ABSTRACT
CONTENTS 15.1 Introduction ............................................................................................................................. 223 15.2 Microtubule Cytoskeleton ....................................................................................................... 224
15.2.1 Fungicide-Resistance Genes Identify Tubulins in Aspergillus nidulans .................. 225 15.2.2 Organization of the Interphase Microtubule Cytoskeleton ....................................... 226
15.3 Origin of Microtubules ........................................................................................................... 227 15.3.1 Microtubule Plus End ................................................................................................ 229 15.3.2 MT Lattice ................................................................................................................. 231 15.3.3 MT-Dependent Motor Proteins .................................................................................. 231 15.3.4 Cell-End Markers at the Cortex ................................................................................. 233
15.4 Cell-Cycle Controls ................................................................................................................. 234 15.4.1 Genetic Analysis of the Nuclear Division Cycle ....................................................... 235 15.4.2 Regulation of the G2/M Transition ............................................................................ 236 15.4.3 Involvement of Calcium in the G2/M Transition ...................................................... 238 15.4.4 APC and the Metaphase-Anaphase Transition .......................................................... 238 15.4.5 Anaphase .................................................................................................................... 239 15.4.6 Mitotic Exit and the Septation Initiation Network .................................................... 241 15.4.7 Genome Surveillance ................................................................................................. 242
15.5 Hyphal Morphogenesis and the Cell Cycle ............................................................................ 243 15.6 Branching and Cell Cycle Control .......................................................................................... 244
15.6.1 Developmental Regulators Impose New Discipline on the Cell Cycle ..................... 244 15.7 Actin Cytoskeleton .................................................................................................................. 246
15.7.1 Organization of the Actin Cytoskeleton ..................................................................... 246 15.7.2 Polarisome .................................................................................................................. 246 15.7.3 Actin-Dependent Motor Proteins ............................................................................... 247
15.8 Genes Required for the Establishment of Polarity ................................................................. 247 15.9 Conclusions ............................................................................................................................. 248 Acknowledgments .............................................................................................................................. 248 References .......................................................................................................................................... 248
15.1 Introduction Microtubules (MTs), fi lamentous actin (F-actin), and their associated motor proteins, kinesin, dynein, and myosin, play important roles in all eukaryotes providing cells with a dynamic structural framework called the cytoskeleton. The cytoskeleton plays crucial roles in many processes that require reorganization of the
cytoplasm, such as growth, nuclear division, and cell division. In this chapter, we review the organization of the cytoskeleton in fi lamentous fungi, its role in polarized growth, mitosis and cell division. We focus on Aspergillus nidulans because work on this species has provided major insights in this area, most of which pertains to eukaryotes generally, but other fungal systems are mentioned and compared throughout the chapter.
