Comparative proteomics of copper exposure and toxicity in rainbow trout, common carp and gibel carp.

Species specific differences in transporters, chaperones, metal binding proteins and other targets are important in metal toxicity. Therefore, we have studied the effects of copper exposure on the proteome of gill tissue from Oncorhynchus mykiss, Cyprinus carpio and Carassius auratus gibelio, which have different sensitivities toward copper. Fish were exposed to the Flemish water quality standard for surface waters, being 50µg/L, for 3 days. Sampled gill tissue was subjected to a 2D-Dige and an iTRAQ analysis. While gibel carp showed more positive responses such as increased apolipoprotein A-I, transferrin and heat shock protein 70, common carp's gill tissue on the other hand displayed a changed actin cytoskeleton, and indications of a changed metabolism. These last two traits were evident in rainbow trout as well, together with decreased expressions of transferrin and albumin. urthermore, the Weighted Gene Co-Expression Network Analysis of rainbow trout data revealed a network of 98 proteins related to Cu accumulation in gill, of which the occurrence of proteins related to oxidative stress, such as superoxide dismutase and cytochrome c were promising. Additionally, the outcome of the different proteomics techniques demonstrates the usefulness of iTRAQ analysis compared to 2D-Dige and the need for fully annotated genomes.

Aquatic multi-species acute toxicity of (chlorinated) anilines: experimental versus predicted data.

Aquatic toxicity information is essential in environmental risk assessment to determine the potential hazards and risks of new and existing chemicals. Prediction and modelling techniques, such as quantitative structure activity relationships (QSAR) and species sensitivity distributions (SSDs), are applied to fill data gaps and to predict, assess and extrapolate the toxicity of chemicals. In this study, both techniques (i.e. the ECOSAR programme as QSAR tool and SSDs) were assessed for a set of polar narcotic structural analogues that differ in their degree of chloro-substitution (aniline, 4-chloroaniline, 3,5-dichloroaniline and 2,3,4-chloroaniline). The acute toxicity of these compounds was tested in one prokaryote species (Escherichia coli) and three eukaryote aquatic species (Pseudokirchneriella subcapitata, Daphnia magna and Danio rerio). Consequently, the experimental acute toxicity data were compared to the QSAR predictions made by the ECOSAR programme and compared to the species sensitivity modelling results. Large interspecies differences in sensitivity were observed (D. magna>P. subcapitata>D. rerio>E. coli). 4-Chloroaniline acted as an outlier in P. subcapitata toxicity. Whereas in D. magna, toxicity decreased rather than increased with increasing logK(ow) of the test compounds. In general, large interchemical and interspecies differences in toxicity of these relatively simple chemical structures were observed. Moreover, this species variation could not entirely be characterized by the ECOSAR tool. SSD modelling is particularly focussed on species variations and emphasis is put on protecting those species that are most affected by chemical exposure. Compared to QSARs, SSDs offer broader perspectives regarding species sensitivity ranking, however, in this study they could only be applied for aniline and 4-chloroaniline.

Long-term warm or cold acclimation elicits a specific transcriptional response and affects energy metabolism in zebrafish.

Organisms are often forced to acclimate to changing environmental temperature. Temperature compensation mechanisms have been reported, which enable organisms to minimize some of the temperature related effects. To investigate this process, zebrafish (Danio rerio) were acclimated to a control (26 degrees C), an increased (34 degrees C) or a decreased (18 degrees C) temperature for 4, 14 and 28 days. In general, warm acclimation depleted energy stores and decreased the condition factor, while cold acclimation increased both. The energy parameters as well as the transcriptional responses (investigated using printed 15k microarrays and real time PCR) indicated that warm acclimation was particularly stressful. However, after 28 days of warm acclimation, energy stores had recovered from the initial depletion. This could have been facilitated by the observed downregulation of transcripts involved in catabolic processes. Transcriptional regulation seemed to be an important means of coordinating the temperature compensation process. We could distinguish an early response which was independent of the direction of the temperature change and a direction specific long-term response. The early response was characterized by the upregulation of defence mechanisms, tissue regeneration and hemopoiesis. In the long-term response there was a strong emphasis on compensating for the altered metabolic rate as well as cell structure and replacement.