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Abstract: In order to clarify the mechanisms of reproductive toxicity in a QSAR approach, the transcriptional signatures upon the 2day exposure to the 28days EC50 of a series of increasingly chlorinated aniline compounds and 1,2,3,4-tetrachlorobenzene were measured in Folsomia candida. In general, the transcriptional patterns associated with all compounds revealed toxicity at the cellular membranes and hence components of narcosis type I, but a principal component analysis revealed a deviating response by the pentachloroaniline and 2,3,5,6-tetrachloroaniline exposure. Moreover the expression of a subset of mainly biotransformation related genes showed a significant relationship with the logKow, which stresses the presence of narcosis type I. This was confirmed by GO term enrichment at the level of cellular component. Genes involved in the three phases of xenobiotic biotransformation exhibited strict compound specific transcription patterns, which may reflect biotransformation processes in F. candida. Additional toxic mechanisms were especially observed for the 2,3,5,6-tetrachloroaniline, which possible works as an uncoupler or inhibitor of electron transport systems, which is revealed by the up-regulation of genes that encode different members of the electron transport chain. The aniline and 2,3,4-trichloroaniline exposure caused the induction of genes in the ROS defense system. Additional toxicity mechanisms were less clear, but they include the attack of microbial pathogens for the six other compounds and for 2,3,5,6-tetrachloroaniline an effect on mitochondrial protein folding. [Copyright &y& Elsevier]

Abstract: Genetic and molecular evidence to support the hypothesis that fungal secondary metabolites play a significant role in protecting the fungi against fungivory is scarce. We investigated the impact of fungal secondary metabolites on transcript regulation in the fungivorous springtail Folsomia candida feeding on mixed vs. single diets. Aspergillus nidulans, which is able to produce secondary metabolites including sterigmatocystin, and a knockout mutant with reduced secondary metabolism (A. nidulans ΔLaeA) were combined with the high quality fungus Cladosporium cladosporioides as mixed diets or offered as single diets. We hypothesized that (i) A. nidulans WT triggers more genes associated with stress responses compared to the A. nidulans ΔLaeA strain with suppressed secondary metabolism, (ii) C. cladosporioides causes significantly different transcript regulation than the A. nidulans strains ΔLaeA and WT, and (iii) mixed diets will cause significantly different transcript expression levels than single diets. All three hypotheses are generally supported regardless of the fact that functions of many of the differentially transcribed genes are still enigmatic and that a relatively subtle response, devoid of characteristic stress response genes, was observed towards the toxic fungi in the diet. The wild type A. nidulans strain elicited 30% more differentially expressed genes than the ΔLaeA mutant strain. Differentially expressed genes were not observed in the mixture diet of the C. cladosporoides × A. nidulans WT diet, indicating selective grazing on C. cladosporoides. The results bring molecular evidence for the existence of a link between fungal secondary metabolites and responses in springtails supporting the hypothesis that fungal secondary metabolites act as a shield against fungivory. [ABSTRACT FROM AUTHOR]

A capture enzyme-linked immunosorbent assay (cELISA) was developed using intimin-specific monoclonal antibodies to detect specific antibody in rabbits that have been in contact with enteropathogenic Escherichia coli (EPEC). Sera from 121 EPEC-negative, minimum-disease-level (MDL) rabbits were used for negative controls, and sera from 25 MDL rabbits, experimentally infected with EPEC of bio-/serotype 3−/O15, for positive controls. These were used to determine a cut-off value for a positive cELISA result. The value selected gave the test a sensitivity of 80.0% and a specificity of 98.4% on an individual level. At this value, a flock level sensitivity and specificity of 79.2 and 85.2%, respectively were calculated for a flock with a prevalence of seven per cent, if 40 animals were tested, and a minimum of two reactors were obtained. The test characteristics improve with increasing prevalence. To evaluate the diagnostic potential of the cELISA, sera from 40 to 50 slaughter rabbits per flock from 25 rabbit flocks with bacteriologically determined EPEC status were tested. The results demonstrated that this test can be a useful tool to determine the EPEC status of a rabbitry, provided that it is used at regular intervals. [Copyright &y& Elsevier]