Movement, Fine Structure, and Fusion of Pseudopods of an Enclosed Amoeba, Difflugiella Sp

1972 ◽  
Vol 10 (2) ◽  
pp. 563-583
Author(s):  
J. L. GRIFFIN
Keyword(s):  
Fine Structure ◽  
Cell Body ◽  
Activity Cycle ◽  
Different Types ◽  
Anterior Extension

In Difflugiella sp., strain F-20, a small amoeba enclosed in a flexible mantle, pseudopods extended through a mouth or aperture and seemed to function only for movement and feeding. Pseudopods from different cells fused on contact and cell clumps shared common pseudopods and moved in a co-ordinated way. During locomotion, pseudopods or pseudopod complexes usually exhibited an activity cycle of 3 phases: anterior extension with the tip firmly adhering; stable hold as other pseudopods advanced; and flaccid posterior retraction. While distal adhesive tips advanced, proximal unattached parts of pseudopods simultaneously shortened as the cell body advanced. Microtubules were numerous in pseudopods within the mouth but extended for only 1-2 µm into pseudopods up to 20-30 µm long. Microfilaments were present where pseudopods adhered to the substratum, to the mantle, or to bacteria and were also associated with pinocytotic invaginations. Pseudopod ground plasm was either reticulate or amorphous; no axial rods or aligned filaments related to pseudopod rigidity were seen. Simultaneous pseudopod adhesion, extension, and proximal shortening apparently account for locomotion or cell body translation of Difflugiella. While some similarities to other amoeboid systems were noted, the need for detailed studies on different types of organisms or cells is emphasized.

The Function and Fine Structure of the Cephalic Airflow Receptor in Schistocerca Gregaria

1966 ◽  
Vol 1 (4) ◽  
pp. 463-470
Author(s):  
D. M. GUTHRIE
Keyword(s):  
Fine Structure ◽  
Cell Body ◽  
Schistocerca Gregaria ◽  
Tube Wall ◽  
Sense Organ ◽  
Hair Shaft ◽  
Sensory Axons ◽  
Steady Rate ◽  
Neuron Cell Body ◽  
Tormogen Cell

Electron micrographs of parts of the sense organ showed that the dendritic axis consisted of a large and a small envelope containing microtubules as their main inclusion. The envelopes are supported by a thick-walled tube believed to be part of the Ist-tier sheath cells. The small envelope is segregated from the large envelope near its apex by a fold of the tube wall. The packing of the neurotubular array within the small envelope is both more dense and more regular than within the large envelope. The tube is separated by an extracellular space from the trichogen-tormogen cell. Sections through the apex of the dendrite reveal a homogeneous cap unlikely to be part of a structure continued into the upper region of the hair shaft. No ciliary structures were visible within the dendrite, whose microtubules pass into the neuron cell body proximally. Sections through the neuron cell body reveal branched mitochondria, and numerous microtubules. Rates of discharge in sensory axons from these hair organs produced by deflexion of the hair shaft were found to be within the range 300-100 impulses/sec. There is an initial phase of rapid adaptation which gives place to a steady rate. It is suggested that the fine structure of the receptor may indicate mechano-electrical transduction at a more proximal level than is believed to be the case in some other types of receptor. The diaphragms that support the hair shaft laterally can be seen to be composed of fine cuticular strands.

scholarly journals DAFNE-Light DXR1 Soft X-Ray Synchrotron Radiation Beamline: Characteristics and XAFS Applications

2019 ◽  
Vol 4 (1) ◽  
pp. 7 ◽  
Author(s):  
Antonella Balerna
Keyword(s):  
Fine Structure ◽  
Synchrotron Radiation ◽  
Disordered Systems ◽  
Beam Line ◽  
Long Range Order ◽  
X Ray ◽  
Xafs Spectroscopy ◽  
Insertion Device ◽  
Different Types ◽  
X Ray Absorption

X-ray Absorption Fine Structure Spectroscopy (XAFS) is a powerful technique to investigate the local atomic geometry and the chemical state of atoms in different types of materials, especially if lacking a long-range order, such as nanomaterials, liquids, amorphous and highly disordered systems, and polymers containing metallic atoms. The INFN-LNF DAΦNE-Light DXR1 beam line is mainly dedicated to soft X-ray absorption spectroscopy; it collects the radiation of a wiggler insertion device and covers the energy range from 0.9 to 3.0 keV or the range going from the K-edge of Na through to the K-edge of Cl. The characteristics of the beamline are reported here together with the XAFS spectra of reference compounds, in order to show some of the information achievable with this X-ray spectroscopy. Additionally, some examples of XAFS spectroscopy applications are also reported.

scholarly journals THE CULTIVATION OF TRICHOMONAS OF THE HUMAN MOUTH (TETRATRICHOMONAS HOMINIS)

1917 ◽  
Vol 25 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Tokuzo Ohira ◽  
Hideyo Noguchi
Keyword(s):  
Cultural Studies ◽  
Cell Body ◽  
Trichomonas Vaginalis ◽  
The Body ◽  
The Other ◽  
Other Hand ◽  
Deep Groove ◽  
Different Types ◽  
The Difference

Trichomonades from the mouth were studied by Steinberg who proposed to group them into three distinct types; namely, Trichomonas elongata, Trichomonas caudata, and Trichomonas flagellata. Doflein (3) regards them as probably identical with Trichomonas hominis. Opinions differ as to whether or not Trichomonas vaginalis Donné and Trichomonas hominis Grassi are the same species. Lynch, for instance, believes that they are the same species, while von Prowazek (4), Bensen (5), and others (6, 7) insist that they are different types. Bensen's view seems to be well supported by the difference alleged to be found between the mode of encystment in the two trichomonades, were it not for the fact that our knowledge about the so called cyst of trichomonades is still obscure. According to Alexeieff (8) many of the so called cysts were evidently blastomyces contained in the cell body of the trichomonas. An autogamy alleged to take place in cysts as described by Bohne and von Prowazek (9) has not been confirmed by Dobell (10). And Wenyon (11) contends that it has never been found possible to produce any development of these cysts outside the body on the warm stage as can be done with the cysts of Entamœba coli. Therefore, it is still premature to take the process of encystment into consideration as far as the classification of trichomonas is concerned. On the other hand, Rodenwaldt (12) seems to think that there are many species of trichomonas in the human intestines, and Wenyon has described a new trichomonas from the human intestines (Macrostoma mesnili Wenyon). Further cultural studies in the morphology and biology of these organisms must be carried out in order to solve these problems. In the light of modern investigations there are five subgenera to be included under the genus Trichomonas Donné. They are as follows: (1) Protrichomonas Alexeieff, with three anterior flagella, without an undulating membrane. (2) Trichomastix Biitschli) with three anterior flagella and a trailing flagellum (Schleppgeissel) without an undulating membrane. (3) Trichomonas Donné, with three anterior flagella and an undulating membrane. (4) Macrostoma Alexeieff, Amend, Wenyon (11), with three anterior flagella and an undulating membrane wedged in a deep groove (peristome). (5) Tetratrichomonas Parisi (13), with four anterior flagella and an undulating membrane. As far as our culture trichomonas from the human mouth is concerned, it has been shown that it is not strictly a trichomonas and that it should be classed under the subgenus Tetratrichomonas.

scholarly journals Stellar Archaeology: Using Metal-Poor Stars to Test Theories of the Early Universe

2008 ◽  
Vol 4 (S255) ◽  
pp. 336-340
Author(s):  
Anna Frebel ◽  
Jarrett L. Johnson ◽  
Volker Bromm
Keyword(s):  
Fine Structure ◽  
Low Mass Stars ◽  
First Stars ◽  
Abundance Patterns ◽  
Cosmological Context ◽  
Different Types ◽  
The Galaxy ◽  
Structure Line ◽  
History Of ◽  
Low Mass

AbstractConstraints on the chemical yields of the first stars and supernova can be derived by examining the abundance patterns of different types of metal-poor stars. We show how metal-poor stars are employed to derive constraints of the formation of the first low-mass stars by testing a fine-structure line cooling theory. The concept of stellar archaeology, that stellar abundances truly reflect the chemical composition of the earliest times, is then addressed. The accretion history of a sample of metal-poor stars is examined in detail in a cosmological context, and found to have no impact on the observed abundances. Predictions are made for the lowest possible Fe and Mg abundances observable in the Galaxy, [Fe/H]min = −7.5 and [Mg/H]min = −5.5. The absence of stars below these values is so far consistent with a top-heavy IMF. These predictions are directly relevant for future surveys and the next generation of telescopes.

scholarly journals FINE STRUCTURE OF SMOOTH MUSCLE CELLS GROWN IN TISSUE CULTURE

1971 ◽  
Vol 49 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Gordon R. Campbell ◽  
Yasuo Uehara ◽  
Gerda Mark ◽  
Geoffrey Burnstock
Keyword(s):  
Electron Microscopy ◽  
Smooth Muscle ◽  
Fine Structure ◽  
Cell Membrane ◽  
Smooth Muscle Cells ◽  
Phase Contrast ◽  
Muscle Cells ◽  
Different Types ◽  
Membrane Infoldings

The fine structure of smooth muscle cells of the embryo chicken gizzard cultured in monolayer was studied by phase-contrast optics and electron microscopy. The smooth muscle cells were irregular in shape, but tended to be elongate. The nucleus usually contained prominent nucleoli and was large in relation to the cell body. When fixed with glutaraldehyde, three different types of filaments were noted in the cytoplasm: thick (150–250 A in diameter) and thin (30–80 A in diameter) myofilaments, many of which were arranged in small bundles throughout the cytoplasm and which were usually associated with dark bodies; and filaments with a diameter of 80–110 A which were randomly orientated and are not regarded as myofilaments. Some of the aggregated ribosomes were helically arranged. Mitochondria, Golgi apparatus, and dilated rough endoplasmic reticulum were prominent. In contrast to in vivo muscle cells, micropinocytotic vesicles along the cell membrane were rare and dense areas were usually confined to cell membrane infoldings. These cells are compared to in vivo embryonic smooth muscle and adult muscle after treatment with estrogen. Monolayers of cultured smooth muscle will be of particular value in relating ultrastructural features to functional observations on the same cells.

Exafs Evidence For Atom Location In Icosahedral TiZrNi And Hydrogenated TiZrNi Quasicrystals

1998 ◽  
Vol 553 ◽  
Author(s):  
A. Sadoc ◽  
J. K. Kim ◽  
K.F. Kelton
Keyword(s):  
Fine Structure ◽  
Metal Atom ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Absorption Fine ◽  
Different Types ◽  
X Ray Absorption ◽  
Absorption Edges

AbstractWe present results from the first extended X-ray absorption fine-structure studies in a Ti/Zrbased quasicrystal. The icosahedral Ti53Zr27Ni20 phase and an icosahedral Ti45Zr38Ni17 phase that also contains 1.7 hydrogen atoms for each metal atom were investigated. Experiments performed above the Ti, Ni and Zr K absorption edges have allowed to identify different types of atomic subshells around the Ti, Ni and Zr atoms. Significant differences are observed between these two quasicrystalline alloys, suggesting preferential sites for the hydrogen atoms.

The fine structure of uniporous and nonporous pegs on the distal antennal segment of the diving beetle Graphoderus occidentalis Horn (Coleoptera: Dytiscidae)

1991 ◽  
Vol 69 (2) ◽  
pp. 334-352 ◽  
Author(s):  
J. C. Jensen ◽  
R. Y. Zacharuk
Keyword(s):  
Fine Structure ◽  
Antennal Segment ◽  
Terminal Segment ◽  
Sheath Cell ◽  
Terrestrial Habitat ◽  
Insect Sensilla ◽  
Virus Like Particles ◽  
Accessory Cells ◽  
Different Types ◽  
Diving Beetle

The terminal segment of the antenna of the predaceous diving beetle Graphoderus occidentalis Horn bears approximately 50 sensilla of nine different types. There are six types of uniporous chemosensilla, one type of nonporous mechanosensitive peg, and two types of multiporous pegs. Two types of uniporous pegs, which occur only at the antennal tip, have features of both contact chemosensilla and thermo- and hygro-sensilla. Three other types that occur only on the terminal segment below the apex also exhibit some features of chemosensilla and thermo- and hygro-sensilla. The sensilla are innervated by one to four neurons and most are ensheathed by two accessory cells. Four types of sensilla exhibit elaborate sheath cell configurations and secretions associated with their sinus that may reflect an adaptation to an aquatic or a dual aquatic–terrestrial habitat. All are atypical of generalized insect sensilla in having portions of the proximal dendrites and axons as well as the entire neuronal perikarya unsheathed and exposed to the hemocoel. The neuronal perikarya of two sensillar types contain virus-like particles.

Some Aspects of the Cytology of Polycelis nigra

1961 ◽  
Vol s3-102 (59) ◽  
pp. 295-317
Author(s):  
R. J. SKAER
Keyword(s):  
Fine Structure ◽  
Epithelial Cells ◽  
Basement Membrane ◽  
Muscle Fibre ◽  
Cell Body ◽  
Basal Body ◽  
Sense Organs ◽  
Gland Cells ◽  
Secretion Granules ◽  
Undifferentiated Cells

The triclad, Polycelis nigra, has been found to be fully cellular. Gland-cells, undifferentiated cells, and the cell-bodies of muscle-cells, make up the parenchyma. The fine structure of the component cells of the parenchyma, nervous, and excretory systems, testis, pharynx, and epidermis is described. Acidophil secretion granules, produced by certain parenchymatous gland-cells, have a characteristic, doubly-banded ultrastructure which is not invariably associated with the property of adhesiveness. The parenchymatous cell-body of the muscles is often up to 10 µ. from the musclefibre, to which it is joined by tenuous cytoplasmic connexions. The muscle-fibre itself consists of coarse and fine sets of hexagonally arranged myofilaments, but is unhanded. The basement membrane of the epidermis is composed of fine, banded fibrils, apparently randomly arranged in the plane of the membrane. Permeating the epidermis at a level just above the basement membrane is a system of extracellular spaces, which may have a hydrostatic function and assist in the extrusion of secretion granules. Epidermal sense organs, whose fine structure resembles the basal body of the cilia, are considered to have a functionally significant distribution on the surface of the animal. The rhabdites have been shown to develop in special cells of the parenchyma. Such rhabdite-forming cells, together with their contained rhabdites, have been found apparently passing through the basement membrane of the epidermis. As all the epidermal epithelial cells contain rhabdites, it is suggested that the epidermis as a whole is renewed by centrifugal migration of rhabdite-forming cells. The rhabdites themselves appear to consist of arginine and some tyrosine, together with a purine, probably adenine. They may be an excretory product.

scholarly journals The fine structure of phloem fibres I. Untreated and swollen hemp

1940 ◽  
Vol 128 (851) ◽  
pp. 214-231 ◽  
Keyword(s):  
Optical Properties ◽  
Fine Structure ◽  
Natural Condition ◽  
Anatomical Study ◽  
Longitudinal Axis ◽  
Cellulose Chain ◽  
X Ray ◽  
Different Types

During an anatomical study of the jute and hemp plants carried out by one of us (B. C. K.), the opportunity was taken of reinvestigating in these plants the structure of the walls of the fibres, using the term “fibre” in its botanical sense. The so-called “bast” fibres are of particular interest in wall studies since it was apparently on the basis of their investigation that the “crossed fibrillar” conception was first introduction. Thus we find Reimers (1922) stating that in a number of plants, including hemp, the walls of these fibres are composed of two or more layers differing considerably in cellulose-Chain direction. Since that time numerous other statement of this kind have been made for different types of cell (Freudenberg and Dürr 1932; Ritter 1930; Ritter and Chidester 1928; Bailey and Kerr 1935); v. Iterson 1937; Wuhrmann-Meyer 1939). It seems rather a common feature of the evidence quoted in support of such a structure that it is derived from material swollen considerably either in acid or alkali. Certainly the optical properties of the wall have been used in support (Freudenberg and Durr 1932; Bailey and Kerr 1935 v. Iterson 1937; Wuhrmann-Meyer 1939). It seems rather a common feature of the evidence quoted in support of such a structure that it is derived from material swollen considerably either in acid or alkali. Certainly the optical properties of the wall have been used in support (Freudenberg and Durr 1932; Bailey and Kerr 1935 v. Iterson 1937; Wuhrmann-Meyer 1939). It seems rather a common feature of the evidence quoted in support of such a structure that it is derived from material swollen considerably either in acid or alkali. Certainly the optical properties of the wall have been used in support (Freudenberg and Durr 1932; Bailey and Kerr 1935; v. Iterson 1937; Wuhrmann-Meyer 1939). It seems rather a common feature of the evidence quoted in support of such a structure that it is derived from material swollen considerably either in acid or alkali. Certainly the optical properties of the wall have been used in support (Freudenberg and Dürr 1932; Bailey and Kerr 1935) but the implication of such work have already been discussed elsewhere (Preston 1939 a ). We are here concerned chiefly with the swelling technique. While it is not to be suggested that treatment with swelling reagents totally invalidates all observations of this type, it is quite clear that in some cases at least observation of swollen material can give an entirely erroneous conception of the wall in its natural condition. This is perhaps particularly clear in the case of jute, for which Osborne (1935, quoted also by Barker 1938) refers to the fibres as being composed of a series of chains lying at a considerable angle to the longitudinal axis of the cell, in spite of contrary X-ray evidence.

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