Structure-activity relationships of larvicidal monoterpenes and derivatives against Aedes aegypti Linn

In the search for larvicidal compounds against Aedes aegypti L. (Diptera: Culicidae), a collection of monoterpenes were selected and evaluated. R- and S-limonene exhibited the highest larvicidal potency (LC₅₀ = 27 and 30 ppm, respectively), followed by γ-terpinene (LC₅₀ = 56 ppm) and RS-carvone (LC₅₀ = 118 ppm). Structural characteristics which may contribute to the understanding of the larvicidal activity of monoterpenes were empirically identified. The presence of heteroatoms in the basic hydrocarbon structure decreases larvicidal potency. Conjugated and exo double bonds appear to increase larvicidal potency. Replacement of double bonds by more reactive epoxides decreases the larvicidal potency. The presence of hydroxyls in the cyclic structure resulted in decreased potency, probably due to increased polarity indicanting that lipophilicity seems to play an important role in increasing the larvicidal potency in this set of compounds.     

Development of an analytical strategy based on liquid chromatography-high resolution mass spectrometry for measuring perfluorinated compounds in human breast milk: application to the generation of preliminary data regarding perinatal exposure in France

Perfluorinated compounds (PFCs) are man-made chemicals for which endocrine disrupting properties and related possible side effects on human health have been reported, particularly in the case of an exposure during the early stages of development, (notably the perinatal period). Existing analytical methods dedicated to PFCs monitoring in food and/or human fluids are currently based on liquid chromatography coupled to tandem mass spectrometry, and were recently demonstrated to present some limitations in terms of sensitivity and/or specificity. An alternative strategy dedicated to the analysis of fourteen PFCs in human breast milk was proposed, based on an effective sample preparation followed by a liquid chromatography coupled to high resolution mass spectrometry measurement (LC-HRMS). This methodology confirmed the high interest for HRMS after negative ionization for such halogenated substances, and finally permitted to reach detection limits around the pg mL(-1) range with an outstanding signal specificity compared to LC-MS/MS. The proposed method was applied to a first set of 30 breast milk samples from French women. The main PFCs detected in all these samples were PFOS and PFOA with respective median values of 74 (range from 24 to 171) and 57 (range from 18 to 102) pg mL(-1), respectively. These exposure data appeared in the same range as other reported values for European countries.     

Hepatitis A Virus: State of the Art

Hepatitis A is the most common among all hepatitis worldwide in spite of an efficient vaccine and improved hygiene. Shellfish-borne outbreaks are still of major concern causing hundreds of cases and huge economical losses in the present context of global food trade. Hepatitis A virus (HAV) is a unique picornavirus with many differences in its molecular biology including both its incapacity to induce the inhibition of the cellular protein synthesis and a highly biased and deoptimized codon usage with respect the cell. The final goal of this intriguing strategy seems to be the need for a fine-tuning control of the translation kinetics, particularly at the capsid coding region, and the underlying mechanism is the use of a right combination of common and rare codons to allow a regulated ribosome traffic rate thus ensuring the proper protein folding. Capsid folding is critical to warrant a high environmental stability for a virus transmitted through the fecal–oral route with long extracorporeal periods.     

Egg antimicrobials, embryo sex and chick phenotype in the yellow-legged gull

Maternal effects through albumen quality are largely unexplored, despite the fundamental role that albumen exerts as source of proteins and water, as well as for antimicrobial defence of the embryo. We analysed the variation of two major albumen antimicrobials, avidin and lysozyme, by extracting samples from freshly laid eggs of the yellow-legged gull (Larus michahellis) and by correlating their levels to egg features. Lysozyme concentration increased along the laying sequence, while avidin concentration decreased. Both antimicrobials declined during the season. In addition, avidin concentration declined from first- to last-laid male eggs, whereas the opposite was true among the female eggs. We also analysed chick body mass and size and immune response, in relation to albumen antimicrobial levels in their original egg while controlling for potential covariation between egg quality and rearing conditions by cross-fostering eggs between nests. Tarsus length decreased with avidin concentration, particularly early in the season. Avidin concentration negatively predicted tarsus length of chicks and the phytohaemagglutinin response of females, but not males. However, chick phenotype did not covary with lysozyme albumen concentration. This is the first study where maternal effects mediated by albumen antimicrobials are investigated in relation to both sex and egg features in any wild bird species. Whether the observed patterns of variation in antimicrobial concentration are the by-product of maternal physiological constraints, or reflect adaptive allocation strategies, cannot be ascertained. The covariation between chick cell-mediated immunity and albumen avidin concentration might be causal, according to the documented effects of albumen proteins on immunity in other species.     

Stormwater treatment: examples of computational fluid dynamics modeling

Control of rainfall-runoff particulate matter (PM) and PM-bound chemical loads is challenging; in part due to the wide gradation of PM complex geometries of many unit operations and variable flow rates. Such challenges and the expense associated with resolving such challenges have led to the relatively common examination of a spectrum of unit operations and processes. This study applies the principles of computational fluid dynamics (CFD) to predict the particle and pollutant clarification behavior of these systems subject to dilute multiphase flows, typical of rainfall-runoff, within computationally reasonable limits, to a scientifically acceptable degree of accuracy. The Navier-Stokes (NS) system of nonlinear partial differential equations for multiphase hydrodynamics and separation of entrained particles are solved numerically over the unit operation control volume with the boundary and initial conditions defined and then solved numerically until the desired convergence criteria are met. Flow rates examined are scaled based on sizing of common unit operations such as hydrodynamic separators (HS), wet basins, or filters, and are examined from 1 to 100 percent of the system maximum hydraulic operating flow rate. A standard turbulence model is used to resolve flow, and a discrete phase model (DPM) is utilized to examine the particle clarification response. CFD results closely follow physical model results across the entire range of flow rates. Post-processing the CFD predictions provides an in-depth insight into the mechanistic behavior of unit operations by means of three dimensional (3-D) hydraulic profiles and particle trajectories. Results demonstrate the role of scour in the rapid degradation of unit operations that are not maintained. Comparisons are provided between measured and CFD modeled results and a mass balance error is identified. CFD is arguably the most powerful tool available for our profession since continuous simulation modeling.     

Stable isotopes identify age- and sex-specific dietary partitioning and foraging habitat segregation in southern giant petrels breeding in Antarctica and southern Patagonia

We examined the isotopic signatures (δ¹³C, δ¹⁵N) of adult body feathers from southern giant petrels Macronectes giganteus collected at two breeding colonies in Antarctica (Potter Peninsula and Cape Geddes) and one in southern Patagonia (Observatorio Island), as well as in whole blood collected from adults of both sexes at each Antarctic colonies and from chicks at Potter Peninsula. As body feather moult is a continuous process in giant petrels, feathers provide an integrated annual signal of an adult’s diets and foraging habitats. In contrast, the stable isotope values of adult and chick blood are reflective of their diets during the breeding season. We found that sex-specific dietary segregation in adults breeding in Antarctica was notable during the breeding season (blood samples) but absent when examined across the entire year (feather samples). In addition, blood stable isotope values differed between chicks and adults, indicating that adults provision their offspring with a relatively higher amount of penguin and seal prey that what they consume themselves. This finding confirms previous work that suggests that chicks are preferentially fed with prey of presumably higher nutritional value such as carrion. Finally, based on isotopic differences between major oceanographic zones in the Southern Ocean, our data indicate population-specific differences in foraging distribution, with Antarctic populations move seasonally between Antarctic and subantarctic zones, while Patagonian populations likely forage in subtropical waters and in continental shelf habitats year-round.     

Innate responses to male sexual harassment in female mosquitofish

Male mosquitofish are very persistent in their sexual activity and harass any female they encounter. Gravid females pay a large tribute to this intense male sexual activity in terms of reduced foraging efficiency. Previous observations have demonstrated that gravid females, when chased by a male, dilute male harassment by moving closer to other females to form shoals. They also approach other males to promote male competition, and when males differ in size, they preferentially target large males, whose harassment is less intense. In this study, we tested whether the modulation of females’ social preferences in response to male harassment is innate or learned. We tested social preference in three groups of females that differed in experience of sexual harassment and in the factors affecting it. Females of the first group were reared without any sexual experience, and pregnancy was induced through artificial insemination. The second group was composed of naive females kept singly with a male; these females experienced sexual harassment but were prevented from experiencing the effects of male–male competition and shoaling on the amount of male sexual harassment. In the third group (controls), females were reared in multi-male, multi-female groups and could experience the modulating effects of social interactions on sexual harassment. When exposed to a harassing male, females of the three groups immediately reduced their distance from another female, approached a group of males or moved toward the larger of two available males. Moreover, the results for these three groups of females were similar to those obtained in wild-caught females that were tested in the same three tests in a previous study (Dadda et al. An. Behav., 70:463–471, 2005). This suggests that the strategies adopted by females in response to male sexual harassment do not need to be learned through specific experience of the social contexts.