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Cover  Sporulation in the fission yeast Schizosaccharomyces pombe is a unique process in which the plasma membrane of spores is formed de novo within the cytoplasm of diploid mother cells. A central issue is how this process is coordinated with the progression of meiotic nuclear divisions. This question has recently been investigated using live cell imaging techniques to visualize the assembly process of spore plasma membranes using green fluorescent protein (GFP)-Psy1 fusion proteins (Nakamura et al. (2001) Mol. Biol. Cell 12, 3955-3972). Psy1 is a fission yeast homologue of mammalian syntaxin-1A, which is a component of the plasma membrane docking/fusion complex. In vegatative cells, Psy1 is localized to the plasma membrane. However, in sporulating cells, it is localized intracellularly on the forespore membrane, where it participates in plasma membrane biogenesis. The cover photograph shows a sporulating cell labeled with GFP-Psy1 (green), DAPI (blue), and anto--tubulin antibodies (red). Live cell imaging of GFP-Psy1 reveals that the spore membrane is first assembled at the tips of spindle microtubules at metaphase-II, extends along the nuclear periphery, and eventually encapsulates a haploid nucleus. Notably, GFP-Psy1 at the plasma membrane of mother cells disappears immediately after meiosis-I and relocalizes to the nascent spore membrane as meiosis-II initiates. These changes in the localization of Psy1 appear to play a key role in directing spore membrane assembly. The de novo synthesis of plasma membranes has also been observed in various developmental processes of multicellular eukaryotes.Chikashi Shimoda