scholarly journals Nucleolar Fibrillar Material

2020 ◽  
Author(s):  
Keyword(s):  
Fibrillar Material

Scanning electron microscopy of native biofilms on mung bean sprouts

2003 ◽  
Vol 49 (1) ◽  
pp. 45-50 ◽  
Author(s):  
William F Fett ◽  
Peter H Cooke
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Food Safety ◽  
Vigna Radiata ◽  
Mung Bean ◽  
Fibrillar Material ◽  
Mung Bean Sprouts ◽  
Native Microflora ◽  
Bean Sprouts ◽  
Scanning Electron

Native biofilms present on the adaxial surface of cotyledons of mung bean sprouts (Vigna radiata) were studied by use of scanning electron microscopy. Biofilms were abundant on the cotyledon surfaces and were comprised of rod-shaped bacteria, cocci-shaped bacteria, or yeasts, often with one type of microbe predominant. In contrast to our earlier study of biofilms on green sprouts (alfalfa, clover, broccoli, and sunflower), yeast and cocci were abundant on mung bean. Filamentous fungi were not observed. Sheet-like or fibrillar material (presumably composed of secreted microbial polysaccharides, proteins, lipids, and nucleic acids) fully or partially covered the biofilms. Biofilms up to 5 mm in length were observed, and some biofilms were comprised of more than just a monolayer of microbial cells. Native biofilms on sprout surfaces undoubtedly play an important role in the ecology of plant epiphytic microbes and may also afford protected sites for plant and human bacterial pathogens.Key words: mung bean sprouts, biofilms, native microflora, scanning electron microscopy, food safety.

An Ultrastructural and Radio-Autographic Study of the Evolution of the Interphase Nucleus in Plant Meristematic Cells (Allium Porrum)

1974 ◽  
Vol 14 (2) ◽  
pp. 263-287
Author(s):  
J. G. LAFONTAINE ◽  
A. LORD
Keyword(s):  
Interphase Nucleus ◽  
Structural Changes ◽  
Tritiated Thymidine ◽  
Light And Electron Microscopy ◽  
Allium Porrum ◽  
Meristematic Cells ◽  
Fibrillar Material ◽  
Nuclear Structures ◽  
S Period ◽  
Dense Chromatin

Radioautography under both light and electron microscopy was exploited to investigate the structural changes of the chromatin reticulum which characterizes the interphase nucleus of a number of plants. Allium porrum meristematic plant cells were used for this purpose. In this species, the telophase chromosomes uncoil into dense strands which, during the G1 period, gradually give rise to a coarse reticulum. There then follows an extensive unravelling of portions of these strands, and high-resolution radioautography reveals that labelling with tritiated thymidine predominantly occurs over zones of the nucleus consisting of diffuse fine fibrillar material. As the S-period progresses, a chromatin reticulum reappears throughout the nuclear cavity, the tortuous strands being approximately 0.25 µm in diameter. Most of the radioautographic grains still remain over the light nucleoplasmic areas but a number of these are now located on the outermost portion of the dense chromatin profiles. By the end of the S-period, the chromatin strands are slightly thicker (ca. 0.3 µm) and form a looser reticulum. Labelling has decreased noticeably in nuclei of that period, the radioautographic grains being grouped into clusters resting over more or less spherical regions of the chromatin reticulum. Judging from their localization at the surface of the nucleolus or close to the nuclear envelope, these structures correspond to chromocentres. The additional interesting finding that such nuclear structures appear much less compactly organized strongly suggests that chromocentres undergo important conformational modifications during duplication of their DNA.

The growth of the pollen tube wall in Oenothera organensis

1975 ◽  
Vol 18 (3) ◽  
pp. 519-532
Author(s):  
H.G. Dickinson ◽  
J. Lawson
Keyword(s):  
Pollen Tube ◽  
Tube Wall ◽  
Wall Material ◽  
Fibrillar Material ◽  
Stage Of Development ◽  
Large Numbers ◽  
Membrane Bound ◽  
Pollen Tube Wall ◽  
Different Sources ◽  
Dictyosome Vesicles

The growth of the pollen tube wall of Oenothera is effected by the expulsion of fibrillar material from the cytoplasm into the developing wall. This material may also be seen in the cytoplasm, contained in membrane-bound vesicles. It is not clear how the content of the vesicles is discharged, but it appears not to involve the participation of microtubules. The source of the cytoplasmic fibrillar bodies depends upon the stage of development of the pollen tube. The earilest growth is derived from the inclusion into the wall of vesicles containing pre-formed materials present in the grain on pollination. During the next stage of growth the wall is derived from the content of double-membraned inclusions also present in the pollen. The content of the former vesicles is not so similar to the wall as the latter, but intermediates between the 2 types of vesicle may be seen in the cytoplasm, indicating that the former are formed from the latter. Most of the tube wall is derived from the products of dictyosomes in the pollen grain or tube. These dicytosomes are few in number and they must be exceedingly active. This, and the observation that dictyosome vesicles are frequently associated with banked complexes of mitochondria, indicates that some steps in the metabolism of the vesicular content, perhaps phosphorylation, take place distant from the dicytosomes. These different sources of fibrillar material presumably permit the rapid starting of tube growth, without any attendant metabolism. However, it would be impossible to include enough pre-formed wall material in the grain to enable the full growth of the tube, so once started, it seems that the tube then relies on the elaboration of simple reserves for the contruction of its wall. These reserves are likely to be held in the pollen, and may be the large numbers of starch grains characteristic of the pollen cytoplasm.

scholarly journals Adhesive properties of an outer structure of Clostridium perfringens type A isolated from piglets with with catarrhal enteritis

1999 ◽  
Vol 30 (3) ◽  
pp. 242-248 ◽  
Author(s):  
Elizabeth Pelosi Teixeira ◽  
Marlene Braide Serafim ◽  
Maria Alice Cruz Höfling ◽  
Aureo T. Yamada ◽  
Antonio Fernando Pestana de Castro
Keyword(s):  
Clostridium Perfringens ◽  
Type A ◽  
Negative Control ◽  
Bacterial Cells ◽  
Intestinal Epithelial ◽  
Adhesive Properties ◽  
Ileal Loop ◽  
Fibrillar Material ◽  
Gram Staining ◽  
Transmission Electron

One strain (S32) of Clostridium perfringens type A was isolated from a case of catarrhal enteritis of piglets. This strain was able to adhere to HeLa cells showing an adherence index (AI) of 25.15 ± 1.26 (mean ± 1 standard error of the mean). Treatment of the bacterial cells with trypsin (0.25mg/ml) decreased in 70%-80% the AI and metaperiodate (10mg/ml) abolished completely the adherence, suggesting that the structure responsible for this phenomenon was probably a glycoprotein. Heating of bacterial suspensions (100ºC/5 min) before carrying out the adhesion test decreased the AI rendering it equal to the negative controls. Rabbit homologous S32 antiserum inhibited the adherence up to dilutions of 1: 640, at least. The piglet ileal loop assay, carried out with strains S32 and Jab-1 (negative control) demonstrated that the strain S32 was able to adhere to the intestinal epithelial cells when examined after Gram staining. Transmission electron microcopy (TEM) demonstrated that S32 strain displayed a loose fibrillar material not seen with Jab-1. Stabilization of the bacterial cells with homologous antiserum of strain S32, followed by staining with rhuteniun red, revealed loose long fibrillar material on the outer surface of the cells, that sometimes could be seen spreading out from the cells and linking bacterial cells. The question whether this structure might be an adhesin for this strain of Cl. perfringes type A, perhaps playing a role in the pathogenesis of the catarrhal enteritis of piglets, is dependent on further studies.

The hormonal control and morphology of blastocyst invasion in the mouse uterus in vitro

Development ◽  
1975 ◽  
Vol 34 (2) ◽  
pp. 299-310
Author(s):  
P. S. Grant ◽  
I. Ljungkvist ◽  
O. Nilsson
Keyword(s):  
Hormonal Control ◽  
Mouse Uterus ◽  
Chemically Defined Media ◽  
Fibrillar Material ◽  
Ovariectomized Mice ◽  
Defined Media ◽  
Stromal Tissue ◽  
Ultrastructural Effect

When mature and immature uteri from ovariectomized mice were cultured in chemically defined media, blastocyst invasion occurred in the presence of progesterone but not in media containing only oestradiol. The invaded stromal tissue did not decidualize unless the uteri were taken from mice pretreated with progesterone and oestradiol. Fibrillar material was, however, concentrated in the stromal tissue adjacent to the invasive trophoblast. Neither progesterone nor oestradiol, had any ultrastructural effect on the endometrium of cultured uteri from ovariectomized mice, other than closure of uterine lumina in the presence of progesterone. Embryogenesis became abnormal, probably owing to the failure of formation of a suitable implantation chamber.

The development of the notochord in the chick embryo, studied by scanning and transmission electron microscopy

Development ◽  
1976 ◽  
Vol 35 (2) ◽  
pp. 383-401
Author(s):  
Mary Bancroft ◽  
Ruth Bellairs
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chick Embryo ◽  
Intercellular Spaces ◽  
Notochordal Cells ◽  
Fibrillar Material ◽  
Transmission Electron ◽  
Phases Of Development ◽  
Scanning Electron

The notochord of the chick embryo between stages 5 and 23 inclusive has been studied by scanning electron microscopy, supplemented by transmission electron microscopy. Three main phases of development are described, and these have been designated: bilaminar; rodlike, unvacuolated; rod-like and vacuolated. The change in shape of the organ from bilaminar to rod-like is accompanied by changes in the shape, orientation and position of the cells, an increase in the complexity of the cell contacts, and the laying down of a basal lamina. The change from the unvacuolated to the vacuolated phase is accompanied by increasing complexity within the cytoplasm. Most of the vacuoles are intracellular and appear empty though some contain a granular material. The notochordal sheath appears to be secreted by the notochordal cells and fine fibrillar material has been seen in the intercellular spaces. By stage 23, most of the notochordal cells have become so highly vacuolated that the cytoplasm has become closely packed around the nucleus.

Compositional and structural heterogenicity of the cardiac jelly of the chick embryo tubular heart: a TEM, SEM and histochemical study

Development ◽  
1980 ◽  
Vol 56 (1) ◽  
pp. 211-223
Author(s):  
J. M. Hurle ◽  
J. M. Icardo ◽  
J. L. Ojeda
Keyword(s):  
Alcian Blue ◽  
Regional Differences ◽  
Histochemical Study ◽  
Cetylpyridinium Chloride ◽  
Ruthenium Red ◽  
Heart Tube ◽  
Fibrillar Material ◽  
Low Concentrations ◽  
Dorsal Mesocardium ◽  
Myocardial Layer

The hearts of chick embryos of stages 9–13 were subjected to SEM, TEM and histochemical studies to ascertain possible regional differences in the structure and composition of the cardiac jelly. Two distinct regions, the cardiac jelly filling the space located between the myocardium and the endocardium (MECJ) and the cardiac jelly filling the dorsal mesocardium (EECJ), were distinguished by their structural and histochemical properties. MECJ is formed by amorphous and fibrillar material arranged between the endocardial and myocardial layer. The amount of its components increases when cetylpyridinium chlorideis introduced into the fixative, and it appears intensely stained by ruthenium red and alcian blue at low concentrations of MgCl2. The amount and arrangement of its componentsincrease during the beginning of the looping process of the heart tube. The EECJ is very rich in ruthenium-red-positive basal-lamina-like material and the addition of cetylpyridinium chloride to the fixative does not modify its appearance. It also appears poorly stained by alcian blue at low concentrations of MgCl2 and its arrangement undergoes modifications closely associated with the events of endocardial fusion. The possible significance of these results in the early morphogenesis of the heart is discussed.

Taxonomic contribution to the genus Sphaerosyllis (Annelida: Syllidae: Exogoninae) in the Black Sea

Zootaxa ◽  
2017 ◽  
Vol 4329 (3) ◽  
pp. 281
Author(s):  
VICTOR SURUGIU ◽  
GUILLERMO SAN MARTÍN
Keyword(s):  
New Species ◽  
Shallow Water ◽  
Black Sea ◽  
New Record ◽  
The Black Sea ◽  
Fibrillar Material ◽  
Unknown Species ◽  
Black Sea Coast ◽  
Sea Coast

During a study of fauna associated with a shallow-water Zostera (Zosterella) noltei bed from the southern part of the Romanian Black Sea coast, among the identified material collected in 2015, a syllid polychaete belonging to the subfamily Exogoninae, Sphaerosyllis taylori Perkins, 1981, represents a new record for the Black Sea. Re-examination of available specimens previously identified as Sphaerosyllis bulbosa Southern, 1914 revealed that they belong to an unknown species, described herein as Sphaerosyllis pontica sp. nov. The new species is characterized by the median antenna inserted more posteriorly than the lateral antennae, dorsal cirri with bulbous bases and very short tips, shorter than the parapodial lobes, dorsal cirri absent on chaetiger 2, parapodial glands with fibrillar material from chaetiger 4 onwards, compound chaetae with short blades and smooth shafts, anterior parapodia with two aciculae each, one straight and one with bent tip. Descriptions of both species are provided together with a key to all Sphaerosyllis species known from the Black Sea.  

Studies of the Blood and Tests of Some Australian Ascidians. II. The Test of Pyura stolonifera (Heller)

1955 ◽  
Vol 6 (2) ◽  
pp. 139 ◽  
Author(s):  
R Endean
Keyword(s):  
Connective Tissue ◽  
Blood Vessels ◽  
Variable Thickness ◽  
Toluidine Blue ◽  
Single Layer ◽  
Protective Layer ◽  
Fibrillar Material ◽  
Columnar Cells ◽  
Cellulose Solvents ◽  
Large Vessels

The test of this species is particularly bulky and consists of gelatinous material which encloses the fleshy part of the animal, leaving openings only for the two siphons. It also forms a resilient basal stem which anchors the animal to the substratum. The outer surface of the test is impregnated with sand grains, which form a hard protective layer. Blood-vessels traverse the gelatinous material. Two large vessels enter the test and these branch to form ultimately a ramifying system of small blood-vessels. Effectively there are two blood circulations in the test. The blood-vessels have a lining consisting of a single layer of large columnar cells, the appearance of which is described. The gelatinous test resolves itself under the microscope into a network of fibres of variable thickness, but the larger ones at least are aggregates of smaller fibrils. In some cases the fibres are orientated in definite directions. The amorphous interfibrillar material seems to be mainly aqueous, as the test consists of over 97 per cent. of plasma. Ferrocytes wander about in amoeboid fashion amongst the fibres. These enter the substance of the test by migrating across the walls of the bloodvessels. Histologically there is a marked similarity between the appearance of the test and that of vertebrate connective tissue, as in both cases cells are present in a groundmass enmeshed by fibres which stain with orcein and fuchsin. However, the fibres of the test are composed of a very insoluble polysaccliaride, Which although resembling plant cellulose in certain respects will not dissolve in special cellulose solvents nor stain with cellulose stains. A mucopolysaccharide which stains metachromatically with toluidine blue is associated with the fibrillar material, and possibly serves to cement the fibres together since these became disarranged on treatment with hyaluronidase, which removes the mucopolysaccharide. The importance of the test in the general economy of the animal is discussed.

scholarly journals FINE STRUCTURE OF MEMBRANOUS AND MICROFIBRILLAR SYSTEMS IN THE CORTEX OF PARAMECIUM CAUDATUM

1971 ◽  
Vol 49 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Richard D. Allen
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Three Dimensional ◽  
Paramecium Caudatum ◽  
Fibrillar Material ◽  
Muscular Function ◽  
Branching System

An electron microscope study of the cortex of Paramecium caudatum has revealed new details pertinent to several unresolved problems. The lateral boundaries of the alveoli do not regularly follow the crests of the polygonal ridges and thus their staining with silver cannot account for the external lattice seen by light microscopists. A granulo-fibrillar material is present, however, within the peaks of the ridges, which would account for the external lattice if so stained. Perforations are present between adjacent alveoli which make the whole mosaic of alveolar sacs within the cell's cortex continuous—both the membranes and the lumen. A microfibrillar system exhibiting a cross-striated pattern lies in the superficial cortex. These bands are inserted at their ends in the epiplasm and have a fine structure and arrangement suggesting a muscular function. The infraciliary lattice is a branching system of fibers with electron-opaque posts at the center of each branching locus. This system is distinct from the striated bands in morphology and in space. The epiplasm is discontinuous along the crests of the ridges, which may account for the pellicles' disposition to tear along these lines. A three-dimensional drawing is presented to show the interrelationships between the above membranous and microfibrillar systems.

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