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.

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 Ultrastructure of Lejeunea spp. leaves surface in a lowland tropical urban forest of Universitas Indonesia Campus, Depok, Indonesia

2020 ◽  
Vol 21 (9) ◽  
Author(s):  
Afiatry Putrika ◽  
Dhita Mutiara Nabella ◽  
Andi Salamah ◽  
Nisyawati NISYAWATI ◽  
Astari Dwiranti
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Cell Surface ◽  
Light Microscope ◽  
Urban Forest ◽  
Wide Distribution ◽  
The Other ◽  
Wall Surface ◽  
The World ◽  
Scanning Electron

Abstract. Putrika A, Nabella DM, Salamah A, Nisyawati, Dwiranti A. 2020. Ultrastructure of Lejeunea spp. leaves surface in a lowland tropical urban forest of Universitas Indonesia Campus, Depok, Indonesia. Biodiversitas 21: 4184-4191. Lejeunea is one of liverworts genera that have a wide distribution in the world. It has many variations of the character that have not been revealed, such as variations of the cell surface. The purpose of this research was to study the ultrastructure of Lejeunea spp. leaves surface in a lowland tropical urban forest of Universitas Indonesia (UI) Campus, Depok, Indonesia. Six species of Lejeunea spp. were studied, i.e., L. anisophylla, L. cocoes, L. exilis, L. papilionacea, L. catanduana, and L. curviloba. The research methods carried out in this study consisted of the sample observation using a light microscope, sample preparation for Scanning Electron Microscope (SEM) observation (fixation, post-fixation, dehydration, drying, mounting), and observations using SEM. The results of observation using a light microscope showed the smooth cell surface of all samples studied. Meanwhile, the differences between six species of Lejeunea in the UI campus could be differentiated under SEM. L. catanduana could be distinguished from other species from its cell wall thickness and texture, ornamentation types, and the number of ornamentations per cell. The texture of the cell wall of L. catanduana was the roughest than the other species due to abundant ornamentation such as papillae on its the cell wall surface. Furthermore, only this species has mamillae on the cell surface. The number of papillae or mamillae was 1-4 per cell. On the other hand, L. cocoes has the thinnest cell wall and slightly rough texture. Only this species has the simple papillae on the cell surface. Thus, the results of this study suggested that the cell surface variations in Lejeunea might be potential to be used as taxonomic characters in grouping species.

scholarly journals LOCALIZATION OF STRUCTURAL POLYMERS IN THE CELL WALL OF NEUROSPORA CRASSA

1967 ◽  
Vol 35 (2) ◽  
pp. 295-302 ◽  
Author(s):  
P. R. Mahadevan ◽  
E. L. Tatum
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Electron Microscope ◽  
Neurospora Crassa ◽  
Outer Layer ◽  
Light Microscope ◽  
Structural Integrity ◽  
Selective Removal ◽  
Microscope Examination ◽  
Structural Polymers

The distribution and localization of structural polymers in the cell wall of Neurospora crassa has been studied by selective removal and light and electron microscope examination. Observations with the light microscope indicated that each polymer by itself can provide structural integrity to the cell wall. Examination by electron microscopy showed that the cell wall consists of an outer layer of thick fibrils, identified chemically as a glucan-peptide-galactosamine complex, and an inner layer made up of ß-1,3 glucan and thin fibrils of chitin.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Selective Staining of Acid Mucopolysaccharides By Ruthenium Red

1968 ◽  
Vol 26 ◽  
pp. 38-39
Author(s):  
J. H. Luft
Keyword(s):  
Electron Microscope ◽  
Light Microscopy ◽  
Light Microscope ◽  
Osmium Tetroxide ◽  
Single Cells ◽  
Ruthenium Red ◽  
Collagen Fibers ◽  
Selective Staining ◽  
Pectic Substances ◽  
Solid Tissues

Ruthenium red is one of the few completely inorganic dyes used to stain tissues for light microscopy. This novelty is enhanced by ignorance regarding its staining mechanism. However, its continued usefulness in botany for demonstrating pectic substances attests to selectivity of some sort. Whether understood or not, histochemists continue to be grateful for small favors.Ruthenium red can also be used with the electron microscope. If single cells are exposed to ruthenium red solution, sufficient mass can be bound to produce observable density in the electron microscope. Generally, this effect is not useful with solid tissues because the contrast is wasted on the damaged cells at the block surface, with little dye diffusing more than 25-50 μ into the interior. Although these traces of ruthenium red which penetrate between and around cells are visible in the light microscope, they produce negligible contrast in the electron microscope. However, its presence can be amplified by a reaction with osmium tetroxide, probably catalytically, to be easily visible by EM. Now the density is clearly seen to be extracellular and closely associated with collagen fibers (Fig. 1).

scholarly journals Insights to enhance the examination of tool marks in human cartilage

2021 ◽  
Author(s):  
Matthias Weber ◽  
Anja Niehoff ◽  
Markus A. Rothschild
Keyword(s):  
Light Microscope ◽  
Cross Correlation ◽  
Costal Cartilage ◽  
Correlation Coefficients ◽  
Human Cartilage ◽  
Cut Marks ◽  
Tool Marks ◽  
The Cross ◽  
Cleaning Methods ◽  
The Individual

AbstractThis work deals with the examination of tool marks in human cartilage. We compared the effectiveness of several cleaning methods on cut marks in porcine cartilage. The method cleaning by multiple casts achieved the significantly highest scores (P = 0.02). Furthermore, we examined the grain-like elevations (dots) located on casts of cut cartilage. The results of this study suggest that the casting material forms these dots when penetrating cartilage cavities, which are areas where the strong collagen fibres leave space for the chondrocytes. We performed fixation experiments to avoid this, without success. In addition, 31 casting materials were compared regarding contrast under light-microscope and 3D tool marks scanner. Under the light-microscope, brown materials achieved significantly higher values than grey (P = 0.02) or black (P = 0.00) whereas under the 3D scanner, black materials reached higher contrast values than grey (P = 0.04) or brown (P = 0.047). To compare the accuracy and reproducibility of 6 test materials for cartilage, we used 10 knives to create cut marks that were subsequently scanned. During the alignment of the individual signals of each mark, the cross-correlation coefficients (Xmax) and lags (LXmax) were calculated. The signals of the marks in agarose were aligned with significantly fewer lags and achieved significantly higher cross-correlation coefficients compared to all tested materials (both P = 0.00). Moreover, we determined the cross-correlation coefficients (XC) for known-matches (KM) per material. Agarose achieved significantly higher values than AccuTrans®, Clear Ballistics™, and gelatine (all P = 0.00). The results of this work provide valuable insights for the forensic investigation of marks in human costal cartilage.

scholarly journals ELECTRON MICROSCOPE STUDIES ON THE DICTYOSOMES AND ACROBLASTS IN THE MALE GERM CELLS OF THE CRICKET

1956 ◽  
Vol 2 (4) ◽  
pp. 123-128 ◽  
Author(s):  
H. W. Beams ◽  
T. N. Tahmisian ◽  
R. L. Devine ◽  
Everett Anderson
Keyword(s):  
Electron Microscope ◽  
Golgi Apparatus ◽  
Electron Micrographs ◽  
Germ Cells ◽  
Light Microscope ◽  
Golgi Body ◽  
Duplex Structure ◽  
Male Germ Cells ◽  
Secondary Spermatocyte ◽  
A Chain

The dictyosome (Golgi body) in the secondary spermatocyte of the cricket appears in electron micrographs as a duplex structure composed of (a) a group of parallel double-membraned lamellae and (b) a group of associated vacuoles arranged along the compact lamellae in a chain-like fashion. This arrangement of ultramicroscopic structure for the dictyosomes is strikingly comparable to that described for the Golgi apparatus of vertebrates. Accordingly, the two are considered homologous structures. Associated with the duplex structure of the dictyosomes is a differentiated region composed of small vacuoles. This is thought to represent the pro-acrosome region described in light microscope preparations. In the spermatid the dictyosomes fuse, giving rise to the acroblast. Like the dictyosomes, the acroblasts are made up of double-membraned lamellae and associated vacuoles. In addition, a differentiated acrosome region is present which, in some preparations, may display the acrosome vacuole and granule. Both the dictyosomes and acroblasts are distinct from mitochondria.

Prefertilization ovule development in Capsella: the dyad, tetrad, developing megaspore, and two-nucleate gametophyte

1986 ◽  
Vol 64 (4) ◽  
pp. 875-884 ◽  
Author(s):  
Patricia Schulz ◽  
William A. Jensen
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Acid Phosphatase ◽  
De Novo ◽  
Periodic Acid ◽  
Aniline Blue ◽  
Ovule Development ◽  
Periodic Acid Schiff ◽  
Fluorescent Material ◽  
Autophagic Vacuoles

Ovules of Capsella bursa-pastoris at the dyad and tetrad stages of meiosis and at the megaspore and two-nucleate stages of the gametophyte were studied with the electron microscope. The cells of the dyad and tetrad are separated by aniline blue fluorescent cross walls and receive all types of organelles and autophagic vacuoles that were present in the meiocyte. Autophagic vacuoles enclose ribosomes and organelles and show reaction product for acid phosphatase. Autophagic vacuoles and some plastids are absorbed into the enlarging vacuoles of the growing megaspore. Other plastids appear to survive meiosis and there is no evidence for their de novo origin. Some mitochondria appear to degenerate in the enlarging megaspore but others look healthy and there is no evidence for the de novo origin of mitochondria. The nucleolus of the developing megaspore becomes very large and the cytoplasm is extremely dense with ribosomes. The cell wall is thickened by an electron-translucent, periodic acid – Schiff negative, aniline blue fluorescent material and contains plasmodesmata that link the megaspore with the nucellus. The plasmalemma of the growing megaspore produces microvilluslike extensions into this wall that disappear with the formation of the two-nucleate gametophyte. Plasmodesmata disappear from the cell wall at the four-nucleate stage.

Cell wall glycoproteins from Chlamydomonas reinhardii, and their self-assembly

Planta ◽  
1978 ◽  
Vol 138 (1) ◽  
pp. 91-98 ◽  
Author(s):  
J. W. Catt ◽  
G. J. Hills ◽  
K. Roberts
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Chlamydomonas Reinhardii
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