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Biology subjects

Berger, E.

Publications and source records attributed to Berger, E..

6 recordsLinked to original sources

varVAMP: automated pan-specific primer design for tiled full genome sequencing and qPCR of highly diverse viral pathogens.

Time- and cost-saving surveillance of viral pathogens is achieved by tiled sequencing in which a viral genome is amplified in overlapping PCR amplicons and qPCR. However, designing pan-specific primers for viral pathogens that have high genomic variability represents a major challenge. Here, we present a bioinformatics command-line tool, called varVAMP (variable virus amplicons). It relies on multiple sequence alignments of highly variable virus sequences and enables automatic pan-specific primer design for qPCR or tiled amplicon whole genome sequencing. The varVAMP software guarantees pan-specificity by two means: it designs primers in regions with minimal variability and introduces degenerate nucleotides into primer sequences to compensate for common sequence variations. We demonstrate varVAMPs utility by designing and evaluating novel pan-specific primer schemes suitable for sequencing the genomes of SARS-CoV-2, Hepatitis E virus, rat Hepatitis E virus, Hepatitis A virus, Borna-disease-virus-1, and Poliovirus. Moreover, we established highly sensitive and specific Poliovirus qPCR assays that could potentially simplify current Poliovirus surveillance. Importantly, wet-lab and bioinformatic techniques established for SARS-CoV-2 tiled amplicon sequencing were readily transferable to these new primer schemes and will allow sequencing laboratories to extend their established methodology to other human pathogens.

bioinformatics↗

Early mitochondrial dysfunction proceeds neuroinflammation, synaptic alteration, and autophagy impairment in hippocampus of App knock-in Alzheimer mouse models

Increased amyloid {beta}-peptide (A{beta}) level is one of the drivers of Alzheimers disease (AD). Amyloid precursor protein (App) knock-in mice recapitulate the human A{beta} pathology, allowing the elucidation of the downstream effects of A{beta} and their temporal appearance upon disease progression. Here we have investigated the sequential onset of AD-like pathologies in the AppNL-F and AppNL-G-F knock-in mouse models by time-course transcriptome analysis of the hippocampus, a region severely affected in AD. Energy metabolism emerged as one of the most significantly altered pathways at an early stage of the development of the pathologies. Functional experiments in mitochondria isolated from AppNL-G-F brain subsequently identified upregulation of oxidative phosphorylation driven by the activity of mitochondrial complexes I, IV and V, combined with higher susceptibility to Ca2+-overload. This was followed by a strong neuroinflammatory response and impaired autophagy. Accumulation of autophagosomes and reduced number of mitochondria content in presynaptic terminals could account for the altered synapse morphology including increased number of synaptic vesicles and lowered thickness of post synaptic density in AppNL-G-F mice. This shows that A{beta}-induced pathways in the App knock-in mice recapitulate some key pathologies observed in AD brain, and our data herein contributes to the understanding of their timewise appearance and potential role in new therapeutic approaches.

neuroscience↗

Microglia integration into human midbrain organoids leads to increased neuronal maturation and functionality.

The human brain is a complex, three-dimensional structure. To better recapitulate brain complexity, recent efforts have focused on the development of human specific midbrain organoids. Human iPSC-derived midbrain organoids consist of differentiated and functional neurons, which contain active synapses, as well as astrocytes and oligodendrocytes. However, the absence of microglia, with their ability to remodel neuronal networks and phagocytose apoptotic cells and debris, represents a major disadvantage for the current midbrain organoid systems. Additionally, neuro-inflammation related disease modeling is not possible in the absence of microglia. So far, no studies about the effects of human iPSC-derived microglia on midbrain organoid neural cells have been published. Here we describe an approach to derive microglia from human iPSCs and integrate them into iPSC-derived midbrain organoids. Using single nuclear RNA Sequencing, we provide a detailed characterization of microglia in midbrain organoids as well as the influence of their presence on the other cells of the organoids. Furthermore, we describe the effects that microglia have on cell death and oxidative stress- related gene expression. Finally, we show that microglia in midbrain organoids affect synaptic remodeling and increase neuronal excitability. Altogether, we show a more suitable system to further investigate brain development, as well as neurodegenerative diseases and neuro- inflammation. Main Points- Macrophage precursors can be efficiently co-cultured with midbrain organoids, they integrate into the tissue and differentiate into microglia in 3D. - Organoids containing microglia have a smaller size and show a down-regulation of oxidative stress-related genes. - Organoids co-cultured with microglia show differences in genes related to synaptic remodeling and action potential, as well as a more spontaneous action potential firing.

neuroscience↗

Intra-individual variability in task performance after cognitive training is associated with long-term outcomes in children

The benefits and mechanistic effects of working memory training in children are the subject of much research and debate. The cumulative evidence indicates that training can alter brain structure and function in the short term and have lasting effects on behaviour. We show that five weeks of working memory training led to greater activity in prefrontal and striatal brain regions, better accuracy, and reduced intra-individual variability in response times. The reduction in intra-individual variability can be explained by changes to the evidence accumulation rates and thresholds in a sequential sampling decision model. Critically, intra-individual variability was more closely associated with academic skills and mental health 6-12 months after the end of training than task accuracy. These results indicate that intra-individual variability may be a useful way to quantify the immediate impact of cognitive training interventions and predict the future emergence of academic and socioemotional skills.

neuroscience↗

Cultivation and characterization of human midbrain organoids in sensor integrated microfluidic chips

1.With its ability to emulate microarchitectures and functional characteristics of native organs in vitro, induced pluripotent stem cell (iPSC) technology has enabled the generation of a plethora of organotypic constructs, including that of the human midbrain. However, reproducibly engineering and differentiating such human midbrain organoids (hMOs) under a biomimetic environment favorable for brain development still remains challenging. This study sets out to address this problem by combining the potential of iPSC technology with the advantages of microfluidics, namely its precise control over fluid flow combined with sensor integration. Here, we present a novel sensor-integrated platform for the long-term cultivation and non-invasive monitoring of hMOs under an interstitial flow regime. Our results show that dynamic cultivation of iPSC-derived hMOs maintains high cellular viabilities and dopaminergic neuron differentiation over prolonged cultivation periods of up to 50 days.

bioengineering↗

Parkinson’s disease phenotypes in patient specific brain organoids are improved by HP-β-CD treatment

The etiology of Parkinsons disease (PD) is only partially understood despite the fact that environmental causes, risk factors, and specific gene mutations are contributors to the disease. Biallelic mutations in the PTEN-induced putative kinase 1 (PINK1) gene involved in mitochondrial homeostasis, vesicle trafficking, and autophagy, are sufficient to cause PD. By comparing PD patient-derived cells, we show differences in their energetic profile, imbalanced proliferation, apoptosis, mitophagy, and a reduced differentiation efficiency to dopaminergic neurons compared to control cells. Using CRISPR/Cas9 gene editing, correction of a patients point mutation ameliorated the metabolic properties and neuronal firing rates but without reversing the differentiation phenotype. However, treatment with 2-Hydroxypropyl-{beta}-Cyclodextrin (HP-{beta}-CD) increased the mitophagy capacity of neurons leading to an improved dopaminergic differentiation of patient specific neurons in midbrain organoids. In conclusion, we show that treatment with a repurposed compound is sufficient for restoring dopaminergic differentiation of PD patient-derived cells.

neuroscience↗