Mitsuru Tada

Chronic Effects of an Insecticide, Fenobucarb, on the Larvae of Two Mayflies, Epeorus latifolium and Baetis thermicus, in Model Streams

Effects of the insecticide fenobucarb on 2 mayfly species, Epeorus latifolium and Baetis thermicus, were examined in indoor model streams. Aqueous concentrations of fenobucarb residues in the model streams were 69–71% of its nominal level until 24 h, except at low concentrations (less than 2 μg l−1 in the water) in the water. Chronic effects of fenobucarb on the growth and emergence of Ephemeropteran larvae were examined over 2 months. For concentrations of 1 and 2 μg l−1, the numbers of individuals of the third larval growth stage (average head width ≥3.0 mm) gradually decreased up to 20 days after the applications; the number of emergent individuals also remained 20 to 25 by the end of the experiment. The number of individuals to emerge at 1 to 2 μg l−1 fenobucarb was restricted in the long-term experiment. These results suggest that fenobucarb affects the emergence of this species through disruption of the endocrine system. On the other hand, the number of emergent individuals of B. thermicus at low concentrations of fenobucarb was not significantly less than that in the control.

Multiparameter Phenotypic Profiling in MCF-7 Cells for Assessing the Toxicity and Estrogenic Activity of Whole Environmental Water

Multi-parameter phenotypic profiling of small molecules is a powerful approach to their toxicity assessment and identifying potential mechanisms of actions. The present study demonstrates the application of image-based multi-parameter phenotypic profiling in MCF-7 cells to assess the overall toxicity and estrogenic activity of whole environmental water. Phenotypic profiling of 30 reference compounds and their complex mixtures was evaluated to investigate the cellular morphological outcomes to targeted biological pathways. Overall toxicity and estrogenic activity of environmental water samples were then evaluated by phenotypic analysis comparing with conventional bioassays and chemical analysis by multivariate analysis. The phenotypic analysis for reference compounds demonstrated that size and structure of cells related to biological processes like cell growth, death, and communication. The phenotypic alteration and nuclei intensity were selected as potential biomarkers to evaluate overall toxicity and estrogenic activities, respectively. The phenotypic profiles were associated with the chemical structure profiles in environmental water samples. Since the phenotypic parameters revealed multiple toxicity endpoints, it could provide more information that is relevant to assessing the toxicity of environmental water samples in compare with conventional bioassays. In conclusion, the image-based multi-parameters phenotypic analysis with MCF-7 cells provides a rapid and information-rich tool for toxicity evaluation and identification in whole water samples.