Filamentous Mats Research Articles

Structural and Geomicrobiological Characteristics of a Microbial Community from a Cold Sulfide Spring

The Ancaster sulfur spring is a cold (9°C) sulfur spring located near Ancaster, Ontario, Canada, which hosts an abundant and diverse microbial mat community. We conducted an extensive microscopical study of the microbial community of this spring using a number of techniques: phase light, confocal scanning laser microscopy, conventional scanning electron microscopy using both chemical/critical point drying and cryofixation preparative techniques, environmental scanning electron microscopy, and transmission electron microscopy. The latter two techniques were coupled with energy dispersive X-ray spectrometry for elemental analysis to complement wet geochemical data collected on bulk spring water and mat pore water. In the anoxic source of the spring, green and purple sulfur bacteria were found together with a sulfide-utilizing type of cyanobacteria that had the unusual characteristic of storing colloidal sulfur intracellularly. Deeper within the source, the mats were dominated by green sulfur bacteria and thick biofilms of cells that precipitated Fe and Zn sulfide minerals on their surfaces. Downstream from the source, thick, filamentous white mats lined the stream channel, formed by a diverse mass of nonphotosynthetic sulfur oxidizers, which were responsible for forming thick masses of spherical colloidal sulfur. These were distinguished by ESEM-EDS from cells by their simple elemental composition (only S was detected). Aqueous geochemistry analysis by ICP-MS showed that some elements (Fe, C, P, Zn, Mg, Ba) were present at higher levels in mat pore water than in bulk spring water. Our approach allowed us to gain an appreciation of the characteristics of this microbial community and allowed us to develop a good understanding of the types of microorganisms present and infer some of the relationships among the members of the community. In addition, we wish to convey the utility of a thorough microscopical approach in geomicrobiological and microbial ecology studies.

Three-Dimensional Micromechanics-Based Constitutive Framework for Analysis of Pultruded Composite Structures

A new 3D micromechanics-based framework is proposed for the nonlinear analysis of pultruded fiber-reinforced polymeric composites. The proposed 3D modeling framework is a nested multiscale approach that explicitly recognizes the response of the composite systems (layers) within the cross section of the pultruded member. These layers can have reinforcements in the form of roving, continuous filament mat (CFM), and/or woven fabrics. Different 3D micromechanical models for the layers can be used to recognize the basic response of the fiber and matrix materials. The framework is implemented with both shell and 3D finite elements. The 3D lamination theory is used to generate a homogenized nonlinear effective response for a through-thickness representative stacking sequence. The proposed modeling framework for pultruded composites is used to predict the stiffness and nonlinear stress-strain response of E-glass/vinylester pultruded materials reinforced with roving and CFM. The roving layer is idealized using a 3D nonlinear micromechanics model for a unidirectional fiber- reinforced material. A simple nonlinear micromechanics model for the CFM layer is also applied. The proposed model shows very good predictive capabilities of the overall effective properties and the nonlinear response of pultruded composites, based on the in situ material properties, and the volume fractions of the constituents. Experimental data from off-axis tests of pultruded plates under uniaxial compression are used to verify the proposed model. The proposed framework can be easily incorporated within displacement-based finite-element models of composite structures.

THE CHITINOUS NATURE OF FILAMENTS EJECTED BY PHAEOCYSTIS (PRYMNESIOPHYCEAE)1

ABSTRACTFilaments ejected by Phaeocystis globosa Scherffel, organized in star‐like structures, were observed and analyzed before and after their discharge from cells. Ultrastructural observations obtained after cryofixation and cryosubstitution led to a model for their storage within the cell and for their ejection from the cell. Electron diffraction analysis on the ejected filaments demonstrated their chitinous composition. This technique indicated without ambiguity that each filament was in fact a whisker‐like α‐chitin crystal, with the axes of the corresponding polymer chains aligned with the filament's axis. X‐ray microanalysis of the mats of filaments indicated that the silica content suggested by earlier workers was an artifact resulting from the filtration procedure.

Species of the algal genus Vaucheria on the Faroes

Species of the algal genus Vaucheria (Tribophyceae) form mats of thin filaments on the ground often at the base of flowering plants. They can be found at places like sides of brooklets, on roadside ditches, and in salt marshes. Samples from such places were collected on Eysturoy, Streymoy, Suðuroy and Viðoy in the first half of July 1994. Only a few Vaucheria species have hitherto been reported from the Faroe Islands. New records for the archipelago reported in this study are: V. aversa, V. canalicularis, V. frigida, V. medusa, V. prona, and a species referred to the V. geminata complex being V. trigemina-Yike.The paper also includes comments to V. coronata and to V. dillwynii and V. hamata earlier reportcd as V. pachyderma var. islandica andW. uncinata respectively. In addition three Vaucheria parasites have been encountered: the rotatorian Proales werneckii, the plasmodiophoralean Woronina glomerata, and the chytrid Zygorhizidium vaucheriae.

Studies of protonemal morphogenesis in mosses IEphemerum

The single germ tubes produced by the spores of Ephemerum comprise highly chlorophyllose cells divided by transverse cross-walls. All subsequent cross-walls are oblique and thus the protonemata of Ephemerum would appear to be almost entirely caulonemal. Initially, the protonema comprises a loose mat of irregularly-branched filaments. Subsequently, leading filaments around the margins produce upright determinate branching systems which give the protonema of Ephemerum its distinctive appearance. The ultimate ramifications of these systems terminate in sharp points with thickened walls whilst their regular branching is predetermined by zig-zag development of the young side branches. Unlike all the other parts of the protonema, the determinate branching system fails to regenerate when transplanted onto new medium. Whereas cytokinins stimulate bud formation and cause the formation of highly attenuate filaments, abscisic acid induces the production of chains of mucilage-invested spherical brood cells, a phenomenon also seen in ageing cultures. These are desiccation resistant and germinate rapidly on new medium. Nutrient-free agar has little effect on protonemal morphogenesis.

Mats of giant sulphur bacteria on deep-sea sediments due to fluctuating hydrothermal flow

FILAMENTOUS sulphide-oxidizing bacteria, Beggiatoa spp., com-monly grow as submillimetre-thin white films on anoxic marine sediments. Unusually thick mats (>1 cm) of giant Beggiatoa filaments, 41–120 μm wide and 2–10 mm long, were observed at 2,000 m water depth in the hydrothermal vent fields of Guaymas Basin, Gulf of California1–4. We investigated how such dense communities of the largest known bacteria overcome severe diffusion limitation of their substrate supply, and what advantage they may have by developing such large cell sizes. Oxygen, sulphide, pH and temperature were therefore measured in Beggiatoa mats directly on the sea floor. We report here the discovery of small-scale hydrothermal fluid circulations around patches of the bacteria, causing a pulsatory seawater flow into the mats and thereby enhancing the supply of oxygen and sulphide to the bacteria.

Chemical Pollutant Toxicity Determined with a Fungal Assay

range in complexity from unicellular yeasts to multicellular, filamentous molds. A mold consists of a mycelium, which is a mat of thread-like filaments, termed hyphae, that function both in nutrition and in reproduction. When inoculated on a nutrient agar medium, some hyphae grow on and in the substrate, releasing digestive enzymes. Extracellularly digested nutrients are then absorbed through the plasma (cell) membranes of the hyphae. If the fungal inoculum is placed in the center of a nutrient agar-containing Petri dish, the mycelial mat will spread, as a progressively increasing circular colony, over the entire culture plate. Some fungal hyphae grow upwards and are involved in the production of reproductive units, or spores. Such reproductive hyphae, with the spores, may be brightly colored.

Fine Structure of the Eggs of Haemagogus equinus and Hg. janthinomys (Diptera: Culicidae)

The eggs of Haemagogus equinus Theobald and Hg. janthinomys Dyar, the first of this genus to be examined with a scanning electron microscope, are described from material collected in Trinidad, West Indies. All surfaces of the eggs are described, including both dorsal and ventral surfaces at the anterior and posterior ends as well as the micropyle and associated apparatus. The dorsal surface, normally attached to the substrate, consists of a dense, hairlike mat of filaments formed from numerous, greatly elongated outer chorionic tubercles. These filaments possibly serve to improve anchorage of the egg as a protection against flushing by rain water or physical removal by predators. The outer chorionic cells on the ventral (upper) surfaces are extremely similar to those of two species of the subgenus Finlaya of Aedes, Ae. albolateralis (Theobald) and Ae. melanopterus (Giles), both collected in Taiwan.

Characterization of an effective Frankia (ISU 0224887) isolated from nodules of Gymnostoma sumatranum

A Frankia strain ISU 0224887 was isolated from spore negative root nodules of Gymnostoma sumatranum and was grown in pure culture. It was infective and effective for Gymnostoma species but failed to nodulate Allocasuarina and Casuarina seedlings. Light and scanning electron microscopy of it in nitrogen free medium revealed a filamentous mat of septate and branched hyphae bearing sporangia and vesicles capable of fixing nitrogen. The strain also produced an orange pigment after 2 weeks culture. The strain utilized only TWEEN 80 and propionate as sole carbon sources. The different antibiotics used showed varying effects on its growth.

Immunoelectron microscopy of type X collagen: Supramolecular forms within embryonic chick cartilage

To determine the supramolecular forms in which avian type X collagen molecules assemble within the matrix of hypertrophic cartilage, we performed immunoelectron microscopy with colloidal gold-labeled monoclonal antibodies. In addition double-labeled analyses were performed for the molecule and type II collagen, employing two monoclonal antibodies attached to different size gold particles. Both in situ limb cartilages and the extracellular matrix of chondrocyte cultures were examined. We observed in both systems that type X collagen is present in two forms. One is as fine filaments (<5 nm in diameter) within mats which are found predominantly in the pericellular matrix of the hypertrophic chondrocytes. The second form is in association with the fibrils (10–20 nm in diameter) which also react with the antibody for type II collagen. It seems that the filamentous mats represent a form in which the type X collagen is initially secreted from the cell. The type X associated with the striated fibrils most likely represents a secondary association of the molecule with preexisting type II/IX/XI fibrils. The data are consistent with our previously proposed hypothesis that type X collagen is involved in, and perhaps even “targets,” certain matrix components for degradation and removal.

Shell torsion and life habit in the recent mytilid bivalve Modiolus philippinarum

Modiolus philippinarum lives byssally attached to a rocky substrate, with the shell completely embedded in a mat of algal filaments and byssus. This mode of life possesses aspects in common with both epibyssate and endobyssate habits. Shell torsion in M. philippinarum has the same general adaptive value as in other twisted bivalves. However, the peculiar life habit of M. philippinarum results in significant differences with respect to truly endobyssate twisted forms.

Composite sound and heat insulating board

A composite sound and heat insulating board comprising a base layer consisting of a compacted mat of filaments, and an additional layer of a material which differs in hardness than the compacted mat, wherein one surface of the base layer is securely attached to one surface of the additional layer. The compacted fiber mat may be composed of filaments of an organic composition, filaments of an inorganic composition, or partially of filaments of an organic composition and partially of filaments of an inorganic composition. The additional layer of the composite board is constructed of a naturally occurring or synthetic resin such as, for example, a relatively hard thermosetting or thermoplastic synthetic resin, or a relatively soft material which is lower in hardness than the compacted fiber mat. The composite board is advantageous when used in association with a source of heat and noise such as, for example, an internal combustion engine of a power driven vehicle.

Response of basal epithelial cell surface and Cytoskeleton to solubilized extracellular matrix molecules.

Corneal epithelium removed from underlying extracellular matrix (ECM) extends numerous cytoplasmic processes (blebs) from the formerly smooth basal surface. If blebbing epithelia are grown on collagen gels or lens capsules in vitro, the basal surface flattens and takes on the smooth contour typical of epithelium in contact with basal lamina in situ. This study examines the effect of soluble extracellular matrix components on the basal surface. Corneal epithelia from 9- to 11-d-old chick embryos were isolated with trypsin-collagenase or ethylenediamine tetraacetic acid, then placed on Millipore filters (Millipore Corp., Bedford, Mass.), and cultured at the medium-air interface. Media were prepared with no serum, with 10% of calf serum, or with serum from which plasma fibronectin was removed. Epithelia grown on filters in this medium continue to bleb for the duration of the experiments (12-14 h). If soluble collagen, laminin, or fibronectin is added to the medium, however, blebs are withdrawn and by 2-6 h the basal surface is flat. Epithelia grown on filters in the presence of albumin, IgG, or glycosaminoglycans continue to bleb. Epithelia cultured on solid substrata, such as glass, also continue to bleb if ECM is absent from the medium. The basal cell cortex in situ contains a compact cortical mat of filaments that decorate with S-1 myosin subfragments; some, if not all, of these filaments point away from the plasmalemma. The actin filaments disperse into the cytoplasmic processes during blebbing and now many appear to point toward the plasmalemma. In isolated epithelia that flatten in response to soluble collagens, laminin, and fibronectin, the actin filaments reform the basal cortical mat typical or epithelial in situ. Thus, extracellular macromolecules influence and organize not only the basal cell surface but also the actin-rich basal cell cortex of epithelial cells.

Fabric Pipelines and Earth Containment Structures

Spun-bonded fabrics are produced by spinning filaments from spinnerets to make a mat of continuous filaments; these are then bonded at their junctions with heat and pressure. The principal advantage of spun-bondeds is reduced production costs. Construction methods are proposed for the use of spun-bonded fabrics in submarine pipes, retaining walls, and dredge-filled marine structures. Estimated costs are compared with existing costs of construction by alternative methods.

Heterogeneity of intermediate filament proteins from rabbit spinal cord.

Large amounts of a nerofilament-enriched fraction may be prepared from spinal cord homogenates by a simple, three-step procedure. This involves flotation of filament-containing axon fragments, extraction with Triton X-100, and washing by sedimentation through a sucrose density gradient. The material obtained by this procedure includes both large mats of individual 10-nm filaments and tightly packed bundles of filaments. SDS-gel electrophoresis of these fractions indicates that the fractions are formed of four polypeptides: the three which are generally considered to form neurofilaments (P200, P150, and P68) and another, with a molecular weight of about 50,000 daltons (P50), which is thought to be derived from fibrous astrocytes. Analysis of these filament fractions on two-dimensional gels indicate heterogeneity among each of the different molecular weight classes. The largest polypeptide of neurofilaments, P200, focuses at several spots in the pH gradient. P68 and P150 are more acidic: each appears as a pair of overlapping spots. P50 resolves into a complex of spots of about the same molecular weight but with different isoelectric points. Heterogeneity is not unique to these filament polypeptides but appears to be a characteristic of all fibrous proteins of the nervous system.

Tyndall blue and surface white of tent caterpillars, Malacosoma SPP.

Blues and surface whites of tent caterpillars are structural colours resulting from the scattering of light by small, transparent, cuticular filaments. The filaments are small enough to be Tyndall-active, that is they scatter the short wavelengths of incident light more effectively than the long wavelengths. Immediately beneath the surface filaments of blue-coloured cuticle there is a layer of dark pigment which absorbs transmitted light. Therefore, only Tyndall-scattered light is reflected from the cuticle and since this light is diminished in long wavelengths it appears blue. Cuticle that is surface white lacks the layer of dark pigment. Light passing through the surface layer is therefore subject to scattering within the cuticle and by underlying tissues. Sufficient complementary long wavelengths are backscattered from below the surface mat of filaments that the reflected light appears white. Tyndall blue systems found in other insects are briefly discussed.

Epithelial-mesenchymal interactions during odontogenesis II. Intercellular matrix vesicles

The present study has demonstrated morphologically the probable sequential formation of matrix vesicles during embryonic rabbit incisor tooth formation. The observations presented suggest that these vesicles may have been selectively formed within each cell type and then exported into the matrix, or that matrix vesicles may have been formed by a pinocytotic mechanism. It is uncertain on the basis of our morphological data whether one or both of these explanations is adequate. Matrix vesicles were increasingly more concentrated in the matrix region adjacent to dividing inner enamel epithelia and preodontoblast mesenchyme. Thereafter, the concentration of matrix vesicles diminished with the cessation of cell division within each cell type. The vesicles varied considerably in size (500Åto 0.1 μm), shape and the electron density of their contents. They were limited by a unit trilaminar membrane, often coated with a filamentous mat, and contained materials of varying electron density. Morphological data indicate that vesicles observed in the developmentally more advanced dentine organic matrix (in association with nondividing cells) function in the initiation of calcification during dentinogenesis. On the basis of morphological information we anticipate that additional developmental events within dissimilar cell types and within the forming organic matrix may be mediated through matrix vesicles. The interpretation of vesicle functions on the basis of matrix vesicle ultrastructure and location with respect to each cell type must be highly qualified until additional criteria can be employed. However, with regard to possible informational and structural macromolecular transmission and/or ion transport by matrix vesicles, the morphological evidence presented may be highly significant.

Forming mats of carbon filaments: Chapman, D. R. and Rex, N. R. (Courtaulds Ltd) UK Patent Specification, 1,232,007 (19 May 1971)

Forming mats of carbon filaments: Chapman, D. R. and Rex, N. R. (Courtaulds Ltd) UK Patent Specification, 1,232,007 (19 May 1971)