title: Limiting amounts of centrosome material set centrosome size in C. elegans embryos.
abstract: BACKGROUND
  The ways in which cells set the size of intracellular structures is an important but largely unsolved problem [1]. Early embryonic divisions pose special problems in this regard. Many checkpoints common in somatic cells are missing from these divisions, which are characterized by rapid reductions in cell size and short cell cycles [2]. Embryonic cells must therefore possess simple and robust mechanisms that allow the size of many of their intracellular structures to rapidly scale with cell size.
  
  
  RESULTS
  Here, we study the mechanism by which one structure, the centrosome, scales in size during the early embryonic divisions of C. elegans. We show that centrosome size is directly related to cell size and is independent of lineage. Two findings suggest that the total amount of maternally supplied centrosome proteins could limit centrosome size. First, the combined volume of all centrosomes formed at any one time in the developing embryo is constant. Second, the total volume of centrosomes in any one cell is independent of centrosome number. By increasing the amount of centrosome proteins in the cell, we provide evidence that one component that limits centrosome size is the conserved pericentriolar material protein SPD-2 [3], which we show binds to and targets polo-like kinase 1 [3, 4] to centrosomes.
  
  
  CONCLUSIONS
  We propose a limiting component hypothesis, in which the volume of the cell sets centrosome size by limiting the total amount of centrosome components. This idea could be a general mechanism for setting the size of intracellular organelles during development.
authors.affiliation: Max Planck Institute for Cell Biology and Genetics, Dresden 01307 Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Decker
authors.forename: Steffen
authors.initials: S
authors.lastname: Jaensch
authors.forename: Andrei
authors.initials: A
authors.lastname: Pozniakovsky
authors.forename: Andrea
authors.initials: A
authors.lastname: Zinke
authors.forename: Kevin F
authors.initials: KF
authors.lastname: O'Connell
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zachariae
authors.forename: Eugene
authors.initials: E
authors.lastname: Myers
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Hyman
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000196:embryology*; D002453:Cell Cycle; D048429:Cell Size; D018385:Centrosome; D004625:Embryo, Nonmammalian / Q000378:metabolism*