This set of four diagnostic fluorescence images demonstrates the live-cell imaging of histone modifications in a human hTERT-RPE1 nucleus using Fab-based live endogenous modification labeling (FabLEM). Three individual channels show different histone marks: H3K27me3 (trimethylation associated with gene silencing), H3K9me2 (dimethylation), and H3K27ac (acetylation associated with active transcription). The H3K27me3 channel exhibits a highly concentrated, localized signal (indicated by an arrowhead), which identifies the inactive X chromosome. In contrast, the H3K27ac channel shows a broad, uniform distribution across the nucleus but is distinctly excluded from the inactive X chromosome territory. The H3K9me2 channel shows a relatively uniform nuclear distribution with slight enrichment in the same region as K27me3. A fourth composite image overlays H3K27me3 (green) and H3K27ac (magenta), highlighting the mutual spatial exclusion between these epigenetic marks. This visual comparison illustrates the organization of chromatin into distinct functional domains, specifically contrasting heterochromatin (inactive) and euchromatin (active) states within a living human cell.

This diagnostic image demonstrates a fluorescence in situ hybridization (FISH) analysis of a human cell nucleus. The interphase nucleus is visualized with a blue counterstain, likely DAPI, highlighting the chromatin within the nuclear envelope. Inside the nucleus, four distinct bright green punctate signals are visible, representing fluorescently labeled probes targeting the 1p subtelomere region. The spatial arrangement shows a cluster of three signals in close proximity, with a fourth signal located separately within the nuclear territory. Clinically, the presence of four signals instead of the typical two indicates an abnormal copy number, such as tetrasomy or gain of the 1p chromosomal region, which is a significant finding in cytogenetics for diagnosing certain hematologic malignancies or solid tumors. This image is used to teach concepts of clinical genetics, chromosomal abnormalities, and molecular pathology techniques.

This medical illustration depicts the temporal regulation of mitosis and nuclear reassembly through signaling pathways. Panel A shows a cell cycle timeline from early mitosis to late mitotic exit. Key visual milestones include nuclear envelope breakdown (NEBD), chromosome condensation and alignment on the metaphase plate, sister chromatid separation during anaphase, and eventual cytokinesis with nuclear reassembly around decondensing chromatin. A color-coded bar indicates the shifting dominance between kinases (green) and phosphatases (purple) across these stages. Panel B details the molecular signaling network. At mitotic entry (left), Cyclin B-CDK1, Aurora B, and PLK1 dominate, inhibiting phosphatases like PP1 and PP2A-B55 via regulatory proteins like Repo-Man and Greatwall (Gwl)/Endos. At the onset of mitotic exit (center), the Anaphase Promoting Complex/Cyclosome (APC/C) triggers the degradation of Securin and Cyclin B. In late mitotic exit (right), PP1 and PP2A-B55 regain activity, dephosphorylating substrates (SUBS.) and regulatory proteins to promote the reformation of the interphase nucleus and completion of cell division.

This figure presents genomic data visualizations illustrating chromosome interaction structures in Klebsiella pneumoniae for wild-type (WT) and mutant (M1, M2) strains. Panel A displays Chromosome A/B compartments across the genome (0 to 5.0 Mbp). The x-axis represents genomic coordinates, and the y-axis shows eigenvector values ranging from -3 to 3. Positive values (red) denote compartment A (transcriptionally active), while negative values (black) denote compartment B (inactive). The WT shows alternating A/B patterns, whereas M1 and M2 exhibit increased red signal intensity, suggesting a shift toward more open, active chromatin. Panel B illustrates Chromosomal Interaction Domains (CIDs). The y-axis represents the insulation index, with grey lines tracing chromatin density. Vertical green lines demarcate CID boundaries. Visual comparison shows a higher density of boundaries in WT compared to mutants, indicating that smaller CIDs in the WT have merged into larger, less defined domains in M1 and M2. These diagrams are used in microbial genetics and pathophysiology to study how environmental stressors like simulated microgravity alter chromosome folding and gene expression.