Sheng Yang

Reproductive aging is characterized by progressive decline in ovarian reserve, reduced oocyte competence, and impaired endocrine coordination. Although these phenotypic changes are well documented, the molecular mechanisms that integrate aging-associated stress signals into coordinated ovarian dysfunction remain incompletely understood. Increasing evidence indicates that DNA methylation remodeling is closely associated with ovarian aging. Rather than representing isolated promoter-specific events, age-related methylation alterations may reflect progressive imbalance between DNA methyltransferases (DNMTs) and TET-mediated demethylation. Stress-responsive DNMT/TET dysregulation has been linked to distributed epigenetic remodeling across regulatory elements governing PI3K–AKT, TGF-β/SMAD, metabolic, and DNA damage response pathways in ovarian cell populations. We propose a network-level framework in which methylation drift preferentially affects highly connected regulatory hubs, potentially reducing transcriptional robustness and intercellular coordination within the follicular microenvironment. However, current human data remain largely correlative, and functional validation is required to determine whether methylation remodeling acts as a driver, amplifier, or biomarker of ovarian aging. Finally, we discuss translational implications, including circulating cell-free DNA signatures and epigenetic clock models, while emphasizing the importance of cell type-resolved and longitudinal studies. Collectively, the available evidence supports a model in which progressive DNMT/TET imbalance is associated with distributed pathway-level regulatory instability during ovarian aging.

Histone post-translational modifications (PTMs) have emerged as promising epigenetic biomarkers with increasing forensic relevance. Unlike conventional genetic markers such as short tandem repeats (STRs), histone modifications can offer additional layers of biological information, capturing individual-specific regulatory states and remaining detectable even in degraded forensic samples. This review highlights recent advances in understanding histone PTMs in forensic contexts, focusing on three key domains: analysis of degraded biological evidence, differentiation of monozygotic (MZ) twins, and postmortem interval (PMI) estimation. We summarize experimental findings from human cadavers, animal models, and typical forensic samples including bone, blood, and muscle, illustrating the stability and diagnostic potential of marks such as H3K4me3, H3K27me3, and γ-H2AX. Emerging technologies including CUT&Tag, MALDI imaging, and nanopore-based sequencing offer novel opportunities to profile histone modifications at high resolution and low input. Despite technical challenges, these findings support the feasibility of histone-based biomarkers as complementary tools for forensic identification and temporal analysis. Future work should prioritize methodological standardization, inter-laboratory validation, and integration into forensic workflows. However, the forensic applicability of these modifications remains largely unvalidated, and further studies are required to assess their reliability in casework contexts.

Green-to-red photoconvertible fluorescent proteins (PCFPs) serve as key players in single-molecule localization super-resolution imaging. As an early engineered variant, mEos3.2 has limited applications, mostly due to its slow maturation rate. The recent advent of a novel variant, pcStar, obtained by the simple mutation of only three amino acids (D28E/L93M/N166G) in mEos3.2, exhibits significantly accelerated maturation and enhanced fluorescent brightness. This improvement represents an important advance in the field of biofluorescence by enabling early detection with reliable signals, essential for labelling dynamic biological processes. However, the mechanism underlying the significant improvement in fluorescent performance from mEos3.2 to pcStar remains elusive, preventing the rational design of more robust variants through mutagenesis. In this study, we determined the crystal structures of mEos3.2 and pcStar in their green states at atomic resolution and performed molecular-dynamics simulations to reveal significant divergences between the two proteins. Our structural and computational analyses revealed crucial features that are distinctively present in pcStar, including the presence of an extra solvent molecule, high conformational stability and enhanced interactions of the chromophore with its surroundings, tighter tertiary-structure packing and dynamic central-helical deformation. Resulting from the triple mutations, all of these structural features are likely to establish a mechanistic link to the greatly improved fluorescent performance of pcStar. The data described here not only provide a good example illustrating how distant amino-acid substitutions can affect the structure and bioactivity of a protein, but also give rise to strategic considerations for the future engineering of more widely applicable PCFPs.