IST Austria Thesis

Directed cell migration is a hallmark feature, present in almost all multi-cellular organisms. Despite its importance, basic questions regarding force transduction or directional sensing are still heavily investigated. Directed migration of cells guided by immobilized guidance cues - haptotaxis - occurs in key-processes, such as embryonic development and immunity (Middleton et al., 1997; Nguyen et al., 2000; Thiery, 1984; Weber et al., 2013). Immobilized guidance cues comprise adhesive ligands, such as collagen and fibronectin (Barczyk et al., 2009), or chemokines - the main guidance cues for migratory leukocytes (Middleton et al., 1997; Weber et al., 2013). While adhesive ligands serve as attachment sites guiding cell migration (Carter, 1965), chemokines instruct haptotactic migration by inducing adhesion to adhesive ligands and directional guidance (Rot and Andrian, 2004; Schumann et al., 2010). Quantitative analysis of the cellular response to immobilized guidance cues requires in vitro assays that foster cell migration, offer accurate control of the immobilized cues on a subcellular scale and in the ideal case closely reproduce in vivo conditions. The exploration of haptotactic cell migration through design and employment of such assays represents the main focus of this work. Dendritic cells (DCs) are leukocytes, which after encountering danger signals such as pathogens in peripheral organs instruct naïve T-cells and consequently the adaptive immune response in the lymph node (Mellman and Steinman, 2001). To reach the lymph node from the periphery, DCs follow haptotactic gradients of the chemokine CCL21 towards lymphatic vessels (Weber et al., 2013). Questions about how DCs interpret haptotactic CCL21 gradients have not yet been addressed. The main reason for this is the lack of an assay that offers diverse haptotactic environments, hence allowing the study of DC migration as a response to different signals of immobilized guidance cue. In this work, we developed an in vitro assay that enables us to quantitatively assess DC haptotaxis, by combining precisely controllable chemokine photo-patterning with physically confining migration conditions. With this tool at hand, we studied the influence of CCL21 gradient properties and concentration on DC haptotaxis. We found that haptotactic gradient sensing depends on the absolute CCL21 concentration in combination with the local steepness of the gradient. Our analysis suggests that the directionality of migrating DCs is governed by the signal-to-noise ratio of CCL21 binding to its receptor CCR7. Moreover, the haptotactic CCL21 gradient formed in vivo provides an optimal shape for DCs to recognize haptotactic guidance cue. By reconstitution of the CCL21 gradient in vitro we were also able to study the influence of CCR7 signal termination on DC haptotaxis. To this end, we used DCs lacking the G-protein coupled receptor kinase GRK6, which is responsible for CCL21 induced CCR7 receptor phosphorylation and desensitization (Zidar et al., 2009). We found that CCR7 desensitization by GRK6 is crucial for maintenance of haptotactic CCL21 gradient sensing in vitro and confirm those observations in vivo. In the context of the organism, immobilized haptotactic guidance cues often coincide and compete with soluble chemotactic guidance cues. During wound healing, fibroblasts are exposed and influenced by adhesive cues and soluble factors at the same time (Wu et al., 2012; Wynn, 2008). Similarly, migrating DCs are exposed to both, soluble chemokines (CCL19 and truncated CCL21) inducing chemotactic behavior as well as the immobilized CCL21. To quantitatively assess these complex coinciding immobilized and soluble guidance cues, we implemented our chemokine photo-patterning technique in a microfluidic system allowing for chemotactic gradient generation. To validate the assay, we observed DC migration in competing CCL19/CCL21 environments. Adhesiveness guided haptotaxis has been studied intensively over the last century. However, quantitative studies leading to conceptual models are largely missing, again due to the lack of a precisely controllable in vitro assay. A requirement for such an in vitro assay is that it must prevent any uncontrolled cell adhesion. This can be accomplished by stable passivation of the surface. In addition, controlled adhesion must be sustainable, quantifiable and dose dependent in order to create homogenous gradients. Therefore, we developed a novel covalent photo-patterning technique satisfying all these needs. In combination with a sustainable poly-vinyl alcohol (PVA) surface coating we were able to generate gradients of adhesive cue to direct cell migration. This approach allowed us to characterize the haptotactic migratory behavior of zebrafish keratocytes in vitro. Furthermore, defined patterns of adhesive cue allowed us to control for cell shape and growth on a subcellular scale

16th Sound and Music Computing Conference SMC 2019 (28–31 May 2019, Malaga, Spain)

The 16th Sound and Music Computing Conference (SMC 2019) took place in Malaga, Spain, 28-31 May 2019 and it was organized by the Application of Information and Communication Technologies Research group (ATIC) of the University of Malaga (UMA). The SMC 2019 associated Summer School took place 25-28 May 2019. The First International Day of Women in Inclusive Engineering, Sound and Music Computing Research (WiSMC 2019) took place on 28 May 2019. The SMC 2019 TOPICS OF INTEREST included a wide selection of topics related to acoustics, psychoacoustics, music, technology for music, audio analysis, musicology, sonification, music games, machine learning, serious games, immersive audio, sound synthesis, etc

Visibility in underwater robotics: Benchmarking and single image dehazing

Dealing with underwater visibility is one of the most important challenges in autonomous underwater robotics. The light transmission in the water medium degrades images making the interpretation of the scene difficult and consequently compromising the whole intervention. This thesis contributes by analysing the impact of the underwater image degradation in commonly used vision algorithms through benchmarking. An online framework for underwater research that makes possible to analyse results under different conditions is presented. Finally, motivated by the results of experimentation with the developed framework, a deep learning solution is proposed capable of dehazing a degraded image in real time restoring the original colors of the image.Una de las dificultades más grandes de la robótica autónoma submarina es lidiar con la falta de visibilidad en imágenes submarinas. La transmisión de la luz en el agua degrada las imágenes dificultando el reconocimiento de objetos y en consecuencia la intervención. Ésta tesis se centra en el análisis del impacto de la degradación de las imágenes submarinas en algoritmos de visión a través de benchmarking, desarrollando un entorno de trabajo en la nube que permite analizar los resultados bajo diferentes condiciones. Teniendo en cuenta los resultados obtenidos con este entorno, se proponen métodos basados en técnicas de aprendizaje profundo para mitigar el impacto de la degradación de las imágenes en tiempo real introduciendo un paso previo que permita recuperar los colores originales

From perception to behavior: The neural circuits underlying prey hunting in larval zebrafish

A key challenge for neural systems is to extract relevant information from the environment and make appropriate behavioral responses. The larval zebrafish offers an exciting opportunity for studying these sensing processes and sensory-motor transformations. Prey hunting is an instinctual behavior of zebrafish that requires the brain to extract and combine different attributes of the sensory input and form appropriate motor outputs. Due to its small size and transparency the larval zebrafish brain allows optical recording of whole-brain activity to reveal the neural mechanisms involved in prey hunting and capture. In this review we discuss how the larval zebrafish brain processes visual information to identify and locate prey, the neural circuits governing the generation of motor commands in response to prey, how hunting behavior can be modulated by internal states and experience, and some outstanding questions for the field

The Processing of Emotional Sentences by Young and Older Adults: A Visual World Eye-movement Study

Carminati MN, Knoeferle P. The Processing of Emotional Sentences by Young and Older Adults: A Visual World Eye-movement Study. Presented at the Architectures and Mechanisms of Language and Processing (AMLaP), Riva del Garda, Italy