Fig. 7: SSNA-1 is required for the structural integrity of centrioles.

A Assay to detect centriole fragmentation and premature disengagement. Males whose centrioles are marked with SPOT::SAS-4 (magenta) are mated to hermaphrodites expressing SAS-4::GFP (green). In wild-type embryos the two paternal centrioles will indelibly be marked magenta while new centrioles will be marked green. Magenta mother/green daughter centriole pairs will remain engaged (and appear white) until telophase. Centriole instability will be detected as >2 magenta centrioles per embryo while premature disengagement will present as loss of green-red coincidence prior to telophase. B WT × WT (top), ssna-1(Δ) × ssna-1(Δ) (middle), and ssna-1(Δ) × WT two-cell stage embryos stained for SPOT::SAS-4 (magenta), SAS-4::GFP (green), and DNA (cyan). The WT × WT and ssna-1(Δ) × WT embryos possess two magenta centrioles indicating centriole stability while the ssna-1(Δ) embryo possesses three magenta centrioles revealing a centriole fragmentation phenotype. Note that in the wild-type embryo, one of the blastomeres in telophase is undergoing centriole duplication where one of the sperm centrioles (1) is producing a new green daughter. Bar = 10 μm. C Quantitation of centriole fragmentation in wild-type and ssna-1(Δ) mutant embryos. Note that in early prophase ssna-1(Δ) mutant embryos have two sperm derived centrioles indicating ssna-1(Δ) sperm contain the normal number of centrioles. However, older ssna-1(Δ) embryos frequently contain more than two magenta foci indicating that the sperm centrioles have fragmented. D Quantitation of SPOT::SAS-4 intensities. Lines connect centrioles from the same embryo. In ssna-1(Δ) embryos with three sperm derived centrioles, one is always significantly brighter than the other two, while in wild-type embryos, the sperm centrioles are much more similar in intensity. E ssna-1 and sas-1 genetically interact. The percentage of viable embryos produced by wild-type n = 23, ssna-1(Δ) n = 19, sas-1(t1476, bs272) n = 22, and sas-1(t1476, bs272); ssna-1(Δ) n = 21 hermaphrodites. Each datapoint represents the progeny of a single hermaphrodite. Mean and SD are shown. F AlphaFold prediction of SSNA-1 tetramer (grey) and SAS-1 (a.a. 539–570) (pink) showing an interaction with a pTM score of 0.65. The SSNA-1 tetramer structure is from Agostini et al.³⁶ Source data are provided as a Source Data file.