Multiple synaptic aberrations are found in <i>pph-4.1</i> mutants.

<p>(A) 3D-SIM image of synapsed chromosomes in a wild-type nucleus. Top row shows maximum-intensity projections of image data in multiple channels; bottom row shows computer-aided traces of the six paired chromosomes. Correspondences between computer model (left) and straightened chromosomes (right) shown by colored dots. (B) A wild-type nucleus stained for SYP-1 and ZIM-3 showing two ZIM-3 foci at the synapsed PC ends of chromosomes I and IV. (C) 3D-SIM image of a <i>pph-4.1</i> nucleus shown in maximum-intensity projection of the entire nucleus (leftmost image, color) and a subset of Z sections (individual grayscale channels) highlighting a nonhomologously synapsed quartet of chromosomes, each making one or two switches of pairing partner. Computer traces (left) show seven individual strands, indicating two chromosomes likely undergoing foldback synapsis in the same nucleus. (D) <i>pph-4.1</i> nucleus stained for SYP-1 and ZIM-3 shows three synapsed foci, indicating non-homologous synapsis. (E) Highlighted examples of aberrant synapsis in two <i>pph-4.1</i> nuclei. HTP-3, SYP-1, and HIM-8 are shown to highlight axial elements, central elements, and the X chromosome. Straightened chromosome images are starred to correspond to individual chromosomes in the 3D traces. All chromosome configurations shown in schematic are inferred from straightened chromosome lengths and the requirement that 12 individual chromosomes are involved.