Ecosystem ecology: Models for acute toxicity of pesticides towards Daphnia magna.

Quantitative structure - activity relationships (QSARs) which are obtained with a representation of the molecular architecture via simplified molecular input-line entry system (SMILES) are applied to build up predictive models of acute toxicity of pesticides towards Daphnia magna. The acute toxicity towards Daphnia magna is an adequate measure of the ecological impact of various substances. The Monte Carlo technique is the basis to build up the above QSAR models. The statistical quality of suggested models is good: the best model is characterized by n = 103, R2 = 0.76, RMSE = 0.91 (training set); n = 53, R2 = 0.82, RMSE = 0.87 (validation set). The approach provides the mechanistic interpretation (e.g. aromaticity and branching of carbon skeleton are promoters of increase for toxicity towards Daphnia magna in the case of the examined set of pesticides). The approach is attractive to build up predictive models since instead of a large number of different molecular descriptors the corresponding model is based on solely one optimal descriptor calculated with SMILES and all necessary calculations can be done using the CORAL software available on the Internet (http://ww.insilico.eu/coral).

Ovarian follicle structure of Zebrafish (Danio rerio Hamilton) after poly(2-ethyl-2-oxazoline) exposure.

Poly(2-oxazoline)s have been widely known for their biomedical applications. They mimic natural systems and are generally used as liposomes, drug and gene delivery modules and also as pseudopeptides. In this study, effects of different doses (10 and 50 mg/L) of poly(2-ethyl-2-oxazoline) on ovarian follicle ultrastructure of zebrafish were investigated with light and electron microscopy. After five days of administation, ovary tissues were disected and routine histological processes were done. Severe structural deformation at zona radiata, follicular epithelium and outer granulosa cell structure were observed. Edema at follicular epithelium, zona radiata and vitelline envelope stuructures were detected. Dose dependent increase in the number of immature oocytes were seen. Briefly, it was demonstrated that poly(2-ethyl-2-oxazoline) exposure affected oogenesis and caused apoptosis in zebrafish.

Nematodes Relevance in Soil Quality Management and their Significance as Biomarkers in Aquatic Substrates: Review.

BACKGROUND: The interaction of man with the ecosystem is a major factor causing environmental pollution and its attendant consequences such as climate change in our world today. Patents relating to nematodes' relevance in soil quality management and their significance as biomarkers in aquatic substrates were reviewed. Nematodes are useful in rapid, easy and inexpensive method for testing the toxicity of substance (e.g. aquatic substrates). OBJECTIVE: This review paper sets out to examine and discuss the issue of soil pollution, functions of nematodes in soil and aquatic substrates as well as bio-indicators in soil health management in terrestrial ecology. METHODS: The information used were on the basis of secondary sources from previous research. CONCLUSION: It is abundantly clear that the population dynamics of plant parasitic or free-living nematodes have useful potentials as biomonitor for soil health and other forms of environmental contamination through agricultural activities, industrial pollution and oil spillage, and the analysis of nematode community structure could be used as complementary information obtained from conventional soil testing approaches.

Chronic exposure of river sediments to environmentally relevant levels of tetracycline affects bacterial communities but not denitrification rates.

The effects of tetracycline (TC) at chronic sub-inhibitory exposure concentrations on benthic denitrification rates and bacterial communities were explored. River sediments were continuously exposed to different TC concentrations (0.5, 20 and 10,000 µg L(-1)) for 2 weeks in flow-through reactors allowing denitrification and bacterial growth conditions. Bacterial communities were fingerprinted by Denaturing Gradient Gel Electrophoresis of 16S rRNA gene amplification products. Cultivable denitrifiers enriched from the sediment were tested for TC resistance (2-128 mg L(-1)). Denitrification rates were unaffected by exposure to TC, regardless of concentration. In contrast, the bacterial community composition changed significantly from sub-inhibitory (ng-µg L(-1)) to therapeutic (mg L(-1)) exposure concentrations. Furthermore the cultivable denitrifiers showed a high TC sensitivity (<4 mg L(-1)). Maintenance of efficient benthic denitrification rates, even at the highest level of TC exposure most likely originated from an adaptation of the autochthonous bacterial community where dominant species become those that acquire, or already have resistance to antibiotics.

Development and application of a highly selective biomimetic sensor for detection of captopril, an important ally in hypertension control.

A biomimetic sensor is proposed as a promising new analytical method for determination of captopril in different classes of samples. The sensor was prepared by modifying a carbon paste electrode with iron (II) phthalocyanine bis(pyridine) [FePc(dipy)] complex. Amperometric measurements in a batch analytical mode were first carried out in order to optimize the sensor response. An applied potential lower than 0.2 V vs Ag|AgCl in 0.1 mol L-1 of TRIS buffer at pH 8.0 provided the best response, with a linear range of 2.5 x 10-5 to 1.7 x 10-4 mol L-1. A detailed investigation of the selectivity of the sensor, employing seventeen other drugs, was also performed. Recovery studies were carried out using biological and environment samples in order to evaluate the sensor's potential for use with these sample classes. Finally, the performance of the biomimetic sensor was optimized in a flow injection (FIA) system using a wall jet electrochemical cell. Under optimized flow conditions, a broad linear response range, from 5.0 x 10-4 to 2.5 x 10-2 mol L-1, was obtained for captopril, with a sensitivity of 210 ± 1 µA L mol-1.

Effects of aqueous aluminium on four fish ectoparasites.

Effects of aqueous aluminium on four species of fish ectoparasites were studied. Fish infected by Gyrodactylus derjavini, G. macronychus and Anodonta anatina glochidia, and free living Argulus foliaceus were exposed to acidic Al-rich water (pH 5.8), acidic Al-poor water (pH 5.8) and control water (pH 6.3). The results showed that aqueous aluminium had a negative effect on the ectoparasites tested, without any apparent negative effect on the fish hosts. The effect of aluminium was dependent on the kind of organism tested. The gyrodactylids were eliminated, while the duck mussel glochidia showed a decrease in abundance when exposed to 200-260 mug Al/l at pH 5.8. The little fish louse showed increased mortality rate when exposed to aluminium. The effects of aluminium on the parasites in the present study confirm the importance of water quality in general, and acidification in particular, for the distribution and population dynamics of ectoparasites in freshwater environments.