Biology subjects

Wiehlmann, L.

Publications and source records attributed to Wiehlmann, L..

5 recordsLinked to original sources

bioRxiv2026

Post-Weaning Gut Microbiota Colonization Reveals Divergent Recovery of Skeletal Muscle and Peripheral Nerves

We previously demonstrated that the absence of a complex gut microbiota (CGM) impairs the postnatal development of peripheral nerves and motor targets in germ-free (GF) mice. In this study, we investigated whether establishing a complex gut microbiota after weaning could reverse these developmental alterations. To address this question, GF mice were colonized with a complex gut microbiota by co-housing with conventionally raised mice. Microbiota composition, peripheral nerve morphology and transcriptional profiles, skeletal muscle proteome, neuromuscular junction architecture and circulating metabolites were comprehensively analyzed and compared with those of GF, gnotobiotic OMM12 and CGM mice. Post-weaning colonization partially restored microbial diversity and resulted in a compositionally distinct microbial community with reduced alpha diversity and enrichment of Duncaniella muris strain B8. Despite successful microbial colonization, peripheral nerve abnormalities persisted, including axon hypermyelination, transcriptional alterations in sciatic nerves, elongated nodes of Ranvier, and dysregulated axon-glia interactions. In contrast, skeletal muscle defects were largely rescued, with restoration of muscle mass, normalization of proteomic profiles, recovery of metabolic and structural pathways, and reduced fragmentation of the postsynaptic neuromuscular junction, although presynaptic abnormalities persisted. These findings demonstrate that microbiota-dependent developmental alterations differ markedly in their reversibility across the neuromuscular system. Specifically, post-weaning colonization with a complex gut microbiota resulted in broad recovery of skeletal muscle but failed to rescue peripheral nerve abnormalities. Our findings provide a framework for future studies investigating how the timing of microbial colonization, microbiota composition, and microbiota-derived signals influence the reversibility of microbiota-dependent neuromuscular alterations.

neuroscience↗

bioRxiv2022

Wochenende - modular and flexible alignment-based shotgun metagenome analysis

BackgroundShotgun metagenome analysis provides a robust and verifiable method for comprehensive microbiome analysis of fungal, viral, archaeal and bacterial taxonomy, particularly with regard to visualization of read mapping location, normalization options, growth dynamics and functional gene repertoires. Current read classification tools use non-standard output formats, or do not fully show information on mapping location. As reference datasets are not perfect, portrayal of mapping information is critical for judging results effectively. ResultsOur alignment-based pipeline, Wochenende, incorporates flexible quality control, trimming, mapping, various filters and normalization. We observe stringent filtering of mismatches and use of mapping quality sharply reduces the number of false positives. Further modules allow genomic visualization, as well as integration and subsequent plotting of pipeline results. Our novel normalization approach additionally allows calculation of absolute abundance profiles by comparison with reads assigned to the human host genome. ConclusionWochenende has the ability to find and filter alignments to all kingdoms of life using both short and long reads, and requires only good quality reference genomes. Wochenende automatically combines multiple available modules ranging from quality control and normalization to taxonomic visualization. Wochenende is available at https://github.com/MHH-RCUG/nf_wochenende.

bioinformatics↗

bioRxiv2021

MinION nanopore sequencing provides similar methylation estimates to Sanger bisulfite sequencing in the TRPA1 promoter region

Bisulfite sequencing has long been considered the gold standard for measurement of DNA methylation at single CpG resolution. In the meantime, several new approaches have been developed, which are regarded as less error-prone. Since these errors were shown to be sequence-specific, we aimed to verify the methylation data of a particular region of the TRPA1 promoter obtained from our previous studies. For this purpose, we compared methylation rates obtained via direct bisulfite sequencing and nanopore sequencing. Thus, we were able to confirm our previous findings to a large extent.

molecular biology↗

bioRxiv2020

iPSC culture expansion selects against putatively actionable mutations in the mitochondrial genome

While human induced pluripotent stem cells (iPSCs) offer fascinating prospects for research and clinics, evaluating their genomic stability before applications is of utmost importance. During reprogramming, clonal hiPSC lines derived from the same parental cell population were observed to harbor different mitochondrial DNA (mtDNA) variants and variant heteroplasmy levels. It is unknown to date to which extent this unequal segregation of heteroplasmies between cells arises from mosaicism in the parental cell population, selection on mutated mtDNA molecules on the cellular or organelle level, genetic drift during reduction of mtDNA during reprogramming (genetic bottleneck), or de novo mutations. We analyzed mtDNA variants in 26 clonal iPSC lines by mtDNA sequencing. We did not observe a strong bottleneck or any selection for cells with specific mtDNA variants (clonal eliteness) during reprogramming. iPSC culture expansion, however, selects against putatively actionable mutations in the mitochondrial genome that may affect mitochondrial function and cell metabolism. In contrast, heteroplasmy levels of neutral variants remained stable or increased within clonal iPSC lines during culture expansion. Interestingly, the mtDNA copy number per cell got transiently reduced during targeted differentiation of iPSCs into cardiomyocytes, but mtDNA heteroplasmy levels were not affected. Altogether, our results point towards a scenario in which intra-cellular selection on mtDNA during culture expansion, but not during reprogramming or differentiation, pivotally shapes the mutational landscape of the mitochondrial genome in iPSCs. Other mechanisms such as inter-cellular selection, genetic bottleneck, and genetic drift exert minor impact.

genomics↗

bioRxiv2020

Reprogramming enriches for somatic cell clones with small scale mutations in cancer-associated genes

Recent studies demonstrated that the mutational load in human induced pluripotent stem cells (hiPSCs) is largely derived from their parental cells, but it is still unknown whether reprogramming may enrich for individual mutations. 30 hiPSC lines were analyzed by whole exome sequencing. High accuracy amplicon sequencing showed that all analyzed small scale variants pre-existed in their parental cells and that individual mutations present in small subpopulations of parental cells become enriched among hiPSC clones during reprogramming. Among those, putatively actionable driver mutations affect genes related to cell cycle control, cell death and pluripotency, and may confer a selective advantage during reprogramming. Finally, a shRNA-based experimental approach was applied to provide additional evidence for the individual impact of such genes on the reprogramming efficiency. In conclusion, we show that enriched mutations in curated onco- and tumor suppressor genes may account for an increased tumor risk and impact the clinical value of patient-derived hiPSCs.

genomics↗