Figure 4.

Nutrient levels control the differentiation of the outer face of budding yeast spindle pole bodies to generated the meiotic plaque during sporulation. (A–D) Sporulating yeast cells adjust the number of spores they form according to the level of carbon sources available producing asci (= sporulated yeast cells) with only 1, 2 (B), or 3 (C) spores instead of the normal number of 4 (D). There is a corresponding reduction in the number of nuclei as some of the genomes are aborted after the meiotic divisions have occurred. (E) The formation of a regulated number of spores depends entirely on the assembly of the meiotic plaque (MP), a meiosis-II-specific structure of the spindle pole body (SPB). The MP is assembled while attached to the central plaque (CP) on the cytoplasmic side of the SPB. MP assembly at a subset of SPBs is regulated by a dynamic self-organizing system, which is controlled by the abundance of MP components and age-related differences between the SPBs. CP central plaque. Scale bar, 200 nm. Images were kindly provided by M. Knop (Heidelberg, Germany) and reprinted from Taxis et al (2005) with permission from The Rockefeller University Press.