The comet assay is a versatile method to detect nuclear DNA damage in individual eukaryotic cells, from yeast to human. The types of damage detected encompass DNA strand breaks and alkali-labile sites (e.g., apurinic/ apyrimidinic sites), alkylated and oxidized nucleobases, DNA-DNA crosslinks, UV-induced cyclobutane pyrimidine dimers and some chemically induced DNA adducts. Depending on the specimen type, there are important modifications to the comet assay protocol to avoid the formation of additional DNA damage during the processing of samples and to ensure sufficient sensitivity to detect differences in damage levels between sample groups. Various applications of the comet assay have been validated by research groups in academia, industry and regulatory agencies, and its strengths are highlighted by the adoption of the comet assay as an in vivo test for genotoxicity in animal organs by the Organisation for Economic Co-operation and Development. The present document includes a series of consensus protocols that describe the application of the comet assay to a wide variety of cell types, species and types of DNA damage, thereby demonstrating its versatility.

Vermiculite and micaceous minerals are relevant Cs sorbent in soils and sediments. To understand Cs bioavailability in soils resulting from multi-cation exchanges, Cs sorption onto clay minerals have been carried out in batch experiments with solutions containing Ca 2+ , Mg 2+ and K + . A sequence between a vermiculite and various micaceous structures were achieved by conditioning a vermiculite at various amounts of K. Competing cation exchanges were investigated according to the concentration of Cs. The contribution of K on trace Cs desorption is probed by applying different concentrations of K on Cs-doped vermiculite and micaceous structures. Cs sorption isotherms at chemical equilibrium were combined with elemental mass balances in solution and structural analyses. Cs replace easily Mg 2+ > Ca 2+ and competes scarcely with K. Cs is strongly adsorbed on the various matrix and a K/Cs ratio about a thousand is required to remobilize Cs. Cs is exchangeable as long as the clay interlayer space remains open to Ca 2+ . However, excess of K, as well as Cs, in solution leads to the collapse of the interlayer spaces that locks the Cs into the structure. Once K and/or Cs collapse the interlayer space, the external sorption sites are then particularly involved in Cs sorption. Subsequently, Cs + exchanges preferentially with Ca 2+ rather than Mg 2+ . Mg 2+ is extruded from the interlayer space by Cs + and K + adsorption, excluded from short interlayer space and replaced by Ca 2+ as Cs + desorbs.