A walk in the PARC: developing and implementing 21st century chemical risk assessment in Europe

Current approaches for the assessment of environmental and human health risks due to exposure to chemical substances have served their purpose reasonably well. Nevertheless, the systems in place for different uses of chemicals are faced with various challenges, ranging from a growing number of chemicals to changes in the types of chemicals and materials produced. This has triggered global awareness of the need for a paradigm shift, which in turn has led to the publication of new concepts for chemical risk assessment and explorations of how to translate these concepts into pragmatic approaches. As a result, next-generation risk assessment (NGRA) is generally seen as the way forward. However, incorporating new scientific insights and innovative approaches into hazard and exposure assessments in such a way that regulatory needs are adequately met has appeared to be challenging. The European Partnership for the Assessment of Risks from Chemicals (PARC) has been designed to address various challenges associated with innovating chemical risk assessment. Its overall goal is to consolidate and strengthen the European research and innovation capacity for chemical risk assessment to protect human health and the environment. With around 200 participating organisations from all over Europe, including three European agencies, and a total budget of over 400 million euro, PARC is one of the largest projects of its kind. It has a duration of seven years and is coordinated by ANSES, the French Agency for Food, Environmental and Occupational Health & Safety.

DNAscan: personal computer compatible NGS analysis, annotation and visualisation

BACKGROUND

Next Generation Sequencing (NGS) is a commonly used technology for studying the genetic basis of biological processes and it underpins the aspirations of precision medicine. However, there are significant challenges when dealing with NGS data. Firstly, a huge number of bioinformatics tools for a wide range of uses exist, therefore it is challenging to design an analysis pipeline. Secondly, NGS analysis is computationally intensive, requiring expensive infrastructure, and many medical and research centres do not have adequate high performance computing facilities and cloud computing is not always an option due to privacy and ownership issues. Finally, the interpretation of the results is not trivial and most available pipelines lack the utilities to favour this crucial step.

RESULTS

We have therefore developed a fast and efficient bioinformatics pipeline that allows for the analysis of DNA sequencing data, while requiring little computational effort and memory usage. DNAscan can analyse a whole exome sequencing sample in 1 h and a 40x whole genome sequencing sample in 13 h, on a midrange computer. The pipeline can look for single nucleotide variants, small indels, structural variants, repeat expansions and viral genetic material (or any other organism). Its results are annotated using a customisable variety of databases and are available for an on-the-fly visualisation with a local deployment of the gene.iobio platform. DNAscan is implemented in Python. Its code and documentation are available on GitHub: https://github.com/KHP-Informatics/DNAscan . Instructions for an easy and fast deployment with Docker and Singularity are also provided on GitHub.

CONCLUSIONS

DNAscan is an extremely fast and computationally efficient pipeline for analysis, visualization and interpretation of NGS data. It is designed to provide a powerful and easy-to-use tool for applications in biomedical research and diagnostic medicine, at minimal computational cost. Its comprehensive approach will maximise the potential audience of users, bringing such analyses within the reach of non-specialist laboratories, and those from centres with limited funding available.

Body site matters: an evaluation and application of a novel histological methodology on the quantification of mucous cells in the skin of Atlantic salmon, Salmo salar L

Mucous cell size and distribution were investigated in the skin of five salmon using a novel stereology-based methodology: one (48 cm) fish to test 15 tissue treatment combinations on measures of cell area and density on the dorsolateral region and, using the most suitable treatment, we mapped mucous cell differences between body regions on four (52 cm) salmon, comprising a male and a female on each of two diets. The section site, decalcification, embedding medium and plane of sectioning all impacted significantly on mucous cell size, whereas mucous cell density is more robust. There were highly significant differences in both mucosal density and mean mucous cell size depending on body site: the dorsolateral skin of the four salmon had significantly denser (about 8% of skin area) and larger (mean about 160 μm(2)) mucous cells, whereas the lowest mean density (about 4%) and smallest mean area (115 μm(2)) were found on the head. We found that 100 random measurements may be sufficient to distinguish differences >7 μm(2) in mean mucous cell areas. The results further suggest that salmon exhibit a dynamic repeatable pattern of mucous cell development influenced by sex, diet and possibly strain and season.

Evidence suggesting that Homo neanderthalensis contributed the H2 MAPT haplotype to Homo sapiens

The tau (MAPT) locus exists as two distinct clades, H1 and H2. The H1 clade has a normal linkage disequilibrium structure and is the only haplotype found in all populations except those derived from Caucasians. The H2 haplotype is the minor haplotype in Caucasian populations and is not found in other populations. It shows no recombination over a region of 2 Mb with the more common H1 haplotype. The distribution of the haplotype and analysis of the slippage of dinucleotide repeat markers within the haplotype suggest that it entered Homo sapiens populations between approx. 10000 and 30000 years ago. However, sequence comparison of the H2 haplotype with the H1 haplotype and with the chimp sequence suggests that the common founder of the H1 and H2 haplotypes was far earlier than this. We suggest that the H2 haplotype is derived from Homo neanderthalensis and entered H. sapiens populations during the co-existence of these species in Europe from approx. 45000 to 18000 years ago and that the H2 haplotype has been under selection pressure since that time, possibly because of the role of this H1 haplotype in neurodegenerative disease.

Strong association of the Saitohin gene Q7 variant with progressive supranuclear palsy

Recent reports are inconclusive in showing that the Q7R polymorphism of the novel Saitohin gene, nested in intron 9 of the tau gene, is associated with AD. The authors show that this polymorphism is in complete linkage disequilibrium with the extended tau H1/H2 haplotype and that the Q variant and QQ genotype of Q7R are strongly associated with progressive supranuclear palsy, implicating it as a possibly important pathogenic candidate.

Tetrazolium-based assays for cellular viability: a critical examination of selected parameters affecting formazan production

The hydrogen acceptor 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) is commonly utilized to estimate cellular viability in drug screening protocols. The present investigation was prompted, in part, by observations that reduction of MTT to its colored reaction product, MTT formazan, varied between cell lines and with culture age. A correlation was established between the D-glucose concentration of the culture medium at the time of assay and the production of MTT formazan for cell lines representing seven tumor histologies. A decrease in the concentration of D-glucose from culture medium was accompanied by a decrease in MTT specific activity (MTT formazan/microgram cell protein) for a number of cell lines. Cells which extensively metabolized D-glucose exhibited the greatest reduction in MTT specific activity. Further evidence that the D-glucose concentration of the culture medium played an important role in MTT reduction was provided by experiments which demonstrated that transfer of cells to a glucose-free medium (L-15) was accompanied by an immediate decrease in MTT reduction which was pH independent. These studies suggested that cellular transport and constant metabolism of glucose were required for maximum MTT reduction. Decreases in the cellular concentration of the reduced pyridine nucleotides NADH and NADPH were accompanied by concomitant decreases in MTT formazan production. MTT formazan varied significantly among cell lines in both the kinetics of its formation and the degree of saturability exhibited. Apparent IC50 values for Adriamycin varied, in a cell line-specific manner, with MTT exposure time. These results indicate that MTT specific activity is significantly influenced by a number of parameters and suggest that assay conditions should be established which minimize their effects.