Effects of nonylphenol on the brain cytochrome P450 gene expression in F1 generation rats

In order to explore the effects of nonylphenol (NP) on brain cytochrome P450 gene expression in F1 generation rats microarray analysis techniques were used. mRNA were extracted from the brain of 2-day-old F1 generation rats whose F0 male generation were treated with NP, then reversely transcribed to cDNA and labeled with cy5 and cy3 for fluorescence. Subsequently, the cDNA probes were hybridized to the mouse 40S cDNA microarray; and fluorescent signals produced by cy5 and cy3 were scanned and analyzed. Sixteen identified genes were found to be expressed differently from control, including three cytochrome P450 genes, in which two were up-regulated and one down-regulated. Data suggest that NP affects the expression of some cytochrome P450 genes in rat brain when administered perinatally.     

Mutagenicity of diesel engine exhaust in the Ames / Salmonella assay using a direct exposure method

The aim of this study was to investigate the potential mutagenic activity of diesel engine exhaust in the Ames/Salmonella assay using a direct aerosol exposure system. So, TA 98 and TA 100 strains, with or without added S9 mix, were exposed to diesel emissions after varying degrees of filtration. Variants of these two strains, deficient in nitroreductase (TA 98NR and TA 100NR) or over-expressing O-Acetyl Transferase (YG 1024 and YG 1029), were also exposed to total (unfiltered) diesel exhaust to highlight the putative mutagenicity of any nitro-PAHs present in these emissions. Mutagenic activity of the diesel exhaust was demonstrated on Salmonella typhimurium, strains TA 100 and variants TA 100 NR and YG1029. The use of a particle filter did not modify the genotoxicity of the diesel emissions, indicating a major contribution of the gas phase to the mutagenicity of these diesel emissions. The prominent role of the particulate-associated nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) claimed by some authors working on diesel exhaust organic extracts was not confirmed by our results with native diesel exhaust exposure. Our results show that the gas phase is potentially more mutagenic than the particles alone.     

土壤和地下水中污染物迁移模型研究进展

国内外学者已建立了多种模型来描述污染物在土壤和地下水中的环境行为。要选择一个合适的模型在实际中成功地应用,或建立一个新的模型,必须掌握和了解污染物迁移模型的研究现状。文章评述了现有的模型,并对模型的结构作了一定的阐述。     

Resistance of the generalist moth Trichoplusia ni (Noctuidae) to a novel chemical defense in the invasive plant Conium maculatum

Summary. Conium maculatum is an apiaceous species native to Eurasia that is highly toxic to vertebrates due to the presence of piperidine alkaloids, including coniine and γ-coniceine. More than 200 years after invading the United States this species remains mostly free from generalist insect herbivores. The presence of novel chemical defenses in the introduced range could provide invasive species with a competitive advantage relative to native plants. The cabbage looper (Trichoplusia ni) is a generalist lepidopteran found throughout the US that occasionally feeds on C. maculatum. We evaluated the toxicity of piperidine alkaloids to T. ni and determined putative resistance mechanisms, both behavioral and physiological, that allows this insect to develop successfully on C. maculatum foliage. T. ni larvae raised on diets enriched with coniine and γ-coniceine showed a decrease in consumption and longer development time, but no effects on growth were found at any alkaloid concentration. In a diet choice experiment T. ni larvae showed no avoidance of alkaloid-enriched diets, suggesting that the deterrence produced by alkaloids was related to a post-ingestive metabolic response. The ability of T. ni to consume diets high in alkaloid content could be due to at least three different mechanisms: 1) a decreased consumption rate, 2) efficient excretion of at least 1/3 of ingested alkaloids unmetabolized in frass, and 3) partial detoxification of alkaloids by cytochrome P450 s, as shown by the decreased larval growth in the presence of piperonyl butoxide, a P450 inhibitor. Even though T. ni tolerates C. maculatum alkaloids, the use of this species as a host plant could be ecologically disadvantageous due to prolonged larval growth and thus increased exposure to predators. Novel plant secondary compounds do not guarantee increased resistance to generalist herbivores.     

An improved technique for the determination of organic phosphorus in sediments and soils by 31P nuclear magnetic resonance spectroscopy

Knowledge of organic phosphorus (P) species quantity and distribution in sediments and soils is needed to determine the potential for aquatic and terrestrial organism growth. This can be achieved with ³¹P nuclear magnetic resonance spectroscopy (NMR), but resolving peaks within spectra can be problematic because of broadening via paramagnetics, which can cause peaks to overlap. We compared ³¹P NMR spectra of NaOH-EDTA extracts of three sediments and three soils to those that had first been pre-treated with Ca-EDTA-dithionite to remove Fe and Mn, paramagnetics that cause broadening of peaks, but leave organic P alone. Broadening of peaks in Ca-EDTA-dithionite pre-treated samples decreased by 46% and revealed peaks that were hidden compared to untreated samples. The spectrum of one pre-treated soil was similar if not better than the same soil that had received pre-treatment with Chelex resin (also to remove paramagnetics). Therefore, pre-treatment with Ca-EDTA-dithionite is recommended as a simple and cost-effective method for improving organic P idenTIFication and determination in subsequent NaOH-EDTA extracts of sediments and soils rich in Fe and Mn.