scholarly journals The ultrastructure of the Chlamydomonas reinhardtii basal apparatus: identification of an early marker of radial asymmetry inherent in the basal body

2004 ◽  
Vol 117 (13) ◽  
pp. 2663-2674 ◽  
Author(s):  
S. Geimer
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Early Marker ◽  
Basal Apparatus ◽  
Radial Asymmetry

scholarly journals Centrin Scaffold in Chlamydomonas reinhardtii Revealed by Immunoelectron Microscopy

2005 ◽  
Vol 4 (7) ◽  
pp. 1253-1263 ◽  
Author(s):  
Stefan Geimer ◽  
Michael Melkonian
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Immunoelectron Microscopy ◽  
Basal Body ◽  
Flagellar Apparatus ◽  
Single Copy ◽  
Asymmetric Structure ◽  
Transitional Region ◽  
Ef Hand ◽  
Basal Apparatus ◽  
Postembedding Immunoelectron Microscopy

ABSTRACT In the flagellate green alga Chlamydomonas reinhardtii the Ca2+-binding EF-hand protein centrin is encoded by a single-copy gene. Previous studies have localized the protein to four distinct structures in the flagellar apparatus: the nucleus-basal body connector, the distal connecting fiber, the flagellar transitional region, and the axoneme. To explain the disjunctive distribution of centrin, the interaction of centrin with as yet unknown specific centrin-binding proteins has been implied. Here, we demonstrate using serial section postembedding immunoelectron microscopy of isolated cytoskeletons that centrin is located in additional structures (transitional fibers and basal body lumen) and that the centrin-containing structures of the basal apparatus are likely part of a continuous filamentous scaffold that extends from the nucleus to the flagellar bases. In addition, we show that centrin is located in the distal lumen of the basal body in a rotationally asymmetric structure, the V-shaped filament system. This novel centrin-containing structure has also been detected near the distal end of the probasal bodies. Taken together, these results suggest a role for a rotationally asymmetric centrin “seed” in the growth and development of the centrin scaffold following replication of the basal apparatus.

Ultrastructure of the basal body apparatus in epidermal cells of a sponge larva (Aplysilla SP: Demospongiae)

1992 ◽  
Vol 50 (1) ◽  
pp. 928-929
Author(s):  
R.L. Pinto ◽  
R.M. Woollacott
Keyword(s):  
Sodium Bicarbonate ◽  
Epoxy Resin ◽  
Basal Body ◽  
Phosphate Buffer ◽  
Similar Data ◽  
Basal Apparatus ◽  
Striated Rootlet ◽  
The Common ◽  
Basal Foot ◽  
Sexually Mature

The basal body and its associated rootlet are the organelles responsible for anchoring the flagellum or cilium in the cytoplasm. Structurally, the common denominators of the basal apparatus are the basal body, a basal foot from which microtubules or microfilaments emanate, and a striated rootlet. A study of the basal apparatus from cells of the epidermis of a sponge larva was initiated to provide a comparison with similar data on adult sponges.Sexually mature colonies of Aplysillasp were collected from Keehi Lagoon Marina, Honolulu, Hawaii. Larvae were fixed in 2.5% glutaraldehyde and 0.14 M NaCl in 0.2 M Millonig’s phosphate buffer (pH 7.4). Specimens were postfixed in 1% OsO4 in 1.25% sodium bicarbonate (pH 7.2) and embedded in epoxy resin. The larva ofAplysilla sp was previously described (as Dendrilla cactus) based on live observations and SEM by Woollacott and Hadfield.

scholarly journals Phosphorylation of nuclear and flagellar basal apparatus proteins during flagellar regeneration in Chlamydomonas reinhardtii

1993 ◽  
Vol 122 (4) ◽  
pp. 877-886 ◽  
Author(s):  
JD Harper ◽  
MA Sanders ◽  
JL Salisbury
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Transcriptional Activation ◽  
Kinase Inhibitor ◽  
Nuclear Periphery ◽  
Immunoblot Analysis ◽  
Basal Region ◽  
Western Immunoblot ◽  
Flagellar Regeneration ◽  
Basal Apparatus ◽  
Western Immunoblot Analysis

The antiphosphoprotein monoclonal antibody MPM-2 was used to investigate protein phosphorylation during flagellar regeneration in Chlamydomonas reinhardtii. MPM-2 recognizes a phosphorylated epitope and detects several Chlamydomonas proteins by Western immunoblot analysis. Two MPM-2 reactive proteins (34 and 90 kD) increase in Western immunoblot intensity after flagellar excision and decrease in intensity during flagellar regeneration. Immunofluorescence and immunogold labeling revealed MPM-2 staining within the nucleus, especially towards the nuclear periphery, the flagellar basal apparatus, and the nucleus-basal body connector after flagellar excision. Comparison of MPM-2 reactivity in wild-type cells and in the mutant bald-2, which lacks functional basal bodies, demonstrates that the 34-kD protein is localized in the nucleus and the 90-kD protein is localized in the flagellar basal region. MPM-2 reactivity is observed in cells competent for flagellar regeneration. However, when cells were treated with the kinase inhibitor, staurosporine, MPM-2 reactivity did not increase after flagellar excision and flagellar regeneration was impaired. These observations suggest that phosphorylation of the 34- and 90-kD proteins may be important for flagellar regrowth. Possible roles for phosphorylation in flagellar regeneration include transcriptional activation and transport of flagellar precursors to the base of the growing flagella.

scholarly journals A nucleus-basal body connector in Chlamydomonas reinhardtii that may function in basal body localization or segregation.

1985 ◽  
Vol 101 (5) ◽  
pp. 1903-1912 ◽  
Author(s):  
R L Wright ◽  
J Salisbury ◽  
J W Jarvik
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Nuclear Dna ◽  
Electron Microscopic Observation ◽  
Variable Number ◽  
Immunofluorescent Staining ◽  
Major Protein ◽  
Basal Bodies ◽  
Electron Microscopic ◽  
And Function

We have isolated a nucleus-basal body complex from Chlamydomonas reinhardtii. The complex is strongly immunoreactive to an antibody generated against a major protein constituent of isolated Tetraselmis striata flagellar roots (Salisbury, J. L., A. Baron, B. Surek, and M. Melkonian, J. Cell Biol., 99:962-970). Electrophoretic and immunoelectrophoretic analysis indicates that, like the Tetraselmis protein, the Chlamydomonas antigen consists of two acidic isoforms of approximately 20 kD. Indirect immunofluorescent staining of nucleus-basal body complexes reveals two major fibers in the connector region, one between each basal body and the nucleus. The nucleus is also strongly immunoreactive, with staining radiating around much of the nucleus from a region of greatest concentration at the connector pole. Calcium treatment causes shortening of the connector fibers and also movement of nuclear DNA towards the connector pole. Electron microscopic observation of negatively stained nucleus-basal body complexes reveals a cluster of approximately 6-nm filaments, suspected to represent the connector, between the basal bodies and nuclei. A mutant with a variable number of flagella, vfl-2-220, is defective with respect to the nucleus-basal body association. This observation encourages us to speculate that the nucleus-basal body union is important for accurate basal body localization within the cell and/or for accurate segregation of parental and daughter basal bodies at cell division. A physical association between nuclei and basal bodies or centrioles has been observed in a variety of algal, protozoan, and metazoan cells, although the nature of the association, in terms of both structure and function, has been obscure. We believe it likely that fibrous connectors homologous to those described here for Chlamydomonas are general features of centriole-bearing eucaryotic cells.

Ultrastructure of the flagellar roots in Chlamydomonas gametes

1984 ◽  
Vol 67 (1) ◽  
pp. 133-143
Author(s):  
R.L. Weiss
Keyword(s):  
Basal Body ◽  
Direct Contact ◽  
The Other ◽  
Basal Bodies ◽  
Flagellar Roots ◽  
Mating Structure ◽  
Membrane Extension ◽  
Microtubular Root ◽  
Basal Apparatus ◽  
Microtubular System

The cytoskeleton of Chlamydomonas reinhardtii gametes has been studied by electron microscopy. The microtubular system, consisting of four flagellar roots inserted into the basal apparatus, is shown to include two daughter basal bodies and two striated fibres, newly described in this report. One new fibre associates with the 3-over-1 root and is similar to its counterpart, the striated fibre of the 2-member root. These similar root fibres connect each daughter basal body to the V-shaped microtubular root pair. The other new striated fibre joins the daughter basal body to both flagellar roots and is similar to the proximal striated fibre. In mt+ gametes, the conventional root microtubules make direct contact with the doublet zone of the non-activated mating structure. During activation, doublet zone microfilaments associate with the daughter basal body and the finely striated fibre of the 3-over-1 root. These observations suggest that the cytoskeleton acts as a scaffolding for membrane extension by the mt+ mating structure microfilaments.

scholarly journals The basal bodies of Chlamydomonas reinhardtii. Formation from probasal bodies, isolation, and partial characterization.

1975 ◽  
Vol 65 (1) ◽  
pp. 65-74 ◽  
Author(s):  
R R Gould
Keyword(s):  
Electron Microscopy ◽  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Sodium Dodecyl ◽  
Basal Bodies ◽  
Polyethylene Glycol 400 ◽  
Thin Sections ◽  
Particulate Contamination ◽  
Whole Mount ◽  
Carbon Coated

The assembly and composition of basal bodies was investigated in the single-celled, biflagellate green alga, Chlamydomonas reinhardtii, using the cell wall-less strain, cw15. In the presence of EDTA, both flagellar axonemes remained attached to their basal bodies while the entire basal body-axoneme complex was separated from the cell body, without cell lysis, by treatment with polyethylene glycol-400. The axonemes were then removed from the basal bodies in the absence of EDTA, leaving intact basal body pairs, free from particulate contamination from other regions of the cell. The isolated organelles produced several bands on sodium dodecyl sulfate-urea polyacrylamide gels, including two tubilin bands which co-electrophoresed with flagellar tubulin. The formation of probasal bodies was observed by electron microscopy of whole mount preparations. Synchronous cells were lysed, centrifuged onto carbon-coated grids, and either negatively stained or shadowed with platinum. The two probasal bodies of each cell appeared shortly after mitosis as thin "annuli," not visible in thin sections, each consisting of nine rudimentary triplet microtubules. Each annulus remained attached to one of the mature basal bodies by several filaments about 60 in diameter, and persisted throughout interphase until just before the next cell division. It then elongated into a mature organelle. The results revive the possibility of the nucleated assembly of basal bodies.

scholarly journals Abnormal basal-body number, location, and orientation in a striated fiber-defective mutant of Chlamydomonas reinhardtii.

1983 ◽  
Vol 96 (6) ◽  
pp. 1697-1707 ◽  
Author(s):  
R L Wright ◽  
B Chojnacki ◽  
J W Jarvik
Keyword(s):  
Genetic Analysis ◽  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Mendelian Gene ◽  
Defective Mutant ◽  
Rotational Orientation ◽  
Striated Fiber

We describe a mutant of Chlamydomonas reinhardtii in which basal body associated striated fibers are absent or incomplete. Basal body spacing, angle, and relative rotational orientation are abnormal and extremely variable. Abnormal partitioning of cellular contents at cytokinesis is also evident. Mating, maintenance of flagellar length equality, and backward swimming response are normal. Genetic analysis indicates mutation of a new Mendelian gene--vfl-3--linked to the centromere of Chromosome VI.

scholarly journals The Uni2 Phosphoprotein is a Cell Cycle–regulated Component of the Basal Body Maturation Pathway in Chlamydomonas reinhardtii

2008 ◽  
Vol 19 (1) ◽  
pp. 262-273 ◽  
Author(s):  
Brian P. Piasecki ◽  
Matthew LaVoie ◽  
Lai-Wa Tam ◽  
Paul A. Lefebvre ◽  
Carolyn D. Silflow
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Basal Bodies ◽  
Mitotic Progression ◽  
Transition Zones ◽  
Phosphatase Treatment ◽  
Flagellar Assembly ◽  
A Cell ◽  
Sequential Assembly

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.

scholarly journals Three-dimensional Organization of Basal Bodies from Wild-Type and δ-Tubulin Deletion Strains of Chlamydomonas reinhardtii

2003 ◽  
Vol 14 (7) ◽  
pp. 2999-3012 ◽  
Author(s):  
Eileen T. O'Toole ◽  
Thomas H. Giddings ◽  
J. Richard McIntosh ◽  
Susan K. Dutcher
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Specimen Preparation ◽  
Basal Bodies ◽  
Wild Type ◽  
Tubulin Isoforms ◽  
Striated Fiber ◽  
And Function

Improved methods of specimen preparation and dual-axis electron tomography have been used to study the structure and organization of basal bodies in the unicellular alga Chlamydomonas reinhardtii. Novel structures have been found in both wild type and strains with mutations that affect specific tubulin isoforms. Previous studies have shown that strains lacking δ-tubulin fail to assemble the C-tubule of the basal body. Tomographic reconstructions of basal bodies from the δ-tubulin deletion mutant uni3-1 have confirmed that basal bodies contain mostly doublet microtubules. Our methods now show that the stellate fibers, which are present only in the transition zone of wild-type cells, repeat within the core of uni3-1 basal bodies. The distal striated fiber is incomplete in this mutant, rootlet microtubules can be misplaced, and multiflagellate cells have been observed. A suppressor of uni3-1, designated tua2-6, contains a mutation in α-tubulin. tua2-6; uni3-1 cells build both flagella, yet they retain defects in basal body structure and in rootlet microtubule positioning. These data suggest that the presence of specific tubulin isoforms in Chlamydomonas directly affects the assembly and function of both basal bodies and basal body-associated structures.

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