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.

scholarly journals Bld10p, a novel protein essential for basal body assembly in Chlamydomonas

2004 ◽  
Vol 165 (5) ◽  
pp. 663-671 ◽  
Author(s):  
Kumi Matsuura ◽  
Paul A. Lefebvre ◽  
Ritsu Kamiya ◽  
Masafumi Hirono
Keyword(s):  
Basal Body ◽  
Cell Biology ◽  
Early Stage ◽  
Rotational Symmetry ◽  
Coiled Coil ◽  
Electron Microscopic Observation ◽  
Basal Bodies ◽  
Mitotic Spindles ◽  
Electron Microscopic ◽  
Cytoplasmic Microtubules

How centrioles and basal bodies assemble is a long-standing puzzle in cell biology. To address this problem, we analyzed a novel basal body-defective Chlamydomonas reinhardtii mutant isolated from a collection of flagella-less mutants. This mutant, bld10, displayed disorganized mitotic spindles and cytoplasmic microtubules, resulting in abnormal cell division and slow growth. Electron microscopic observation suggested that bld10 cells totally lack basal bodies. The product of the BLD10 gene (Bld10p) was found to be a novel coiled-coil protein of 170 kD. Immunoelectron microscopy localizes Bld10p to the cartwheel, a structure with ninefold rotational symmetry positioned near the proximal end of the basal bodies. Because the cartwheel forms the base from which the triplet microtubules elongate, we suggest that Bld10p plays an essential role in an early stage of basal body assembly. A viable mutant having such a severe basal body defect emphasizes the usefulness of Chlamydomonas in studying the mechanism of basal body/centriole assembly by using a variety of mutants.

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.

Extragenic Bypass Suppressors of Mutations in the Essential Gene BLD2 Promote Assembly of Basal Bodies With Abnormal Microtubules in Chlamydomonas reinhardtii

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 163-181
Author(s):  
Andrea M Preble ◽  
Thomas H Giddings ◽  
Susan K Dutcher
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Insertional Mutagenesis ◽  
Essential Gene ◽  
Basal Bodies ◽  
Cleavage Furrow ◽  
Wild Type ◽  
Lethal Phenotype ◽  
Flagellar Assembly ◽  
And Function

Abstract bld2-1 mutant Chlamydomonas reinhardtii strains assemble basal bodies with singlet microtubules; bld2-1 cells display flagellar assembly defects as well as positioning defects of the mitotic spindle and cleavage furrow. To further understand the role of the BLD2 gene, we have isolated three new bld2 alleles and three partially dominant extragenic suppressors, rgn1-1, rgn1-2, and rgn1-3. bld2 rgn1-1 strains have phenotypes intermediate between those of bld2 and wild-type strains with respect to flagellar number, microtubule rootlet organization, cleavage furrow positioning, and basal body structural phenotypes. Instead of the triplet microtubules of wild-type cells, bld2 rgn1-1 basal bodies have mixtures of no, singlet, doublet, and triplet microtubules. The bld2-4 allele was made by insertional mutagenesis and identified in a noncomplementation screen in a diploid strain. The bld2-4 allele has a lethal phenotype based on mitotic segregation in diploid strains and in haploid strains generated by meiotic recombination. The lethal phenotype in haploid strains is suppressed by rgn1-1; these suppressed strains have similar phenotypes to other bld2 rgn1-1 double mutants. It is likely that BLD2 is an essential gene that is needed for basal body assembly and function.

The Scanning Electron Microscopic Observation of the Vestibular Sensory Epithelia

1969 ◽  
Vol 27 ◽  
pp. 40-41
Author(s):  
D.J. Lim ◽  
W.C. Lane
Keyword(s):  
Semicircular Canals ◽  
Electron Microscopic Observation ◽  
Gravitational Acceleration ◽  
Electron Microscopic ◽  
Sensory Epithelia ◽  
Scanning Electron Microscopic ◽  
Vestibular Sensory Epithelia ◽  
And Function ◽  
Sand Piles ◽  
Active Investigation

The morphology and function of the vestibular sensory organs has been extensively studied during the last decade with the advent of electron microscopy and electrophysiology. The opening of the space age also accelerated active investigation in this area, since this organ is responsible for the sensation of balance and of linear, angular and gravitational acceleration.The vestibular sense organs are formed by the saccule, utricle and three ampullae of the semicircular canals. The maculae (sacculi and utriculi) have otolithic membranes on the top of the sensory epithelia. The otolithic membrane is formed by a layer of thick gelatin and sand-piles of calcium carbonate crystals (Fig.l).

scholarly journals Centriole Disassembly In Vivo and Its Effect on Centrosome Structure and Function in Vertebrate Cells

1998 ◽  
Vol 143 (6) ◽  
pp. 1575-1589 ◽  
Author(s):  
Y. Bobinnec ◽  
A. Khodjakov ◽  
L.M. Mir ◽  
C.L. Rieder ◽  
B. Eddé ◽  
...  
Keyword(s):  
Posttranslational Modification ◽  
Electron Microscopic Observation ◽  
Cell Number ◽  
Animal Cells ◽  
Electron Microscopic ◽  
Long Term Stability ◽  
Pericentriolar Material ◽  
Immunofluorescence Labeling ◽  
And Function

Glutamylation is the major posttranslational modification of neuronal and axonemal tubulin and is restricted predominantly to centrioles in nonneuronal cells (Bobinnec, Y., M. Moudjou, J.P. Fouquet, E. Desbruyères, B. Eddé, and M. Bornens. 1998. Cell Motil. Cytoskel. 39:223–232). To investigate a possible relationship between the exceptional stability of centriole microtubules and the compartmentalization of glutamylated isoforms, we loaded HeLa cells with the monoclonal antibody GT335, which specifically reacts with polyglutamylated tubulin. The total disappearance of the centriole pair was observed after 12 h, as judged both by immunofluorescence labeling with specific antibodies and electron microscopic observation of cells after complete thick serial sectioning. Strikingly, we also observed a scattering of the pericentriolar material (PCM) within the cytoplasm and a parallel disappearance of the centrosome as a defined organelle. However, centriole disappearance was transient, as centrioles and discrete centrosomes ultimately reappeared in the cell population. During the acentriolar period, a large proportion of monopolar half-spindles or of bipolar spindles with abnormal distribution of PCM and NuMA were observed. However, as judged by a quasinormal increase in cell number, these cells likely were not blocked in mitosis. Our results suggest that a posttranslational modification of tubulin is critical for long-term stability of centriolar microtubules. They further demonstrate that in animal cells, centrioles are instrumental in organizing centrosomal components into a structurally stable organelle.

scholarly journals Immunoelectron microscopic demonstration of S-100b protein-like in centriole, cilia, and basal body.

1988 ◽  
Vol 36 (6) ◽  
pp. 693-696 ◽  
Author(s):  
T Uchida ◽  
T Endo
Keyword(s):  
Basal Body ◽  
Colloidal Gold ◽  
Protein A ◽  
Ultrastructural Localization ◽  
Basal Bodies ◽  
Cell Organelles ◽  
Gold Particles ◽  
Microscopic Demonstration ◽  
S 100 ◽  
And Function

We report here the ultrastructural localization of S-100b protein-like immunoreactivity in the centriole, cilia, and basal body. Duodenum and trachea of guinea pigs and rats were fixed and immunostained by the protein A-gold method. All centrioles, cilia, and basal bodies observed showed clear S-100b protein-like immunoreactivity. Specific colloidal gold particles were located over the microtubules in these cell organelles. However, other microtubules scattered throughout the cytoplasm were devoid of immunoreactivity. Although the functional significance of S-100b protein-like immunoreactivity in the centriole, cilia, and basal bodies remains to be elucidated, the present results introduce new perspectives into the investigation of localization and function of S-100 proteins.

Restoration of Brain Stem Auditory-Evoked Potentials by Gene Transfer in Shiverer Mice

1994 ◽  
Vol 103 (6) ◽  
pp. 449-456 ◽  
Author(s):  
Tatsuya Fujiyoshi ◽  
Leroy Hood ◽  
T. J. Yoo
Keyword(s):  
Transgenic Mice ◽  
Evoked Potentials ◽  
Brain Stem ◽  
Myelin Sheath ◽  
Auditory Evoked Potentials ◽  
Electron Microscopic Observation ◽  
Recessive Mutation ◽  
Major Protein ◽  
Electron Microscopic ◽  
Hearing Disorders

We studied the shiverer mouse as a model for correcting hearing disorders resulting from genetic abnormalities of the central nervous system (CNS). Shiverer mice are homozygous for an autosomal recessive mutation (deletion) in the gene for myelin basic protein (MBP), a major protein component of the myelin sheath in the CNS. Under electron microscopic observation of the cochlear nerve, the CNS portion in shiverer mice showed hypomyelination, but the peripheral portion, including spiral ganglion cells, was normal. We produced MBP-transgenic mice by microinjection of an MBP cosmid clone into the pronucleus of fertilized eggs from shiverer mice. The transgenic mice were found to recover MBP levels up to 25% of normal. A greater number of axons in the transgenic mice were myelinated than in the shiverer mice, but the myelin sheath was not as thick as in normal controls. Every interpeak latency of brain stem auditory-evoked potentials was prolonged in the shiverer mice and improved in the transgenic mice. This study provides an example of gene therapy for hearing disorders caused by a CNS abnormality. We discuss some strategies for researching genetic hearing impairment or deafness in both animals and humans.

The ultrastructure of the somatic cortex of Pseudomicrothorax dubius: structure and function of the epiplasm in ciliated protozoa

1977 ◽  
Vol 25 (1) ◽  
pp. 367-385
Author(s):  
R.K. Peck
Keyword(s):  
Cell Surface ◽  
Basal Body ◽  
Structure And Function ◽  
Basal Bodies ◽  
Ciliated Protozoa ◽  
Somatic Cortex ◽  
And Function

The ultrastructure of the somatic cortex of the ciliate Pseudomicrothorax dubius is studied with emphasis on the epiplasm layer which lies immediately under the inner alveolar membrane and is continuous with the terminal plates of cortical basal bodies. In addition to a clearly demonstrable cytoskeletal role, the epiplasm appears to function as a comenting substance which integrates numerous cortical fibres and membranes. The kinetodesmal, postciliary and transverse fibre systems which originate at the proximal ends of basal bodies extend toward the cell surface and end at or in the epiplasm. Inner alveolar membranes and trichocyst membranes are attached to the epiplasm. Basal bodies are anchored into the epiplasm via their terminal plates. The epiplasm appears to be morphogenetically important as a matrix into which newly formed basal bodies insert. Electron-opaque arms occur at the terminal plate level of new basal bodies, and these arms fuse with the epiplasm when basal body insertion occurs. The position of trichocysts in the cortex is specified by the epiplasm. Evidence from numerous other ciliates tends to confirm both structural and morphogenetic roles of the epiplasm.

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 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.

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