Slime molds Sample Clauses

Slime molds. Multiple species of syncital fungi have been identified; the nuclear activity of five have been studied: Neuropora crassa, Ashbya gossypii, Ceratocystis fagacearum, Fusarium oxysporum, and Aspergillus nidulans. These fungi grow from germinated spores. As they grow, the nucleus divides and both daughter nuclei remain in the common cytoplasm. Large fungi can accumulate hundreds of nuclei. The nuclei of C. fagacearum all undergo mitosis together. In F. oxisporum and A. nidulans, coordinated waves of nuclear division sweep through the cell. In contrast, N. crassa and A. gossypii nuclei progress through the cell cycle independently of one another (▇▇▇▇▇▇▇▇▇▇, Hungerbuehler et al. 2006). Nuclei as close as 1–2 µm can be in different mitotic stages (▇▇▇▇▇▇▇▇▇▇, Hungerbuehler et al. 2006). These differences in nuclear activity are not due to different cellular domains, because nuclei are mobile and move through different regions of the cells (▇▇▇▇▇▇▇▇, ▇▇▇▇ et al. 2013). Neither can they be attributed to differences in subcellular cyclin localization, because the concentration of cyclins does not vary among nuclei, despite being in different stages of mitosis (▇▇▇▇▇▇▇▇▇▇, Hungerbuehler et al. 2006). Two properties that contribute to asynchronous division are nuclear spacing and lineal relation to other nuclei. Nuclear spacing increases before mitosis; artificially decreasing nuclear spacing increases synchronicity of nuclear division (▇▇▇▇▇▇▇▇, ▇▇▇▇ et al. 2013). Tracking the lag times between nuclear divisions revealed that the two daughter nuclei of a single nuclear division had more similar lag times between divisions than the lag times of other nuclei. This similarity in time to nuclear division in daughter nuclei perdured regardless of their position in the cell (▇▇▇▇▇▇▇▇, ▇▇▇▇ et al. 2013). Nuclear transport receptors distribute evenly among nuclei (Markina-Inarrairaegui, Etxebeste et al. 2011), but some transcription factors are selectively targeted to a subset of nuclei located at the apex of the cell (Etxebeste, Ni et al. 2008). Thus, multiple mechanisms likely regulate differences among nuclei in syncytial fungi.