Biology subjects

Gasser, C.

Publications and source records attributed to Gasser, C..

8 recordsLinked to original sources

bioRxiv2026

Shamonda virus EU1 in Northern Italy, August 2026.

Background Following the emergence of a novel Shamonda-like virus (SHAV) in Europe, suspected clinical cases in dairy cattle were reported in Northeastern Italy. Investigation was required in dairy cattle in Northeastern Italy. Methods Samples were collected from 28 farms displaying fever and reduced milk yield and were screened using molecular methods (PanSimbu real-time RT-PCR followed by Sanger sequencing and differential PCRs for SBV/BTV). Positive samples were subsequently confirmed by Sanger sequencing and selected samples underwent whole-genome sequencing using a metagenomic approach. Results Twenty-four among sera and blood samples from 12 farms tested positive for SHAV. WGS confirmed that Italian strains share maximum identity with the European SHAV-EU1 clade. Limitations This study concerns the results of clinical investigations on suspected cases in the two autonomous provinces of Trento and Bolzano. At present, it is not possible to infer on the circulation of the virus in other Italian provinces. Conclusions This study documents the first detection and genetic characterization of SHAV-EU1 in Italian cattle, indicating active circulation of this virus across Europe. Its identification in two north-eastern Italian provinces does not rule out wider, undetected circulation. In this regard, assessing its geographical extent requires careful evaluation, just as much remains to be discovered about its host range and the severity of symptoms.

microbiology↗

bioRxiv2025

Community Challenge towards Consensus on Characterization of Biological Tissue: C4Bios First Findings

This study investigates methodological variability across various expert laboratories worldwide, with regards to characterizing the mechanical properties of biological tissues. Two testing rounds were conducted on the specific use case of uniaxial tensile testing of porcine aorta. In the first round, 24 labs were invited to apply their established methods to assess inter-laboratory variability. This revealed significant methodological diversity and associated variability in the stress-stretch results, underscoring the necessity for a standardized approach. In the second round, a consensus protocol was collaboratively developed and adopted by 19 labs in an attempt to minimize variability. This involved standardized sample preparation and uniformity in testing protocol, including the use of a common cutting and thickness measurement tool. Despite protocol harmonization, significant variability persisted across labs, which could not be solely attributed to inherent biological differences in tissue samples. These results illustrate the challenges in unifying testing methods across different research settings, underlining the necessity for further refinement of testing practices. Enhancing consistency in biomechanical experiments is pivotal when comparing results across studies, as well as when using the resulting material properties for in silico simulations in medical research.

bioengineering↗

bioRxiv2023

Evidence for impaired hippocampal circuitry in schizophrenia and its link to memory dysfunction

Pattern separation and pattern completion are opposing yet complementary components of mnemonic processing that heavily rely on the hippocampus. It has been shown that processing within the dentate gyrus (DG) subfield promotes pattern separation while operations within the CA3 subfield are important for pattern completion. Schizophrenia has been associated with anatomical and functional hippocampal abnormalities, including within the DG and CA3. We hypothesized that an impairment in hippocampal circuitry in individuals with first-episode schizophrenia leads to deficits in pattern separation (mnemonic discrimination) and pattern completion (recognition memory), that these deficits contribute to delusions, and that antipsychotic treatment improves circuit functioning. We measured behavioral and neural responses during the identification of new, repeated, and similar stimuli using high-resolution fMRI in 45 medication-free or minimally-treated patients with first-episode schizophrenia and 49 matched controls. We found recognition memory and pattern separation deficits in patients and a negative association between memory performance and the severity of delusions. Neural analyses revealed deficits in both univariate BOLD responses and multivariate patterns in the hippocampus during mnemonic discrimination in patients compared to controls. Importantly, by investigating the association between trial-level neural activity and behavior before and after treatment, we found that antipsychotics normalized DG activity during pattern separation and CA3 activity during pattern completion. Lastly, trial-level cortical responses during mnemonic discrimination predicted performance in patients at baseline, suggesting a compensatory role. This study provides new insight into the impact of schizophrenia and antipsychotic treatment on memory systems and uncovers systems-level contributions to pattern separation and pattern completion.

neuroscience↗

bioRxiv2022

Principled clustering of functional signals reveals gradients in processing both within the anterior hippocampus and across its long axis

A particularly elusive puzzle concerning the hippocampus is how the structural differences along its long, anteroposterior axis might beget meaningful functional differences, particularly in terms of the granularity of information processing. One measure posits to quantify this granularity by calculating the average statistical independence of the BOLD signal across neighboring voxels, or inter-voxel similarity (IVS), and has shown the anterior hippocampus to process coarser-grained information than that in the posterior hippocampus. This model of the hippocampus, however, conflicts with a number of task-oriented findings, many of which have varied in their fMRI acquisition parameters and hippocampal parcellation methods. In order to reconcile these findings, we measured IVS across two separate resting-state fMRI acquisitions and compared the results across many of the most widely used parcellation methods in a large young-adult sample (Acquisition 1, N = 253; Acquisition 2, N = 183). Finding conflicting results across acquisitions and parcellations, we reasoned that a principled, data-driven approach to hippocampal parcellation is necessary. To this end, we implemented a group masked independent components analysis (mICA) to identify functional subunits of the hippocampus, most notably separating the anterior hippocampus into separate anterior-medial, anterior-lateral, and posteroanterior-lateral components. Measuring IVS across these components revealed a decrease in IVS along the medial-lateral axis of the anterior hippocampus but an increase from anterior to posterior. We conclude that representational granularity may not change linearly or unidirectionally across the hippocampus, and that moving the study of the hippocampus towards reproducibility requires grounding it in a functionally informed approach. Significance StatementProcessing information along hierarchical scales of granularity is critical for many of the feats of cognition considered most human. Recently, the changes in structure, cortical connectivity, and apparent functional properties across parcels of the hippocampal long axis have been hypothesized to underlie this hierarchical gradient in information processing. We show here, however, that the choice of parcellation method itself drastically affects the perceived granularity across the hippocampus, and that a principled, functionally informed approach to parcellation reveals gradients both within the anterior hippocampus and in non-linear form across the long axis. These results point to the issue of parcellation as a critical one in the study of the hippocampus and reorient interpretation of existing results.

neuroscience↗

bioRxiv2020

Sister-chromatid-sensitive Hi-C reveals the conformation of replicated human chromosomes

The three-dimensional organization of the genome supports regulated gene expression, recombination, DNA repair, and chromosome segregation during mitosis. Chromosome conformation capture (Hi-C)1-3 has revealed a complex genomic landscape of internal chromosome structures in vertebrate cells4-11 yet how sister chromatids topologically interact in replicated chromosomes has remained elusive due to their identical sequences. Here, we present sister-chromatid-sensitive Hi-C (scsHi-C) based on nascent DNA labeling with 4-thio-thymidine. Genome-wide conformation maps of human chromosomes revealed that sister chromatid pairs interact most frequently at the boundaries of topologically associating domains (TADs). Continuous loading of a dynamic cohesin pool separates sister-chromatid pairs inside TADs and is required to focus sister chromatid contacts at TAD boundaries. We identified a subset of TADs that are overall highly paired, characterized by facultative heterochromatin, as well as insulated topological domains that form separately within individual sister chromatids. The rich pattern of sister chromatid topologies and our scsHi-C technology will make it possible to dissect how physical interactions between identical DNA molecules contribute to DNA repair, gene expression, chromosome segregation, and potentially other biological processes.

cell biology↗

bioRxiv2019

Dynamic arousal signals construct memories of time and events

Everyday life unfolds continuously, yet we tend to remember past experiences as discrete event sequences or episodes. Although this phenomenon has been well documented, the brain mechanisms that support the transformation of continuous experience into memorable episodes remain unknown. Here we show that a sudden change in context, or event boundary, elicits a burst of autonomic arousal, as indexed by pupil dilation. These boundaries during dynamic experience also led to the segmentation of adjacent episodes in later memory, evidenced by changes in memory for the timing, order, and perceptual details of recent event sequences. Critically, we find that distinct cognitive components of this pupil response were associated with both subjective (temporal distance judgements) and objective (temporal order discrimination) measures of episodic memory, suggesting that multiple arousal-mediated cognitive processes help construct meaningful mnemonic events. Together, these findings reveal that arousal processes may play a fundamental role in everyday memory organization.

neuroscience↗

bioRxiv2019

Secondary ossification centers evolved to make endochondral bone growth possible under the weight-bearing demands of a terrestrial environment

Growth plate and articular cartilage constitute a single anatomical entity early in development, but later separate into two distinct structures by the secondary ossification center (SOC). The reason for such separation remains unknown. We found that evolutionarily SOC appears in animals conquering the land - amniotes. Analysis of ossification pattern in mammals with specialized extremities (whales, bats, jerboa) revealed that SOC development correlates with the extent of mechanical loads. Mathematical modelling revealed that SOC reduces mechanical stress within the growth plate. Functional experiments revealed high vulnerability of hypertrophic chondrocytes to mechanical stress and showed that SOC protects these cells from apoptosis caused by extensive loading. Atomic force microscopy showed that hypertrophic chondrocytes are the least mechanically stiff cells within the growth plate. Altogether, these findings suggest that SOC has evolved to protect the hypertrophic chondrocytes from the high mechanical stress encountered in the terrestrial environment.

evolutionary biology↗

bioRxiv2018

Silk assembly integrates cells into a 3D fibrillar network that promotes cell spreading and proliferation

Tissues are built of cells integrated in an extracellular matrix (ECM) which provides a three-dimensional (3D) fibrillar network with specific sites for cell anchorage. By genetic engineering, motifs from the ECM can be functionally fused to recombinant silk proteins. Such a silk protein, FN-silk, which harbours a motif from fibronectin, has the ability to self-assemble into fibrillar networks under physiological-like conditions. Herein we describe a method by which mammalian cells are added to the silk solution before assembly, and thereby get uniformly integrated between the formed fibrils. In the resulting 3D scaffold, the cells proliferate and spread out with tissue-like morphology. Elongated cells containing filamentous actin and defined focal adhesion points confirm proper cell attachment to the FN-silk. The cells remain viable in culture for at least 90 days. The method is also scalable to macro-sized 3D cultures. Silk fibers with integrated cells are both strong and extendable, with mechanical properties similar to that of artery walls. The described method enables both differentiation of stem- or precursor cells in 3D and facile co-culture of several different cell types. We show that inclusion of endothelial cells leads to the formation of vessel-like structures throughout the tissue constructs. Hence, silk-assembly in presence of cells constitutes a viable option for 3D culture of cells integrated in a fibrillary ECM-like network, with potential as base for engineering of functional tissue.

bioengineering↗