Identification of proteins induced by polycyclic aromatic hydrocarbon in Mycobacterium vanbaalenii PYR-1 using two-dimensional polyacrylamide gel electrophoresis and de novo sequencing methods

Protein profiles of Mycobacterium vanbaalenii PYR-1 grown in the presence of high-molecular-weight polycyclic aromatic hydrocarbons (HMW PAHs) were examined by two-dimensional gel electrophoresis (2-DE). Cultures of M. vanbaalenii PYR-1 were incubated with pyrene, pyrene-4,5-quinone (PQ), phenanthrene, anthracene, and fluoranthene. Soluble cellular protein fractions were analyzed and compared, using immobilized pH gradient (IPG) strips. More than 1000 gel-separated proteins were detected using a 2-DE analysis program within the window of isoelectric point (pI) 4-7 and a molecular mass range of 10-100 kDa. We observed variations in the protein composition showing the upregulation of multiple proteins for the five PAH treatments compared with the uninduced control sample. By N-terminal sequencing or mass spectrometry, we further analyzed the proteins separated by 2-DE. Due to the lack of genome sequence information for this species, protein identification provided an analytical challenge. Several PAH-induced proteins were identified including a catalase-peroxidase, a putative monooxygenase, a dioxygenase small subunit, a small subunit of naphthalene-inducible dioxygenase, and aldehyde dehydrogenase. We also identified proteins related to carbohydrate metabolism (enolase, 6-phosphogluconate dehydrogenase, indole-3-glycerol phosphate synthase, and fumarase), DNA translation (probable elongation factor Tsf), heat shock proteins, and energy production (ATP synthase). Many proteins from M. vanbaalenii PYR-1 showed similarity with protein sequences from M. tuberculosis and M. leprae. Some proteins were detected uniquely upon exposure to a specific PAH whereas others were common to more than one PAH, which indicates that induction triggers not only specific responses but a common response in this strain.     

Ant semiochemicals limit apterous aphid dispersal

Some organisms can manipulate the nervous systems of others or alter their physiology in order to obtain benefit. Ants are known to limit alate aphid dispersal by physically removing wings and also through chemical manipulation of the alate developmental pathway. This results in reduced dispersal and higher local densities of aphids, which benefit ants in terms of increased honeydew and prey availability. Here, we show that the walking movement of mutualistic apterous aphids is also reduced by ant semiochemicals. Aphids walk slower and their dispersal from an unsuitable patch is hampered by ants. If aphid walking dispersal has evolved as a means of natural enemy escape, then ant chemicals may act as a signal indicating protection; hence, reduced dispersal could be adaptive for aphids. If, however, dispersal is primarily a means to reduce competition or to maintain persistent metapopulations, then manipulation by ants could be detrimental. Such manipulation strategies, common in host-parasite and predator-prey interactions, may be more common in mutualism than expected.     

微生物降解多环芳烃的研究进展

多环芳烃(PAHs)是具有严重危害的环境污染物质。介绍PAHs的降解菌,降解机理和PAHs的生物修复方面的研究进展。土壤中PAHs的生物修复被认为是解决污染的有效方法,目前,菲的生物降解途径已经比较清楚,但对结构更为复杂的多环芳烃研究较少。文章还对消除环境中多环芳烃的相关生物技术提出展望。     

Asymmetric reduction of alpha, beta-unsaturated ketone to (R) allylic alcohol by Candida chilensis

A pilot scale whole cell process was developed for the enantioselective 1,2-reduction of prochiral alpha,beta-unsaturated ketone to (R) allylic alcohol using Candida chilensis. Initial development showed high enantiomeric excess (EE > 95%) but low product yield (10%). Process development, using a combination of statistically designed screening and optimization experiments, improved the desired alcohol yield to 90%. The fermentation growth stage, particularly medium composition and growth pH, had a significant impact on the bioconversion while process characterization identified diverse challenges including the presence of multiple enzymes, substrate/product toxicity, and biphasic cellular morphology. Manipulating the fermentation media allowed control of the whole cell morphology to a predominantly unicellular broth, away from the viscous pseudohyphae, which were detrimental to the bioconversion. The activity of a competing enzyme, which produced the undesired saturated ketone and (R) saturated alcohol, was minimized to < or =5% by controlling the reaction pH, temperature, substrate concentration, and biomass level. Despite the toxicity effects limiting the volumetric productivity, a reproducible and scaleable process was demonstrated at pilot scale with high enantioselectivity (EE > 95%) and overall yield greater than 80%. This was the preferred route compared to a partially purified process using ultra centrifugation, which led to improved volumetric productivity but reduced yield (g/day). The whole cell approach proved to be a valuable alternative to chemical reduction routes, as an intermediate step for the asymmetric synthesis of an integrin receptor antagonist for the inhibition of bone resorption and treatment of osteoporosis.     

An Overview of the Development,Status, and Application of Equilibrium Partitioning Sediment Benchmarks for PAH Mixtures

This article provides an overview of the development, theoretical basis, regulatory status, and application of the U.S. Environmental Protection Agency's (USEPA's) Equilibrium Partitioning Sediment Benchmarks (ESBs) for PAH mixtures. ESBs are compared to other sediment quality guidelines (SQGs) for PAHs. Data that examine the ability of the ESB approach to predict toxic effects to invertebrates are discussed. A USEPA draft methodology for the development of site-specific ESBs that takes into account the limited bioavailability of PAHs at certain sites is discussed. Research is presented that compares the ability of ESBs and site-specific ESBs to predict the toxicity of sediments collected from manufactured gas plants (MGPs). Site-specific ESBs that accounted for adsorption of PAHs onto black carbon were better predictors of the toxicity of sediments from MGP sites than ESBs that did not account for adsorption to black carbon.     

Increased levels of urinary biomarkers of lipid peroxidation products among workers occupationally exposed to diesel engine exhaust

Diesel engine exhaust (DEE) was found to induce lipid peroxidation (LPO) in animal exposure studies. LPO is a class of oxidative stress and can be reflected by detecting the levels of its production, such as malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), and etheno-DNA adducts including 1,N⁶-etheno-2′-deoxyadenosine (?dA) and 3,N⁴-etheno-2′-deoxycytidine (?dC). However, the impact of DEE exposure on LPO has not been explored in humans. In this study, we evaluated urinary MDA, 4-HNE, ?dA, and ?dC levels as biomarkers of LPO among 108 workers with exclusive exposure to DEE and 109 non-DEE-exposed workers. Results showed that increased levels of urinary MDA and ?dA were observed in subjects occupationally exposed to DEE before and after age, body mass index (BMI), smoking status, and alcohol use were adjusted (all p?p?p?相似文献   

Phytoremediation of polycyclic hydrocarbon contaminated soil: part II. Impact on ecotoxicity

Several biological assays were used to evaluate the toxic effects of contaminants in soil after phytoremediation. During the treatment process, significant decreases in overall toxicity were observed. Specifically, earthworm survivability and lettuce germination increased over the study period. Microbial respiration improved, but only in planted treatments. Toxicity and total polycyclic aromatic hydrocarbon concentrations showed some correlation, but the relationships generally were not significant. Soil moisture was less of a predictor for biological responses. The presence of plants did not provide a clear advantage for improving toxicity compared to unplanted treatments.     

多环芳烃微生物降解基因的研究进展

多环芳烃(PAHs)是环境中普遍存在的一类有机污染物,微生物的降解是PAHs去除的主要途径。近年来,有关PAHs微生物降解途径和代谢产物的研究已有很多报道。小分子PAHs一般可以直接被微生物降解,而大分子PAHs则需要微生物以共代谢的方式降解。在过去20年中,微生物降解PAHs的基因相继被发现,各种基因在调控PAHs降解过程中的功能也越来越清晰。本文概述了PAHs微生物降解基因方面的研究进展,详细介绍了微生物对萘、菲的降解基因,最后对PAHs微生物降解基因的应用前景进行了展望。     

Compounds in urban air compete with 2,3,7,8-tetrachlorodibenzo-p-dioxin for binding to the receptor protein

Acetone extracts of filter-collected urban airborne particulate matter contain compounds which can competitively inhibit 2,3,7,8-[1,6-3H]tetrachlorodibenzo-p-dioxin (TCDD) binding to the rat liver TCDD-receptor protein. The concentration of conventional polycyclic aromatic hydrocarbons (PAHs) or chlorinated dioxins and dibenzofurans cannot account for more than 1-30% of the observed competition for [3H]TCDD binding to the receptor protein. The difference in potency between samples collected in urban areas during different periods of the year and a background sample is 25-400-fold. Collecting samples in the presence of increased concentrations of nitrogen dioxide, nitrous acid, nitric acid or ozone did not increase the amount of compounds with receptor affinity. However, with nitrogen dioxide and especially with nitric acid, a substantial increase of the mutagenic effects in the Ames Salmonella assay in the absence of mammalian activation as well as a degradation of several PAHs were noted. Affinity for the TCDD-receptor protein, mutagenicity in the absence of mammalian metabolic activation in the Ames Salmonella assay and PAH-content are characteristics of urban particulate matter showing the presence of compounds, that represent potential health risks. The compounds with affinity for the receptor may constitute a group of substances different from both conventional PAHs and direct-acting mutagens.