Researchers Develop Standardized MNase-seq Framework for Reproducible Nucleosome Profiling
Scientists have published a scalable, standardized micrococcal nuclease sequencing (MNase-seq) workflow for profiling nucleosome positioning across multiple cell types, including human stem cells and cardiomyocytes. The protocol addresses longstanding reproducibility problems caused by sensitivity to reaction conditions and the absence of unified standards across laboratories. The framework could improve comparability of chromatin accessibility studies across diverse biological models.
A team of researchers has developed and validated a modular MNase-seq framework designed to overcome key technical barriers in chromatin profiling, including variability in digestion conditions, high cell input demands, and the lack of cross-laboratory standardization. The workflow optimizes buffer composition, DNA purification chemistry, fixation and decrosslinking parameters, and cell input scalability, and incorporates an in-house yeast spike-in for quantitative normalization. The protocol was validated across human induced pluripotent stem cells (hiPSCs), hiPSC-derived cardiomyocytes at multiple differentiation stages, primary murine embryonic cardiac cells, and adult mouse cardiomyocytes. Despite marked differences in cellular architecture and chromatin organization among these models, the workflow achieved comparable digestion efficiencies and kinetics. Genome-wide MNase-seq in hiPSCs, analyzed with the nucMACC bioinformatic pipeline, successfully resolved nucleosomal occupancy and precise nucleosome positioning at pluripotency-related regulatory elements. The end-to-end platform is intended to serve as a community standard for reproducible MNase-based chromatin studies in both in vitro and in vivo settings.
What's missing
As a preprint on bioRxiv, this work has not yet undergone formal peer review, so the robustness and generalizability of the protocol remain to be independently validated. The study does not report direct benchmarking against existing commercial or widely-used MNase-seq protocols, which would help quantify the improvement in reproducibility.
What different sources said
- bioRxivCenter
A scalable MNase-seq framework for reproducible nucleosome profiling across pluripotent stem cell and cardiomyocyte models
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.