The SPF27 Homologue Num1 Connects Splicing and Kinesin 1-Dependent Cytoplasmic Trafficking in Ustilago maydis
(A) Induction of the bE1/bW2 heterodimer in wild-type cells (AB31) induces a G2 cell cycle arrest, resulting in hyphae with a single nucleus positioned in the tip compartment. In AB31Δnum1, 18% of the hyphae contain more than one nucleus, usually separated by a septum or a septum-like chitin structure, which is not always visible in the DIC-channel (see also Figure S6). In some cases, delocalized septa give rise to compartments that are devoid of any nuclei (bottom panel). Filaments were stained with DAPI and Congo Red, which effectively stains chitin in fungal cell walls , to visualize nuclei and septa within the same hypha. Scale bars: 10 µm. (B) Sensitivity of an FB2Δnum1 deletion strain to DNA-damage in comparison to wild-type cells. Serial 10-fold dilutions were spotted on complete medium containing the indicated DNA-damage inducing supplements, or subsequently irradiated with 300 J/m2 UV light (254 nm), respectively. Pictures were taken 2–3 days after incubation at 28°C.