Organelle scaling over a 100-fold cell size range.

Cell volume in a proliferating cell population generally varies over a limited range (∼2-4-fold). Within such populations, organelle content increases with cell volume maintaining a relatively constant organelle density (amount per cell volume). However, cells of different types can differ greatly in cell volume as well as in organelle composition. In such cases, it is often unclear to what degree, if any, the differences in organelle composition are due to the difference in cell volume. In principle, this issue could be resolved by examining situations where a proliferating population of cells of the same cell type exhibit much greater volume variation. Here we characterize how organelle content scales with cell volume in the polymorphic fungus, A. pullulans, whose proliferating cells span a ∼100-fold volume range. We find that mitochondria and ER content increases in proportion to cell volume, while this is not the case for vacuoles and peroxisomes. Thus, organelle composition is affected by cell volume in this system. [Media: see text] [Media: see text] [Media: see text] [Media: see text].