Biology subjects

Cen, Z.

Publications and source records attributed to Cen, Z..

4 recordsLinked to original sources

bioRxiv2026

Single-cell variant landscape of the human mitochondrial genome reveals cell type-specific functions and disease mechanisms

Mitochondrial DNA (mtDNA) heteroplasmy is a significant source of cellular genetic diversity and can cause disease yet its distribution and functional importance across different human cell types are poorly understood. Here we present scMOCHA (Single-Cell Mitochondrial Omics for Cellular Heteroplasmy Analysis), a scalable computational framework that resolves highconfidence, single-cell resolution mtDNA heteroplasmy directly from standard single-cell RNA sequencing (scRNA-seq) data. Using this tool to interrogate publicly available scRNA-seq datasets from human peripheral blood mononuclear cells (PBMC) and bone marrow (BM) uncovered the single-cell landscape of mtDNA single-nucleotide variants (SNVs) and heteroplasmy across ages in human hematopoietic cell types. PBMCs and BM share many inherited homoplasmic and highly heteroplasmic SNVs, whereas somatic SNVs are tissue- and cell type-specific and distributed across the mtDNA genome, suggesting that they arise largely stochastically. mtDNA replication error is a dominant force shaping homoplasmic variants, while oxidative stress potentially drives a significant portion of heteroplasmic and somatic mutations. Importantly, we discover previously unknown cell type-specific and human disease-associated mtDNA SNVs. By coupling mtDNA genotypes with matched single-cell nuclear transcriptomes and structural modeling, we uncover potential molecular mechanisms by which disease-associated mtDNA SNVs impact cellular processes such as inflammation and contribute to disease. Together, these findings define the single-cell variant landscape of the human mitochondrial genome and reveal previously unrecognized lineage- and disease-associated patterns of mtDNA variation in the human hematopoietic system.

genetics↗

bioRxiv2026

Environment-dependent epistasis shapes adaptation to fluctuating resources.

Microbial populations frequently experience fluctuations in resource availability, yet how these fluctuations reshape genetic interactions during adaptation remains unclear. Here, we identify the rapid evolution of latent antimicrobial susceptibility in Escherichia coli populations experimentally evolved under repeated feast-famine cycles. Longitudinal population genomics revealed recurrent mutations in the transport genes acrB and ompF, and reconstruction of these mutations demonstrated environment-dependent fitness effects characterized by positive epistasis after 1 day of culture and reciprocal sign epistasis after 10 days. Together, our results support a two-step adaptive trajectory in which mutations affecting efflux are followed by changes in porin permeability, generating genotypes that are jointly beneficial across feast and famine. More broadly, our findings demonstrate how fluctuating environments reshape adaptive genetic interactions, producing historically contingent evolutionary trajectories and latent phenotypes. Article SummaryHow fluctuating environments shape genetic interactions and evolutionary trajectories remains a central question in evolutionary genetics. We identified latent antimicrobial susceptibility in Escherichia coli populations evolved under repeated feast-famine cycles and reconstructed evolved mutations to resolve the genotype-to-phenotype map underlying this trait. The responsible mutations arose in key transport genes, exhibited environmental-dependent epistasis, and increased fitness across both feast and famine conditions. Our findings provide experimental evidence that fluctuating environments can select for interacting mutations that optimize fitness across a dynamic adaptive seascape.

evolutionary biology↗

bioRxiv2026

AAV-Mediated Dual-Gene Therapy Restores Metabolic Function in Mice with Propionic Acidemi

Background and AimsPropionic acidemia (PA) is a rare autosomal recessive disorder caused by mutations in PCCA or PCCB, which encode the two subunits of propionyl-CoA carboxylase (PCC). PCC deficiency causes toxic metabolite accumulation and multi-organ damage. Current management, including dietary restriction, pharmacological support, and liver transplantation, does not restore enzymatic activity. We developed a dual-gene adeno-associated virus (AAV) therapy that delivers both PCC subunits to treat both PA subtypes. MethodsWe generated a clinically relevant PCCA-R73W knock-in mouse model and administered AAV8 vectors encoding native human PCCA and PCCB under the control of a liver-specific thyroxine-binding globulin promoter (AAV8-TBG-hPCCA-P2A-hPCCB). Metabolite levels and organ safety were longitudinally assessed. ResultsDual-gene therapy produced dose-dependent reductions in plasma C3/C2 ratio, 3-hydroxypropionic acid, 2-methylcitric acid, and propionylglycine, and significantly outperformed single-gene (PCCA-only) therapy. Neonatal facial-vein injection achieved metabolic correction comparable to or better than adult treatment. The longitudinal follow-up revealed sustained efficacy over a 16-week period, with no signs of hepatotoxicity or adverse effects. ConclusionsSingle-dose, dual-gene AAV therapy achieves sustained metabolic correction and demonstrates long-term safety in a clinically relevant PA model, supporting its translational potential for both type I and type II propionic acidemia.

genetics↗

bioRxiv2023

Trade-offs, trade-ups, and high mutational parallelism underlie microbial adaptation to extreme feast/famine

Microbes are robust organisms capable of rapidly adapting to complex stress, enabling the colonization of harsh environments. In nature, microbes are regularly challenged by starvation, which is a particularly complex stress because resource limitation often co-occurs with changes in pH, osmolarity, and toxin accumulation created by metabolic waste. Often overlooked are the additional complications introduced by eventual resource replenishment as successful microbes must withstand rapid environmental shifts before swiftly capitalizing on replenished resources to avoid invasion by competing species. To understand how microbes navigate trade-offs between growth and survival, ultimately adapting to thrive in environments with extreme fluctuations, we experimentally evolved 16 Escherichia coli populations for 900 days to repeated feast/famine cycles of 100-day starvation before resource replenishment. Using longitudinal population-genomic analysis, we found that evolution in response to extreme feast/famine is characterized by narrow adaptive trajectories with high mutational parallelism and notable mutational order. Genetic reconstructions reveal that early mutations result in trade-offs for biofilm and motility but trade-ups for growth and survival, as these mutations conferred correlated advantages during both short-term and long-term culture. Our results demonstrate how microbes can navigate the adaptive landscapes of regularly fluctuating conditions and ultimately follow mutational trajectories that confer benefits across diverse environments.

evolutionary biology↗