Tracking down the molecular architecture of the synaptonemal complex by expansion microscopy

Fabian U. Zwettler, Marie-Christin Spindler, Sebastian Reinhard, Teresa Klein, Andreas Kurz, Ricardo Benavente, Markus Sauer

Nature Communications, Vol. 11(1), p. 3222 · 2020

DOI: 10.1038/s41467-020-17017-7 ISSN: 2041-1723

Abstract

The synaptonemal complex (SC) is a meiosis-specific nuclear multiprotein complex that is essential for proper synapsis, recombination and segregation of homologous chromosomes. We combined structured illumination microscopy (SIM) with different expansion microscopy (ExM) protocols including U-ExM, proExM, and magnified analysis of the proteome (MAP) to investigate the molecular organization of the SC. Comparison with structural data obtained by single-molecule localization microscopy of unexpanded SCs allowed us to investigate ultrastructure preservation of expanded SCs. For image analysis, we developed an automatic image processing software that enabled unbiased comparison of structural properties pre- and post-expansion. Here, MAP-SIM provided the best results and enabled reliable three-color super-resolution microscopy of the SCs of a whole set of chromosomes in a spermatocyte with 20–30 nm spatial resolution. Our data demonstrate that post-expansion labeling by MAP-SIM improves immunolabeling efficiency and allowed us thus to unravel previously hidden details of the molecular organization of SCs.

Keywords

Super-resolution microscopy Nanoscale biophysics Single-molecule biophysics

Cite this article 

@article{zwettler_tracking_2020,
  title = {Tracking down the molecular architecture of the synaptonemal complex by expansion microscopy},
  volume = {11},
  copyright = {2020 The Author(s)},
  issn = {2041-1723},
  doi = {10.1038/s41467-020-17017-7},
  abstract = {The synaptonemal complex (SC) is a meiosis-specific nuclear multiprotein complex that is essential for proper synapsis, recombination and segregation of homologous chromosomes. We combined structured illumination microscopy (SIM) with different expansion microscopy (ExM) protocols including U-ExM, proExM, and magnified analysis of the proteome (MAP) to investigate the molecular organization of the SC. Comparison with structural data obtained by single-molecule localization microscopy of unexpanded SCs allowed us to investigate ultrastructure preservation of expanded SCs. For image analysis, we developed an automatic image processing software that enabled unbiased comparison of structural properties pre- and post-expansion. Here, MAP-SIM provided the best results and enabled reliable three-color super-resolution microscopy of the SCs of a whole set of chromosomes in a spermatocyte with 20–30 nm spatial resolution. Our data demonstrate that post-expansion labeling by MAP-SIM improves immunolabeling efficiency and allowed us thus to unravel previously hidden details of the molecular organization of SCs.},
  language = {en},
  number = {1},
  urldate = {2021-12-06},
  journal = {Nature Communications},
  author = {Zwettler, Fabian U. and Spindler, Marie-Christin and Reinhard, Sebastian and Klein, Teresa and Kurz, Andreas and Benavente, Ricardo and Sauer, Markus},
  year = {2020},
  keywords = {Super-resolution microscopy, Nanoscale biophysics, Single-molecule biophysics},
  pages = {3222},
}
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