Goats from the Zagros Mountains may represent the earliest examples of goat herding.
Image credit: The Central Zagros Project.
Edited* by Jennifer Lippincott-Schwartz, National Institutes of Health, Bethesda, MD, and approved December 19, 2014 (received for review August 2, 2014)
Significance
Synaptonemal complexes (SCs) are meiosis-specific, 200-nm-wide, ladder-like structures that are essential for synapsis, recombination, and segregation of homologous chromosomes. Despite its importance for the spatial organization of individual components during meiosis, the molecular architecture of the SC is still unknown. We used super-resolution imaging by direct stochastic optical reconstruction microscopy (dSTORM), which provides subdiffraction resolution for structural investigation of the SC. The helical ladder-like structure allowed us to reconstruct the 3D molecular organization of the mammalian SC from 2D “frontal” and “lateral” views with isotropic resolution. In combination with particle averaging, we managed to elucidate the molecular organization of the mammalian SC with nanometer precision and unraveled previously unknown details of its molecular architecture.
Abstract
Synaptonemal complexes (SCs) are meiosis-specific multiprotein complexes that are essential for synapsis, recombination, and segregation of homologous chromosomes, but the molecular organization of SCs remains unclear. We used immunofluorescence labeling in combination with super-resolution imaging and average position determination to investigate the molecular architecture of SCs. Combination of 2D super-resolution images recorded from different areas of the helical ladder-like structure allowed us to reconstruct the 3D molecular organization of the mammalian SC with isotropic resolution. The central element is composed of two parallel cables at a distance of ∼100 nm, which are oriented perpendicular to two parallel cables of the lateral element arranged at a distance of ∼220 nm. The two parallel cable elements form twisted helical structures that are connected by transversal filaments by their N and C termini. A single-cell preparation generates sufficient localizations to compile a 3D model of the SC with nanometer precision.
Footnotes
↵1K.S. and T.H. contributed equally to this work.
- ↵2To whom correspondence may be addressed. Email: m.sauer{at}uni-wuerzburg.de or benavente{at}biozentrum.uni-wuerzburg.de.
Author contributions: M.S. and R.B. designed research; K.S. and T.H. performed research; K.S., T.H., and C.F. analyzed data; and K.S., T.H., C.F., M.S., and R.B. wrote the paper.
The authors declare no conflict of interest.
↵*This Direct Submission article had a prearranged editor.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1414814112/-/DCSupplemental.
Freely available online through the PNAS open access option.
Synaptonemal complex as seen by dSTORM
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