The making of a mushroom: Mitosis, nuclear migration and the actin network

Abstract

<p>Basidiomycetes feature a prolonged dikaryotic life stage. A dispute over open versus closed mitosis could be<br />solved using in vivo fluorescence videomicroscopy of histone 2B::EGFP and Lifeact labeled Schizophyllum commune.<br />It revealed nuclei to condense to approximately one fifth in diameter during mitotic prophase. In addition,<br />the specifics of clamp cell formation typical of many basidiomycetes included an actin network at the future site<br />of nuclear division, which allowed for cessation of nuclear movement and re-localization of one nucleus towards<br />the emerging clamp cell, while the other divided along the hyphal axis. Subsequent fusion of the clamp cell to<br />form the clamp connection restored the close association of the two nuclei in a very fast process after clamp<br />fusion. Septation was preceded by actin patches and vesicles involved in formation of the actin ring.</p>