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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of the Eyespot and its Possible Significance in Phototaxis of Tetracystis excentrica (1967)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 14 (1967), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. The eyespot of the zoospore of Tetracystis excentrica (a green alga) has been studied by light and electron microscopy. In Tetracystis the eyespot consists of about 110 osmiophilic granules which form a plate in the anterior third of the cell. The granules are about 80 Å in diameter and are found in the outermost portion of the chloroplast; they commonly show hexagonal close packing and a hexagonal shape. The granules are confined positionally by the chloroplast envelope and an inner thylakoid. The plasmalemma over the eyespot is thickened and is separated from the chloroplast envelope by a 50 mμ space. The eyespot of Tetracystis is compared with others reported in the literature and the possible functional significance of these studies is discussed. The possibility that the eyespot plate in Tetracystis serves as a shading device rather than the primary photoreceptor is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1967.tb02038.x
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  • 2
    Electronic Resource
    Electronic Resource
    Comparative Immunology of Selected Wild Types, Varieties and Mutants of Chlamydomonas (1967)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 14 (1967), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SYNOPSIS. Rabbit antisera to strains of different mating types of Chlamydomonas moewusii and to one strain of C. eugametos were tested against strains of C. reinhardti, C. eugametos, and C. moewussi, and against strains of 2 varieties and 6 mutant types of C. moewusii. Technics of double diffusion, absorption, and immunoelectrophoresis revealed marked serological differences between the sexually incompatible, distinct genetic species C. moewusii and C. reinhardti. Less distinct serological differences were resolved between C. moewusii and the so-called “species”C. eugametos, which is sexually compatible with the former, thus reconfirming the conspecificity between the 2 strains as suggested by Gowans. Marked serological differences were noted between C. moewusii and 2 of its varieties (C. moewusii var. tenuichloris and C. moewusii var. rotunda) which constitute 2 additional genetic species because of sexual incompatibility between themselves and with C. moewusii. Wild types and certain mutants of C. moewusii were compared serologically and could be distinguished on this basis. Strains of different mating types as well as certain mutant strains (e.g., paralyzed flagella, flagella-less, twins and monsters) could be differentiated serologically altho differences were often very subtle. Some antigens were common to organisms tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1967.tb02010.x
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrasmall particles of cadmium selenide and cadmium sulfide formed in Nafion by an ion-dilution technique (1990)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 94 (1990), S. 7543-7549 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100382a044
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  • 4
    Electronic Resource
    Electronic Resource
    A model for the pattern of deposition of microfibrils in the cell wall of Glaucocystis (1978)
    Springer
    Planta 141 (1978), S. 51-58 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall ; Cellulose ; Freeze-etching ; Glaucocystis ; Microfibrils (cellulose) ; Morphogenesis ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Freeze-fracturing of Glaucocystis nostochinearum Itzigsohn cells during cell-wall microfibril deposition indicates that unidirectionally polarized microfibril ends are localized in a “zone of synthesis” covering about 30% of the sarface area of the plasma membrane. Within this zone there are about 6 microfibril ends/μm2 cell surface. It is proposed that microfibrils are generated by the passage of their tips over the cell surface and that the pattern of microfibril organization at the poles of the cells, in which microfibrils of alternate layers are interconnected at 3 “rotation centres”, results directly from the pattern of this translation of microfibril tips. In a model of the deposition pattern it is proposed that the zone of synthesis may split into 3 sub-zones as the poles are approached, each sub-zone being responsible for the generation of one rotation centre. It is demonstrated that the microfibrillar component of the entire wall could be generated by the steady translation of the microfibril tips (at which synthesis is presumed to occur) over the cell surface at a rate of 0.25–0.5 μm min-1. Microcinematography indicates that the protoplast rotates during cell-wall deposition, and it is proposed that this rotation may play a role in the generation of the microfibril deposition pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387744
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  • 5
    Electronic Resource
    Electronic Resource
    The assembly of cellulose microfibrils in Valonia macrophysa Kütz (1984)
    Springer
    Planta 160 (1984), S. 372-381 
    Details
    ISSN: 1432-2048
    Keywords: Cellulose microfibril synthesis ; Chlorophyta ; Terminal synthesizing complex ; Valonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The assembly of cellulose microfibrils was investigated in artificially induced protoplasts of the alga, Valonia macrophysa (Siphonocladales). Primary-wall microfibrills, formed within 72 h of protoplast induction, are randomly oriented. Secondary-wall lamellae, which are produced within 96 h after protoplast induction, have more than three orientations of highly ordered microfibrils. The innermost, recently deposited micofibrils are not parallel with the cortical microtubules, thus indicating a more indirect role of microtubules in the orientation of microfibrils. Fine filamentous structures with a periodicity of 5.0–5.5 nm and the dimensions of actin were observed adjacent to the plasma membrane. Linear cellulose-terminal synthesizing complexes (TCs) consisting of three rows, each with 30–40 particles, were observed not only on the E fracture (EF) but also on P fracture (PF) faces of the plasma membrane. The TC appears to span both faces of the bimolecular leaflet. The average length of the TC is 350 nm, and the number of TCs per unit area during primary-wall synthesis is 1 per μm2. Neither paired TCs nor granule bands characteristic of Oocystis were observed. Changes in TC structure and distribution during the conversion from primary- to secondary-wall formation have been described. Cellulose microfibril assembly in Valonia is discussed in relation to the process among other eukaryotic systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393419
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  • 6
    Electronic Resource
    Electronic Resource
    Further characterization of the alkali-stable material from the scales of Pleurochrysis scherffelii: A cellulosic glycoprotein (1972)
    Springer
    Planta 105 (1972), S. 79-92 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Crude and alkali-purified fractions of scales isolated from the haptophycean alga Pleurochrysis scherffelii Pringsheim were analyzed. The predominantly cellulosic nature of the fibrillar, alkali-resistent polysaccharide component has been confirmed by gas chromatography of the hydrolysate, by X-ray diffraction and by viscosimetric studies using the nitrified product. Peptide material is covalently linked to this cellulosic structural polysaccharide and remains associated with it through the harsh purification treatments. The amino acid composition of this peptide moiety is given. The relationship of this cellulosic “glycoprotein” to other cell wall glycoproteins is discussed and possible functions during the formation and secretion of wall materials are hypothesized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385167
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  • 7
    Electronic Resource
    Electronic Resource
    The control of cellulose microfibril deposition in the cell wall of higher plants (1982)
    Springer
    Planta 154 (1982), S. 489-500 
    Details
    ISSN: 1432-2048
    Keywords: Cellulose microfibril deposition ; Membrane flow ; Pinus ; Pit field ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In maize (Zea mays L.) and pine (Pinus taeda L.) seedlings, cellulose microfibril impressions are present on freeze-fractured plasma membranes. It has been proposed that impressions of newly synthesized microfibrils are a record of the movement of terminal synthesizing complexes through the plasma membrane (Mueller and Brown, 1980, J. Cell Biol. 84, 315–326). The association of terminal complexes with the ends of microfibril impressions or with the ends of microfibrils torn through the membrane indicates the orientation of microfibril tips. Unidirectionally-oriented microfibril tips (all pointing in the same direction) are associated with the organized deposition of parallel arrays of microfibrils. Multidirectionally-oriented microfibril tips were observed in a cell in which microfibril deposition was unusually disorganized. Microfibril patterns around pit fields are asymmetric and resemble flow patterns. Unidirectionally-oriented tears are associated with these microfibrils. Although microfibril orientations are deflected around pit fields, the main axis of microfibril orientation is maintained across the surface of the cell. The hypothesis is proposed that the interaction of a flowing plasma membrane with microfibril synthesizing complexes in the plane of the membrane may result in unidirectional deposition and asymmetric microfibril impressions around pit fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402993
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  • 8
    Electronic Resource
    Electronic Resource
    The control of cellulose microfibril deposition in the cell wall of higher plants (1982)
    Springer
    Planta 154 (1982), S. 501-515 
    Details
    ISSN: 1432-2048
    Keywords: Cellulose microfibril deposition ; Colchicine ; Cytoskeleton ; Ethylene ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cells of maize (Zea mays L.) seedling that are not fixed or cryoprotected contain the impressions of cellulose microfibrils on freeze-fractured plasma membranes. Impressions of the most recently deposited microfibrils have terminal complexes associated with them (see preceding paper). The orientations of microtubules in cytoplasmic fractures are parallel to the newest microfibrils observed on adjacent plasma membrane fractures. Small groups of microfibrils, distinguished from the next older layer by their new orientation, are sometimes observed directly adjacent and parallel to individual microtubules. Whereas microtubules are parallel to microfibril orientations which vary from transverse to occasionally longitudinal, microfilaments are parallel to the longitudinal cell axis. After colchicine treatment, cytoplasmic microtubules are absent, as are the bands of microfibrils that are observed on the membrane of control cells. Parallel orientations of microfibrils and normal pitfield outlines are often still observed after colchicine treatment. However, on some membranes, multidirectionally-oriented microfibril tips occur, associated with perturbations of microfibril orientation and rounded pit-field outlines. In ethylene-treated cells, some membranes have microfibril tips oriented in only one direction in new layers of longitudinal microfibrils. On other membranes, longitudinal bands of microfibril tips are oriented in opposing directions. We propose that after colchicine treatment, the patterns of microfibrils reflect an orientation mechanism which has been uncoupled from the influence of microtubules but which is still under some other form of cellular control. We propose that membrane flow could orient the lateral movement of synthesizing complexes in the membrane and that microtubules modulate this movement, apparently organizing the microfibrils into parallel bands in newly-forming wall layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402994
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  • 9
    Electronic Resource
    Electronic Resource
    A microtubular crystal associated with the Golgi field of Pleurochrysis scherffelii (1971)
    Springer
    Planta 96 (1971), S. 354-363 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In young vegetative cells of the Chrysophycean alga Pleurochrysis scherffelii, a characteristic array of microtubules is associated with the Golgi apparatus. This novel structure is described from frozen-etched preparations. The microtubular crystals flank the Golgi stack at either side at an oblique angle and lie in between the Golgi and the periplastidal ER and a parietal vacuole. The microtubules have an outer diameter of 195–230 Å and are spaced in a hexagonal pattern with center-to-center distances of 300–330 Å. The crystals lie free in the cytoplasm and are not surrounded by a membrane although they frequently associate with membraneous elements of the parietal vacuole or periplastidal ER. The microtubules are interconnected by bridge-like links. Possible functions of these crystals, especially in relation to secretion and protoplast rotation, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386949
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  • 10
    Electronic Resource
    Electronic Resource
    Replication Cycle of an Insect Granulosis Virus (1965)
    [s.l.] : Nature Publishing Group
    Nature 207 (1965), S. 106-107 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1. Section through, two granules, side by side in the same cells; note the apparent extrusion and elongation of the virus rod; the outer membrane now encloses only half the rod (arrows); note also an apparent membrane surrounding the granules. (x 82,500) Fig. 2Low power electron micrograph of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/207106a0
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