• at P22, the length of proximal axonemes labeled by RP1 (retinitis pigmentosa 1 protein) is slightly but significantly reduced; by 3 months, RP1+ axoneme length is 56% of that in single
Cetn3tm1a(EUCOMM)Wtsi homozygotes
• CETN1 is gradually depleted from the connecting cilium (CC) distal and proximal ends and accumulates in the central CC; the length of the CETN1+ CC fragment is reduced to 78.5% at P25 and to 56.3% by 3 months
• at 3 months but not at P25, the Ac-tubulin signal ratio (at CC versus proximal axoneme) is significantly reduced, indicating a gradual deacetylation of CC microtubules but hyperacetylation of proximal OS axoneme microtubules
• at 2.5 months, ~20-30% of photoreceptors show variable dilation at the distal CC and OS proximal axoneme, ranging from a slight expansion to extreme dilation with invasion of vertically aligned disc membranes and loss of microtubule doublet integrity
• at 2 months, SPATA7 (a key organizer of the photoreceptor-specific distal CC) is partially depleted starting from the CC mid-segment, and by 3 months SPATA7 is almost undetectable along the entire CC length, indicating that distal CC dilation correlates with SPATA7 depletion