A method to rapidly generate gene replacement constructs by fusion PCR is described for Aspergillus nidulans. The utility of the approach is demonstrated by green fluorescent protein (GFP) tagging of A. nidulans ndc80 to visualize centromeres through the cell cycle. The methodology makes possible large-scale GFP tagging, promoter swapping, and deletion analysis of A. nidulans.

We conclude that partial NPC disassembly under control of NIMA and Cdk1 in A. nidulans may represent a new mechanism for regulating closed mitoses. We hypothesize that proteins locate by their relative binding affinities within the cell during A. nidulans' closed mitosis, analogous to what occurs during open mitosis.

Phosphorylation of histone H3 serine 10 correlates with chromosome condensation and is required for normal chromosome segregation in Tetrahymena. This phosphorylation is dependent upon activation of the NIMA kinase in Aspergillus nidulans. NIMA expression also induces Ser-10 phosphorylation inappropriately in S phase-arrested cells and in the absence of NIMX(cdc2) activity. At mitosis, NIMA becomes enriched on chromatin and subsequently localizes to the mitotic spindle and spindle pole bodies. The chromatin-like localization of NIMA early in mitosis is tightly correlated with histone H3 phosphorylation. Finally, NIMA can phosphorylate histone H3 Ser-10 in vitro, suggesting that NIMA is a mitotic histone H3 kinase, perhaps helping to explain how NIMA promotes chromatin condensation in A. nidulans and when expressed in other eukaryotes.

No abstract