ABSTRACT
A critical structure poised to coordinate chromosome segregation with division plane specification is the central spindle that forms between separating chromosomes after anaphase onset. The central spindle acts as a signalling centre that concentrates proteins essential for division plane specification and contractile ring constriction. However, the molecular mechanisms that control the initial stages of central spindle assembly remain elusive. Using Caenorhabditis elegans zygotes, we found that the microtubule-bundling protein SPD-1(PRC1) and the motor ZEN-4(MKLP-1) are required for proper central spindle structure during its elongation. In contrast, we found that the kinetochore controls the initiation of central spindle assembly. Specifically, central spindle microtubule assembly is dependent on kinetochore recruitment of the scaffold protein KNL-1, as well as downstream partners BUB-1, HCP-1/2(CENP-F) and CLS-2(CLASP); and is negatively regulated by kinetochore-associated protein phosphatase 1 activity. This in turn promotes central spindle localization of CLS-2(CLASP) and initial central spindle microtubule assembly through its microtubule polymerase activity. Together, our results reveal an unexpected role for a conserved kinetochore protein network in coupling two critical events of cell division: chromosome segregation and cytokinesis.
Subject(s)
Caenorhabditis elegans Proteins/metabolism , Cell Division , Kinetochores/metabolism , Microtubule-Associated Proteins/metabolism , Spindle Apparatus/metabolism , Animals , Animals, Genetically Modified , Caenorhabditis elegans/embryology , Caenorhabditis elegans/genetics , Caenorhabditis elegans/growth & development , Caenorhabditis elegans Proteins/genetics , Chromosomal Proteins, Non-Histone/genetics , Chromosomal Proteins, Non-Histone/metabolism , Chromosome Segregation , Cytokinesis , Kinesins/genetics , Kinesins/metabolism , Microscopy, Fluorescence , Microscopy, Video , Microtubule-Associated Proteins/genetics , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , RNA Interference , Signal Transduction , Spindle Apparatus/genetics , Time FactorsABSTRACT
Reproducible data analysis is an approach aiming at complementing classical printed scientific articles with everything required to independently reproduce the results they present. "Everything" covers here: the data, the computer codes and a precise description of how the code was applied to the data. A brief history of this approach is presented first, starting with what economists have been calling replication since the early eighties to end with what is now called reproducible research in computational data analysis oriented fields like statistics and signal processing. Since efficient tools are instrumental for a routine implementation of these approaches, a description of some of the available ones is presented next. A toy example demonstrates then the use of two open source software programs for reproducible data analysis: the "Sweave family" and the org-mode of emacs. The former is bound to R while the latter can be used with R, Matlab, Python and many more "generalist" data processing software. Both solutions can be used with Unix-like, Windows and Mac families of operating systems. It is argued that neuroscientists could communicate much more efficiently their results by adopting the reproducible research paradigm from their lab books all the way to their articles, thesis and books.
