<i>Drosophila</i> cells without centrioles can form acentriolar microtubule organizing centers (aMTOCs).

<p>(A) <i>Drosophila</i> larval brain cells were stained with antibodies against Ana1 (green) to mark the centrioles, Cnn (red) to mark the PCM and α-tubulin (white) to mark the spindle. DNA is in blue. <i>Sas-4</i> mutants do not have centrioles as indicated by the lack of Ana1 on the spindle poles, but often have some Cnn detectable at either one (middle panel) or both (lower panel) of their mitotic spindle poles (arrows). <i>WT</i> and <i>Sas-4</i> cells were recorded using identical microscope settings, visualising the much fainter staining of Cnn on spindle poles in <i>Sas-4</i> mutant cells. Scale bars represent 5μm. (B) Quantification of Cnn recruitment to mitotic spindle poles in <i>WT</i> and <i>Sas-4</i> mutant cells (as judged by Cnn staining on at least one spindle pole) shows that Cnn staining on spindle poles can be detected in 100% ± 0 of <i>WT</i> cells and 55.93% ± 3.16 of <i>Sas-4</i> cells. A minimum of 120 cells from 4 brains were quantified per genotype. Data are expressed as mean±SEM with average per brain representing one data point. (C, D) Quantification of Cnn intensity (C) and the size of the Cnn foci (D) in <i>WT</i> or <i>Sas-4</i> mutant <i>Drosophila</i> brain cells stained with anti-Ana1 as centriole marker, anti-α-tubulin to visualise spindles and anti-Cnn. Cnn foci on 20 different spindle poles were analysed for each genotype. Data are expressed as mean±SEM with Cnn staining on each spindle pole representing one data point. P-values were calculated using a Mann-Whitney test.