Total metal burdens in the freshwater amphipod Gammarus fasciatus: contribution of various body parts and influence of gut contents

1. The distribution of trace metals among body parts of the freshwater amphipod Gammarus fasciatus was investigated and the effect of depuration on the total body burden was assessed.
2. Concentrations of Cr, Fe, Mn and Ni were one order of magnitude higher in the gut contents than in the various body parts, accounting for 40–72% of the total body burdens of amphipods. Depuration caused a decrease of total metal concentrations of 35–88%.
3. Levels of Cd and Cu were higher in the hepatopancreas than in other body parts, whereas levels of Zn were relatively constant throughout the body. For Cd, Cu and Zn, depuration had no effect on mean body concentrations.
4. For Pb, an important fraction of the total body burden was associated with the exoskeleton; depuration caused a decrease in Pb body concentrations.
5. Regression between amphipod metal concentrations before and after depuration is a potential tool for correcting for the effect of gut contents. This correcting method was found to be promising for Cd, Cu, Mn and Zn, with R ² varying between 0.66 and 0.98. It was less efficient for Cr, Fe and Pb, and was useless for Ni.     

A role for oxalic acid generation in ozone‐induced signallization in Arabidopis cells

Ozone (O₃) is an air pollutant with an impact increasingly important in our industrialized world. It affects human health and productivity in various crops. We provide the evidences that treatment of Arabidopsis thaliana with O₃ results in ascorbate‐derived oxalic acid production. Using cultured cells of A. thaliana as a model, here we further showed that oxalic acid induces activation of anion channels that trigger depolarization of the cell, increase in cytosolic Ca²⁺ concentration, generation of reactive oxygen species and cell death. We confirmed that O₃ reacts with ascorbate in the culture, thus resulting in production of oxalic acid and this could be part of the O₃‐induced signalling pathways that trigger programmed cell death.     

Development and mapping of a public reference set of SSR markers in Lolium perenne L.

We report on the characterization and mapping of 76 simple sequence repeat (SSR) markers for Lolium perenne. These markers are publicly available or obtained either from genomic libraries enriched for SSR motifs or L. perenne expressed sequence tag (EST) clones. Four L. perenne mapping populations were used to map the SSR markers. A consensus linkage map of the four mapping populations containing 65 of the SSR markers is presented, together with primer information and a quality score indicating the usefulness of the SSR marker in different populations. The SSR markers identified all seven L. perenne linkage groups.     

Total metal burdens in the freshwater amphipod Gammarus fasciatus: contribution of various body parts and influence of gut contents

1. The distribution of trace metals among body parts of the freshwater amphipod Gammarus fasciatus was investigated and the effect of depuration on the total body burden was assessed.
2. Concentrations of Cr, Fe, Mn and Ni were one order of magnitude higher in the gut contents than in the various body parts, accounting for 40–72% of the total body burdens of amphipods. Depuration caused a decrease of total metal concentrations of 35–88%.
3. Levels of Cd and Cu were higher in the hepatopancreas than in other body parts, whereas levels of Zn were relatively constant throughout the body. For Cd, Cu and Zn, depuration had no effect on mean body concentrations.
4. For Pb, an important fraction of the total body burden was associated with the exoskeleton; depuration caused a decrease in Pb body concentrations.
5. Regression between amphipod metal concentrations before and after depuration is a potential tool for correcting for the effect of gut contents. This correcting method was found to be promising for Cd, Cu, Mn and Zn, with R ² varying between 0.66 and 0.98. It was less efficient for Cr, Fe and Pb, and was useless for Ni.     

USE OF THREE RAPID DETECTION SYSTEMS TO EVALUATE THE PREVALENCE AND DISSEMINATION OF SALMONELLA IN A BRAZILIAN POULTRY SLAUGHTERHOUSE

Prevalence and dissemination of Salmonella in a Brazilian poultry slaughterhouse were evaluated by three rapid detection systems (SS/SV^TM, VICAM, OSRT^TM, Unipath/Oxoid, and REVEAL^TM, Neogen), plus the conventional procedure. The carcasses were sampled after bleeding (P1), defeathering (P2), evisceration (P3), washing (P4), chilling (P5) and the packaged end-product (P6). In the first set of carcasses, the Salmonella incidence determined by the conventional method was 38.3% and 22.5% by SS/SV^TM. In the set for evaluation of OSRT^TM, the number of positive samples was the same detected by the cultural procedure (49.0%). In the third set, the positivity by the conventional procedure was 33.3%, and 5.0% by REVEAL^TM. The comparisons of positives in the first and third sets of carcasses were significantly different (P < 0.05). The positivity for Salmonella, in carcasses at P1 to P6, as determined by at least one of the methods, was 47.5%, 47.5%, 32.5%, 30.0%, 30.0% and 37.7%, respectively.     

Summer depth selection in crustacean zooplankton in nutrient‐poor boreal lakes is affected by recent residential development

1. Strong vertical gradients in light, water temperature, oxygen, algal concentration and predator encounters during summer in stratified lakes may influence patterns of depth selection in crustacean zooplankton, especially Daphnia species. 2. To test how crustacean depth selection varies among lakes along a gradient of catchment disturbance by recent residential development and land use change, we calculated the weighted mean depth distribution of the biomass of crustaceans by day and night in eight nutrient‐poor boreal lakes. 3. Generally, the greatest biomass of crustaceans was located at the metalimnion or at the lower boundary of the euphotic zone during thermal stratification in July. The crustacean zooplankton avoided warm surface layers and tended to stay in colder deep waters by both day and night. They also remained at greater depths in lakes with a more extensive euphotic zone. 4. There was some evidence of upward nocturnal migrations of large Daphnia and copepods in some lakes, and one case of downward migration in a lake inhabited by chaoborid larvae. 5. Multivariate regression trees (MRT) were used to cluster crustaceans and Daphnia species in homogeneous groups based on lake natural and disturbance factors. For crustaceans, the depth of the euphotic zone, the sampling depth (epilimnion, metalimnion and hypolimnion), time (day or night) of sampling and the biomass of chlorophyll a were the main driving factors. For Daphnia species, the drainage area, the sampling depth, the cleared land surface area within the catchment and the concentration of total dissolved phosphorus were the main factors.