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The oral toxicity of culture media of the symbiotic bacteria, Photorhabdus temperata, mutually associated with entomopathogenic nematode Heterorhabditis megidis and Photorhabdus luminescens ssp. laumondii (TT01) mutually associated with Heterorhabditis bacteriophora, were investigated in the adults of Bemisia tabaci. The oral ingestion of sucrose diet solutions (20%) containing bacteria-free supernatant of the culture media from symbiotic bacteria gradually increased mortalities and was completely lethal at 60 h after the treatments, whereas the mortalities of the controls, sucrose solutions with or without media that uncultured with bacteria, were less than 17% up to 84 h of incubation. The effects of oral ingestion of symbiont culture media were demonstrated on the expression rates of several genes of B. tabaci using quantitative real-time RT-PCR analysis. Genes associated with immunity (knottin) and nervous system (acetylcholine receptor, acetylcholine esterase and sodium channel) were up-regulated while genes involved in metabolism (cytochromep450 and carboxylesterase) were down-regulated, but genes involved in development (ecdysone receptor), reproduction (vitellogenin) and stress (hsp70, hsp90 and shsp) did not change transcription rates. Our results provide information for the understanding of the mechanism of symbiont pathogenic factors for the manipulation of host physiology at the transcription level., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The murine embryonic stem cell test (EST) is designed to evaluate developmental toxicity based on compound-induced inhibition of embryonic stem cell (ESC) differentiation into cardiomyocytes. The addition of transcriptomic evaluation within the EST may result in enhanced predictability and improved characterization of the applicability domain, therefore improving usage of the EST for regulatory testing strategies. Transcriptomic analyses assessing factors critical for risk assessment (i.e. dose) are needed to determine the value of transcriptomic evaluation in the EST. Here, using the developmentally toxic compound, flusilazole, we investigated the effect of compound concentration on gene expression regulation and toxicity prediction in ESC differentiation cultures. Cultures were exposed for 24 h to multiple concentrations of flusilazole (0.54-54 μM) and RNA was isolated. In addition, we sampled control cultures 0, 24, and 48 h to evaluate the transcriptomic status of the cultures across differentiation. Transcriptomic profiling identified a higher sensitivity of development-related processes as compared to cell division-related processes in flusilazole-exposed differentiation cultures. Furthermore, the sterol synthesis-related mode of action of flusilazole toxicity was detected. Principal component analysis using gene sets related to normal ESC differentiation was used to describe the dynamics of ESC differentiation, defined as the 'differentiation track'. The concentration-dependent effects on development were reflected in the significance of deviation of flusilazole-exposed cultures from this transcriptomic-based differentiation track. Thus, the detection of developmental toxicity in EST using transcriptomics was shown to be compound concentration-dependent. This study provides further insight into the possible application of transcriptomics in the EST as an improved alternative model system for developmental toxicity testing., (Copyright © 2010 Elsevier Inc. All rights reserved.)