Article ID Journal Published Year Pages File Type
2043319 Current Biology 2009 6 Pages PDF
Abstract

SummaryCell size is one of the critical parameters controlling the size of intracellular structures. A well-known example is the constant nuclear-to-cytoplasmic ratio (N/C ratio) 1, 2, 3, 4 and 5. The length of the metaphase spindle is proportional to cell size, but it has an upper limit during early embryogenesis [6]. During anaphase, the mitotic spindle elongates and delivers the centrosomes and sister chromatids near the centers of the nascent daughter cells. Here, we quantified the relationship between spindle elongation and cell size in the early embryo of Caenorhabditis elegans and propose possible models for cell-size-dependent spindle elongation. Quantitative measurements revealed that the extent and speed of spindle elongation are correlated with cell size throughout early embryogenesis. RNAi knockdown of Gα proteins and their regulators revealed that the spindles failed to fully elongate and that the speed of spindle elongation was almost constant regardless of cell size. Our results suggest that spindle elongation is controlled by two qualitatively distinct mechanisms, i.e., Gα-dependent and -independent modes of elongation. Simulation analyses revealed that the constant-pulling model and the force-generator-limited model reproduced the dynamics of the Gα-independent and Gα-dependent mechanisms, respectively. These models also explain how the set length of spindles is achieved.

Keywords
Related Topics
Life Sciences Agricultural and Biological Sciences Agricultural and Biological Sciences (General)
Authors
, ,