Essential oil from the leaves of Cryptomeria japonica acts as a silverfish (Lepisma saccharina) repellent and insecticide

This is the first article to report the evaluation of a natural product used as an antisilverfish agent. Silverfish (Lepisma saccharina), primitive wingless insects, feed on a variety of materials, including paper, cotton, starch, and cereals. They can be a problem in libraries and other places where books, documents, and papers are stored. In this pilot study, the essential oil from leaves of Cryptomeria japonica was investigated to test its properties as a silverfish repellent and insecticide. The results from a repellency bioassay show that the essential oil significantly repelled silverfish. The repellent activity was 80% at a dosage of 0.01 mg/cm³. When silverfish were exposed to a concentration of 0.16 mg/cm³ of essential oil, they were killed within 10h. The chemical composition of essential oil, the emissions from a test chamber, and the residue left on filter papers previously soaked with the essential oil in a chamber were analyzed by gas chromatography-mass spectrometry. The components of the essential oil were found to be: elemol (18.22%), 16-kaurene (11.63%), 3-carene (9.66%), sabinene (9.37%), 4-terpineol (9.06%), β-eudesmol (5.70%), α-pinene (5.62%), and limonene (5.26%). Only some constituents of the essential oil compounds collected by solid-phase microextraction were found to be emitted in the test chamber. The main constituents were: 3-carene (21.03%), p-cymene (10.95%), limonene (9.49%), β-myrcene (9.39%), γ-terpinene (9.10%), α-terpinene (8.57%), and 4-terpineol (7.97%).     

Determination of nitrofuran residues in milk of dairy cows using liquid chromatography-tandem mass spectrometry

An analytical method has been developed for the determination of total bound and extractable residues of the nitrofuran drugs furazolidone, nitrofurazone, furaltadone, and nitrofurantoin in milk of dairy cows. The method involves overnight acid hydrolysis and simultaneous derivatization of the released side chains with 2-nitrobenzaldehyde. During hydrolysis, the bound metabolites are hydrolyzed to the side chains. After pH adjustment and solid-phase extraction cleanup, the derivatives are detected and quantitated using a liquid chromatography-tandem mass spectrometry system with an atmospheric pressure chemical ionization interface. Validation of the method is accomplished by fortifying control milk with a mixture of side chains at 1, 2, and 4 ng/g. Internal standards are added at the beginning of the procedure to compensate for matrix effects and recovery losses. Method accuracies range from 83 to 104% with coefficients of variation less than 13% for all four analytes. The limits of detection are相似文献   

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济宁青山羊高繁殖力候选基因类固醇21-羟化酶基因(CYP21)的研究

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A single application of Cu to field soil has long-term effects on bacterial community structure, diversity, and soil processes

Long-term diversity-disturbance responses of soil bacterial communities to copper were determined from field-soils (Spalding; South Australia) exposed to Cu in doses ranging from 0 through to 4012 mg Cu kg⁻¹ soil. Nearly 6 years after application of Cu, the structure of the total bacterial community showed change over the Cu gradient (PCR-DGGE profiling). 16S rRNA clone libraries, generated from unexposed and exposed (1003 mg Cu added kg⁻¹ soil) treatments, had significantly different taxa composition. In particular, Acidobacteria were abundant in unexposed soil but were nearly absent from the Cu-exposed sample (P<0.05), which was dominated by Firmicute bacteria (P<0.05). Analysis of community profiles of Acidobacteria, Bacillus, Pseudomonas and Sphingomonas showed significant changes in structural composition with increasing soil Cu. The diversity (Simpsons index) of the Acidobacteria community was more sensitive to increasing concentrations of CaCl-extractable soil Cu (Cu_Ext) than other groups, with decline in diversity occurring at 0.13 Cu_Ext mg kg⁻¹ soil. In contrast, diversity in the Bacillus community increased until 10.4 Cu_Ext mg kg⁻¹ soil, showing that this group was 2 orders of magnitude more resistant to Cu than Acidobacteria. Sphingomonas was the most resistant to Cu; however, this group along with Pseudomonas represented only a small percentage of total soil bacteria. Changes in bacterial community structure, but not diversity, were concomitant with a decrease in catabolic function (BioLog). Reduction in function followed a dose-response pattern with Cu_Ext levels (R²=0.86). The EC₅₀ for functional loss was 0.21 Cu_Ext mg kg⁻¹ soil, which coincided with loss of Acidobacteria diversity. The microbial responses were confirmed as being due to Cu and not shifts in soil pH (from use of CuSO₄) as parallel Zn-based field plots (ZnSO₄) were dissimilar. Changes in the diversity of most bacterial groups with soil Cu followed a unimodal response - i.e. diversity initially increased with Cu addition until a critical value was reached, whereupon it sharply decreased. These responses are indicative of the intermediate-disturbance-hypothesis, a macroecological theory that has not been widely tested in environmental microbial ecosystems.     

Effect of soil copper on the response of soil fungal communities to the addition of plant residues

Organic residues provide the fundamental energy supply supporting soil fungal communities. Provision of adequate energy is required for soil microbial communities to adapt and function in the presence of ecological stress, such as copper (Cu) contamination. However, contamination can also lead to decreased ecological fitness of microorganisms, limiting their ability to access substrates. Thus, complex interactions exist between substrates, metals, energy supply/accessibility, fungal communities and their processes, and these have implications for ecosystem processes. We investigated the interaction between energy resources and Cu tolerance on soil fungal communities, including Fusarium and Trichoderma (model disease causing and beneficial genera). Using quantitative PCR and DGGE fingerprinting, the effects of increasing soil Cu levels (0 to >3000 mg Cu kg⁻¹ soil) on size and structure of soil fungal communities were tested under basal and plant-residue (medic; Medicago trunculata) added conditions. The interaction between increasing soil Cu levels and the addition of plant resources on fungal community structure was tested using multivariate analysis. The relative size (DNA copies per unit of soil DNA) of soil fungal communities, including Trichoderma and Fusarium, significantly (P < 0.05) increased (94% and 32% respectively) with addition of medic to soil. In medic-applied samples, the bacterial to fungal ratio decreased, demonstrating the selective influence of the cellulose-rich substrate on the fungal community. Under the high nutrient conditions fungal DNA increased as a fraction of the total soil DNA, demonstrating the tolerance of fungi to Cu (relative to other microbiota) given adequate energy resources. Copper had no impact on the abundance of Fusarium or Trichoderma, but significantly affected community structure (PERMANOVA; P < 0.05). With increasing Cu, species selection and replacement could be observed, particularly in soils where medic had been included. Plant residue addition itself was a highly selective factor affecting the structure of communities of Trichoderma and Fusarium (P < 0.05). The effects of increasing Cu could be seen in both medic and basal soils for Trichoderma, but only in the basal treatments for soil Fusarium. This was due to very low dispersion in Fusarium community structure in the medic-added treatment (PERMDISP; P < 0.05). The results show the interactive influence of organic matter inputs and heavy metal contamination on size and structure of soil fungal communities. The data show that species selection and replacement is an important mechanism for community adaptation to increasing levels of soil Cu, and this mechanism can be influenced by addition of resources to the soil.