Application of advanced fluorescence microscopy to the structure of meiotic chromosomes

Abstract

Chromosomes undergoing meiosis are defined by a macromolecular protein assembly called the synaptonemal complex which holds homologs together and carries out important meiotic functions. By retaining the molecular specificity, multiplexing ability, and in situ imaging capabilities of fluorescence microscopy, but with vastly increased resolution, 3D-SIM and other superresolution techniques are poised to make significant discoveries about the structure and function of the synaptonemal complex. This review discusses recent developments in this field and poses questions approachable with current and future technology.

Meiotic cohesin subunits RAD21L and REC8 are positioned at distinct regions between lateral elements and transverse filaments in the synaptonemal complex of mouse spermatocytes

“…3D-SIM has a resolution of 120 nm along the x-y directions, and is advantageous for the localization of molecules of interest with a great robustness in sample preparation [34]. Moreover, immunoreactivity is generally better preserved in the samples fixed with paraformaldehyde and used for 3D-SIM than in those fixed with glutaraldehyde commonly used for electron microscopy [35].…”

Super-Resolution Microscopy in Studying the Structure and Function of the Cell Nucleus

“…In condensin I subunit knockout cells, mitotic chromosomes had become shorter and wider and had a diffuse scaffold; in condensin II subunit knockout cells, the scaffold was more defined and the chromosomes were more stretched and lacked axial rigidity [77]. The spatial organization of a meiotic chromosome was studied using various SRM methods [78]. In yeast cells, 3D-SIM demonstrated the formation of a chromosome axis from meiotic cohesin, as well as impairment in the chromosome structure in the absence of cohesin [79, 80].…”

Studying the organization of DNA repair by single-cell and single-molecule imaging

“…Intriguingly, a thinner and highly mobile RecA filament was detected that extended into the interior of the nucleoid, presumably as part of the homology search process [29] . The increased resolution of SIM over conventional microscopy also helped to directly observe the spatial organization of eukaryotic meiotic chromosomes and revealed the ∼100 nanometer wide synaptonemal complex that is sandwiched between homologs [50] .…”