Serotonergic Circuits: Role in Sleep and Enhanced Genetic Tools for Access and Optical Recording

Overall, this thesis encompasses three main directions: the study of neural circuits in sleep (Chapter 2), the development and testing of tools for measuring neuromodulator release (Chapter 3), and methods for in vivo characterization of gene delivery vehicles (Chapter 5). The role of the neuromodulator serotonin in sleep has been debated for over 60 years. Until recently, the serotonergic system was widely thought to be part of the arousal system and promote wakefulness. In Chapter 2, we investigate the function of serotonin-producing neurons in murine and zebrafish sleep with tools featuring superior specificity and precision compared to previously employed techniques. Our results demonstrate that the serotonergic raphe are sleep-promoting and required for sleep homeostasis. Intriguingly, serotonergic neurons in mice can have opposing effects on sleep depending on the firing mode. The release of serotonin from neurons can be regulated by the frequency of neuronal firing and can occur at classical synapses, varicosities, soma, and dendrites. Further examination of the complex signaling mechanism of serotonin would benefit from tools capable of measuring the release of serotonin in vivo with long-term stability and high spatiotemporal resolution. To this end, we developed and characterized iSeroSnFR, an intensity-based genetically encoded serotonin indicator. In Chapter 3, we demonstrate that iSeroSnFR can detect serotonin release in freely behaving mice during fear conditioning, social interaction, and sleep-wake transitions. Adeno-associated viruses (AAVs) have been extensively used as gene delivery vehicles in basic neuroscience and gene therapy. However, optimization of transduction efficiency and target specificity remain a key challenge to overcome. Several AAV vector engineering approaches have been devised for this purpose and yield large collections of candidates that require further in vivo characterization. However, conventional characterization methods fall short with regard to in-depth cell type tropism analysis and/or high-throughput capabilities. In Chapter 5, we address this shortcoming with single-cell RNA sequencing technologies based on the Drop-seq method. We established an experimental and computational pipeline that allows us to profile the viral tropism of multiple AAV variants in parallel across numerous complex cell types.</p

Relationships between diffusion parameters and phosphorus precipitation during the POCl3 diffusion process

The POCl3 diffusion process is still a common way to create the pn-junction of Si solar cells. Concerning the screen-printing process, it is necessary to find a compromise between low emitter recombination, low contact resistance and high lateral conductivity. The formation of a homogeneous emitter during the POCl3 diffusion process depends on several diffusion parameters, including duration, temperature and gas flow. This primarily controls the growth of the highly doped phosphosilicate glass (PSG) layer, which acts as a dopant source during the diffusion process. Detailed investigations of the PSG layer have shown a distinct correlation between the process gas flows and the composition of the PSG layer. Specifically, in this research we examine the influence of phosphorus precipitation at the PSG/Si interface. Furthermore, we show the influence of phosphorus precipitation during the pre-deposition phase on the passivation quality of the corresponding emitter. In a second step, we use the results to create emitters with a reduced density of phosphorus precipitates. In a last step, the optimized emitter structure was transferred to screen-printed solar cell processes, whereby efficiencies up to 19.4% abs. were achieved on monocrystalline p-type Cz material with full area Al-BSF rear side

Analyzing a Single Nucleotide Polymorphism (SNP) in Schizophrenia: A meta-analysis approach

Human arm swing looks and feels highly automated, yet it is increasingly apparent that higher centres, including the cortex, are involved in many aspects of locomotor control. The addition of a cognitive task increases arm swing asymmetry during walking, but the characteristics and mechanism of this asymmetry are unclear. We hypothesized that this effect is lateralized and a Stroop word-colour naming task—primarily involving left hemisphere structures—would reduce right arm swing only. We recorded gait in 83 healthy subjects aged 18–80 walking normally on a treadmill and while performing a congruent and incongruent Stroop task. The primary measure of arm swing asymmetry—an index based on both three-dimensional wrist trajectories in which positive values indicate proportionally smaller movements on the right—increased significantly under dual-task conditions in those aged 40–59 and further still in the over-60s, driven by reduced right arm flexion. Right arm swing attenuation appears to be the norm in humans performing a locomotor-cognitive dual-task, confirming a prominent role of the brain in locomotor behaviour. Women under 60 are surprisingly resistant to this effect, revealing unexpected gender differences atop the hierarchical chain of locomotor control

Optimizing phosphorus diffusion for photovoltaic applications: Peak doping, inactive phosphorus, gettering, and contact formation

The phosphosilicate glass (PSG), fabricated by tube furnace diffusion using a POCl3 source, is widely used as a dopant source in the manufacturing of crystalline silicon solar cells. Although it has been a widely addressed research topic for a long time, there is still lack of a comprehensive understanding of aspects such as the growth, the chemical composition, possible phosphorus depletion, the resulting in-diffused phosphorus profiles, the gettering behavior in silicon, and finally the metal-contact formation. This paper addresses these different aspects simultaneously to further optimize process conditions for photovoltaic applications. To do so, a wide range of experimental data is used and combined with device and process simulations, leading to a more comprehensive interpretation. The results show that slight changes in the PSG process conditions can produce high-quality emitters. It is predicted that PSG processes at 860?°C for 60?min in combination with an etch-back and laser doping from PSG layer results in high-quality emitters with a peak dopant density Npeak?=?8.0?×?1018?cm?3 and a junction depth dj?=?0.4?m, resulting in a sheet resistivity?sh?=?380 ?/sq and a saturation current-density J0 below 10 fA/cm2. With these properties, the POCl3 process can compete with ion implantation or doped oxide approaches

Sex differences of vascular brain lesions in patients with atrial fibrillation.

OBJECTIVE To examine sex differences in prevalence, volume and distribution of vascular brain lesions on MRI among patients with atrial fibrillation (AF). METHODS In this cross-sectional analysis, we included 1743 patients with AF (27% women) from the multicentre Swiss Atrial Fibrillation study (SWISS-AF) with available baseline brain MRI. We compared presence and total volume of large non-cortical or cortical infarcts (LNCCIs), small non-cortical infarcts, microbleeds (MB) and white matter hyperintensities (WMH, Fazekas score ≥2 for moderate or severe degree) between men and women with multivariable logistic regression. We generated voxel-based probability maps to assess the anatomical distribution of lesions. RESULTS We found no strong evidence for an association of female sex with the prevalence of all ischaemic infarcts (LNCCI and SNCI combined; adjusted OR 0.86, 95% CI 0.67 to 1.09, p=0.22), MB (adjusted OR 0.91, 95% CI 0.68 to 1.21, p=0.52) and moderate or severe WMH (adjusted OR 1.15, 95% CI 0.90 to 1.48, p=0.27). However, total WMH volume was 17% larger among women than men (multivariable adjusted multiplicative effect 1.17, 95% CI 1.01 to 1.35; p=0.04). Lesion probability maps showed a right hemispheric preponderance of ischaemic infarcts in both men and women, while WMH were distributed symmetrically. CONCLUSION Women had higher white matter disease burden than men, while volume and prevalence of other lesions did not differ. Our findings highlight the importance of controlling risk factors for cerebral small vessel disease in patients with AF, especially among women

Environmental DNA metabarcoding:Transforming how we survey animal and plant communities

The genomic revolution has fundamentally changed how we survey biodiversity on earth. High-throughput sequencing (?HTS?) platforms now enable the rapid sequencing of DNA from diverse kinds of environmental samples (termed ?environmental DNA? or ?eDNA?). Coupling HTS with our ability to associate sequences from eDNA with a taxonomic name is called ?eDNA metabarcoding? and offers a powerful molecular tool capable of noninvasively surveying species richness from many ecosystems. Here, we review the use of eDNA metabarcoding for surveying animal and plant richness, and the challenges in using eDNA approaches to estimate relative abundance. We highlight eDNA applications in freshwater, marine and terrestrial environments, and in this broad context, we distill what is known about the ability of different eDNA sample types to approximate richness in space and across time. We provide guiding questions for study design and discuss the eDNA metabarcoding workflow with a focus on primers and library preparation methods. We additionally discuss important criteria for consideration of bioinformatic filtering of data sets, with recommendations for increasing transparency. Finally, looking to the future, we discuss emerging applications of eDNA metabarcoding in ecology, conservation, invasion biology, biomonitoring, and how eDNA metabarcoding can empower citizen science and biodiversity educationpublishersversionPeer reviewe

The Serotonergic Raphe Promote Sleep in Zebrafish and Mice

The role of serotonin (5-HT) in sleep is controversial: early studies suggested a sleep-promoting role, but eventually the paradigm shifted toward a wake-promoting function for the serotonergic raphe. Here, we provide evidence from zebrafish and mice that the raphe are critical for the initiation and maintenance of sleep. In zebrafish, genetic ablation of 5-HT production by the raphe reduces sleep, sleep depth, and the homeostatic response to sleep deprivation. Pharmacological inhibition or ablation of the raphe reduces sleep, while optogenetic stimulation increases sleep. Similarly, in mice, ablation of the raphe increases wakefulness and impairs the homeostatic response to sleep deprivation, whereas tonic optogenetic stimulation at a rate similar to baseline activity induces sleep. Interestingly, burst optogenetic stimulation induces wakefulness in accordance with previously described burst activity of the raphe during arousing stimuli. These results indicate that the serotonergic system promotes sleep in both diurnal zebrafish and nocturnal rodents