Alvarado, N. | Search bioRxiv

bioRxiv2026

Chromatin-Assisted Targeting Enables Precise DNA Methylation Editing in Plants

Precise installation of DNA methylation at selected loci offers a powerful strategy for regulating gene expression without altering DNA sequence, but existing plant epigenome editors are constrained by limited efficiency, locus dependence, and genome-wide off-target methylation. Here, we developed SunTag-MQ1v variants incorporating TRBIP1, which promotes removal of the antagonistic H3K4me3 mark, and CHLAMY, an oligomerizing alpha crystalline domain protein from Chlamydomonas reinhardtii. TRBIP1 enhanced methylation and silencing at the Arabidopsis FWA promoter but caused widespread off-target methylation and severe developmental defects. Adding CHLAMY produced SunTag-CHLAMY-TRBIP1-MQ1v (designated as SunTag-NOVA), which successfully overcame the lethality and widespread off-target effects associated with direct TRBIP1-MQ1v fusions. We demonstrate that CHLAMY drives higher-order oligomerization of the editing complex, which enhances target specificity and mitigates off-target accumulation. SunTag-NOVA robustly installed DNA methylation and repressed transcription at the endogenous FWA, FT and TMM genes with minimal genome-wide off-target consequences. These results show that combining local chromatin modification with controlled effector assembly can improve targeted DNA methylation, and establish SunTag-NOVA as a specific epigenome-editing platform for plants.

plant biology↗

bioRxiv2025

Echoes of 1816: Microbial Footprints in Heritage Artifacts From Argentina's Museum of Independence

Historical artifacts preserved in museums are invaluable cultural treasures, yet they are often vulnerable to biodeterioration caused by microbial colonization. This study presents the first comprehensive investigation of microbial communities inhabiting heritage artifacts from Argentinas Museum of Independence. By integrating advanced microscopy with phenotypic and genomic characterization, we analyzed samples collected from wooden objects, textiles, architectural elements, and exterior walls. Scanning electron microscopy revealed diverse and well-structured biofilms, with intricate three-dimensional arrangements embedded in extracellular polymeric substances. A total of 49 bacterial strains were isolated and identified via VITEK MALDI-TOF mass spectrometry, with a predominance of Gram-positive genera such as Bacillus, Micrococcus, and Kocuria. Remarkably, the 19th-century albumen print photograph emerged as the most biodiverse artifact, yielding 21 distinct strains, including Streptomyces, Oceanobacillus, and thermophilic Caldibacillus thermoamylovorans. The protein-rich and halophilic environment of the albumen layer likely facilitated microbial colonization and persistence. Pseudomonas species were exclusively associated with this photographic substrate, further underscoring its niche specificity. Human-associated taxa like Staphylococcus epidermidis and Staphylococcus equorum were prevalent in high-contact areas, while exterior surfaces displayed distinct microbial signatures, including potential pathogens linked to environmental exposure. These findings reveal a complex and artifact-specific microbial landscape, emphasizing the need for tailored, bio-informed conservation strategies. This work advances the field of heritage microbiology and supports efforts to safeguard culturally significant objects through a deeper understanding of their microbial ecosystems.

microbiology↗