Three-tiered approach for standard information requirements for polymers requiring registration under REACH.

Polymers are a very large class of chemicals comprising often complex molecules with multiple functions used in everyday products. The EU Commission is seeking to develop environmental and human health standard information requirements (SIRs) for man-made polymers requiring registration (PRR) under a revised Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) Regulation. Conventional risk assessment approaches currently used for small molecules may not apply to most polymers.

Heterogeneity in biological assemblages and exposure in chemical risk assessment: Exploring capabilities and challenges in methodology with two landscape-scale case studies.

Chemical exposure concentrations and the composition of ecological receptors (e.g., species) vary in space and time, resulting in landscape-scale (e.

Moving persistence assessments into the 21st century: A role for weight-of-evidence and overall persistence.

Assessing the persistence of chemicals in the environment is a key element in existing regulatory frameworks to protect human health and ecosystems. Persistence in the environment depends on many fate processes, including abiotic and biotic transformations and physical partitioning, which depend on substances' physicochemical properties and environmental conditions. A main challenge in persistence assessment is that existing frameworks rely on simplistic and reductionist evaluation schemes that may lead substances to be falsely assessed as persistent or the other way around-to be falsely assessed as nonpersistent.

Pax6 organizes the anterior eye segment by guiding two distinct neural crest waves.

Cranial neural crest (NC) contributes to the developing vertebrate eye. By multidimensional, quantitative imaging, we traced the origin of the ocular NC cells to two distinct NC populations that differ in the maintenance of sox10 expression, Wnt signalling, origin, route, mode and destination of migration. The first NC population migrates to the proximal and the second NC cell group populates the distal (anterior) part of the eye.

EmbryoMiner: A new framework for interactive knowledge discovery in large-scale cell tracking data of developing embryos.

State-of-the-art light-sheet and confocal microscopes allow recording of entire embryos in 3D and over time (3D+t) for many hours. Fluorescently labeled structures can be segmented and tracked automatically in these terabyte-scale 3D+t images, resulting in thousands of cell migration trajectories that provide detailed insights to large-scale tissue reorganization at the cellular level. Here we present EmbryoMiner, a new interactive open-source framework suitable for in-depth analyses and comparisons of entire embryos, including an extensive set of trajectory features.

Intrinsic Xenobiotic Metabolizing Enzyme Activities in Early Life Stages of Zebrafish (Danio rerio).

Early life stages of zebrafish (Danio rerio, zf) are gaining attention as an alternative invivo test system for drug discovery, early developmental toxicity screenings and chemical testing in ecotoxicological and toxicological testing strategies. Previous studies have demonstrated transcriptional evidence for xenobiotic metabolizing enzymes (XME) during early zf development. However, elaborate experiments on XME activities during development are incomplete.

Fishing for contaminants: identification of three mechanism specific transcriptome signatures using Danio rerio embryos.

In ecotoxicology, transcriptomics is an effective way to detect gene expression changes in response to environmental pollutants. Such changes can be used to identify contaminants or contaminant classes and can be applied as early warning signals for pollution. To do so, it is important to distinguish contaminant-specific transcriptomic changes from genetic alterations due to general stress.

Fold-change threshold screening: a robust algorithm to unmask hidden gene expression patterns in noisy aggregated transcriptome data.

Transcriptomics is often used to investigate changes in an organism's genetic response to environmental contamination. Data noise can mask the effects of contaminants making it difficult to detect responding genes. Because the number of genes which are found differentially expressed in transcriptome data is often very large, algorithms are needed to reduce the number down to a few robust discriminative genes.

An ensemble-averaged, cell density-based digital model of zebrafish embryo development derived from light-sheet microscopy data with single-cell resolution.

A new era in developmental biology has been ushered in by recent advances in the quantitative imaging of all-cell morphogenesis in living organisms. Here we have developed a light-sheet fluorescence microscopy-based framework with single-cell resolution for identification and characterization of subtle phenotypical changes of millimeter-sized organisms. Such a comparative study requires analyses of entire ensembles to be able to distinguish sample-to-sample variations from definitive phenotypical changes.

Impacts of different exposure scenarios on transcript abundances in Danio rerio embryos when investigating the toxicological burden of riverine sediments.

Purpose: Recently, a proof-of-concept study revealed the suitability of transcriptome analyses to obtain and assess changes in the abundance of transcripts in zebrafish (Danio rerio) embryos after exposure to organic sediment extracts. The present study investigated changes in the transcript abundance in zebrafish embryos exposed to whole sediment samples and corresponding organic extracts in order to identify the impact of different exposure pathways on sediment toxicity.

Materials And Methods: Danio rerio embryos were exposed to sublethal concentrations of three sediment samples from the Danube River, Germany.

Fast segmentation of stained nuclei in terabyte-scale, time resolved 3D microscopy image stacks.

Automated analysis of multi-dimensional microscopy images has become an integral part of modern research in life science. Most available algorithms that provide sufficient segmentation quality, however, are infeasible for a large amount of data due to their high complexity. In this contribution we present a fast parallelized segmentation method that is especially suited for the extraction of stained nuclei from microscopy images, e.

Contribution of priority PAHs and POPs to Ah receptor-mediated activities in sediment samples from the River Elbe Estuary, Germany.

The estuary of the River Elbe between Hamburg and the North Sea (Germany) is a sink for contaminated sediment and suspended particulate matter (SPM). One major concern is the effect of human activities on the hydrodynamics, particularly the intensive dredging activities in this area that may result in remobilization of sediment-bound pollutants. The aim of this study was to identify pollutants contributing to the toxicological risk associated with re-suspension of sediments in the Elbe Estuary by use of an effect-directed analysis that combines chemical and biological analyses in with specific fractionation techniques.

A combined DNA-microarray and mechanism-specific toxicity approach with zebrafish embryos to investigate the pollution of river sediments.

The zebrafish embryo has repeatedly proved to be a useful model for the analysis of effects by environmental toxicants. This proof-of-concept study was performed to investigate if an approach combining mechanism-specific bioassays with microarray techniques can obtain more in-depth insights into the ecotoxicity of complex pollutant mixtures as present, e.g.

Toxicity, dioxin-like activities, and endocrine effects of DDT metabolites--DDA, DDMU, DDMS, and DDCN.

Background, Aim, And Scope: 2,2-bis(chlorophenyl)-1,1,1-trichloroethane (DDT) metabolites, other than those routinely measured [i.e., 2,2-bis(chlorophenyl)-1,1-dichloroethylene (DDE) and 2,2-bis(chlorophenyl)-1,1-dichloroethane (DDD)], have recently been detected in elevated concentrations not only in the surface water of Teltow Canal, Berlin, but also in sediment samples from Elbe tributaries (e.

Spatio-temporal development of CYP1 activity in early life-stages of zebrafish (Danio rerio).

Endpoints of planar halogenated aromatic hydrocarbon (pHAH) and polycyclic aromatic hydrocarbon (PAH) toxicity are mediated via activation of the aryl hydrocarbon receptor (AhR) followed by activation of the so called "AhR-battery" of genes including the cytochrome P450 1 (CYP1) isoforms. The aim of this study was to develop a method to identify CYP1 activity in early life-stages of zebrafish (Danio rerio) in order to elucidate the spatio-temporal pattern of basal and induced CYP1 activities. Preliminary experiments with the fish embryo toxicity test (FET) were carried out to determine toxic effect thresholds of the AhR agonist β-naphthoflavone.

A bioassay approach to determine the dioxin-like activity in sediment extracts from the Danube River: ethoxyresorufin-O-deethylase induction in gill filaments and liver of three-spined sticklebacks (Gasterosteus aculeatus L.).

Sediment samples from the upper Danube River in Germany have previously been characterized as ecotoxicologically hazardous and contaminants in these sediments may contribute to the observed decline of fish populations in this river section. For the investigation of sediment toxicity there is a need for development, standardization and implementation of in vivo test systems using vertebrates. Therefore, the main objective of this study was to apply and evaluate a recently established fish gill EROD assay as a biomarker in sediment toxicity assessment by using extracts of well characterised sediment samples from the upper Danube River.