SC components across model organisms.

The successful delivery of genetic material to gametes requires tightly regulated interactions between the parental chromosomes. Central to this regulation is a conserved chromosomal interface called the synaptonemal complex (SC), which brings the parental chromosomes in close proximity along their length. While many of its components are known, the interfaces that mediate the assembly of the SC remain a mystery. Here, we survey findings from different model systems while focusing on insight gained in the nematode C. elegans. We synthesize our current understanding of the structure, dynamics, and biophysical properties of the SC and propose mechanisms for SC assembly.</div

SC structure in <i>C</i>. <i>elegans</i>.

Top: Electron micrograph of meiotic chromosomes in C. elegans (adapted from [12]). The electron-dense mass to the sides of the SC is chromatin. Axes (salmon) organize each of the parental chromosomes into an elongated structure by stacking the bases of chromatin loops (blue). The CR (green) assembles between the parallel axes of the homologs. Bottom: Magnified views of the CR and the axis. The CR (left) is composed of SYP-1 through SYP-6. The axis (right) is composed of ring-shaped cohesins (mauve) and the HORMA-domain proteins HTP-3 (orange), which, in turn, recruits the HORMA-domain proteins HIM-3 and HTP-1 and HTP-2 (pink). See Table 1 for more details.</p