Basal body loss during fungal zoospore encystment: evidence against centriole autonomy

1986 ◽  
Vol 83 (1) ◽  
pp. 135-140
Author(s):  
I.B. Heath ◽  
S.G. Kaminskyj ◽  
T. Bauchop
Keyword(s):  
Life Cycle ◽  
Cell Line ◽  
Basal Body ◽  
Generative Cell ◽  
Basal Bodies ◽  
Cilia And Flagella ◽  
Endosymbiotic Origin

The controversial question of the possible autonomy of centrioles, as shown by the persistence of all or part of them in the generative cell line throughout the life cycle of organisms, remains unresolved. All previous reports on shedding or withdrawal of cilia and flagella showed that their basal bodies (= centrioles) were retained in the cells where they may, or may not, subsequently disassemble. We show that in the fungus Neocallimastix sp. the basal bodies are discarded with the flagella when zoospores encyst. This shedding of basal bodies argues against centriolar persistence in any form and thus against their autonomy and endosymbiotic origin.

scholarly journals The Two SAS-6 Homologs in Tetrahymena thermophila Have Distinct Functions in Basal Body Assembly

2009 ◽  
Vol 20 (6) ◽  
pp. 1865-1877 ◽  
Author(s):  
Brady P. Culver ◽  
Janet B. Meehl ◽  
Thomas H. Giddings ◽  
Mark Winey
Keyword(s):  
Basal Body ◽  
Structural Component ◽  
Tetrahymena Thermophila ◽  
Basal Bodies ◽  
Hub And Spoke ◽  
Structural Role ◽  
Higher Eukaryotes ◽  
Centriole Assembly ◽  
Cilia And Flagella

Cilia and flagella are structurally and functionally conserved organelles present in basal as well as higher eukaryotes. The assembly of cilia requires a microtubule based scaffold called a basal body. The ninefold symmetry characteristic of basal bodies and the structurally similar centriole is organized around a hub and spoke structure termed the cartwheel. To date, SAS-6 is one of the two clearly conserved components of the cartwheel. In some organisms, overexpression of SAS-6 causes the formation of supernumerary centrioles. We questioned whether the centriole assembly initiation capacity of SAS-6 is separate from or directly related to its structural role at the cartwheel. To address this question we used Tetrahymena thermophila, which expresses two SAS-6 homologues, TtSAS6a and TtSAS6b. Cells lacking either TtSAS6a or TtSAS6b are defective in new basal body assembly. TtSas6a localizes to all basal bodies equally, whereas TtSas6b is enriched at unciliated and assembling basal bodies. Interestingly, overexpression of TtSAS6b but not TtSAS6a, led to the assembly of clusters of new basal bodies in abnormal locations. Our data suggest a model where TtSAS6a and TtSAS6b have diverged such that TtSAS6a acts as a structural component of basal bodies, whereas TtSAS6b influences the location of new basal body assembly.

scholarly journals Drosophila Bld10 Is a Centriolar Protein That Regulates Centriole, Basal Body, and Motile Cilium Assembly

2009 ◽  
Vol 20 (10) ◽  
pp. 2605-2614 ◽  
Author(s):  
Violaine Mottier-Pavie ◽  
Timothy L. Megraw
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Basal Body ◽  
Human Diseases ◽  
Cell Physiology ◽  
Basal Bodies ◽  
Male Sterile ◽  
Central Pair ◽  
Animal Development ◽  
Cilia And Flagella

Cilia and flagella play multiple essential roles in animal development and cell physiology. Defective cilium assembly or motility represents the etiological basis for a growing number of human diseases. Therefore, how cilia and flagella assemble and the processes that drive motility are essential for understanding these diseases. Here we show that Drosophila Bld10, the ortholog of Chlamydomonas reinhardtii Bld10p and human Cep135, is a ubiquitous centriolar protein that also localizes to the spermatid basal body. Mutants that lack Bld10 assemble centrioles and form functional centrosomes, but centrioles and spermatid basal bodies are short in length. bld10 mutant flies are viable but male sterile, producing immotile sperm whose axonemes are deficient in the central pair of microtubules. These results show that Drosophila Bld10 is required for centriole and axoneme assembly to confer cilium motility.

scholarly journals Scalar constraints in Tetrahymena evolution. Quantitative basal body variations within and between species.

1978 ◽  
Vol 79 (3) ◽  
pp. 727-736 ◽  
Author(s):  
D L Nanney ◽  
S S Chen ◽  
E B Meyer
Keyword(s):  
Life Cycle ◽  
Cell Division ◽  
Basal Body ◽  
Dna Content ◽  
Growth Cycle ◽  
Scalar Function ◽  
Basal Bodies ◽  
Limited Variation ◽  
Size Dispersion ◽  
Macronuclear Division

Tetrahymenas of 17 species of the T. pyriformis complex have been stained with protargol and analyzed for numbers of basal bodies in half cells just before cell division. At this stage, cells of all strains manifest considerable variation in numbers of basal bodies; the coefficient of variation (sigma/m) is usually between 0.05 and 0.10. Much of this variability is observed in cells in the same nutritional state, at the same stage of the growth cycle, and in the same part of the life cycle. The basal body variability may be related to the variation in macronuclear DNA content that results from the imprecise amitotic macronuclear division. With a few exceptions, strains of different species are difficult to distinguish on the basis of basal body numbers. The species means in the samples examined show a range only from 234 (T. furgasoni) to 481 (T. capricornis), about a twofold difference. This limited variation in the means suggests that these organisms are constrained within narrow limited by some scalar function of their organismic design, which prevents an evolutionary size dispersion--even though molecular scrambling has occurred in the complex at an appreciable rate for a very long evolutionary interval.

Ciliary coordination in newt lung cells requires microtubule-based linkages between basal bodies: A correlative light and EM study

1992 ◽  
Vol 50 (1) ◽  
pp. 570-571
Author(s):  
Robert Hard ◽  
Gerald Rupp ◽  
Matthew L. Withiam-Leitch ◽  
Lisa Cardamone
Keyword(s):  
Basal Body ◽  
Untreated Control ◽  
Beat Frequency ◽  
Primary Cultures ◽  
Living Cells ◽  
Power Stroke ◽  
Ultrastructural Changes ◽  
Lung Cells ◽  
Basal Bodies ◽  
Ciliated Cells

In a coordinated field of beating cilia, the direction of the power stroke is correlated with the orientation of basal body appendages, called basal feet. In newt lung ciliated cells, adjacent basal feet are interconnected by cold-stable microtubules (basal MTs). In the present study, we investigate the hypothesis that these basal MTs stabilize ciliary distribution and alignment. To accomplish this, newt lung primary cultures were treated with the microtubule disrupting agent, Colcemid. In newt lung cultures, cilia normally disperse in a characteristic fashion as the mucociliary epithelium migrates from the tissue explant. Four arbitrary, but progressive stages of dispersion were defined and used to monitor this redistribution process. Ciliaiy beat frequency, coordination, and dispersion were assessed for 91 hrs in untreated (control) and treated cultures. When compared to controls, cilia dispersed more rapidly and ciliary coordination decreased markedly in cultures treated with Colcemid (2 mM). Correlative LM/EM was used to assess whether these effects of Colcemid were coupled to ultrastructural changes. Living cells were defined as having coordinated or uncoordinated cilia and then were processed for transmission EM.

Structural Analysis of Basal Bodies of The Isolated Oral Apparatus of Tetrahymena Pyriformis

1970 ◽  
Vol 6 (3) ◽  
pp. 679-700
Author(s):  
J. WOLFE
Keyword(s):  
Structural Analysis ◽  
Cell Membrane ◽  
Basal Body ◽  
Structural Integrity ◽  
Tetrahymena Pyriformis ◽  
Basal Plate ◽  
Basal Bodies ◽  
The Third ◽  
Ionic Detergent

The oral apparatus of Tetrahymena pyriformis was isolated using a non-ionic detergent to disrupt the cell membrane. The mouth consists largely of basal bodies and microfilaments. Each basal body is attached to the mouth by a basal plate which is integrated into the meshwork of microfilaments that confers upon the oral apparatus its structural integrity. Each basal body is composed of 9 triplet microtubules. Two of the 3 tubules, subfibres ‘A’ and ‘B’ are composed of filamentous rows of globules with a spacing of 4.5nm. The third tubule, subfibre ‘C’, is only one-third the length of the basal body.

Comparative Isolation of Cilia and Flagella from the Lamellibranch Mollusc, Aequipecten irradians

1973 ◽  
Vol 12 (2) ◽  
pp. 345-367
Author(s):  
R. W. LINCK
Keyword(s):  
Atpase Activity ◽  
Cross Sections ◽  
Basal Body ◽  
Electron Dense Material ◽  
The Matrix ◽  
Fine Structures ◽  
Dynein Arms ◽  
Cilia And Flagella ◽  
Triton X ◽  
Ciliary Ultrastructure

Gill cilia and sperm flagella from the lamellibranch mollusc Aequipecten irradians were compared with respect to their ultrastructures and adenosinetriphosphatase activities. Cilia were isolated from excised gills using 3 different solutions: twice-concentrated seawater, 10 % ethanol-10 mM CaCl2 and 60% glycerol. In each case deciliation occurs by the severance of the cilium at the junction of the transition zone and the basal body, and in each case the ciliary ultrastructure is maintained. Sperm flagella were purified by mechanical decapitation. Cilia and sperm flagella have similar fine structures, except that the matrix of the cilia contains substantially more electron-dense material than that of flagella. The ATPase activity of purified cilia is approximately 0.09,µmol P1/min/mg protein; that of flagella is 0.13. Ciliary and flagellar axonemes were prepared by repeated extraction of the membranes with 1% Triton X-100. Ciliary axonemes maintain their 9 + 2 cylindrical orientation, whereas flagellar axonemes often appear as opened or fragmented arrays of the 9 + 2 structure, due to the partial breakdown of the flagellar nexin fibres. A-subfibre arms which were obvious in whole organelles are rarely seen in axoneme preparations. Again the ciliary matrix is considerably more amorphous than in flagellar axonemes. The ATPase activities of ciliary and flagellar axonemes are 0.13 and 0.12 µmol P1/min/mg protein respectively; however, activities of ciliary axonemes may vary by a factor of 2, depending on the method of isolation. The difficulty in observing A-subfibre arms in cross-sections of ciliary and flagellar axonemes is discussed in terms of random, non-reinforcing arrangements of the dynein arms.

scholarly journals The ultrastructure of cell division in Euglena gracilis

1978 ◽  
Vol 31 (1) ◽  
pp. 25-35
Author(s):  
M.A. Gillott ◽  
R.E. Triemer
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Basal Body ◽  
Euglena Gracilis ◽  
Equatorial Region ◽  
Basal Bodies ◽  
Cleavage Furrow ◽  
Free Zone ◽  
Prophase Nucleus

The ultrastructure of mitosis in Euglena gracilis was investigated. At preprophase the nucleus migrates anteriorly and associates with the basal bodies. Flagella and basal bodies replicate at preprophase. Cells retain motility throughout division. The reservoir and the prophase nucleus elongate perpendicular to the incipient cleavage furrow. One basal body pair surrounded by a ribosome-free zone is found at each of the nuclear poles. The spindle forms within the intact nuclear envelope- Polar fenestrae are absent. At metaphase, the endosome is elongated from pole to pole, and chromosomes are loosely arranged in the equatorial region. Distinct, trilayered kinetochores are present. Spindle elongates as chromosomes migrate to the poles forming a dumb-bell shaped nucleus by telophase. Daughter nuclei are formed by constriction of the nuclear envelope. Cytokinesis is accomplished by furrowing. Cell division in Euglena is compared with that of certain other algae.

scholarly journals Dynamics of the IFT machinery at the ciliary tip

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Alexander Chien ◽  
Sheng Min Shih ◽  
Raqual Bower ◽  
Douglas Tritschler ◽  
Mary E Porter ◽  
...  
Keyword(s):  
Basal Body ◽  
Full Range ◽  
Intraflagellar Transport ◽  
Feedback Mechanism ◽  
Conventional Imaging ◽  
Range Of Movement ◽  
Anterograde Transport ◽  
Traffic Jam ◽  
Negative Feedback Mechanism ◽  
Cilia And Flagella

Intraflagellar transport (IFT) is essential for the elongation and maintenance of eukaryotic cilia and flagella. Due to the traffic jam of multiple trains at the ciliary tip, how IFT trains are remodeled in these turnaround zones cannot be determined by conventional imaging. Using PhotoGate, we visualized the full range of movement of single IFT trains and motors in Chlamydomonas flagella. Anterograde trains split apart and IFT complexes mix with each other at the tip to assemble retrograde trains. Dynein-1b is carried to the tip by kinesin-II as inactive cargo on anterograde trains. Unlike dynein-1b, kinesin-II detaches from IFT trains at the tip and diffuses in flagella. As the flagellum grows longer, diffusion delays return of kinesin-II to the basal body, depleting kinesin-II available for anterograde transport. Our results suggest that dissociation of kinesin-II from IFT trains serves as a negative feedback mechanism that facilitates flagellar length control in Chlamydomonas.

Basal Body and Flagellar Development During the Vegetative Cell Cycle and the Sexual Cycle of Chlamydomonas Reinhardii

1974 ◽  
Vol 16 (3) ◽  
pp. 529-556 ◽  
Author(s):  
T. CAVALIER-SMITH
Keyword(s):  
Basal Body ◽  
Vegetative Cell ◽  
Amorphous Material ◽  
Sexual Cycle ◽  
Transitional Region ◽  
Basal Bodies ◽  
Vegetative Cells ◽  
Chlamydomonas Reinhardii ◽  
Body Development ◽  
Microtubular Roots

Basal body development and flagellar regression and growth in the unicellular green alga Chlamydomonas reinhardii were studied by light and electron microscopy during the vegetative cell cycle in synchronous cultures and during the sexual life cycle. Flagella regress by gradual shortening prior to vegetative cell division and also a few hours after cell fusion in the sexual cycle. In vegetative cells basal bodies remain attached to the plasma membrane by their transitional fibres and do not act as centrioles at the spindle poles during division. In zygotes the basal bodies and associated microtubular roots and cross-striated connexions all dissolve, and by 6.5 h after mating all traces of flagellar apparatus and associated structures have disappeared. They remain absent for 6 days throughout zygospore maturation and then are reassembled during zygospore germination, after meiosis has begun. Basal body assembly in developing zygospores occurs close to the plasma membrane (in the absence of pre-existing basal bodies) via an intermediate stage consisting of nine single A-tubules surrounding a central ‘cartwheel’. Assembly is similar in vegetative cells (and occurs prior to cell division), except that new basal bodies are physically attached to old ones by amorphous material. In vegetative cells, amorphous disks, which may possibly be still earlier stages in basal-body development occur in the same location as 9-singlet developing basal bodies. After the 9-singlet structure is formed, B and C fibres are added and the basal body elongates to its mature length. Microtubular roots, striated connexions and flagella are then assembled. Both flagellar regression and growth are gradual and sequential, the transitional region at the base of the flagellum being formed first and broken down last. The presence of amorphous material at the tip of the axoneme of growing and regressing flagella suggests that the axoneme grows or shortens by the sequential assembly or disassembly at its tip. In homogenized cells basal bodies remain firmly attached to each other by their striated connexions. The flagellar transitional region, and parts of the membrane and of the 4 microtubular roots, also remain attached; so also do new developing basal bodies, if present. These structures are well preserved in homogenates and new fine-structural details can be seen. These results are discussed, and lend no support to the idea that basal bodies have genetic continuity. It is suggested that basal body development can be best understood if a distinction is made between the information needed to specify the structure of a basal body and that needed to specify its location and orientation.

Localization of actin in the Tetrahymena basal body-cage complex

1992 ◽  
Vol 103 (3) ◽  
pp. 629-641 ◽  
Author(s):  
J.G. Hoey ◽  
R.H. Gavin
Keyword(s):  
Basal Body ◽  
Specific Binding ◽  
Ultrastructural Level ◽  
Basal Bodies ◽  
Muscle Actin ◽  
Cage Complex ◽  
Contractile System ◽  
Chicken Muscle ◽  
Filament Bundles

In the ciliate cytoskeleton, basal bodies are contained within separate, filamentous cages which are closely associated with basal body microtubules. We have used two polyclonal anti-actin antibodies to localize actin within the basal body-cage complex of Tetrahymena. An antiserum against a Tetrahymena oral apparatus fraction enriched for basal body proteins was produced in rabbits. Agarose-linked chicken muscle actin was used to affinity-purify anti-Tetrahymena actin antibodies from the anti-oral apparatus antiserum. Agarose-linked chicken muscle actin was used to affinity-purify anti-chicken muscle actin antibodies from a commercially available antiserum against chicken muscle actin. Both affinity-purified antibodies were monospecific for Tetrahymena actin on immunoblots containing total oral apparatus protein. The anti-actin antibodies were localized to both somatic and oral basal bodies in Tetrahymena by immunofluorescence microscopy. At the ultrastructural level with the immunogold technique, these antibodies labeled actin epitopes in four distinct regions of the basal body-cage complex: (a) basal body walls, (b) basal plate filaments, (c) proximal-end filaments and (d) cage wall filaments. In addition, the antibody labeled filament bundles that interconnect groups of basal bodies (membranelles) within the oral apparatus. Identical labeling patterns were observed with basal bodies in the isolated oral apparatus, basal bodies in the in situ oral apparatus and somatic basal bodies in situ. Quantitative analysis of gold particle distribution was used to demonstrate the specificity of the antibodies for the basal body-cage complex and to show that non-specific binding of the antibodies was negligible. Preadsorption of the antibody with muscle actin effectively eliminated the capacity of the antibody to bind to proteins on immunoblots and to basal body structures with the immunogold labeling technique. These results provide evidence for actin in the basal body-cage complex and raise the possibility of a contractile system associated with basal bodies.

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