Genetic variability and ontogeny predict microbiome structure in a disease-challenged montane amphibian

Amphibian populations worldwide are at risk of extinction from infectious diseases, including chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). Amphibian cutaneous microbiomes interact with Bd and can confer protective benefits to the host. The composition of the microbiome itself is influenced by many environment- and host-related factors. However, little is known about the interacting effects of host population structure, genetic variation and developmental stage on microbiome composition and Bd prevalence across multiple sites. Here we explore these questions in Amietia hymenopus, a disease-affected frog in southern Africa. We use microsatellite genotyping and 16S amplicon sequencing to show that the microbiome associated with tadpole mouthparts is structured spatially, and is influenced by host genotype and developmental stage. We observed strong genetic structure in host populations based on rivers and geographic distances, but this did not correspond to spatial patterns in microbiome composition. These results indicate that demographic and host genetic factors affect microbiome composition within sites, but different factors are responsible for host population structure and microbiome structure at the between-site level. Our results help to elucidate complex within- and among- population drivers of microbiome structure in amphibian populations. That there is a genetic basis to microbiome composition in amphibians could help to inform amphibian conservation efforts against infectious diseases

Hybrid cellular Potts model for solid tumor growth

We present a hybrid computational framework whose aim is to reproduce and analyze the early growth of a solid tumor. The model couples an extended version of the discrete Cellular Potts Model, used to represent the phenomenological behavior of malignant cells, with a continuous approach of reaction-diffusion equations, employed to describe the evolution of microscopic variables, as the growth factors and the matrix proteins present in the host tissue and the proteolytic enzymes secreted by the tumor. The behavior of each cancer cell is determined by a balance of interaction forces, such as homotypic (cell-cell) and heterotypic (cell-matrix) adhesions and haptotaxis, and is mediated by its molecular state, which regulates the motility and proliferation rate. The resulting model captures the different phases of the development of the tumor mass, i.e. its exponential growth and the subsequent stabilization in a steady-state due to limitations in vital molecules. The proposed approach also predicts the influence on the cancer morphology of changes in specific intercellular adhesive mechanisms

Conductive AFM for nanoscale analysis of high-k dielectric metal oxides

Conductive atomic force microscopy has become a valuable tool for investigation of electronic transport properties with utmost lateral resolution. In this chapter, we prevent an overview about C-AFM applications to high-k semiconductors, which are key materials for future energy-efficient information technology