FINE STRUCTURE OF CELL DIVISION IN <i>CHLAMYDOMONAS REINHARDI  </i>

Johnson, Ursula G.; Porter, Keith R.

doi:10.1083/jcb.38.2.403

Cited by 377 publications

(258 citation statements)

References 44 publications

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“…Previous reports have suggested that basal bodies in C. reinhardtii dissociate from attached flagella at the onset of mitosis (Johnson and Porter, 1968;Gould, 1975). Subsequent reports, however, have suggested that flagellar resorption is completed before mitosis (Cavalier-Smith, 1974;Gaffal, 1988).…”

Section: Discussionmentioning

confidence: 99%

“…Despite the ultrastructural defect in TZs in uni2 mutant cells, the mitotic migration of the Uni2 protein to the spindle poles suggests it is not a TZ component. Previous ultrastructural studies have shown that TZs remain associated with remnants of flagella during mitosis (Johnson and Porter, 1968) and that the TZ is resorbed along with the flagellum during mitosis (Cavalier-Smith, 1974).…”

Section: Discussionmentioning

confidence: 99%

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The Uni2 Phosphoprotein is a Cell Cycle–regulated Component of the Basal Body Maturation Pathway inChlamydomonas reinhardtii

Piasecki

LaVoie

Tam

et al. 2008

MBoC

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Mutations in the UNI2 locus in Chlamydomonas reinhardtii result in a "uniflagellar" phenotype in which flagellar assembly occurs preferentially from the older basal body and ultrastructural defects reside in the transition zones. The UNI2 gene encodes a protein of 134 kDa that shares 20.5% homology with a human protein. Immunofluorescence microscopy localized the protein on both basal bodies and probasal bodies. The protein is present as at least two molecular-weight variants that can be converted to a single form with phosphatase treatment. Synthesis of Uni2 protein is induced during cell division cycles; accumulation of the phosphorylated form coincides with assembly of transition zones and flagella at the end of the division cycle. Using the Uni2 protein as a cell cycle marker of basal bodies, we observed migration of basal bodies before flagellar resorption in some cells, indicating that flagellar resorption is not required for mitotic progression. We observed the sequential assembly of new probasal bodies beginning at prophase. The uni2 mutants may be defective in the pathways leading to flagellar assembly and to basal body maturation. INTRODUCTIONCentrioles are evolutionarily ancient organelles, possibly extant in a common ancestor of all eukaryotic cells (CavalierSmith, 2002). They are required for the organization of interphase and mitotic microtubule arrays and as basal bodies they serve as templates for the growth of nine doublet microtubules in axonemes of cilia and flagella (for review see Marshall, 2007). Although flowering plants and more derived fungi have reduced or eliminated centrioles and cilia, metazoans have diversified their functions in numerous sensory and developmental processes (for reviews see Singla and Reiter, 2006;Dawe et al., 2007). Several mammalian genetic disorders have been linked to defects in centrioles or cilia (for review see Afzelius, 2004;Pan et al., 2005). For example, the proteins associated with Bardet-Biedl syndrome, a debilitating pleiotropic human disorder characterized by obesity, renal abnormalities, polydactyly, retinal degeneration, and genitourinary tract malformations have been shown to localize to or around centrioles and cilia (for review see Beales, 2005;Blacque and Leroux, 2006).Centrioles in actively dividing cells show conservative replication and semiconservative segregation during division (for review see Dawe et al., 2007). As a result, each pair of centrioles consists of an older and a younger centriole that differ in age by at least one cell generation. The "mother" centriole differs both in structure and function from the "daughter" centriole. For example, in the single pair of centrioles found in most types of mammalian cells, the mother centriole nucleates the growth of the primary cilium and contains proteins not present in the daughter centriole. The daughter centriole becomes competent for ciliary assembly only in the ensuing cell cycle (for review see Bornens, 2002). Extension of the pathway for sequential maturation of basal bodies has been ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Uni2 Phosphoprotein is a Cell Cycle–regulated Component of the Basal Body Maturation Pathway inChlamydomonas reinhardtii

Piasecki

LaVoie

Tam

et al. 2008

MBoC

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“…It should be noted that the mitotic cleavage furrow of C. reinhardtii contains microtubules but apparently no microfilaments (9), in contrast to most furrowing cells where microfilaments abound (14,21,23). It would appear, therefore, that C. reinhardtii restricts its ability to generate microfilaments to a brief but critical stage in its life cycle, and this ability is apparently dependent on the presence of a normal doublet zone.…”

Section: Microfilament Involvement In the Mating Regionmentioning

confidence: 99%

Gametic differentiation in Chlamydomonas reinhardtii. III. Cell wall lysis and microfilament-associated mating structure activation in wild-type and mutant strains.

Goodenough¹,

Weiss²

1975

The Journal of Cell Biology

121

100

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Cell fusion between mating type plus (mr +) and minus (rot-) gametes ofChlamydomonas reinhardtii is analyzed structurally and subjected to experimental manipulation. Cell wall lysis, a necessary prelude to fusion, is shown to require flagellar agglutination between competent gametes; glutaraldehyde-fixed gametes ("corpses") of one mating type will elicit both agglutination and cell wall lysis in the opposite mating type, whereas nonagglutinating impotent (imp) mutant strains are without effect. The fusion process is mediated by a narrow fertilization tubule which extends from the mt+ gamete and establishes contact with the mt-gamete. Formation of the tubule requires the "activation" of a specialized mating structure associated with the mt + cell membrane; activation causes microfilaments to polymerize from the mating structure into the growing fertilization tubule. Mating structure activation is shown to depend on gametic flagellar agglutination; isoagglutination mediated by the lectin concanavalin A has no effect. Gametes carrying the imp-I mt+ mutation are able to agglutinate but not fuse with rotcells; the imp-1 gametes are shown to have structurally defective mating structures that do not generate microfilaments in response to gametic agglutination.The mating reaction of the biflagellate alga Chlamydomonas reinhardtii involves an elaborate sequence of events that can be presumed to depend on precise levels of cellular communication. The reaction is initiated by an agglutination between the flagellar tips of mating type plus (mr +) and minus (mr-) gametes (18), as illustrated in Fig. 1, an interaction that appears to involve surface components of the flagellar membranes (1, 24). Four events follow in quick succession: (a) a lytic activity digests the cell walls so that gametes are converted to naked protoplasts (2): (b) a cytoplasmic protuberance [the fertilization tubule (4)] extends from the mt+ cell surface (Fig. 1, tong arrow), an event mediated by the specialized mating structure first described by Friedmann et al. (4); (c) the fertilization tubule makes contact with an mt-mating structure to form a narrow cytoplasmic bridge (4); and (d) the bridge expands in diameter until the mating pair is transformed into a single quadriflagellate zygote, an event that can be termed zygotic cell fusion (see Fig. I). Quadriflagellate zygotes typically appear within 5 rain after mt § and rot-gametes are mixed; all of these events must therefore occur in a rapid and highly coordinated fashion.

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“…The genetics of this organism have been well studied (15) and mutants may be characterized by recombination analysis in mating cells or by complementation analysis in temporary dikaryons (26) and stable diploids (4,5). The structure of the organism's two flagella have also been well described (9,23) as have the microtubular systems which are present during interphase, mitosis, and cytokinesis (12). Flagella may be experimentally amputated and their subsequent regeneration used to study morphogenesis (19).…”

mentioning

confidence: 99%

Temperature-sensitive mutations affecting flagellar assembly and function in Chlamydomonas reinhardtii.

Huang¹,

Rifkin²,

Luck³

1977

The Journal of Cell Biology

147

115

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A series of conditional mutants of the algal, biflagellate Chlamydomonas reinhardtii with temperature-sensitive defects in flagellar assembly and function were isolated. The genetics and phenotypes of 21 mutants displaying a rapid alteration in flagellar function upon shift from the permissive (20"C) to the restrictive (32~ temperatures are described. These mutants designated as "drop-down" or dd-mutants have been placed in four categories on the basis of their defective phenotypes: (a) ddassembly mutants -the preformed flagella are resorbed at 32~ and reassembly of flagella is inhibited; (b) dd-fragile flagella mutants -the flagella are lost by detachment at 32~ but can be reassembled; (c) dd-motility mutants -the flagella are retained at 32~ but are functionally defective; (d) dd-lethal mutants -display combined defects in flagellar function and cell growth. Tetrad analysis of the mutants back-crossed to wild-type, recombination analysis of intermutant crosses, and complementation tests in the construction of heterozygous diploid strains indicate that at least 14 nuclear genetic loci are represented among the 21 mutants. The availability of temperature-sensitive mutations affecting the assembly and function of the flagellum suggests that the morphogenesis of this complex eukaryotic organelle is amenable to genetic dissection.In an attempt to study the genetic control of flagellar assembly and to investigate interrelationships between cellular microtubules and those of the flagellar axoneme, we have undertaken the isolation of

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FINE STRUCTURE OF CELL DIVISION IN CHLAMYDOMONAS REINHARDI

Cited by 377 publications

References 44 publications

The Uni2 Phosphoprotein is a Cell Cycle–regulated Component of the Basal Body Maturation Pathway inChlamydomonas reinhardtii

The Uni2 Phosphoprotein is a Cell Cycle–regulated Component of the Basal Body Maturation Pathway inChlamydomonas reinhardtii

Gametic differentiation in Chlamydomonas reinhardtii. III. Cell wall lysis and microfilament-associated mating structure activation in wild-type and mutant strains.

Temperature-sensitive mutations affecting flagellar assembly and function in Chlamydomonas reinhardtii.

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