The ultrastructure of Ulothrix mucosa. II. The flagellar apparatus of the zoospore

1986 ◽  
Vol 64 (1) ◽  
pp. 166-176 ◽  
Author(s):  
G. M. Lokhorst ◽  
W. Star
Keyword(s):  
Basal Body ◽  
Spatial Configuration ◽  
Rotational Symmetry ◽  
Flagellar Apparatus ◽  
Taxonomic Status ◽  
Proximal Region ◽  
Basal Bodies ◽  
Serial Sectioning ◽  
Counterclockwise Direction ◽  
Microtubular Roots

The actual spatial configuration of the flagellar apparatus of the quadriflagellate zoospore of Ulothrix mucosa Thuret has been reconstructed by serial sectioning analysis. This apparatus shows an architecture quite similar to that found in related Ulvophyceae. Common characteristics are the differently leveled basal body pairs; the 180° rotational symmetry of the flagellar apparatus; the proximal overlap of the upper basal bodies which are displaced with respect to each other in the counterclockwise direction; terminal caps; four cruciately arranged microtubular roots (R2, R4); a distinctly striated distal connecting fibre that interconnects the upper basal bodies; and striated bands (SB1) that join the R4s to the lower basal bodies. Specific features are the arrangement of the R4 in a three over one configuration when entering the proximal region of the flagellar apparatus; the differently shaped proximal sheaths and their association with a proximal sheath connecting band; the presence of two system II fibres (rhizoplasts) which arise from the lower basal body pair; the striated bands (SB2) that connect the R2s to the lower basal bodies; the distinct striation of the system I fibre, which is not only intimately associated with the R2, but also with the R4 (not earlier reported for an ulvophycean alga); and, finally, the relevant displacement of the lower basal body pair in a counterclockwise direction of approximately half a basal body diameter. In light of these findings the taxonomic status of the Ulotrichales as well as of the Ulvophyceae is discussed.

Ultrastructure and development of the flagellar apparatus and flagellar motion in the colonial graeen alga Astrephomene gubernaculifera

1983 ◽  
Vol 63 (1) ◽  
pp. 21-41
Author(s):  
H.J. Hoops ◽  
G.L. Floyd
Keyword(s):  
Basal Body ◽  
Rotational Symmetry ◽  
Amorphous Material ◽  
Flagellar Apparatus ◽  
The Other ◽  
Basal Bodies ◽  
Mature Cell ◽  
Embryonic Cleavage ◽  
Development Proceeds ◽  
Concurrent Events

Immediately following embryonic cleavage, the cells of Astrephomene have four equal-sized basal bodies, two of which are connected by a striated distal fibre and two striated proximal fibres. The four microtubular rootlets, which alternate between having 3/1 and 2 members, are arranged cruciately. The two basal bodies that are connected by the striated fibres then extend into flagella, while the two accessory basal bodies are now markedly shorter. At this stage the flagellar apparatus has 180 degrees rotational symmetry and is very similar to the flagellar apparatus of the unicellular Chlamydomonas and related algae. Development proceeds with a number of concurrent events. The basal bodies begin to separate at their proximal ends and become nearly parallel. Each striated proximal fibre detaches at one end from one of the basal bodies. Each half of the flagellar apparatus, which consists of a flagellum and attached basal body, an accessory basal body, two rootlets and a striated fibre (formerly one of the proximal striated fibres), rotates about 90 degrees, the two halves rotating in opposite directions. An electron-dense strut forms near one two-membered rootlet and grows past both basal bodies. During this time a fine, fibrous component appears between newly developed spade-like structures and associated amorphous material connected to each basal body. The basal bodies continue to separate as the distal fibre stretches and finally detaches from one of them. These processes result in the loss of the 180 degree rotational symmetry present in previous stages. Although the flagella continue to separate, there is no further reorganization of the components of the flagellar apparatus. In the mature cell of Astrephomene, the two flagella are inserted separately and are parallel. The four microtubular rootlets are no longer arranged cruciately. Three of the rootlets are nearly parallel, while the fourth is approximately perpendicular to the other three. A straited fibre connects each basal body to the underside of the strut. These fibres run in the direction of the effective stroke of the flagella and might be important either in anchoring the basal bodies or in the initiation of flagellar motion. Unlike the case in the unicellular Chlamydomonas, the two flagella beat in the same direction and in parallel planes. The flagella of a given cell may or may not beat in synchrony. The combination of this type of flagellar motion and the parallel, separate flagella appears to be suited to the motion of this colonial organism.

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.

scholarly journals The Vfl1 Protein in Chlamydomonas Localizes in a Rotationally Asymmetric Pattern at the Distal Ends of the Basal Bodies

2001 ◽  
Vol 153 (1) ◽  
pp. 63-74 ◽  
Author(s):  
Carolyn D. Silflow ◽  
Matthew LaVoie ◽  
Lai-Wa Tam ◽  
Susan Tousey ◽  
Mark Sanders ◽  
...  
Keyword(s):  
Basal Body ◽  
Rotational Symmetry ◽  
Coiled Coil ◽  
Mutant Phenotype ◽  
Basal Bodies ◽  
Repeat Sequences ◽  
Coiled Coil Domain ◽  
Cell Biol ◽  
Asymmetric Pattern ◽  
Rotational Orientation

In the unicellular alga Chlamydomonas, two anterior flagella are positioned with 180° rotational symmetry, such that the flagella beat with the effective strokes in opposite directions (Hoops, H.J., and G.B. Witman. 1983. J. Cell Biol. 97:902–908). The vfl1 mutation results in variable numbers and positioning of flagella and basal bodies (Adams, G.M.W., R.L. Wright, and J.W. Jarvik. 1985. J. Cell Biol. 100:955–964). Using a tagged allele, we cloned the VFL1 gene that encodes a protein of 128 kD with five leucine-rich repeat sequences near the NH2 terminus and a large α-helical–coiled coil domain at the COOH terminus. An epitope-tagged gene construct rescued the mutant phenotype and expressed a tagged protein (Vfl1p) that copurified with basal body flagellar apparatuses. Immunofluorescence experiments showed that Vfl1p localized with basal bodies and probasal bodies. Immunogold labeling localized Vfl1p inside the lumen of the basal body at the distal end. Distribution of gold particles was rotationally asymmetric, with most particles located near the doublet microtubules that face the opposite basal body. The mutant phenotype, together with the localization results, suggest that Vfl1p plays a role in establishing the correct rotational orientation of basal bodies. Vfl1p is the first reported molecular marker of the rotational asymmetry inherent to basal bodies.

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 DEVELOPMENT OF THE FLAGELLAR APPARATUS OF NAEGLERIA

1966 ◽  
Vol 31 (1) ◽  
pp. 43-54 ◽  
Author(s):  
Allan D. Dingle ◽  
Chandler Fulton
Keyword(s):  
Cell Membrane ◽  
Cell Surface ◽  
Basal Body ◽  
Flagellar Apparatus ◽  
Basal Bodies ◽  
Naegleria Gruberi

Flagellates of Naegleria gruberi have an interconnected flagellar apparatus consisting of nucleus, rhizoplast and accessory filaments, basal bodies, and flagella. The structures of these components have been found to be similar to those in other flagellates. The development of methods for obtaining the relatively synchronous transformation of populations of Naegleria amebae into flagellates has permitted a study of the development of the flagellar apparatus. No indications of rhizoplast, basal body, or flagellum structures could be detected in amebae. A basal body appears and assumes a position at the cell surface with its filaments perpendicular to the cell membrane. Axoneme filaments extend from the basal body filaments into a progressive evagination of the cell membrane which becomes the flagellum sheath. Continued elongation of the axoneme filaments leads to differentiation of a fully formed flagellum with a typical "9 + 2" organization, within 10 min after the appearance of basal bodies.

scholarly journals Basal body reorientation mediated by a Ca2+-modulated contractile protein.

1987 ◽  
Vol 105 (2) ◽  
pp. 903-912 ◽  
Author(s):  
G I McFadden ◽  
D Schulze ◽  
B Surek ◽  
J L Salisbury ◽  
M Melkonian
Keyword(s):  
Green Algae ◽  
Basal Body ◽  
Flagellar Apparatus ◽  
Immunoblot Analysis ◽  
Contractile Protein ◽  
Immunogold Electron Microscopy ◽  
Basal Bodies ◽  
Photophobic Response ◽  
Parallel Configuration

A rapid, Ca2+-dependent change in the angle between basal bodies (up to 180 degrees) is associated with light-induced reversal of swimming direction (the "photophobic" response) in a number of flagellated green algae. In isolated, detergent-extracted, reactivated flagellar apparatus complexes of Spermatozopsis similis, axonemal beat form conversion to the symmetrical/undulating flagellar pattern and basal body reorientation (from the antiparallel to the parallel configuration) are simultaneously induced at greater than or equal to 10(-7) M Ca2+. Basal body reorientation, however, is independent of flagellar beating since it is induced at greater than or equal to 10(-7) M Ca2+ when flagellar beating is inhibited (i.e., in the presence of 1 microM orthovanadate in reactivation solutions; in the absence of ATP or dithiothreitol in isolation and reactivation solutions), or when axonemes are mechanically removed from flagellar apparatuses. Although frequent axonemal beat form reversals were induced by varying the Ca2+ concentration, antiparallel basal body configuration could not be restored in isolated flagellar apparatuses. Observations of the photophobic response in vivo indicate that even though the flagella resume the asymmetric, breaststroke beat form 1-2 s after photostimulation, antiparallel basal body configuration is not restored until a few minutes later. Using an antibody generated against the 20-kD Ca2+-modulated contractile protein of striated flagellar roots of Tetraselmis striata (Salisbury, J. L., A. Baron, B. Surek, and M. Melkonian, 1984, J. Cell Biol., 99:962-970), we have found the distal connecting fiber of Spermatozopsis similis to be immunoreactive by indirect immunofluorescence and immunogold electron microscopy. Electrophoretic and immunoblot analysis indicates that the antigen of S. similis flagellar apparatuses consists, like the Tetraselmis protein, of two acidic isoforms of 20 kD. We conclude that the distal basal body connecting fiber is a contractile organelle and reorients basal bodies during the photophobic response in certain flagellated green algae.

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.

scholarly journals The centrin-based cytoskeleton of Chlamydomonas reinhardtii: distribution in interphase and mitotic cells.

1988 ◽  
Vol 107 (2) ◽  
pp. 635-641 ◽  
Author(s):  
J L Salisbury ◽  
A T Baron ◽  
M A Sanders
Keyword(s):  
Nuclear Envelope ◽  
Polyclonal Antibodies ◽  
Flagellar Apparatus ◽  
Immunogold Labeling ◽  
Basal Bodies ◽  
Flagellar Roots ◽  
Cell Biol ◽  
Immunofluorescence Studies ◽  
Descending Fibers

Monoclonal and polyclonal antibodies raised against algal centrin, a protein of algal striated flagellar roots, were used to characterize the occurrence and distribution of this protein in interphase and mitotic Chlamydomonas cells. Chlamydomonas centrin, as identified by Western immunoblot procedures, is a low molecular (20,000-Mr) acidic protein. Immunofluorescence and immunogold labeling demonstrates that centrin is a component of the distal fiber. In addition, centrin-based flagellar roots link the flagellar apparatus to the nucleus. Two major descending fibers extend from the basal bodies toward the nucleus; each descending fiber branches several times giving rise to 8-16 fimbria which surround and embrace the nucleus. Immunogold labeling indicates that these fimbria are juxtaposed to the outer nuclear envelope. Earlier studies have demonstrated that the centrin-based linkage between the flagellar apparatus and the nucleus is contractile, both in vitro and in living Chlamydomonas cells (Wright, R. L., J. Salisbury, and J. Jarvik. 1985. J. Cell Biol. 101:1903-1912; Salisbury, J. L., M. A. Sanders, and L. Harpst. 1987. J. Cell Biol. 105:1799-1805). Immunofluorescence studies show dramatic changes in distribution of the centrin-based system during mitosis that include a transient contraction at preprophase; division, separation, and re-extension during prophase; and a second transient contraction at the metaphase/anaphase boundary. These observations suggest a fundamental role for centrin in motile events during mitosis.

scholarly journals Organization of the flagellar apparatus and associate cytoplasmic microtubules in the quadriflagellate alga Polytomella agilis.

1976 ◽  
Vol 69 (1) ◽  
pp. 106-125 ◽  
Author(s):  
D L Brown ◽  
A Massalski ◽  
R Patenaude
Keyword(s):  
Anterior Part ◽  
Flagellar Apparatus ◽  
Microtubule Assembly ◽  
Immunofluorescent Staining ◽  
Body Region ◽  
Basal Bodies ◽  
Cytoplasmic Microtubule ◽  
Large Numbers ◽  
Attachment Sites ◽  
Cytoplasmic Microtubules

The organization of microtubular systems in the quadriflagellate unicell Polytomella agilis has been reconstructed by electron microscopy of serial sections, and the overall arrangement confirmed by immunofluorescent staining using antiserum directed against chick brain tubulin. The basal bodies of the four flagella are shown to be linked in two pairs of short fibers. Light microscopy of swimming cells indicates that the flagella beat in two synchronous pairs, with each pair exhibiting a breast-stroke-like motion. Two structurally distinct flagellar rootlets, one consisting of four microtubules in a 3 over 1 pattern and the other of a striated fiber over two microtubules, terminate between adjacent basal bodies. These rootlets diverge from the basal body region and extend toward the cell posterior, passing just beneath the plasma membrane. Near the anterior part of the cell, all eight rootlets serve as attachment sites for large numbers of cytoplasmic microtubules which occur in a single row around the circumference of the cell and closely parallel the cell shape. It is suggested that the flagellar rootless may function in controlling the patterning and the direction of cytoplasmic microtubule assembly. The occurrence of similar rootlet structures in other flagellates is briefly reviewed.

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.

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