No abstract

The diuron degrading activity of 17 streptomycete strains, obtained from agricultural and non-agricultural soils, was determined in the laboratory. All strains were identified as Streptomyces sp. by phenotypic characteristics and PCR-based assays. The strains were cultivated in liquid medium with diuron (4 mg L -1 ) at 25 1C for 15 days. Biodegradation activity was determined by high-performance liquid chromatography. The results indicated that all strains were able to degrade diuron, but to different amounts. Twelve strains degraded the herbicide by up to 50% and four of them by up to 70%. Strain A7-9, belonging to S. albidofl cluster, was the most efficient organism in the degradation of diuron, achieving 95% degradation after five days of incubation and no herbicide remained after 10 days. Overall, the strains isolated from agricultural soils exhibited higher degradation percentages and rates than those isolated from non-agricultural soils. Given the high degradation activity observed here, the streptomycete strains show a good potential for bioremediation of soils contaminated with diuron.

Vitellogenin (VTG) is a protein produced in the liver of oviparous animals in response to oestrogens. Abnormal production of VTG by males, therefore, is used as a biological indicator of exposure to xeno-oestrogens. In this study, a sandwich-ELISA for measuring VTG in Liza aurata (golden grey mullet) was developed and validated. Plasma VTG was purified from 17beta-oestradiol-injected immature individuals of mullet, by size-exclusion and ion-exchange chromatography. Polyclonal antibodies against VTG were raised in rabbits. A sensitive immunoassay was developed for measurement of vitellogenin in L. aurata serum, reaching a quantification limit of 0.01 microg mL(-1) and a dynamic range from 0.02 to 2 microg mL(-1). The assay is specific, because high levels (>100 microg mL(-1)) of carp (Cyprinus carpio), goldfish (Carassius auratus), tilapia (Oreochromis niloticus), tench (Tinca tinca), rainbow trout (Oncorhynchus mykiss), European eel (Anguilla anguilla) and frog (Rana perezi) purified VTG, give negligible responses. The assay was used to analyse plasma samples from wild mullet.

Methyl tert-buthyl ether (MTBE) is used as an oxygenate additive in gasoline, and in the last years contamination of natural water, soils or air has taken place as result of MTBE use. Furthermore, MTBE is the second most common volatile compound (VOC) detected in a survey of shallow urban aquifers. This review focuses on the most critical steps, for sample preparation methodologies from an analytical point of view. Several enrichment and injection techniques are discussed, including direct injection, headspace analysis, purge and trap and solid-phase microextraction. The methods for the determination of methyl tert-butyl ether (MTBE) in environmental samples have been rapidly developed during last decade. Also, the current status of the analytical methods used in the determination of MTBE in water and soil is reviewed including the compound-specific stable isotope analysis (CSIA), which is an important tool in environmental sciences and allows the allocation of contaminant sources.

Modulation of support wettability used for microarray format biosensing has led to an improvement of results. Hydrophobicity of glass chips was set by derivatizing with single vinyl organosilanes of different chain length and silane mixtures. Thiol-ene photochemical linking has been used as effective chemistry for covalent anchoring of thiolated probes. Lowest unspecific binding and highest signal intensity and SNR were obtained with large hydrocarbon chain (C) silanes or a shorter one (C) containing fluorine atoms. SNR resulting values are improved, reaching levels higher than 1500 in some cases, when using vinyl silanes modified with 1% C alkyl fluorinated one, because mild hydrophobicity was achieved (water contact angle ca. 110°) for all silanes, including the short C and C, thus giving rise to smaller and better defined array spots. In addition, unspecific binding of reagents and targets was totally withdrawn. Hence, good-performing surfaces for biosensing applications can be built using appropriate organosilane reagent selection, including fluorinated ones. Graphical abstract ᅟ.