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Standardized grass cultures are routinely used to evaluate the accumulation of air pollutants. For the assessment of air pollutant accumulation in grass cultures, it is particularly important to distinguish between “normal” concentrations and the significantly increased accumulation caused by air pollution. This article presents a method to determine “normal” element concentrations (background levels) and define threshold values for the significantly elevated accumulation of pollutants for individual series of grass cultures. By applying the same method for the data from six regional air quality measuring programs, it was possible to derive universally applicable “normal” concentrations and threshold values for grass cultures. The described method is not limited to the evaluation of data from grass cultures but is also suitable for other biological or ecological data. It allows to distinguish between “normal” element concentrations and unusually high or low concentrations. 相似文献
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Anna B. Fischer J. P. Buchet R. R. Lauwerys 《Environmental geochemistry and health》1989,11(3-4):87-92
The cytotoxicity of trivalent and pentavalent inorganic arsenic was studied in cultured mouse fibroblasts. Concentrations of As(III) in the M range and approximately 10-fold higher concentrations of As(V) led to a reduction of cellular proliferation and viability with a concomitant increase of LDH release and stimulation of lactate production. Cells pretreated with a low As(III) concentration were less sensitive to toxic doses of As(III) or As(V).Uptake of As(III) by the cells was greater than that of As(V). Both forms of inorganic arsenic were converted intracellularly to monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which were subsequently released into the culture medium. In As-pretreated cells, which proved more resistant to As toxicity, biotransformation of inorganic to MMA and DMA was increased. 相似文献
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We know that animals are harmed in plant production. Unfortunately, though, we know very little about the scale of the problem. This matters for two reasons. First, we can’t decide how many resources to devote to the problem without a better sense of its scope. Second, this information shortage throws a wrench in arguments for veganism, since it’s always possible that a diet that contains animal products is complicit in fewer deaths than a diet that avoids them. In this paper, then, we have two aims: first, we want to collect and analyze all the available information about animal death associated with plant agriculture; second, we try to show just how difficult it’s to come up with a plausible estimate of how many animals are killed by plant agriculture, and not just because of a lack of empirical information. Additionally, we show that there are significant philosophical questions associated with interpreting the available data—questions such that different answers generate dramatically different estimates of the scope of the problem. Finally, we document current trends in plant agriculture that cause little or no collateral harm to animals, trends which suggest that field animal deaths are a historically contingent problem that in future may be reduced or eliminated altogether. 相似文献
268.
V. Rivas A. González D. W. Fischer A. Cendrero 《Journal of Environmental Planning and Management》1994,37(3):305-322
The problems involved in environmental assessment of land‐use plans are discussed. A methodology is proposed for incorporating into the assessment of a plan the modifications that the physical environment would experience as a result of the plan's implementation. Thus, EIA can be integrated into the planning process. Impact assessment and comparison between alternative plans can be made using quantitative and qualitative indicators, some of which are proposed. Several case studies in northern Spain are used as the basis for the suggestions made. 相似文献
269.
Most animals can modulate nutrient storage pathways according to changing environmental conditions, but in honey bees nutrient storage is also modulated according to changing behavioral tasks within a colony. Specifically, bees involved in brood care (nurses) have higher lipid stores in their abdominal fat bodies than forager bees. Pheromone communication plays an important role in regulating honey bee behavior and physiology. In particular, queen mandibular pheromone (QMP) slows the transition from nursing to foraging. We tested the effects of QMP exposure on starvation resistance, lipid storage, and gene expression in the fat bodies of worker bees. We found that indeed QMP-treated bees survived much longer compared to control bees when starved and also had higher lipid levels. Expression of vitellogenin RNA, which encodes a yolk protein that is found at higher levels in nurses than foragers, was also higher in the fat bodies of QMP-treated bees. No differences were observed in expression of genes involved in insulin signaling pathways, which are associated with nutrient storage and metabolism in a variety of species; thus, other mechanisms may be involved in increasing the lipid stores. These studies demonstrate that pheromone exposure can modify nutrient storage pathways and fat body gene expression in honey bees and suggest that chemical communication and social interactions play an important role in altering metabolic pathways. 相似文献
270.
It is frequently assumed that males have an almost unlimited reproductive capacity, while access to receptive females is typically
limiting. Consequently, sexual selection is expected to favor vigorous courtship behavior in males. If such behavior is associated
with non-trivial costs, ample current mating opportunities should be accompanied by a reduction in future mating vigor. To
test this hypothesis, three treatments differing in sex ratio were established using the tropical butterfly Bicyclus anynana: 50 males each were housed either with 0, 25, or 50 females. Mating trials involving the competition among males from each
treatment for a single virgin female were carried out on days 3, 9, and 15 after allocation to treatments. While there was
no difference on day 3, prior mating opportunity clearly reduced mating success on days 9 and 15, being lowest if identical
numbers of males and females were housed together. This finding suggests accumulating costs associated with high courtship
and/or mating activity. Further, older males were more active and initiated copulation earlier than the younger ones, consistent
with the residual reproductive value hypothesis. We found no evidence for a survival or fertility cost of mating. 相似文献