Putting pharmaceuticals into the wider context of challenges to fish populations in rivers

The natural range of fish species in our rivers is related to flow, elevation, temperature, local habitat and connectivity. For over 2000 years, humans have altered to varying degrees the river habitat. In the past 200 years, we added to the environmental disruption by discharging poorly treated sewage, nutrients and industrial waste into our rivers. For many rivers, the low point arrived during the period of 1950s–1970s, when rapid economic development overrode environmental concerns and dissolved oxygen concentrations dropped to zero. In these more enlightened times, gross river pollution is a thing of the past in the Developed World. However, persistent legacy chemical contaminants can be found in fish long after their discharge ceased. Changes in habitat quality and morphology caused and continue to cause the disappearance of fish species. The range of fish stressors has now increased as temperatures rise, and non-native fish introductions bring new diseases. The threat from pharmaceuticals to fish populations remains hypothetical, and no studies have yet linked change in fish populations to exposure

Improving the method of solar radiation durability determination of cable products

The authors suggest an extra physic-mechanical procedure to determine durability of cable goods to solar radiation exposure. The test check was carried out using the standard and the proposed procedures. The results of two tests were compared and analyzed. The use of the proposed technique allows improving the validity and reliability of the laboratory experiment conducted in a real production environment and exclude the low-quality cable items. The only disadvantage of the proposed technique is its labor intensiveness

Vegetation and flow rate impact on in-stream longitudinal dispersion and retention processes

This paper is an attempt to explain influence of vegetation and flow rate in natural stream (Epre, Germany) on mixing and transport processes. For this purpose, we conducted two tracer tests in Germany using rhodamine WT (RWT) as a fluorescence dye. Both tests were performed under different vegetation and flow rate conditions. The STIR (Solute Transport In Rivers) code was used for calibration of dispersion coefficients, exchange rates and residence times. We used the STIR model to separate short—and long—time retention. Our tracer test results confirm previous findings and also reveal a correlation between storage zone exchanges rate and reach lengths, strong influence of vegetation and flow rate on transport and mixing parameters, and the significance of the equipment on storage domain characterisation

Impact of saturation on dispersion and mixing in porous media: Photobleaching pulse injection experiments and shear-enhanced mixing model

International audienceThe dynamics of solute dispersion and mixing in unsaturated flows is analyzed from photobleaching experiments in two-dimensional porous micromodels. This technique allows producing pulse line (delta-Dirac) injections of a conservative tracer by bleaching a finite volume of fluorescent without disturbing the flow field. The temporal evolution of the concentration field and the spatial distribution of the air and water phases can be monitored at pore scale. We study the dispersion and mixing of a line of tracer under different water saturations. While dispersion in saturated porous media follows an approximately Fickian scaling, a shift to ballistic scaling is observed as soon as saturation is lowered. Hence, at the time scale of observation, dispersion in our unsaturated flows is dominated by the ballistic separation of tracer blobs within the water phase, between trapped clusters and preferential flow paths. While diffusion plays a minor role in the longitudinal dispersion during the time scale of the experiments, its interplay with fluid deformation is apparent in the dynamics of mixing. The scalar dissipation rates show an initial stretching regime, during which mixing is enhanced by fluid deformation, followed by a dissipation regime, during which diffusion overcomes compression induced by stretching. The transition between these two regimes occurs at the mixing time, when concentration gradients are maximum. We propose a predictive analytical model, based on shear-enhanced diffusion, that captures the dynamics of mixing from basic unsaturated porous media parameters, suggesting that this type of model may be a useful framework at larger scales

Intrachromosomal colocalization strengthens co-expression, co-modification and evolutionary conservation of neighboring genes

Abstract Background Gene order and location in chromosomes of species are non-random. Neighboring gene pairs tend to display some similarities, such as co-expression and co-modification. However, the contribution of linear proximity, spatial proximity, and evolutionary proximity to these similarities remain unclear, together with whether the presence of several types of proximity can strengthens the similarities. Results In this study, we investigated the properties of three kinds of colocalized gene pairs: intrachromosomal colocalized gene pairs, always-neighboring gene pairs, and evolutionary neighboring gene pairs. Our analysis showed that (1) Different types of colocalized genes differentially contribute to co-expression, co-modifications and conservation across species; (2) Intrachromosomal colocalization can strengthen co-expression and co-modification of neighboring gene pairs and their conservation across species; (3) The combination of the three kinds of colocalization can lead to the strongest co-modification and is most strongly conserved across species. (4) Colocalized gene pairs are indicative of phylogenetic relationships and whole genome duplications (WGDs). Conclusions These results provide valuable clues for future efforts to understand the characteristics of colocalized gene pairs and how the neighborhood affects their interactions

Microbe–microbe interactions trigger Mn(II)-oxidizing gene expression

Manganese (Mn) is an important metal in geochemical cycles. Some microorganisms can oxidize Mn(II) to Mn oxides, which can, in turn, affect the global cycles of other elements by strong sorption and oxidation effects. Microbe-microbe interactions have important roles in a number of biological processes. However, how microbial interactions affect Mn(II) oxidation still remains unknown. Here, we investigated the interactions between two bacteria (Arthrobacter sp. and Sphingopyxis sp.) in a co-culture, which exhibited Mn(II)-oxidizing activity, although neither were able to oxidize Mn(II) in isolation. We demonstrated that the Mn(II)-oxidizing activity in co-culture was most likely induced via contact-dependent interactions. The expressed Mn(II)-oxidizing protein in the co-culture was purified and identified as a bilirubin oxidase belonging to strain Arthrobacter. Full sequencing of the bilirubin oxidase-encoding gene (boxA) was performed. The Mn(II)-oxidizing protein and the transcripts of boxA were detected in the co-culture, but not in either of the isolated cultures. This indicate that boxA was silent in Arthrobacter monoculture, and was activated in response to presence of Sphingopyxis in the co-culture. Further, transcriptomic analysis by RNA-Seq, extracellular superoxide detection and cell density quantification by flow cytometry indicate induction of boxA gene expression in Arthrobacter was co-incident with a stress response triggered by co-cultivation with Sphingopyxis. Our findings suggest the potential roles of microbial physiological responses to stress induced by other microbes in Mn(II) oxidation and extracellular superoxide production