Nuclear movement in filamentous fungi.

One of the most striking features of eukaryotic cells is the organization of specific functions into organelles such as nuclei, mitochondria, chloroplasts, the endoplasmic reticulum, vacuoles, peroxisomes or the Golgi apparatus. These membrane-surrounded compartments are not synthesized de novo but are bequeathed to daughter cells during cell division. The successful transmittance of organelles to daughter cells requires the growth, division and separation of these compartments and involves a complex machinery consisting of cytoskeletal components, mechanochemical motor proteins and regulatory factors. Organelles such as nuclei, which are present in most cells in a single copy, must be precisely positioned prior to cytokinesis. In many eukaryotic cells the cleavage plane for cell division is defined by the location of the nucleus prior to mitosis. Nuclear positioning is thus absolutely crucial in the unequal cell divisions that occur during development and embryogenesis. Yeast and filamentous fungi are excellent organisms for the molecular analysis of nuclear migration because of their amenability to a broad variety of powerful analytical methods unavailable in higher eukaryotes. Filamentous fungi are especially attractive models because the longitudinally elongated cells grow by apical tip extension and the organelles are often required to migrate long distances. This review describes nuclear migration in filamentous fungi, the approaches used for and the results of its molecular analysis and the projection of the results to other organisms.