NSC177365

Electrophoretic mobility shift assay detects protein-nucleic acid binding by incubating a labeled DNA or RNA probe with purified protein or cell extract, then separating free probe from slower-migrating protein-probe complexes on a native gel. For cancer cells, primary neurons, mouse tumor samples, intestinal organoids, inflammatory macrophages, or drug-treated samples, EMSA can measure transcription-factor DNA binding or RNA-binding protein activity in extracts, but it does not directly measure transcription, protein expression, or chromatin occupancy in intact cells. Specificity is judged by competition with unlabeled wild-type probe, failure of mutated or unrelated competitors to compete, and antibody supershift or disruption when the binding protein identity must be confirmed.

Infectious-disease experiments test how pathogens interact with host barriers, innate immune receptors, inflammatory signaling, pathogen replication, and tissue injury; pattern-recognition receptors such as TLRs, RIG-I-like receptors, NOD-like receptors, and inflammasomes detect microbial molecules and activate NF-κB, interferon, and cytokine responses. The central hypothesis is that infection severity reflects the balance between pathogen burden and host response: protective inflammation restricts pathogen growth, whereas excessive or mislocalized inflammation contributes to tissue damage and disease phenotype. Unresolved questions include which host pathways are protective versus pathogenic, why some infection models fail to translate to human disease, and which combined readouts best predict clinically relevant infection outcomes.

The LIVE/DEAD bacterial viability staining method is based on differential permeability of nucleic-acid-binding fluorescent dyes, most commonly SYTO 9 and propidium iodide (PI), which enables discrimination of bacterial populations with intact versus compromised cytoplasmic membranes. SYTO 9 penetrates both intact and damaged bacterial membranes and binds nucleic acids to produce green fluorescence, whereas propidium iodide penetrates only cells with compromised membranes and fluoresces red while also reducing SYTO 9 signal through competitive binding and fluorescence interactions. The resulting fluorescence pattern is interpreted as a proxy for membrane integrity, which is widely used as an indicator of bacterial viability in microscopy, flow cytometry, and spectroscopic platforms. However, mechanistic studies show that SYTO 9 and PI interactions involve displacement and fluorescence resonance energy transfer effects, which can influence signal interpretation depending on dye ratios a