Cadmium removal by Anabaena sp. ATCC 33047 immobilized in polyurethane foam

The nitrogen-fixing cyanobacterium Anabaena sp. ATCC 33047, which generates substantial amounts of exopolysaccharide, was immobilized by entrapment within the reticulate network of polyurethane foam discs. The immobilized Anabaena sp. system has been investigated as a potential biosorbent for the removal of cadmium from aqueous solutions. The results showed that it was a highly fast process, with 80 % of the adsorption taking place in the first 10 min, reaching full equilibrium in about 50 min. Data analysis indicated that the behaviour of the system accurately fits to a monolayer adsorption model (Langmuir isotherm). The maximal biosorption capacity determined for the immobilized Anabaena sp. system was as high as 162 mg Cd (II) per gram dry biomass. The outstanding properties established for immobilized Anabaena sp. in polyurethane foam underline the relevance of such a system as an alternative to current treatments of variety effluents or wastewater contaminated with cadmium.Peer reviewe

Cardiac injections of AntagomiRs as a novel tool for knockdown of miRNAs during heart development

Background: Studying microRNA networks during heart development is essential to obtain a better understanding of developmental defects and diseases associated with the heart and to identify novel opportunities for therapeutics. Here we highlight the advantages of chicken embryos as a vertebrate model for studying intermediate processes of heart development. Avians develop a four-chambered heart closely resembling human anatomy and they develop ex utero, which makes them easily accessible. Furthermore, embryos are available all year with a steady supply. Results: In this report we established a novel method for the knockdown of microRNA function by microinjecting AntagomiRs into the chicken heart in ovo. Our approach enables the targeted delivery of antagomirs into a locally restricted area and is not impacted by circulation. After further embryo development the successful miRNA knockdown was confirmed. Loss of function phenotypes can be evaluated rapidly, compared to more time-consuming genetic ablation experiments. The local application avoids potential systemic effects of microRNA knockdown, therefore allowing the assessment of impacts on heart development only. The method can be adjusted for different stages of chicken embryos (HH13-HH18) as well as for knockdown or targeted overexpression of coding genes. Conclusion: In conclusion our method allows targeted and locally restricted delivery of Antagomirs to the heart leading to successful knockdown of microRNA function. This method enables rapid phenotypic assessment, for example by gene expression analysis of multiple cardiac genes

Multiple Front Propagation Into Unstable States

The dynamics of transient patterns formed by front propagation in extended nonequilibrium systems is considered. Under certain circumstances, the state left behind a front propagating into an unstable homogeneous state can be an unstable periodic pattern. It is found by a numerical solution of a model of the Fr\'eedericksz transition in nematic liquid crystals that the mechanism of decay of such periodic unstable states is the propagation of a second front which replaces the unstable pattern by a another unstable periodic state with larger wavelength. The speed of this second front and the periodicity of the new state are analytically calculated with a generalization of the marginal stability formalism suited to the study of front propagation into periodic unstable states. PACS: 47.20.Ky, 03.40.Kf, 47.54.+rComment: 12 page

Effects of in utero heat stress on subsequent reproduction performance of first-calf Holstein heifers

Aim of study: To determine the reproductive performance of heifers gestated under maternal conditions of heat stress in late gestation.Area of study: Northern Mexico (25° 32’ N, 103° 23’ W).Material and methods: The study included reproductive records of 4976 first-calf Holstein heifers in a hot environment.Main results: Heifers born to cows experiencing no heat stress three months before parturition but with a THI >83 at calving were older (p<0.05) at first calving (743 ± 67 vs. 729 ± 55 days) than heifers gestated under maternal conditions of heat stress. A two-fold increase (p<0.01) in pregnancy rate occurred in heifers gestated under maternal conditions of no heat stress during two or three months before pregnancy and no heat stress at parturition, compared with heifers gestated under maternal conditions of no heat stress. Overall, across in utero heat stress one, two or three months before calving, pregnancy rate to all services was higher (p<0.05) for first-calf heifers gestated under maternal conditions of no heat stress during delivery, compared with heifers gestated under maternal conditions of heat stress (66.7 vs. 51.1%). Median days for getting pregnant was higher (140 d) for heifers whose dams were exposed to THI >83 at calving than heifers whose mothers were exposed to <76 or 76-83 (117 and 114 d) at calving.Research highlights: These data suggest that in utero heat stress during the last three months of gestation negatively affects the reproductive performance of first-calf Holstein heifers

Further properties of causal relationship: causal structure stability, new criteria for isocausality and counterexamples

Recently ({\em Class. Quant. Grav.} {\bf 20} 625-664) the concept of {\em causal mapping} between spacetimes --essentially equivalent in this context to the {\em chronological map} one in abstract chronological spaces--, and the related notion of {\em causal structure}, have been introduced as new tools to study causality in Lorentzian geometry. In the present paper, these tools are further developed in several directions such as: (i) causal mappings --and, thus, abstract chronological ones-- do not preserve two levels of the standard hierarchy of causality conditions (however, they preserve the remaining levels as shown in the above reference), (ii) even though global hyperbolicity is a stable property (in the set of all time-oriented Lorentzian metrics on a fixed manifold), the causal structure of a globally hyperbolic spacetime can be unstable against perturbations; in fact, we show that the causal structures of Minkowski and Einstein static spacetimes remain stable, whereas that of de Sitter becomes unstable, (iii) general criteria allow us to discriminate different causal structures in some general spacetimes (e.g. globally hyperbolic, stationary standard); in particular, there are infinitely many different globally hyperbolic causal structures (and thus, different conformal ones) on $\R^2$, (iv) plane waves with the same number of positive eigenvalues in the frequency matrix share the same causal structure and, thus, they have equal causal extensions and causal boundaries.Comment: 33 pages, 9 figures, final version (the paper title has been changed). To appear in Classical and Quantum Gravit

The effects of periparturient events, mastitis, lameness and ketosis on reproductive performance of Holstein cows in a hot environment

The aim of this study was to determine the association among periparturient events such as mastitis, lameness (infectious and non-infectious) and ketosis and the reproductive performance of high producing Holstein cows in a hot environment. The health status and reproductive data variables were recorded from 6,566 completed lactations in a large dairy operation. A logistic regression model with the stepwise procedure was used, considering the occurrence of the health problems during the pre-breeding period as fixed effect risk factors and reproductive variables as dependent variables. Pregnancy rate of cows contracting clinical mastitis (CM) around the period of first inseminations was five percentage points lower than cows without this disease. Cows with CM shortly before or after the first service had twice the risk of requiring more than three services per pregnancy than cows with healthy udders. Cows experiencing abortion, laminitis or metritis were two times more likely to require >3 services per pregnancy than cows not experiencing these reproductive disorders. Cows experiencing lameness, mastitis and metritis presented a significantly longer interval between calving and pregnancy compared to healthy cows. Ketosis and lameness increased the odds of a cow of being inseminated for the first time after 70 days in milk. In conclusion, these results suggest that abortion, ketosis, CM, retained placenta (RP), metritis, and lameness are associated with decreased reproductive performance in high producing Holstein cows subjected to thermal stress

Growth rate, scrotal circumference, sperm characteristics, and sexual behavior of mixed-breed goat bucks fed three leguminous trees

Aim of study: To investigate the effect of feeding foliage of leguminous trees on growth rate, semen characteristics, and sexual behavior of bucks. Area of study: Northeastern Mexico (23°44' N, 99°8' W). Material and methods: Twenty-two young goat bucks were randomly allocated to one of four treatment groups: 33% alfalfa hay (dry matter basis), 33%; Acacia farnesiana; Leucaena leucocephala; or Prosopis laevigata foliage (n=4 for alfalfa; n=6 for the rest of groups). Main results: Average daily gain (ADG) did not differ between bucks fed alfalfa, A. farnesiana, or L. leucocephala (120 ± 26, 134 ± 37, and 103 ± 29 g/d, respectively), but ADG of bucks offered P. laevigata was the lowest (72 ± 8 g; p<0.05). Bucks fed alfalfa had the highest feed efficiency (6.59 ± 1.25 kg of feed consumed/kg of gain; p<0.05) and bucks offered leguminous trees had the lowest (average 9.85 ± 2.3). Bucks offered alfalfa, and A. farnesiana had increased (p<0.05) scrotal circumference (26.6 ± 0.4 and 25.8 ± 1.5 cm) than bucks fed L. leucocephala, or P. laevigata (24.3 ± 1.2 and 24.1 ± 2.0 cm). Mean ejaculate volume was two-fold higher in alfalfa-fed bucks than all other dietary treatments. Sexual behavior did not differ among bucks fed the different legumes. Research highlights: Foliage of both A. farnesiana and L. leucocephala could totally replace alfalfa hay for rearing growing goat bucks in confinement without affecting daily weight gain, most semen characteristics, and copulation ability. P. laevigata reduced body weight and reproductive function

The role of late Quaternary tectonic activity and sea-level changes on sedimentary processes interaction in the Gulf of Cadiz upper and middle continental slope (SW Iberia)

A morphological and seismic-stratigraphic analysis of the Gulf of Cadiz area near the Strait of Gibraltar is presented in this work, focused on the sedimentary evolution of the upper and proximal middle-continental slope since the Mid-Pleistocene. Based on the analysis of seismic reflection profiles and swath bathymetry data, this work analyses the close influence of the activity of buried and outcropping diapiric ridges and late Quaternary sea-level changes on the evolution of contouritic features related to the Mediterranean Outflow Water (MOW) and Eastern North Atlantic Central Water (ENACW), gravitational features and fluid-escape structures. The stratigraphic architecture reveals that, under active diapiric deformation, the upper slope plastered drift grew during low sea-level stages, when sediment supply was high and the ENACW swept the upper slope, contrasting with the present-day highstand situation dominated by northwest-trending MOW flow. The south-estward ENACW flow forced asymmetry and lateral migration of gullies incised in the plastered drift. Two evolutionary stages have been established: 1) After the Mid Pleistocene, activity of diapirs with a NE trend determined the location of the deepest depressions which were infilled by plastered contouritic drifts; 2) Between Late Quaternary and present, a drastic change of buried diapirs growth pattern and orientation to a NW trend enhanced slope-derived gravitational processes affecting the bottom current dynamics. Adjustments to tectonic changes led to a phase of plastered drift growth on the upper slope during which depocenters varied their distribution and orientation. In a long-term the structural control on sedimentation shows a northwestward displacement of deformation, resulting in an overall extension of the contourite depositional system to the NW. In a short-term, sea-level changes favored drift deposition, gullies incision and the strengthening of water masses. This work evidences the importance of tectonic deformation in sedimentation at recent time scales, and the twodirectional interplay between recent tectonic activity and bottom current dynamics.Versión del edito

Ordering and finite-size effects in the dynamics of one-dimensional transient patterns

We introduce and analyze a general one-dimensional model for the description of transient patterns which occur in the evolution between two spatially homogeneous states. This phenomenon occurs, for example, during the Freedericksz transition in nematic liquid crystals.The dynamics leads to the emergence of finite domains which are locally periodic and independent of each other. This picture is substantiated by a finite-size scaling law for the structure factor. The mechanism of evolution towards the final homogeneous state is by local roll destruction and associated reduction of local wavenumber. The scaling law breaks down for systems of size comparable to the size of the locally periodic domains. For systems of this size or smaller, an apparent nonlinear selection of a global wavelength holds, giving rise to long lived periodic configurations which do not occur for large systems. We also make explicit the unsuitability of a description of transient pattern dynamics in terms of a few Fourier mode amplitudes, even for small systems with a few linearly unstable modes.Comment: 18 pages (REVTEX) + 10 postscript figures appende