Ecologically Appropriate Xenobiotics Induce Cytochrome P450s in Apis mellifera

BACKGROUND: Honey bees are exposed to phytochemicals through the nectar, pollen and propolis consumed to sustain the colony. They may also encounter mycotoxins produced by Aspergillus fungi infesting pollen in beebread. Moreover, bees are exposed to agricultural pesticides, particularly in-hive acaricides used against the parasite Varroa destructor. They cope with these and other xenobiotics primarily through enzymatic detoxificative processes, but the regulation of detoxificative enzymes in honey bees remains largely unexplored. METHODOLOGY/PRINCIPAL FINDINGS: We used several approaches to ascertain effects of dietary toxins on bee susceptibility to synthetic and natural xenobiotics, including the acaricide tau-fluvalinate, the agricultural pesticide imidacloprid, and the naturally occurring mycotoxin aflatoxin. We administered potential inducers of cytochrome P450 enzymes, the principal biochemical system for Phase 1 detoxification in insects, to investigate how detoxification is regulated. The drug phenobarbital induces P450s in many insects, yet feeding bees with phenobarbital had no effect on the toxicity of tau-fluvalinate, a pesticide known to be detoxified by bee P450s. Similarly, no P450 induction, as measured by tau-fluvalinate tolerance, occurred in bees fed xanthotoxin, salicylic acid, or indole-3-carbinol, all of which induce P450s in other insects. Only quercetin, a common pollen and honey constituent, reduced tau-fluvalinate toxicity. In microarray comparisons no change in detoxificative gene expression was detected in phenobarbital-treated bees. However, northern blot analyses of guts of bees fed extracts of honey, pollen and propolis showed elevated expression of three CYP6AS P450 genes. Diet did not influence tau-fluvalinate or imidacloprid toxicity in bioassays; however, aflatoxin toxicity was higher in bees consuming sucrose or high-fructose corn syrup than in bees consuming honey. CONCLUSIONS/SIGNIFICANCE: These results suggest that regulation of honey bee P450s is tuned to chemicals occurring naturally in the hive environment and that, in terms of toxicological capacity, a diet of sugar is not equivalent to a diet of honey

Autonomous Aeromagnetic Surveys Using a Fluxgate Magnetometer

Recent advances in the research of autonomous vehicles have showed a vast range of applications, such as exploration, surveillance and environmental monitoring. Considering the mining industry, it is possible to use such vehicles in the prospection of minerals of commercial interest beneath the ground. However, tasks such as geophysical surveys are highly dependent on specific sensors, which mostly are not designed to be used in these new range of autonomous vehicles. In this work, we propose a novel magnetic survey pipeline that aims to increase versatility, speed and robustness by using autonomous rotary-wing Unmanned Aerial Vehicles (UAVs). We also discuss the development of a state-of-the-art three-axis fluxgate, where our goal in this work was to refine and adjust the sensor topology and coupled electronics specifically for this type of vehicle and application. The sensor was built with two ring-cores using a specially developed stress-annealed CoFeSiB amorphous ribbon, in order to get sufficient resolution to detect concentrations of small ferrous minerals. Finally, we report on the results of experiments performed with a real UAV in an outdoor environment, showing the efficacy of the methodology in detecting an artificial ferrous anomaly

Internal Filters : Prospects for UV-Acclimation in Higher Plants

Wavelength-selective absorption of solar radiation within plant leaves allows penetration of visible radiation to the chloroplats, while removing much of the damaging ultraviolet-B radiation. Flavonoids are important in this wavelength-selective absorption. Induction of flavonoid synthesis by solar radiation, and specifically by UV-B radiation, is discussed as this relates to the potential acclimation of plants to enhanced solar UV-B radiation that would result from stratospheric ozone reduction

Resistência ao cisalhamento de um latossolo sob diferentes uso e manejo Shear strength of a latosol under different use and management

A resistência do solo ao cisalhamento é uma importante propriedade dinâmica do solo, a qual vem sendo desconsiderada na maioria das pesquisas que investigam a influência do uso e manejo, assim como os estados de consistência , sobre o comportamento da estrutura dos solos agrícolas. Isto tem contribuído para a adoção de estratégias quase sempre equivocadas, tendo, como conseqüência, o depauperamento das propriedades físicas e mecânicas do solo. Este trabalho teve como objetivo estudar a resistência ao cisalhamento de um Latossolo Vermelho distrófico submetido ao preparo convencional e semeadura direta, tendo, como tratamento-testemunha, o cerradão, considerando diferentes conteúdos de água: 0,05; 0,16; 0,18 e 0,38 kg kg-1. Com base nos resultados encontrados, verificou-se que a resistência ao cisalhamento do solo, avaliada na profundidade de 0-0,05 m do Latossolo Vermelho distrófico, foi influenciada pelo aumento da umidade, tipo de uso e manejo. De maneira geral, as equações ajustadas conforme o modelo de Coulomb constataram maior resistência do solo ao cisalhamento no cerradão, seguido do preparo convencional e semeadura direta. A menor resistência ao cisalhamento do solo estudado, corroborada pelo menor atrito interno (tg f) e maior coesão aparente (c), especificamente nos teores de água 0,16 e 0,27 kg kg-1 (contemplando, portanto, a faixa friável do solo), confere à semeadura direta a condição de maior possibilidade de preservação da sustentabilidade da estrutura do Latossolo Vermelho distrófico. A predição da tensão de cisalhamento apresentou-se sensível aos efeitos da variação do teor de água no solo, ao tipo de uso, podendo contribuir, particularmente, em estudos da sustentabilidade da estrutura dos solos agrícolas, a qual normalmente é comprometida em áreas cujo tráfego e preparo do solo são realizados inadequadamente.<br>Shear soil strength is an important dynamic property of the soil, as well as the state of soil consistence concerning the structure behavior of agricultural soils, which are mostly being ignored in research into the influence of use and management. This fact has been contributing to the perennial problem of fallacious strategies, causing degradation of the physical and mechanical soil properties. This study aimed at an evaluation of the shear soil strength of a dystrophic Red Latosol submitted to conventional tillage, direct seeding, and Cerrado as control treatment, with different water contents: 0.05; 0.16; 0.18, and 0.38 kg kg-1. Results allowed the conclusion that the shear strength of the soil, appraised at a depth of 0-0.05 m of a dystrophic Red Latosol, was affected by water content increases, use and management type. In general, the adjusted equations according to the Coulomb model evidenced greater shear strength in the Cerrado, followed by conventional tillage, and direct seeding. The lowest shear strength of the studied soil, corroborated by the smallest internal friction angle (tg f) and larger apparent cohesion (c), specifically for the water content 0.16 and 0.27 kg kg-1 (contemplating, therefore, the friable range of the soil), pointed to direct seeding as the management with the greatest possibilities of preserving the structural sustainability of the soil studied. The prediction of shear tension proved to be sensitive to the effects of soil water variations and the use type. This enables significant contributions, particularly to studies on the structural sustainability of agricultural soils, which are usually impaired by inadequate traffic and tillage operations