活细胞成像的有丝分裂

Mitosis consists of prophase, prometaphase, metaphase, anaphase, telophase, and cytokinesis. During prophase, DNA condenses into sister chromatids and centrosomes assemble spindle fibers. Prometaphase involves nuclear membrane breakdown and kinetochore assembly. Metaphase aligns chromosomes at the metaphase plate. Anaphase separates sister chromatids to opposite cell ends. Telophase disassembles the spindle and decondenses chromatin. Cytokinesis divides the parent cell into two daughter cells via an actin/myosin cleavage furrow.

Scientists use fluorescent molecules that absorb light at one wavelength and emit at another. DNA binding dyes like Hoechst label nucleic acids and are cell permeable. Fluorescently tagged antibodies label proteins such as microtubules but require microinjection since they're membrane impermeable. Genetic labeling allows cells to express fluorescently tagged proteins that mark mitotic components like chromosomes. Excessive light exposure must be avoided to prevent photobleaching.

Confocal microscopy uses lasers to focus light onto single points, providing increased optical resolution and clearer images compared to epifluorescent microscopy, which passes light over the entire field of view. The point illumination in confocal microscopy also reduces phototoxicity, or increased cell death caused by excessive light exposure. Although confocal microscopes are more expensive, their superior image quality and reduced cell damage make them the preferred choice for detailed mitotic visualization.

Z-stacks are multiple optical slices captured at different depths of field along the Z-axis for each position on the culture dish. They allow researchers to reconstruct three-dimensional images of mitotic cells, accurately revealing spatial relationships between mitotic machinery components. This is critical because structures appearing adjacent in two-dimensional images may actually be far apart in three dimensions, providing essential information about the true organization of the dividing cell.

Montages are the most common presentation method, displaying multiple images in a grid-like pattern based on time to clearly show mitotic progression and allow determination of time spent in individual phases. Sequential combination of these images creates dynamic movies for more engaging presentation. Confocal Z-stacks can be combined to generate 3D recreations that reveal spatial relationships between mitotic components with greater accuracy than 2D analysis alone.

Cells must be cultured on glass bottom dishes or coverslips for optimal visualization. They're maintained in a controlled environment until labeling is performed using the appropriate technique. After labeling, the culture dish is placed into a specialized microscope chamber that maintains cell culture conditions during imaging. Excitation and emission wavelengths are set based on the labeling molecule, and time points and X-Y positions are configured to capture complete coverage of all mitotic stages.

Live cell imaging reveals mitotic mechanisms critical for understanding cell division proliferation cancer and development. Researchers use it to observe neural progenitor cell division during brain development, track DNA repair protein localization throughout division, and study spindle assembly checkpoints that pause division when chromosomes aren't properly connected. These applications have substantially helped scientists understand how mitosis is biologically controlled and how disruption of this process contributes to diseases like cancer.