Biology subjects

Heumann, J.

Publications and source records attributed to Heumann, J..

5 recordsLinked to original sources

bioRxiv2025

Peer victimization and subsequent cognitive-affective biases in threat attention, reactivity, and interpretation

BackgroundPeer victimization (PV) in adolescence--verbal, social, and physical aggression--may disrupt normative developmental processes and is associated with psychosocial difficulties. Although previous research has established associations between early adversity and altered attention and cognitive-affective processing, the specific mechanisms of information-processing through which adolescent PV may affect later social functioning remain unclear. MethodsWe conducted a counterfactual multimethod study in a sample of young adults (age 22; n = 191; 47.1% female), comparing individuals with and without a history of PV between ages 11-20. Specifically we employed: (1) an eye tracking task using a free-viewing paradigm to assess spontaneous threat-related attention; (2) a longitudinal analysis of changes in hostile attribution and reactive aggression using baseline data collected prior to PV exposure and follow-up data in young adulthood; and (3) a morph-based task assessing facial emotion discrimination capabilities between happy and angry expressions. ResultsRelative to controls, victims exhibited a vigilance-avoidance attentional pattern and blunted affective responses; they showed reduced initial gaze allocation, repeated returns to angry faces, and a tendency to rate more angry faces as neutral. Over adolescence, a flatter decline in hostile attribution and a steeper drop in reactive aggression led to elevated hostile attribution and reduced reactive aggression. ConclusionsThese results suggest a victim profile characterized by impaired attentional processing with biased social threat perception, a more hostile view of the social world, and blunted affect. Our study offers preliminary evidence that adolescent PV may induce enduring changes in social information processing, with implications for maladaptive social cognition and increased risk for psychopathology.

bioinformatics↗

bioRxiv2025

Adolescent Peer Victimization Through a Trauma Lens: Heightened Startle Response, Increased Pupil Dilation, Elevated Cortisol, and Reduced Heart Rate Variability in Young Adulthood

BACKGROUNDAdolescent peer victimization (PV) is a prevalent social stressor associated with potential long-term psychological and physiological consequences. Yet, the mechanisms underlying enduring alterations in stress-regulatory systems remain underexplored. This multimodal study examines autonomic, endocrine, and affective reactivity in young adults with a history of severe PV. METHODSEyeblink startle electromyograms, pupil dilation, hair cortisol, resting heart rate variability, and self-reported state anxiety were assessed in 182 young adults (age 22) with longitudinal data on adolescent PV (ages 11-20). Effects were estimated using a counterfactual framework with genetically informed inverse probability weighting--leveraging polygenic risk scores and genetic ancestry--and adjustment for time-varying confounders. RESULTSVictims exhibited heightened startle amplitudes compared to controls, with negative stimuli (angry faces) further exaggerating amplitude and prolonging latency. Pupil dilation increased in response to negative stimuli, but was otherwise blunted. Victims also showed reduced resting heart rate variability, elevated hair cortisol, and slower state anxiety recovery across the session. Depression moderated several effects; more depressed victims showed hypocortisolism and reduced autonomic reactivity. CONCLUSIONSFindings provide converging evidence and mechanistic insight into potential links between PV and trauma-like physiological effects, suggesting sustained alterations into young adulthood. Targeted interventions are needed to reduce PV and its stress-related dysregulation, preventing potential long-term psychiatric and societal sequelae.

physiology↗

bioRxiv2024

Peer victimization in adolescence alters gene expression and cytokine profiles

Social adversity downregulates antiviral genes and upregulates inflammatory genes, altering cytokine levels. This study investigated the effects of peer victimization (PV) during adolescence on gene expression, cellular dynamics, and cytokine profiles in young adulthood. Data from the Zurich Brain and Immune Gene Study (z-GIG, n = 200; 47% female) captured PV between ages 11 and 20, with mRNA and plasma cytokines analyzed in 144 participants at age 22. A counterfactual design with genetically informed inverse probability weighting adjusted for baseline confounders in individual and environmental characteristics. In silico deconvolution revealed altered leukocyte composition in victims, including an M2-like monocyte-skewed profile. Differentially expressed genes in victims were enriched in preselected Reactome pathways, including Interferon signaling, Metabolism and Signal transduction. Exploratory Reactome-wide queries confirmed pathways in the Immune System and Metabolism, highlighted their downregulation, and identified additional pathways, such as those involved in Chromatin organization and Metabolism of proteins. Transcription factors STAT2, IRF2, and NF-{kappa}B emerged as key regulators in victims, with target genes prominently mapped to Interferon signaling and Chromatin organization pathways. Victims exhibited altered cytokine levels, including pro-inflammatory CCL4, TNF, CXCL9, and CXCL10. These findings suggest that adolescent PV can lead to changes in gene regulation and cytokine levels, potentially altering the immune profile into young adulthood. The results underscore the importance of health policies aimed at prevention, building resilience, and mitigating the long-term effects of PV.

genomics↗

bioRxiv2021

Structural heterogeneity of the microtubule lattice

Microtubules are tubes of about 25 nm in diameter that are critically involved in a variety of cellular functions including motility, compartmentalization, and division. They are considered as pseudo-helical polymers whose constituent {beta}-tubulin heterodimers share lateral homotypic interactions, except at one unique region called the seam. Here, we used a segmented sub-tomogram averaging strategy to reassess this paradigm and analyze the organization of the {beta}-tubulin heterodimers in microtubules assembled from purified porcine brain tubulin in the presence of GTP and GMPCPP, and in Xenopus egg cytoplasmic extracts. We find that in all conditions, microtubules incorporate variable protofilament and/or tubulin subunit helical-start numbers, as well as variable numbers of seams. Strikingly, the seam number and location vary along individual microtubules, generating holes of one to a few subunits in size within their lattices. Together, our results reveal that the formation of mixed and discontinuous microtubule lattices is an intrinsic property of tubulin that requires the formation of unique lateral interactions without longitudinal ones. They further suggest that microtubule assembly is tightly regulated in a cytoplasmic environment.

cell biology↗

bioRxiv2018

Cryo-EM Structure of OSCA1.2 from Oryza sativa: Mechanical basis of hyperosmolality-gating in Plants

Sensing and responding to environmental water deficiency and osmotic stresses is essential for the growth, development and survival of plants. Recently, an osmolality-sensing ion channel called OSCA1 was discovered that functions in sensing hyperosmolality in Arabidopsis. Here, we report the cryo-EM structure and function of an ion channel from rice (Oryza sativa; OsOSCA1.2), showing how it mediates hyperosmolality sensing and ion permeability. The structure reveals a dimer; the molecular architecture of each subunit consists of eleven transmembrane helices and a cytosolic soluble domain that has homology to RNA recognition proteins. The transmembrane domain is structurally related to the TMEM16 family of calcium dependent ion channels and scramblases. The cytosolic soluble domain possesses a distinct structural feature in the form of extended intracellular helical arms that is parallel to the plasma membrane. These helical arms are well positioned to sense lateral tension on the inner leaflet of the lipid bilayer caused by changes in turgor pressure. Computational dynamic analysis suggests how this domain couples to the transmembrane portion of the molecule to open the channel. Hydrogen-deuterium exchange mass spectrometry (HDXMS) experimentally confirms the conformational dynamics of these coupled domains. The structure provides a framework to understand the structural basis of hyperosmolality sensing in an important crop plant, extends our knowledge of the anoctamin superfamily important for plants and fungi, and provides a structural mechanism for translating membrane stress to ion transport regulation.

biophysics↗