Biology subjects

Bittner, A.

Publications and source records attributed to Bittner, A..

4 recordsLinked to original sources

bioRxiv2026

Advancing Cardiac Tissue Engineering: Melt Electrowriting Conductive Polymer-Hydrogel Scaffolds

Myocardial infarction highlights an urgent need for strategies to regenerate functional cardiac tissue. Cardiac tissue engineering offers a promising approach; however, fabricating scaffolds that simultaneously integrate precise architectural anisotropy, mechanical compliance, and electrical conductivity remains an open challenge. In this work, we utilized melt electrowriting (MEW) to construct well-defined, 20-layer anisotropic rhomboidal polycaprolactone (PCL) scaffolds. We characterised them by tensile testing and by micro- and nanoscale microscopy. While introducing electrical conductivity via bulk blending with fillers (polypyrrole (PPy), polyaniline, or graphene oxide) compromised MEW print fidelity and failed to achieve physiological conductivity, surface coating strategies effectively combined conductivity from structural mechanics. Electrical and mechanical testing revealed that gold sputter coating and in situ PPy polymerization both imparted robust electrical conductivity while preserving the microfibrous architecture. However, when seeded with human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in fibrin hydrogels, only the gold-coated scaffolds supported synchronized, robust, and sustained contractile activity. PPy-coating resulted in functionally restricted constructs, suggesting that excessive structural rigidity limited tissue deformability. Gene expression analysis further revealed that elevated electrical conductivity alone does not drive hiPSC-CM maturation. Our data indicates that successful cardiac patch design relies on the integrated optimization of mechanics and architecture rather than treating conductivity as an isolated parameter, offering foundational guidelines for developing translational bioengineered heart patches. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=170 SRC="FIGDIR/small/740898v2_ufig1.gif" ALT="Figure 1"> View larger version (90K): org.highwire.dtl.DTLVardef@8c6656org.highwire.dtl.DTLVardef@192c99forg.highwire.dtl.DTLVardef@1f2f6f1org.highwire.dtl.DTLVardef@325ec1_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

With or without a Ca2+ signal;A proteomics approach towards Ca2+ dependent and independent proteome changes in response to oxidative stress in A. thaliana

Calcium (Ca2+) and reactive oxygen species (ROS) are key secondary messengers in plant stress signaling, yet their interplay in regulating proteome-wide responses remains poorly understood. In this study, we employed label-free quantitative (LFQ) proteomics to investigate Ca2+-dependent and independent changes in the proteome of Arabidopsis thaliana leaves upon oxidative stress induced by hydrogen peroxide (H2O2). To dissect the role of Ca2+ signaling, we inhibited H2O2-induced Ca2+ transients by pretreatment with LaCl3, a plasma membrane Ca2+ channel blocker. We then analysed the proteome of plants treated with H202 or ddH2O after 10 and 30 min of treatment and detected 3724 and 3757 proteins, respectively. From these, 581 proteins showed significant changes in abundance after 10 min and 909 proteins after 30 min. Remarkably, the combined LaCl3 and H2O2 treatment resulted in the highest number of differentially abundant proteins (DAPs), indicating a strong attenuating effect of Ca2+ signaling on the oxidative stress response. Specifically responsive to only H2O2 were 37 and 57 proteins with distinct subsets of strictly Ca2+-dependent, partially Ca2+- dependent, and Ca2+-independent proteins. Notably, Ca2+-independent H2O2-responsive proteins predominantly showed increased abundance, while strictly Ca2+-dependent proteins exhibited decreased abundance, suggesting a role for Ca2+ signaling in protein degradation. Furthermore, three proteins--WLIM1, CYP97C1, and AGAP1--underwent Ca2+-dependent shifts between the two time points, pointing to a dynamic nature of Ca2+-regulated proteomic changes. This study provides novel insights into short-term Ca2+-dependent and independent regulation of the Arabidopsis leaf proteome in response to oxidative stress, identifying key stress-responsive proteins and potential new targets for further research on plant stress resilience mechanisms.

plant biology↗

bioRxiv2023

Stress Knowledge Map: A knowledge graph resource for systems biology analysis of plant stress responses

Stress Knowledge Map (SKM, https://skm.nib.si) is a publicly available resource containing two complementary knowledge graphs describing current knowledge of biochemical, signalling, and regulatory molecular interactions in plants: a highly curated model of plant stress signalling (PSS, 543 reactions) and a large comprehensive knowledge network (CKN, 488,390 interactions). Both were constructed by domain experts through systematic curation of diverse literature and database resources. SKM provides a single entrypoint for plant stress response investigations and the related growth tradeoffs. SKM provides interactive exploration of current knowledge. PSS is also formulated as qualitative and quantitative models for systems biology, and thus represents a starting point of a plant digital twin. Here, we describe the features of SKM and show, through two case studies, how it can be used for complex analyses, including systematic hypothesis generation, design of validation experiments, or to gain new insights into experimental observations in plant biology.

plant biology↗

bioRxiv2023

High within-tree leaf trait variation and its response to species diversity and soil nutrients

O_LILeaf functional traits provide important insights into plants responses to different environments. Leaf traits have been increasingly studied within-species in the last decade, following the growing realisation that neglecting the intra-specific scale can result in misreading plants response to environmental change. However, while likely to lead to similar pitfalls, within-individual leaf traits are under-researched despite being the scale at which elementary interactions shape ecosystem processes. C_LIO_LITo address this critical lack of understanding at the local scale, we assessed leaf trait variation in a large biodiversity-ecosystem functioning experiment in subtropical China. We used optical spectroscopy to determine nine morphological and biochemical traits of >5800 leaves from 414 trees representing 14 species. We evaluated the relative importance of the intra-individual level for total leaf trait variation, and the interacting effect of two trait variations drivers, soil nutrient availability, and a local species richness gradient. C_LIO_LIComparing the amount of trait variation at the between-species, between-individuals and intra-individual levels, we found that intra-individual variation accounted on average for >25% of total trait variation. Additionally, intra-individual variation was the most prominent component of intra-specific variation. We found partial support for positive effects of soil nutrient availability and species diversity on intra-individual trait variation, and a strong interdependence of both effects. Contrary to the amplifying effects we expected, trait variation increased with soil nutrient availability at intermediate diversity, but decreased at low and high diversity. C_LIO_LIOur findings quantify the relevance of intra-individual level for leaf trait variation, and expose a complex interaction between its drivers. In particular, interactive effects of soil nutrient availability and local species diversity on trait variation suggest responses ranging from alleviating competition to enhancing complementarity. Taken together, our work highlights the importance of integrating an intra-individual perspective to understand trait-based mechanisms in biodiversity-ecosystem functioning relationships. C_LI

ecology↗