Biology subjects

Schorn, A.

Publications and source records attributed to Schorn, A..

4 recordsLinked to original sources

bioRxiv2025

A Combined Chemo-Enzymatic Treatment for the Oxidation of Epoxy-Based Carbon Fiber-Reinforced Polymers (CFRPs)

Carbon fiber-reinforced polymers (CFRPs), particularly epoxy-based composites, have become essential in the aerospace, automotive, and wind energy industries due to their robust mechanical properties, and lightweight nature. However, there is a lack of recycling technologies that are environmentally sustainable while also ensuring the recovery of carbon fibers in their original state. Although certain bacterial and fungal strains can colonize epoxy polymers, enzymes capable of efficiently degrading these materials have not yet been reported. Consequently, there is an urgent need for an effective, sustainable, and biologically inspired solution for CFRP recycling. Here, a chemo-enzymatic two-step oxidation process was developed. A chemical pre-treatment with propionic acid and hydrogen peroxide was used to recover imbedded carbon fibers. Additionally, three novel bacterial laccases isolated from the European spruce bark beetle (Ips typographus) demonstrated the ability to degrade three epoxy resin scaffolds from Hexflow(R) RTM6, used in aircraft applications. The sequential combination of both oxidative steps enabled the retrieval of clean carbon fibers and partial modification of epoxy functional groups, with the release of defined products over time. This bio-inspired approach renders the process more environmentally friendly and marks an initial step toward developing a bio-based recycling method for epoxy CFRPs.

biochemistry↗

bioRxiv2021

Dicer promotes genome stability via the bromodomain transcriptional co-activator Brd4.

RNA interference is essential for transcriptional silencing and genome stability, but conservation of this role in mammals has been difficult to demonstrate. Dicer1-/- mouse embryonic stem cells have microRNA-independent proliferation defects, and we conducted a CRISPR-Cas9 screen to restore viability. We identified suppressor mutations in transcriptional activators, H3K9 methyltransferases, and chromosome segregation factors, strongly resembling Dicer suppressors in fission yeast. Suppressors rescued chromosomal defects, and reversed strand-specific transcription of major satellite repeats in Dicer1-/-. The strongest suppressors were in Brd4, and in the transcriptional elongator/histone acetyltransferase Elp3. Using viable mutants and pharmaceutical inhibitors, we demonstrate that deletion of specific residues in Brd4 rescue genome instability defects of Dicer1-/- in both mammalian cells and fission yeast, implicating Dicer in coordinating transcription and replication of satellite repeats. SummaryReplication and segregation defects in Dicer1-/- stem cells depend on centromeric transcription by Brd4, and are deeply conserved in fission yeast.

genetics↗

bioRxiv2020

HMGXB4 Targets Sleeping Beauty Transposition to Vertebrate Germinal Stem Cells

Transposons are parasitic genetic elements that frequently hijack key cellular processes of the host. HMGXB4 is a Wnt signalling-associated HMG-box protein, previously identified as a transcriptional regulating host factor of Sleeping Beauty (SB) transposition. Here, we establish that HMGXB4 is highly expressed from the zygote stage, and declines after transcriptional genome activation. Nevertheless, HMGXB4 is activated by its own promoter at 4-cell stage, responding to the parental-to-zygotic transition, marks stemness, and maintains its expression during germ cell specification. The HMGXB4 promoter is located at an active chromatin domain boundary. As a vertebrate-specific modulator of SETD1A and NuRF complexes, HMGXB4 links histone H3K4 methyltransferase- and ATP-dependent nucleosome remodelling activities. The expression of HMGXB4 is regulated by the KRAB-ZNF/TRIM28 epigenetic repression machinery. A post-transcriptional modification by SUMOylation diminishes its transcriptional activator function and regulates its nucleolar trafficking. Collectively, HMGXB4 positions SB transposition into an elaborate stem cell-specific transcriptional regulatory mechanism that is active during early embryogenesis and germline development, thereby potentiating heritable transposon insertions in the germline.

developmental biology↗

bioRxiv2020

The Arabidopsis "retrovirome" and its regulation by epigenetically activated small RNA

In Arabidopsis, LTR-retrotransposons are activated by mutations in the chromatin remodeler DECREASE in DNA METHYLATION 1 (DDM1), giving rise to 21-22nt epigenetically activated siRNAs (easiRNAs) that depend on RNA DEPENDENT RNA POLYMERASE 6 (RDR6). We purified virus-like-particles (VLPs) from ddm1 and ddm1rdr6 mutants in which genomic RNA is reverse transcribed into complementary DNA. Next generation short-read and long-read sequencing of VLP DNA (VLP DNA-seq) revealed a comprehensive catalog of active LTR-retrotransposons without the need for mapping transposition, and independent of genomic copy number. Linear replication intermediates of a functionally intact copia element EVADE revealed multiple central polypurine tracts (cPPT), a feature shared with HIV where cPPT promote nuclear localization. For one member of the ATCOPIA52 subfamily (SISYPHUS), cPPT intermediates were not observed, but abundant circular DNA indicated transposon "suicide" by auto-integration within the VLP. easiRNA targeted EVADE genomic RNA, polysome association of GYPSY (ATHILA) subgenomic RNA, and transcription via histone H3 lysine-9 dimethylation. VLP DNA-seq provides a comprehensive landscape of LTR-retrotransposons, and their control at transcriptional, post-transcriptional and reverse transcriptional levels.

genomics↗