Sabrina Weber

Paracrine Wnt/β-catenin signalling is important during developmental processes, tissue regeneration and stem cell regulation. Wnt proteins are morphogens, which form concentration gradients across responsive tissues. Little is known about the transport mechanism for these lipid-modified signalling proteins in vertebrates. Here we show that Wnt8a is transported on actin-based filopodia to contact responding cells and activate signalling during neural plate formation in zebrafish. Cdc42/N-Wasp regulates the formation of these Wnt-positive filopodia. Enhanced formation of filopodia increases the effective signalling range of Wnt by facilitating spreading. Consistently, reduction in filopodia leads to a restricted distribution of the ligand and a limited signalling range. Using a simulation, we provide evidence that such a short-range transport system for Wnt has a long-range signalling function. Indeed, we show that a filopodia-based transport system for Wnt8a controls anteroposterior patterning of the neural plate during vertebrate gastrulation. Distribution of Wnt morphogens in tissues is often graded, but it is unclear how these secreted factors move to form concentration gradients. Here, the authors show that Wnt8a is transported on actin-based filopodia, known also as cytonemes, that contact the signal-receiving cells during zebrafish gastrulation.

BACKGROUND: In cancer patients, circulating cell-free DNA (ccfDNA) can contain tumor-derived DNA (ctDNA), which enables noninvasive diagnosis, real-time monitoring, and treatment susceptibility testing. However, ctDNA fractions are highly variable, which challenges downstream applications. Therefore, established preanalytical work flows in combination with cost-efficient and reproducible reference materials for ccfDNA analyses are crucial for analytical validity and subsequently for clinical decision-making. METHODS: We describe the efforts of the Innovative Medicines Initiative consortium CANCER-ID (http://www.cancer-id.eu) for comparing different technologies for ccfDNA purification, quantification, and characterization in a multicenter setting. To this end, in-house generated mononucleosomal DNA (mnDNA) from lung cancer cell lines carrying known TP53 mutations was spiked in pools of plasma from healthy donors generated from 2 different blood collection tubes (BCTs). ccfDNA extraction was performed at 15 partner sites according to their respective routine practice. Downstream analysis of ccfDNA with respect to recovery, integrity, and mutation analysis was performed centralized at 4 different sites. RESULTS: We demonstrate suitability of mnDNA as a surrogate for ccfDNA as a process quality control from nucleic acid extraction to mutation detection. Although automated extraction protocols and quantitative PCR-based quantification methods yielded the most consistent and precise results, some kits preferentially recovered spiked mnDNA over endogenous ccfDNA. Mutated TP53 fragments derived from mnDNA were consistently detected using both next-generation sequencing-based deep sequencing and droplet digital PCR independently of BCT. CONCLUSIONS: This comprehensive multicenter comparison of ccfDNA preanalytical and analytical work flows is an important contribution to establishing evidence-based guidelines for clinically feasible (pre)analytical work flows.

The biological basis of psychopathy has not yet been fully elucidated. Few studies deal with structural neuroimaging in psychopaths. The aim of this article is to review these studies in order to contribute to our understanding of the biological basis of psychopathy. Data in the literature report a reduction in prefrontal gray matter volume, gray matter loss in the right superior temporal gyrus, amygdala volume loss, a decrease in posterior hippocampal volume, an exaggerated structural hippocampal asymmetry, and an increase in callosal white matter volume in psychopathic individuals. These findings suggest that psychopathy is associated with brain abnormalities in a prefrontal-temporo-limbic circuit-i.e. regions that are involved, among others, in emotional and learning processes. Additionally, data indicate that psychopathic individuals cannot be seen as a homogeneous group. The associations between structural changes and psychopathic characteristics do not enable causal conclusions to be drawn, but point rather to the important role of biological brain abnormalities in psychopathy. To gain a comprehensive understanding of this, psychopathy must be viewed as a multifactorial process involving neurobiological, genetic, epidemiological and sociobiographical factors.