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Uranium extraction, processing, and storage have resulted in a legacy of uranium-contaminated groundwater aquifers worldwide. An emerging remediation technology for such sites is the in situ immobilization of uranium via biostimulation of dissimilatory metal-reducing bacteria (DMRB). While this approach has been successfully demonstrated in experimental studies, advances in understanding and optimization of the technique are needed. The motivation of this work was to understand better how dual-porosity (DP) porous media may affect immobilization efficiency via interactions with the dominant geochemical and microbial processes. A biogeochemical reactive transport model was developed for uranium immobilization by DMRB in both single- and dual-porosity porous media. The impact that microbial residence location has on the success of biostimulated U(VI) immobilization in DP porous media was explored under various porosity and mass transfer conditions. Simulations suggest that DP media are likely to show delayed U(VI) immobilization relative to single-porosity systems. U(VI) immobilization is predicted to be less when microbial activity is restricted to diffusion-dominant regions but not when restricted to advective-dominant regions. The results further highlight the importance of characterizing the bioresidency status of field sites if biogeochemical models are to predict accurately remediation schemes in physically heterogeneous media. [ABSTRACT FROM AUTHOR]

A quantitative genetics approach was developed to identify the genomic regions that control relative water content (RWC) in field-grown barley. The trait was previously demonstrated to be a relevant screening tool of drought-tolerance in cereals, as well as a good indicator of plant water-status. The trait was measured at the heading stage on flag leaves recorded from 167 recombinant inbred lines grown in several Mediterranean sites (Montpellier, France; Meknès, Morocco; Le Kef, Tunisia). The results obtained confirmed that several genomic regions are implicated in the total phenotypic variation of RWC. A total of nine chromosomal regions were identified. One region situated on the long arm of chromosome 6H contains the most-consistent QTL obtained in the present study. This region was previously identified as controlling RWC, as well as leaf osmotic potential under water stress and osmotic adjustment, from an experiment conducted in growth-chamber conditions with the same genetic background. The confirmation of the role of this region in the genetic control of water and turgor status underlined its interest for breeding purposes in the Mediterranean area. In addition, the presence of several dehydrin loci in the same chromosomal area reinforce its interest for genomics analyses to confirm, or not to confirm, the implication of these genes in the variation of RWC. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluates the efficacy of cholestyramine to reduce the zearalenone (ZEN) toxicity in mice. The study used orthogonal polynomials to examine the response to increasing cholestyramine level in the diet and the analysis of variance, which were applied to uterine weight (wt) and wt gain. Results show that a 12% level of the dose response was observed when the ZEN concentration increased from four to eight mg/kg.

The article presents a study on the use of mouse bioassay for deoxynivalenol (DON), as a substitute to animal research. The study used Weanling outbred mice, which were subjected to experiments such as dietary treatments, hematological analysis, and analysis of variance. Results show factors that are considered in improving sensitivity of mouse bioassay as a model for animal studies, such as sensitivity to DON and food intake of low energy diet.

The effects of low dietary concentrations of Fusarium myco toxins (deoxynivalenol (DON), 1 5-acetyl-DON, and zearalenone) on growth, immunological, and hematological parameters were determined in young pigs during a 28-day feeding experiment. Clean and naturally contaminated corn were incorporated into basal diets formulated to contain 0.00, 0.75, 1.50, and 3.00 mg DON/kg diet. A pair-fed control animal was used for comparison with each animal receiving the highest level of contamination (diet 4). Skin temperature, measured during the first week of the experiment, decreased linearly as the dietary mycotoxin concentration increased. Several other linear effects were observed: depressed feed intake throughout the experiment, reduction in thyroid size (absolute/relative), and changes in the appearance of the esophageal region of the stomach (thicker and higher degree of folding with increasing toxin concentration). Serum T (thyroxine) levels increased quadratically after 7 and 28 days of exposure compared to control animals. This change coincided with an increase in albumin levels, a decrease in α-globulin levels, and an overall increase in albumin/globulin ratio as the level of contamination increased. After immunization with sheep red blood cells (SRBC), animals fed contaminated diets showed a delayed response in peak titers. At the end of the experiment an increase in the segmented neutrophil count was observed. The following observations were made for ani mals consuming diet 4 as compared to the pair-fed controls: lower skin temperature, better feed efficiency, more corrugated stomachs, reduced α-globulin levels, and lower antibody titers to SRBC. The study showed a physiobiochemical adaptation response of animals exposed to mycotoxin-contaminated diets. Although most changes seem to be related to the nutritional status of the animal, others such as reduced skin temperature, altered stomach condition, and reduced α-globulin levels suggest specific effects due to the toxins. The pair-feeding treatment was important in reaching these conclusions, but it is also evident that the treatment itself introduces changes in response to a reduced feed intake. [ABSTRACT FROM PUBLISHER]

Deoxynivalenol (DON, vomitoxin), a Fusarium mycotoxin, is suspected of inducing its anorectic/feed refusal activity through a serotoninergic (5HT) mechanism, possible via 5HT2-receptors. In this study the efficiency of cyproheptadine (CYP), a serotonin antagonist and known appetite stimulant, to attenuate the adverse effect of DON was investigated in mice. CYP was administered in the feed for two days before animals began receiving the DON, which was also added to the feed. Both agents were administered concurrently thereafter for a 12-day period. Dosing levels included various combinations of the two compounds, ranging from 0--16 ppm DON and 0--20 ppm CYP. Results showed that CYP could effectively offset the reduction in feed intake caused by dietary DON, but only when dose levels were optimized (CYP appeared to have a narrow effective dose range, which was also dependenton the DON concentration). In fact, optimum CYP doses were able to enhance feed intake in DON-fed mice above control levels, indicating that more than just a direct block of the toxin's effect was occurring. Conversely though, the effect of CYP on weight gain (WG) was ambiguous. At the lower CYP doses (/= 8 ppm) the overall WG generally remained depressed, and tended to be reduced further by increasing doses of CYP. These results provide additional support that serotoninergic mechanisms probably play a role in mediating DON-induced reduction in feed intake. Where and how DON actually initiates its anorectic effect, however, has not been resolved. [ABSTRACT FROM AUTHOR]