Biology subjects

Fröhlich, T.

Publications and source records attributed to Fröhlich, T..

5 recordsLinked to original sources

bioRxiv2026

Phosphoproteomics in Daphnia magna as a tool to decipher molecular mechanisms in ecotoxicological studies

Pollution of aquatic environments poses an increasingly severe threat to ecosystems worldwide, and understanding its molecular consequences for aquatic organisms requires extensive research and the development of advanced analytical tools. Phosphoproteomics can be particularly valuable for this purpose, as shifts in phosphorylation states can serve as early molecular indicators of toxic exposure. The cladoceran Daphnia is a keystone species in aquatic ecosystems, linking lower and higher trophic levels, and is therefore widely used as a model organism in ecotoxicology to study biological consequences of pollution. Here, we present a simple and effective strategy to analyse the phosphoproteome of Daphnia magna, a commonly used Daphnia species in ecotoxicology. Following TiO2-based phosphopeptide enrichment and LC-MS/MS analysis, we identified a comprehensive dataset of 3,532 phosphorylation sites across 1,329 phosphoproteins. These proteins were especially involved in signaling pathways and cellular structure and the vast majority have not yet been demonstrated in other Daphnia species. In conclusion, our results demonstrate that a straightforward phosphoproteomic LC-MS/MS workflow in D. magna can serve as a powerful tool for investigating adverse molecular effects caused by anthropogenic pollution, such as microplastics or pharmaceuticals. Statement of significanceThe dataset presented here demonstrates the feasibility of a simple yet effective strategy to perform phosphoprotemics in Daphnia magna, and it will be particularly valuable for future ecotoxicoproteomics research using this model organism.

pharmacology and toxicology↗

bioRxiv2026

A bifunctional H/ACA snoRNP mediates both pseudouridylation and rRNA scaffolding during ribosome assembly

The early steps of eukaryotic large ribosomal subunit assembly remain poorly understood due to the structural flexibility of pre-60S intermediates, whose rRNA is extensively modified by small nucleolar RNPs (snoRNPs). Some snoRNPs, however, lack any modification function and instead scaffold ribosome assembly through largely unknown mechanisms. Here, we show that the H/ACA snoRNP snR37 integrates both modifying and scaffolding roles. Biochemical and structural analyses reveal a canonical H/ACA core that pseudouridylates a conserved uridine in the A site of the peptidyl transferase center, the catalytic heart of the 60S subunit. Additional RNA helices recruit non-core proteins, the Upa1-Upa2 heterodimer and Rbp95, which mediate stable snR37 association with pre-60S complexes. These proteins cooperate with the Npa1 rRNA chaperone complex to link four rRNA domains, thereby structurally organizing early pre-60S intermediates and promoting proper formation of the PTC. This dual organization establishes a paradigm for snoRNPs combining rRNA modification and scaffolding functions.

biochemistry↗

bioRxiv2025

Genetic parallels in biomineralization of the calcareous sponge Sycon ciliatum and stony corals

The rapid emergence of mineralized structures in diverse animal groups during the late Ediacaran and early Cambrian periods likely resulted from modifications of pre-adapted biomineralization genes inherited from a common ancestor. As the oldest extant phylum with mineralized structures, sponges are key to understanding animal biomineralization. Yet, the biomineralization process in sponges, particularly in forming spicules, is not well-understood. To address this, we conducted transcriptomic, genomic, and proteomic analyses on the calcareous sponge Sycon ciliatum, supplemented by in situ hybridization. We identified 829 genes overexpressed in regions of increased calcite spicule formation, including 17 calcarins--proteins analogous to corals galaxins localized in the spicule matrix and expressed in sclerocytes. Their expression varied temporally and spatially, specific to certain spicule types, indicating that fine-tuned gene regulation is crucial for biomineralization control. Similar subtle expression changes are also relevant in stony coral biomineralization. Tandem gene arrangements and expression changes suggest that gene duplication and neofunctionalization have significantly shaped Sycon ciliatums biomineralization, similar to that in corals. These findings suggest a parallel evolution of carbonate biomineralization in the calcitic Sycon ciliatum and aragonitic corals, exemplifying the evolution of mechanisms crucial for animals to act as ecosystem engineers and form reef structures.

evolutionary biology↗

bioRxiv2025

Multi-modal analysis of satellite cells reveals early impairments at pre-contractile stages of myogenesis in Duchenne muscular dystrophy

Recent studies on the role of myogenic satellite cells (SC) in Duchenne muscular dystrophy (DMD) documented altered division capacities and impaired regeneration potential of SC in DMD patients and animal models. It remains unknown, however, if SC-intrinsic effects trigger these deficiencies at pre-contractile stages of myogenesis rather than resulting from the pathologic environment. Addressing this, we isolated SC from muscle biopsies of a porcine DMD model for characterization. Traction force microscopy (TFM) revealed that DMD SC produce a significantly higher strain energy than wild-type cells (WT; 0.136 {+/-} 0.016 {micro}J vs. 0.057 {+/-} 0.008 {micro}J). By RNA-seq, we identified 1,390 differentially expressed genes and proteomics measurements detected 1,261 proteins with altered abundance in DMD vs. WT. Dysregulated pathways uncovered by Gene Ontology (GO) enrichment analysis included sarcomere organization, focal adhesion, and response to hypoxia. We integrated the data using multi-omics factor analysis (MOFA) and identified five factors accounting for the variance with an overall higher contribution of the transcriptomic (61.95 %) than the proteomic data (54.02 %). Our findings suggest SC impairments result from their inherent genetic abnormality rather than environmental influences. The observed biological changes are independent and not reactive to the pathological surrounding of DMD muscle.

pathology↗

bioRxiv2023

Gene Therapy for Cardiomyopathy associated with Duchenne Muscular Dystrophy in a Pig Model

BackgroundGenetic cardiomyopathies caused by mutations in the dystrophin gene (DMD) are only partially responsive to current pharmacological heart failure treatments, although dilated and arrhythomogenic phenotypes of cardiomyopathy are frequent. ObjectiveIn this study, we tested whether a normalization of Ca2+-handling by forced expression of SERCA2a in cardiomyocytes mitigates heart failure and arrhythmogenesis in a pig model for Duchenne muscular dystrophy (DMD). Methods and resultsMale offspring of pigs lacking DMD exon 52 are characterized by heart failure with reduced ejection fraction (HFrEF, EF 34.5{+/-}1.8% vs. 49.2{+/-}1.0% in control hearts), arrhythmogenesis due to large apical regions of reduced voltage amplitude and sudden cardiac death with a lifespan of usually less than 4 months. Slow antegrade intracoronary infusion of AAV1.SERCA2a (3x1013 virus genomes (vg) per pig) improved left ventricular ejection fraction (EF 47.3{+/-}2.0%, p<0.05) to a similar extent as germline editing of DMD{Delta}52 to DMD{Delta}51-52, inducing a Becker dystrophy (BMD) genotype (EF 46.7{+/-}3.8%). Moreover, AAV.SERCA2a significantly reduced myocardial inflammation and fibrosis and areas of reduced AP amplitude. ConclusionsIn DMD pigs, 3x1013vg/heart of GMP-grade AAV1.SERCA2a sufficed to normalize left ventricular function and improved electrical vulnerability of the heart. Hence, AAV.SERCA2a may serve as a treatment option for DMD cardiomyopathy.

physiology↗