporarily masked by the dominance of putative heterotrophic taxa in all samples, including OTUs identified as Caulobacter, Methyloversatilis, and Pseudomonas. Subsequent experimental deployments included a methanogen-dominated stage (Methanobacteriales and Methanomicrobiales) 6 months after the perturbation and a return to an assemblage similar to the pre-perturbation community after 9 months. Substrate-associated community differences were again significant within these subsequent phases, however, demonstrating the value of in situ time course experiments to capture a fraction of the microbial assemblage that is frequently difficult to observe in pre-drilled wells

Model-Based Deconvolution of Cell Cycle Time-Series Data Reveals Gene Expression Details at High Resolution

In both prokaryotic and eukaryotic cells, gene expression is regulated across the cell cycle to ensure “just-in-time” assembly of select cellular structures and molecular machines. However, present in all time-series gene expression measurements is variability that arises from both systematic error in the cell synchrony process and variance in the timing of cell division at the level of the single cell. Thus, gene or protein expression data collected from a population of synchronized cells is an inaccurate measure of what occurs in the average single-cell across a cell cycle. Here, we present a general computational method to extract “single-cell”-like information from population-level time-series expression data. This method removes the effects of 1) variance in growth rate and 2) variance in the physiological and developmental state of the cell. Moreover, this method represents an advance in the deconvolution of molecular expression data in its flexibility, minimal assumptions, and the use of a cross-validation analysis to determine the appropriate level of regularization. Applying our deconvolution algorithm to cell cycle gene expression data from the dimorphic bacterium Caulobacter crescentus, we recovered critical features of cell cycle regulation in essential genes, including ctrA and ftsZ, that were obscured in population-based measurements. In doing so, we highlight the problem with using population data alone to decipher cellular regulatory mechanisms and demonstrate how our deconvolution algorithm can be applied to produce a more realistic picture of temporal regulation in a cell

Logrando aprendizajes duraderos en resolución de problemas matemáticos en el VI ciclo de la Institución Educativa N° 86486 - Huaylas

Trabajo académicoEl plan de acción propuesto fue elaborado con el objetivo de elevar el nivel de logros de aprendizaje en la resolución de problemas matemáticos en los estudiantes del VI ciclo de la I.E. Víctor Flores Cortez de Santo Toribio, considerando la problemática identificada, las causas que lo generan y los docentes del área de matemática como muestra. Para la recolección de datos se ha utilizado la técnica de la entrevista y, como instrumento, la guía de entrevista, evidenciando como causas la dificultad en la aplicación de estrategias metodológicas para resolver problemas matemáticos, el limitado monitoreo y acompañamiento a la práctica pedagógica y la limitada responsabilidad de los padres de familia e incumplimiento de normas de convivencia consensuadas por los agentes educativos, las que fueron contrastadas con aportes teóricos y experiencias exitosas. El sustento teórico se plantea en el Marco Curricular Nacional y la teoría del monitoreo y acompañamiento pedagógico de los instrumentos de gestión escolar del MINEDU, en relación al Marco del Buen Desempeño Directivo. De lo manifestado se concluye que la adecuada aplicación de estrategias metodológicas, el pertinente monitoreo y acompañamiento pedagógico con el cumplimiento de las normas de convivencia, reflejan el logro de los aprendizajes de los estudiantes

A comparative study of prokaryotic diversity and physicochemical characteristics of Devils Hole and the Ash Meadows Fish Conservation Facility, a constructed analog

<div><p>Devils Hole is the sole natural habitat of the critically endangered Devils Hole pupfish (<i>Cyprinodon diabolis</i>). To establish a backup population, the Ash Meadows Fish Conservation Facility (AMFCF), a full-scale replica of the uppermost 6.7 m of Devils Hole, was constructed by management agencies in the mid-2010s. Despite rigorous efforts to mimic the bathymetric and physical details of the Devils Hole environment, the biogeochemistry and microbiology of the AMFCF refuge tank remain largely unaddressed. We evaluated water physicochemistry and employed Illumina DNA sequencing of 16S rRNA gene libraries to evaluate planktonic and benthic bacterial and archaeal community composition within their respective physicochemical contexts in Devils Hole and AMFCF on the same day. Major ion concentrations were consistent between the two systems, but water temperature and dissolved oxygen dynamics differed. Bioavailable nitrogen (primarily nitrate) was 5x lower in AMFCF. Devils Hole and AMFCF nitrogen:phosphorus molar ratios were 107:1 and 22:1, indicative of different nutrient control mechanisms. Both sites are microbiologically diverse, with over 40 prokaryotic phyla represented at each, with 37 shared between them and nearly than half deriving from candidate divisions. The abundance and composition of predicted photosynthetic primary producers (Cyanobacteria) was markedly different between sites: Devils Hole planktonic and sediment communities were dominated by <i>Oscillatoria spp</i>. (13.2% mean relative abundance), which proved virtually undetectable in AMFCF. Conversely, AMFCF was dominated by a predicted heterotroph from the Verrucomicrobiaceae family (31.7%); which was comparatively rare (<2.4%) in Devils Hole. We propose that the paucity of bioavailable nitrogen in AMFCF, perhaps resulting from physical isolation from allochthonous environmental inputs, is reflected in the microbial assemblage disparity, influences biogeochemical cycling of other dissolved constituents, and may ultimately impact survivorship and recruitment of refuge populations of the Devils Hole pupfish.</p></div

Relative abundances (mean and SD) of the top 5 differentially abundant operational taxonomic units identified by SIMPER analysis.

<p>Differentially abundant OTUs between <b>a)</b> planktonic samples and <b>b)</b> sediment samples between Devils Hole and Ash Meadows Fish Conservation Facility (AMFCF), along with OTU ID and taxonomy, are shown. Prefixes (p_, o_, f_ and g_) denote phylum, order, family, and genus level OTU identities. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194404#pone.0194404.s008" target="_blank">S6 Table</a> for the percent contribution of each OTU to the dissimilarity between each group of samples.</p

Field sites.

<p>a) The top of the Devils Hole water table viewed looking north. The shallow shelf roughly corresponds to the area below the metal walkway (temporarily installed for this work) and was partially covered with algal mats on the day of sampling. The deep pool occupies the algae-free upper half of the submerged area. b) Refuge tank at the Ash Meadows Fish Conservation Facility, a full-scale bathymetric replica of the shelf at Devils Hole, on the day of sampling. As shown, the shelf occupies the area below the concrete ledge.</p

Major physicochemical characteristics of waters from Devils Hole (DH), Ash Meadows Fish Conservation Facility (AMFCF), and Well P-9.

<p>Major physicochemical characteristics of waters from Devils Hole (DH), Ash Meadows Fish Conservation Facility (AMFCF), and Well P-9.</p

Principal component analysis.

<p>Principal component analysis ordinations of a) pairwise abundance-unweighted UniFrac distances and b) pairwise abundance-weighted UniFrac distances for all samples show separation of samples by sample location and sample type (planktonic vs. sediment). Individual samples are colored according to sample type (planktonic vs. sediment: Devils Hole (DH) planktonic and sediment samples are shown as light blue and dark blue squares, respectively; Ash Meadows Fish Conservation Facility (AMFCF) planktonic and sediment samples are shown as yellow and red triangles, respectively; and the Well P-9 sample is shown as an asterisk.</p

Design, 22-step synthesis, and evaluation of highly potent D-ring modified and linker-equipped analogs of spongistatin 1

With an average GI50 value against the NCI panel of 60 human cancer cell lines of 0.12 nM, spongistatin 1 is among the most potent anti-proliferative agents ever discovered rendering it an attractive candidate for development as a payload for antibody-drug conjugates and other targeted delivery approaches. It is unavailable from natural sources and its size and complex stereostructure render chemical synthesis highly time- and resource-intensive, however, and its development requires more efficient and step-economical synthetic access. Using novel and uniquely enabling direct complex fragment coupling alkallyl- and crotylsilylation reactions, we have developed a 22-step synthesis of a rationally designed D-ring modified analog of spongistatin 1 that is equipotent with the natural product, and have used that synthesis to establish that the C(15) acetate may be replaced with a linker functional group-bearing ester with only minimal reductions in potency.</div