Loss of spatial control of the mitotic spindle apparatus in a Chlamydomonas reinhardtii mutant strain lacking basal bodies

• Published in: Genetics (Austin) 1995-11, Vol.141 (3), p.945-960
• Main Authors: Ehler, L.L. (University of Colorado, Boulder, CO.), Holmes, J.A, Dutcher, S.K
• Format: Article
• Language: English
• Subjects: ACTINA; ACTINE; Actins - analysis; Algae; Animals; Cell Division; Centrioles - physiology; Centrioles - ultrastructure; CHLAMYDOMONAS REINHARDTII; Chlamydomonas reinhardtii - genetics; Chlamydomonas reinhardtii - ultrastructure; CITOLOGIA; CYTOLOGIE; DEFAUT; DEFECTOS; ESTRUCTURA CELULAR; FENOTIPOS; Flagella - ultrastructure; Freshwater; Genes, Plant; Genes, Protozoan; Genetics; GLICOPROTEINAS; GLYCOPROTEINE; IMMUNOLOGIE; INMUNOLOGIA; Investigations; Meiosis; Microtubules - ultrastructure; MITOSE; MITOSIS; MUTACION INDUCIDA; MUTANT; MUTANTES; Mutation; MUTATION PROVOQUEE; ORGANITE CELLULAIRE; ORGANULOS CITOPLASMICOS; PHENOTYPE; Plant Proteins - analysis; Plant Proteins - genetics; Plant Proteins - physiology; Protozoan Proteins - analysis; Protozoan Proteins - genetics; Protozoan Proteins - physiology; Spindle Apparatus - ultrastructure; STRUCTURE CELLULAIRE
• ISSN: 0016-6731; 1943-2631; 1943-2631
• DOI: 10.1093/genetics/141.3.945

The bld2-1 mutation in the green alga Chlamydomonas reinhardtii is the only known mutation that results in the loss of centrioles/basal bodies and the loss of coordination between spindle position and cleavage furrow position during cell division. Based on several different assays, bld2-1 cells lack basal bodies in 99% of cells. The stereotypical cytoskeletal morphology and precise positioning of the cleavage furrow observed in wild-type cells is disrupted in bld2-1 cells. The positions of the mitotic spindle and of the cleavage furrow are not correlated with respect to each other or with a specific cellular landmark during cell division in bld2-1 cells. Actin has a variable distribution during mitosis in bld2-1 cells, but this aberrant distribution is not correlated with the spindle positioning defect. In both wild-type and bld2-1 cells, the position of the cleavage furrow is coincident with a specialized set of microtubules found in green algae known as the rootlet microtubules. We propose that the rootlet microtubule perform the functions of astral microtubules and that functional centrioles are necessary for the organization of the cytoskeletal superstructure critical for correct spindle and cleavage furrow placement in Chlamydomonas