QuEChERS: a sample preparation for extraction of carbaryl from rat feces

Carbamate compounds are an important group of cholinesterase inhibitors. There is a need for creating awareness regarding the risks of the inadequate carbamate use in the residential areas due to potential adverse human effects. Carbaryl is a commonly used pesticide worldwide. A simple, fast, and high-throughput method was developed employing liquid chromatography with fluorescence detector to determine carbaryl residues in rat feces. The extraction was performed by using a rapid, easy, cheap, effective, reliable, and safe (QuEChERS) method, using acetonitrile as the extracting solvent. The parameters for the performance of the extraction method were optimized, such as ratio of mass of sample per volume of extraction solvent, QuEChERS content, and cleanup columns. Linear response was obtained for all calibration curves (solvent and matrix-matched) over the established concentration range (5–500 μg/L) with a correlation coefficients higher than 0.999. The achieved recovery was 97.9% with relative standard deviation values of 1.1% (n = 4) at 167 μg/kg fortified concentration level and the limits of detection and quantification were 27.7 and 92.3 µg/kg, respectively.     

Spatial extremes of wildfire sizes: Bayesian hierarchical models for extremes

In Portugal, due to the combination of climatological and ecological factors, large wildfires are a constant threat and due to their economic impact, a big policy issue. In order to organize efficient fire fighting capacity and resource management, correct quantification of the risk of large wildfires are needed. In this paper, we quantify the regional risk of large wildfire sizes, by fitting a Generalized Pareto distribution to excesses over a suitably chosen high threshold. Spatio-temporal variations are introduced into the model through model parameters with suitably chosen link functions. The inference on these models are carried using Bayesian Hierarchical Models and Markov chain Monte Carlo methods.     

Correlates of male mating success in great bustard leks: the effects of age, weight, and display effort

We examined how mating success varied in relation to age, weight, body size, and display behavior among great bustard Otis tarda males. The estimated mating success was strongly skewed, with 45% of adult males being involved in copulation attempts and only 9.7% actually seen copulating successfully. Unlike most birds, body size continued increasing in great bustards several years after reaching sexual maturity. Age, weight, and display effort were all significant and independent predictors of male mating success. The higher display effort involved performing longer full-display bouts. Older males could detach from the male flock earlier in the season as well as on each day and spend longer seasonal and daily periods displaying as solitary birds, which contributed to increase their mating success. In contrast, males weighing more did not invest more in display, which suggests that they could be recognized as dominants by other males and selected by females through assessment of their plumage sexual traits. In contrast to most other bird species, the system described for great bustards resembles that found in some lek-mating ungulates, where social rank is a complex trait determined by both age and mass, and as in these mammals, it suggests that sexual selection continues to favor a high male weight in this extremely sexually dimorphic species.     

Effects of induced paralysis on hemocytes and tissues of the giant lions-paw scallop by paralyzing shellfish poison

In general, bivalves are not affected by exposure to toxic dinoflagellates that produce paralyzing shellfish poisons (PSP). After injection with PSP extracted from the Gymnodinium catenatum, Nodipecten subnodosus is paralyzed, indicating that PSP provokes effects similar to what is observed in vertebrates, including paralysis and metabolic stress. To investigate the processes involved in poisoning by PSP, lions-paw scallops were injected with gonyautoxin (GTX) 2/3 epimers in the adductor muscle. Mild doses provoked adductor muscle contractions and paralysis, mantle retraction, and incapacity of shell closure, but scallops gradually recovered in a clear, dose-time recovery pattern. With high doses of GTX 2/3, scallops were permanently paralyzed, and hemocytes in hemolymph were reduced. Surprisingly, under these conditions, scallops continued normal feeding and did not show any microscopic defect in intestine or gills, but hemocytes infiltrated the adductor muscle and abnormal vitellogenesis and mantle melanization occurred. Paralysis stress was accompanied by negative scallop responses, based on visible effects, generation of nitric oxide, lipid peroxidation, and changes in antioxidant and hydrolytic enzymes in hemocytes and tissues. These data can be used to understand potential side effects of PSP in bivalves.