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.

In vitro effects of taxol on ciliogenesis in quail oviduct

1989 ◽  
Vol 92 (1) ◽  
pp. 9-20 ◽  
Author(s):  
E. Boisvieux-Ulrich ◽  
M.C. Laine ◽  
D. Sandoz
Keyword(s):  
Basal Body ◽  
In Situ Polymerization ◽  
Neck Region ◽  
Apical Part ◽  
Transitional Region ◽  
Basal Bodies ◽  
Apical Surface ◽  
In Vitro Effects

When induced by in vivo oestrogen stimulation, ciliogenesis continues in culture in vitro of quail oviduct implants. Ultrastructure of ciliogenic cells was compared after culture for 24 or 48 h in the presence or absence of 10(−5) M-taxol. Taxol, which promotes polymerization and stabilization of microtubules, disturbed ciliogenesis, but formation of basal bodies was unaffected by the drug. Conversely, their migration towards the apical surface seemed to be slowed down or blocked and axonemal doublets polymerized onto the distal end of cytoplasmic basal bodies. They elongated and often constituted a more or less complete axoneme, extending between organelles in various orientations. These axonemes, often abnormal, were not surrounded by a membrane, with the exception of the transitional or neck region between the basal body and axoneme. The formation of membrane in this area resulted from the binding of some vesicles to the anchoring fibres of the basal body. They fused in various numbers, occasionally forming a ring, at the site of the transitional region, and exhibited the characteristics of the ciliary necklace. The association of basal bodies with vesicles or with the plasma membrane appeared to be a necessary signal for in situ polymerization of axonemal doublets. In addition, taxol induced polymerization of numerous microtubules in the cytoplasm, especially in the apical part of the cell and in the Golgi area. This network of microtubules may prevent basal body migration.

scholarly journals THE RELATIONSHIP BETWEEN THE FINE STRUCTURE AND DIRECTION OF BEAT IN GILL CILIA OF A LAMELLIBRANCH MOLLUSC

1961 ◽  
Vol 11 (1) ◽  
pp. 179-205 ◽  
Author(s):  
I. R. Gibbons
Keyword(s):  
Fine Structure ◽  
Cell Surface ◽  
Basal Body ◽  
Transitional Region ◽  
Basal Bodies ◽  
Conical Structure ◽  
The Relationship ◽  
Basal Foot ◽  
Different Levels ◽  
Outer Fiber

This paper describes the fine structure and its relationship to the direction of beat in four types of cilia on the gill of the fresh-water mussel Anodonta cataracta. The cilia contain nine outer, nine secondary, and two central fibers, such as have been described previously in other material. Each outer fiber is a doublet with one subfiber bearing arms. One particular pair of outer fibers (numbers 5 and 6) are joined together by a bridge. The two central fibers are enclosed by a central sheath; also present in this region is a single, small mid-fiber. The different groups of fibers are connected together by radial links that extend from the outer to the secondary fibers, and from the secondary fibers to the central sheath. The basal body consists of a cylinder of nine triplet fibers. Projecting from it on one side is a dense conical structure called the basal foot. The cylinder of outer fibers continues from the basal body into the cilium, passing through a complex transitional region in which five distinct changes of structure occur at different levels. There are two sets of fibers associated with the basal bodies: a pair of striated rootlets that extends from each basal body down into the cell, and a system of fine tubular fibers that runs parallel to the cell surface. The relationship between fine structure and direction of beat is the same in all four types of cilia examined. The plane of beat is perpendicular to the plane of the central fibers, with the effective stroke toward the bridge between outer fibers 5 and 6, and toward the foot on the basal body.

scholarly journals THE MORPHOGENESIS OF BASAL BODIES AND ACCESSORY STRUCTURES OF THE CORTEX OF THE CILIATED PROTOZOAN TETRAHYMENA PYRIFORMIS

1969 ◽  
Vol 40 (3) ◽  
pp. 716-733 ◽  
Author(s):  
Richard D. Allen
Keyword(s):  
Basal Body ◽  
Tetrahymena Pyriformis ◽  
Basal Bodies ◽  
Proximal Surface ◽  
Body Development ◽  
Transmission Electron ◽  
Short Cylinder ◽  
Dividing Cells ◽  
Constant Distance ◽  
Single Tubules

Dividing cells of Tetrahymena pyriformis were observed by transmission electron microscopy for signs of morphogenesis of cortical structures. The earliest stage of basal body development observed was of a short cylinder of nine single tubules connected by an internal cartwheel structure. This is set perpendicular to the mature basal body at its anterior proximal surface under the transverse microtubules and next to the basal microtubules. Sequential stages show that the single tubules become triplet tubules and that the "probasal bodies" then elongate and tilt toward the organism's surface while maintaining a constant distance of 75–100 mµ with the "parent." The new basal body after it is fully extended contacts the pellicle, and then assumes a parallel orientation with and moves anterior to the parent basal body. The electron-opaque core in the lumen of the basal body and accessory structures around its outer proximal surface appear after the developing basal body has elongated. These accessory structures associating with their counterparts from other basal bodies and with the longitudinal microtubules may play a role in the final positioning of basal bodies and thus in the maintenance of cortical patterns. Observations on a second sequence of basal body formation suggest that the oral anlage arises by multiple duplication of somatic basal bodies.

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.

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.

Studies on flagella-less, stumpy, and short flagellum mutants of Chlamydomonas reinhardii

1969 ◽  
Vol 173 (1030) ◽  
pp. 59-60 ◽  
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Basal Body ◽  
Light Microscope ◽  
Longitudinal Section ◽  
Transitional Region ◽  
Chlamydomonas Reinhardii ◽  
Electron Dense Material ◽  
The Individual ◽  
Further Development

I will describe briefly some mutants of Chlamydomonas reinhardii which are unable to form a complete flagellum. Eight flagella-less, six stumpy and eleven short flagellum mutants have been studied. Flagella-less mutants are shown to have a normal basal body when examined in the electron microscope. The transitional region, characterized by the presence of a densely staining cylinder with the appearance in longitudinal section of a letter H, is also present (figure 39, plate 12). Outer flagellar tubules extend from the basal body into the transitional region and terminate at its distal end. In transverse sections through the transitional region the outer tubules often appear poorly formed and in some cases incomplete. The 9 + 2 axoneme is completely absent, and the flagellum only extends part way through the tunnel in the cell wall and is thus not visible in the light microscope. These mutants appear to have some abnormality in the structure or assembly of the transitional region which prevents the further development of the external flagellum. Stumpy mutants have flagella less than 1 μ m long from the distal end of the transitional region cylinder. At the tip, the membrane is distended, and the enlarged space between the membrane and the outer axoneme tubules is filled with electron dense material (figures 40, 41, plate 12). This sometimes appears in the form of ribbons in both longitudinal and transverse sections suggesting that it may occur in sheets. It may represent tubule material which failed to become incorporated into organized tubules. The 9 + 2 array of tubules may appear normal as in figure 41, but more frequently some of the individual tubules appear poorly formed or incomplete and the whole array is distorted. No abnormalities are seen in the basal body and transitional regions.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document