A comparative study of the dissolution mechanisms of amorphous and crystalline feldspars at acidic pH conditions

International audienceAbstract The dissolution of amorphous and crystalline oligoclase, a Na-feldspar with traces of Ca and K, was investigated at 90 °C and acidic pH of 1.5 and 3 to unravel the impact of long- and short-range orders on silicate dissolution mechanisms. Experiments were conducted in solutions spiked with 29 SiO 2 (aq) and saturated with respect to SiO 2 (am). Through morphology, structural, and composition characterizations, we showed that on the amorphous samples (glass samples), the altered layer was mostly formed by leaching, while a combination of both interfacial precipitation and leaching explains the layers formed on the crystalline sample. As expected, the altered layer was thicker at the most acidic pH and it became passivating on crystalline sample at pH 3. The alteration was faster on amorphous oligoclase than on its crystalline equivalent due to the more open structure of the glass. The preferential release of Al was suggested to play a key role, by weakening the silicate network of both substrates. Finally, in this study, a large overestimation of the global alteration of the materials was noticed based on the solution analyses. Discrepancies with solid analyses were attributed to an underestimation (≥2-fold factor) of the total reactive surface area

Near-chromosome level genome assembly of the fruit pest Drosophila suzukii using long-read sequencing

Over the past decade, the spotted wing Drosophila, Drosophila suzukii, has invaded Europe and America and has become a major agricultural pest in these areas, thereby prompting intense research activities to better understand its biology. Two draft genome assemblies already exist for this species but contain pervasive assembly errors and are highly fragmented, which limits their values. Our purpose here was to improve the assembly of the D. suzukii genome and to annotate it in a way that facilitates comparisons with D. melanogaster. For this, we generated PacBio long-read sequencing data and assembled a novel, high-quality D. suzukii genome assembly. It is one of the largest Drosophila genomes, notably because of the expansion of its repeatome. We found that despite 16 rounds of full-sib crossings the D. suzukii strain that we sequenced has maintained high levels of polymorphism in some regions of its genome. As a consequence, the quality of the assembly of these regions was reduced. We explored possible origins of this high residual diversity, including the presence of structural variants and a possible heterogeneous admixture pattern of North American and Asian ancestry. Overall, our assembly and annotation constitute a high-quality genomic resource that can be used for both high-throughput sequencing approaches, as well as manipulative genetic technologies to study D. suzukii