Movie 1

MT dynamics at SAPs injected into cycling embryos. The movie shows MT dynamics in a living embryo expressing the MT marker Jupiter-mCherry (red) that has been injected with SAPs that were harvested from a “donor” unfertilised egg overexpressing Sas-6-GFP and Ana2-GFP (green). Several SAPs are visible at the bottom left. The endogenous centrosome pairs and their associated nuclei can be visualised by the prominent astral MTs the centrosomes organise. Note, however, that some cytoplasmic Sas-6-GFP and Ana2-GFP molecules from the “donor” unfertilised egg gets co-injected with the SAPs into the “recipient” developing embryo, and these can incorporate into the nearby endogenous centrioles; these centrioles therefore fluoresce in the green channel, although they are smaller and dimmer than SAPs and so are easily distinguished. The SAPs organise robust asters of MTs whose dynamics appear to cycle in synchrony with the astral MTs organised by the endogenous centrosomes. The MTs are initially moderately long in interphase, become shorter as the embryo enters mitosis (at this point the endogenous centrosomes form spindles around the endogenous chromosomes, whereas the SAPs continue to organise only astral MTs), and then elongate dramatically as the embryo exits mitosis.