Biology subjects

Kos, M.

Publications and source records attributed to Kos, M..

8 recordsLinked to original sources

bioRxiv2026

The Effective Visual Acuity of Butterflies in Flight

The spatial visual acuity of an eye is determined by both the spatial sampling density of the retina and the angular sensitivity of individual photoreceptors. In insect compound eyes, these are respectively characterised by the interommatidial angle, {Delta}{varphi}, and photoreceptor acceptance angle, {Delta}{rho}. During movement, however, finite photoreceptor integration times cause retinal image motion to broaden the effective acceptance angle, potentially degrading spatial resolution beyond its anatomical limit. This problem is especially acute in flying insects, which experience large rotational velocities during locomotion and must actively stabilise gaze to limit retinal image motion. Butterflies present a particularly demanding case because their flight is characterised by large, wingbeat-coupled thoracic oscillations. Here, we quantify how gaze stabilisation limits motion blur in freely flying Monarch butterflies Danaus plexippus by combining free-flight kinematic reconstruction of the head and thorax with separate intracellular measurements of photoreceptor acceptance angles and integration times from quiescent butterflies. We found that, without head compensation, thoracic oscillations would broaden the effective photoreceptor acceptance angle from its quiescent value of 2.17{degrees} to 9.38{degrees} during take-off. Compensatory head movements substantially reduced this motion-induced broadening, limiting the effective acceptance angle to 5.28{degrees}. Nevertheless, this 2.4-fold broadening of effective photoreceptor acceptance angle represents a substantial degradation of spatial acuity in flight, highlighting motion blur as an important constraint on the visual ecology of flying butterflies.

neuroscience↗

bioRxiv2026

CD96-mediated internalisation of ligand CD155 as a novel mechanism for immune regulation

CD96 is a member of the immunoglobulin superfamily including TIGIT and CD226 that bind to a shared ligand, CD155. This family of co-receptors and its ligands are dysregulated in various autoimmune conditions and cancers, highlighting therapeutic potential. While TIGIT and CD226 are recognised co-inhibitory and co-stimulatory receptors respectively, the function of CD96 remains incompletely defined. Here, we assessed CD96-CD155 interaction and downstream trafficking to define a novel CD96 mechanism of action. Using primary human T cells and engineered cell models, we demonstrate that CD96 mediates uptake and internalisation of both soluble and cell-associated CD155. CRISPR-Cas9-mediated receptor knockout in primary human T cells revealed that CD155 uptake was uniquely dependent on CD96, but not TIGIT or CD226, identifying CD96 as the dominant mediator of CD155 internalisation in human T cells. This uptake process was dependent on active receptor cycling, which was partially facilitated by the CD96 cytoplasmic domain. Furthermore, CD96 variant 2 exhibited enhanced ligand binding and uptake efficiency compared with variant 1. Mechanistically, internalised CD155 trafficked to lysosomal compartments and associated with autophagy-related proteins, consistent with degradative processing. These findings reveal a previously unrecognised mechanism by which CD96 may regulate ligand availability through ligand internalisation and trafficking, with potential implications for T cell function and immune regulation. This process may promote changes in the immunoregulatory balance and could inform new targeted therapeutic development.

immunology↗

bioRxiv2025

Neural and Behavioral Responses to Social Norm Violations Across Trust and Fairness Contexts

Trust and fairness sustain cooperation, but social neuroscience has largely studied violations of these social norms in isolation. We asked whether neural sensitivity to betrayal carries forward into the evaluation of unfairness in a separate social exchange. In 132 adults who completed fMRI during the Trust Game and Ultimatum Game, betrayal and unfairness both recruited overlapping voxels within left anterior insula. Yet, individual differences in regional activation were uncorrelated across tasks, arguing against a simple shared-response account. Instead, cross-task structure emerged in connectivity: stronger anterior insula responses to social versus nonsocial betrayal predicted weaker anterior insula-ventromedial prefrontal coupling during social versus nonsocial fairness evaluation. These findings suggest that betrayal and unfairness are linked less by identical regional responses than by how salience signals engage valuation circuitry across contexts. By bridging two canonical social exchange tasks within the same individuals, this study reveals a network-level architecture for generalizing sensitivity to interpersonal norm violations.

neuroscience↗

bioRxiv2025

Novel insights into the chemodiversity and chemical ecology of the extremophile black yeast Hortaea werneckii, unlocking its potential for compound discovery

Hortaea werneckii is a halotolerant yeast, found in various habitats and which specialized metabolism remains largely unexplored. Moreover, its chemical response to high salinities has not been thoroughly investigated. To address this gap, a large-scale metabolomic study based on HPLC-HRMS/MS was conducted on 64 strains, collected from different habitats worldwide, and cultivated both on saline and non-saline media. The culture media salinity significantly modulated the strains metabolomes, suggesting the yeast exhibits a specific chemical response to high salt concentrations, potentially linked to halotolerance mechanisms. Additionally, the metabolomes were influenced by the ecological origin of the strains, with opportunistic pathogenic isolates producing distinct metabolites. Molecular networking revealed that H. werneckii synthesizes various chemical classes, including potential cytotoxic compounds, making this yeast a potentially interesting source of bioactive compounds. Hortein was detected as dominant and ubiquitous, emerging as a potential chemical marker for the species. This study highlights several compounds of interest, related to the chemical ecology and pathogenicity of H. werneckii. As most of them remain unidentified, future research should prioritize their isolation and identification, to improve our understanding of this extremophile organism and harness its potential in natural product discovery.

microbiology↗

bioRxiv2020

Cellular senescence and quiescence are associated with altered ribosomal RNA methylation and processing

The 2-O-methylation (2-O-Me) of ribosomal RNA (rRNA) shows plasticity potentially associated with specific cell phenotypes. We used RiboMeth-seq profiling to reveal 2-O-Me patterns specific to stress induced premature senescent (SIPS), quiescent and proliferating human dermal fibroblasts. The altered methylation levels in SIPS and quiescence partially correlated with the expression of specific snoRNAs but not fibrillarin. Senescence and quiescence were accompanied by a trend towards preferred usage of one of the two alternative ribosome biogenesis pathways.

molecular biology↗

bioRxiv2019

Classification of human physical activity based on the raw accelerometry data via spherical coordinate transformation

Human health is strongly associated with persons lifestyle and levels of physical activity. Therefore, characterization of daily human activity is an important task. Accelerometers have been used to obtain precise measurements of body acceleration. Wearable accelerometers collect data as a three-dimensional time series with frequencies up to 100Hz. Using such accelerometry signal, we are able to classify different types of physical activity.\n\nIn our work, we present a novel procedure for physical activity classification based on the raw accelerometry signal. Our proposal is based on the spherical representation of the data. We classify four activity types: resting, upper body activities (sitting), upper body activities (standing) and lower body activities. The classifier is constructed using decision trees with extracted features consisting of spherical coordinates summary statistics, moving averages of the radius and the angles, radius variance and spherical variance.\n\nThe classification accuracy of our method has been tested on data collected on a sample of 47 elderly individuals who performed a series of activities in laboratory settings. The achieved classification accuracy is over 90% when the subject-specific data are used and 84% when the group data are used. Main contributor to the classification accuracy is the angular part of the collected signal, especially spherical variance. To the best of our knowledge, spherical variance has never been previously used in the analysis of the raw accelerometry data. Its major advantage over other angular measures is its invariance to the accelerometer location shifts.

biophysics↗

bioRxiv2019

Two molecules of Has1 RNA helicase function simultaneously in the biogenesis of small and large ribosomal subunits

The RNA helicase Has1 is involved in the biogenesis of both small and large ribosomal subunits. How it performs these separate roles is not fully understood. Here we provide evidence that two molecules of Has1 are recruited and temporarily present in the same time in 90S pre-ribosomes. We identified multiple Has1 binding sites in the 18S, 5.8S and 25S rRNAs. We show that while the Has1 catalytic activity is not required for binding to 5.8S/25S region in pre-rRNA, it is essential for binding to 18S sites. After the cleavage of pre-rRNA at the site A2 Has1 remains associated not only with pre-60S but unexpectedly also with the pre-40S ribosomes. The recruitment to 90S/pre-40S and pre-60S ribosomes is mutually independent. Our data reconcile some seemingly contradictory observations about Has1 function in ribosome biogenesis.

molecular biology↗

bioRxiv2019

A ribosome assembly stress response regulates transcription to maintain proteome homeostasis

Ribosome biogenesis is a complex and energy-demanding process requiring tight coordination of ribosomal RNA (rRNA) and ribosomal protein (RP) production. Alteration of any step in this process may impact growth by leading to proteotoxic stress. Although the transcription factor Hsf1 has emerged as a central regulator of proteostasis, how its activity is coordinated with ribosome biogenesis is unknown. Here we show that arrest of ribosome biogenesis in the budding yeast S. cerevisiae triggers rapid activation of a highly specific stress pathway that coordinately up-regulates Hsf1 target genes and down-regulates RP genes. Activation of Hsf1 target genes requires neo-synthesis of RPs, which accumulate in an insoluble fraction, leading to sequestration of the RP transcriptional activator Ifh1. Our data suggest that levels of newly-synthetized RPs, imported into the nucleus but not yet assembled into ribosomes, work to continuously balance Hsf1 and Ifh1 activity, thus guarding against proteotoxic stress during ribosome assembly.

molecular biology↗