clay and phenmedipham

The soil oligochaete Enchytraeus albidus is a standard test organism used in biological testing for Environmental Risk Assessment (ERA). Although effects are known at acute and chronic level through survival, reproduction and avoidance behaviour endpoints, very little is known at the sub-cellular and molecular levels. In this study, the effects of soil properties (clay, organic matter and pH) and of the chemicals copper and phenmedipham were studied on E. albidus gene expression, during exposure periods of 2, 4 and 21 days, using DNA microarrays based on a normalised cDNA library for this test species (Amorim et al. 2011). The main objectives of this study were: (1) to assess changes in gene expression of E. albidus over time, and (2) to identify molecular markers for natural and chemical exposures. Results showed an influence of exposure time on gene expression. Transcriptional responses to phenmedipham were seen at 2 days while the responses to copper and the different soils were more pronounced at 4 days of exposure. Some genes were differentially expressed in a stress specific manner and, in general, the responses were related with effects in the energy metabolism and cell growth.

Topics: Aluminum Silicates; Animals; Carbamates; Clay; Computational Biology; Copper; DNA Primers; Environmental Monitoring; Gene Expression; Gene Library; Oligochaeta; Oligonucleotide Array Sequence Analysis; Real-Time Polymerase Chain Reaction; Reproducibility of Results; Reproduction; Sequence Analysis, RNA; Soil; Soil Pollutants

Enchytraeids are ecologically relevant soil species and are commonly used in standardized toxicity tests. Their rapid reaction to a chemical exposure can be used as a toxicological measurement endpoint that assesses the avoidance behavior. The objectives of this investigation were to determine the effects of soil properties on the avoidance behavior of Enchytraeus albidus and to optimize the duration of avoidance test. The avoidance tests included (1) exposures in OECD artificial soil with standard or modified properties (pH, clay or peat content), and (2) exposures to copper chloride, cadmium chloride, and to the organic pesticides dimethoate and phenmedipham for different time periods. Results showed that alteration of OECD soil constituents significantly affected the avoidance behavior of enchytraeids, and that the 48-h exposure was the optimal duration of the test. Consideration of soil properties is important for selecting appropriate experimental design and interpreting the results of the enchytraeid avoidance test.

Topics: Aluminum Silicates; Animals; Avoidance Learning; Behavior, Animal; Cadmium; Carbamates; Clay; Copper; Dimethoate; Herbicides; Hydrogen-Ion Concentration; Oligochaeta; Reproduction; Soil; Soil Pollutants; Time Factors; Toxicity Tests