title: Direct Visualization Reveals Kinetics of Meiotic Chromosome Synapsis.
abstract: The synaptonemal complex (SC) is a conserved protein complex that stabilizes interactions along homologous chromosomes (homologs) during meiosis. The SC regulates genetic exchanges between homologs, thereby enabling reductional division and the production of haploid gametes. Here, we directly observe SC assembly (synapsis) by optimizing methods for long-term fluorescence recording in C. elegans. We report that synapsis initiates independently on each chromosome pair at or near pairing centers-specialized regions required for homolog associations. Once initiated, the SC extends rapidly and mostly irreversibly to chromosome ends. Quantitation of SC initiation frequencies and extension rates reveals that initiation is a rate-limiting step in homolog interactions. Eliminating the dynein-driven chromosome movements that accompany synapsis severely retards SC extension, revealing a new role for these conserved motions. This work provides the first opportunity to directly observe and quantify key aspects of meiotic chromosome interactions and will enable future in vivo analysis of germline processes.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3220, USA; Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815, USA.
authors.forename: Ofer
authors.initials: O
authors.lastname: Rog
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3220, USA; Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815, USA; Department of Genome Dynamics, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, Berkeley, CA 94720, USA. Electronic address: afdernburg@lbl.gov.
authors.forename: Abby F
authors.initials: AF
authors.lastname: Dernburg