The presence of cellulose microfibrils in the proteinaceous slime track of Dictyostelium discoideum

Summary Electron microscopy and enzymatic analysis show that the slime track of Dictyostelium discoideum represents a two-phase system with a fibrillar component, most likely cellulose, embedded in an amorphous, protein containing matrix. In contrast the slime from the sorus of the mature fruiting body is devoid of any fibrillar component. Thus, this organism produces two significantly different types of slime material.     

Production of Slime Polysaccharides by Shigella dysenteriae Type 1

Electron microscopy of ruthenium red-stained ultrathin section of strains of Shigella dysenteriae type 1 grown in the Casamino Acids-yeast extract broth medium showed the presence of an extracellular slime layer. The slime appeared as a dense sheath covering bacteria. The presence of slime promoted hemagglutinating activity of the bacteria. The slime polysaccharide (SPS) isolated from the cell-free culture supernatant or the bacterial surface was less than 162,000 daltons in size and immunochemically similar. The SPS showed cross-reaction with lipopolysaccharide (LPS) antigen in immunological tests; however, it also appeared to be different from LPS since it did not contain 2-keto-3-deoxyoctonate, a core sugar of LPS. A different pattern of separation from LPS was also observed by silver staining of SDS-polyacrylamide gels. From these data it appeared that either LPS and SPS are contaminated with each other or that SPS is the polysaccharide portion of LPS.     

Sieve-plate pores in tobacco and bean

Summary Tobacco and bean plants were wilted and then fixed as whole plants with formaldehyde-glutaraldehyde for electron microscopy. In some tobacco plants the sieve-plate pores were large, with little callose. Light slime plugs were present, but there was no compaction of P-protein in the pores. Some pores in wilted bean plants were also unplugged. In other plants of both tobacco and bean the sieve-plate pores were plugged. The pores in unwilted control plants of both tobacco and bean were invariably plugged. Tobacco plants were also cut into thin slices and then immediately fixed. In specimens prepared in this way there was little callose in the pores, and many of the pores were not plugged with P-protein. These observations provide additional evidence that sieve-plate pores may be unplugged in vivo.     

Some properties ofAchromatium oxaliferum

Studies on cells harvested from the natural habitat showed thatA. oxaliferum is gram-negative and catalase-negative. Electron micrographs of carefully fixed cells revealed the presence of peritrichously arranged appendages with a minimum thickness of 90 Å as well as capsular slime. The hypothesis is advanced that the gliding motility ofAchromatium is caused by peritrichous bacterial flagella beating in a slime layer that surrounds the cell.The skillful help of Mrs. W. M. Batenburg, Miss J. van Hooidonk, Mr. B. Oosterman and Mr. H. W. G. Meesters is gratefully acknowledged.     

LIGHT MICROSCOPE INVESTIGATION OF SIEVE-ELEMENT ONTOGENY AND STRUCTURE IN ULMUS AMERICANA

At maturity the sieve elements of Ulmus americana L. contain a parietal network of very fine strands of slime which is continuous from one sieve element to the next through the sieve-plate pores. Upon injury this parietal network, which is derived from the slime bodies of immature sieve elements, sometimes becomes distorted into longitudinally oriented strands. Some of these strands frequently extend the length of the cells and often are continuous from one sieve element to the next through the sieve-plate pores. At times past such strands have erroneously been interpreted as normal constituents of the mature sieve-element protoplast. Many mature sieve elements of U. americana contain nuclei, which apparently persist for the life of the sieve elements. In addition, some evidence has been found in mature sieve elements for the presence of a membrane which delimits the parietal layer of cytoplasm, including its network of slime strands, from the vacuolar region of the cell.     

The Different Vascular Patterns of Slime Glands in the Hagfishes,Myxine glutinosa Linnaeus and Eptatretus stouti Lockington A Scanning Electron Microscope Study of Vascular Corrosion Casts*

The vascular patterns of the epidermally derived slime glands of the Atlantic hagfish, Myxine glutinosa, and of the Pacific hagfish, Eptatretus stouti, have been studied by scanning electron microscopy of vascular corrosion casts. In Myxine a simple two-dimensional vascular network sheaths the slime glands, while in Eptatretus there is also a great number of capillary loops of different lengths arising from the sheathing network and extending into the interior of the glands. These basic differences in slime glands vascular patterns are thought to reflect substantially different physiological behaviour of the slime glands in Myxine and Eptatretus.     

SOME ASPECTS OF SIEVE CELL ULTRASTRUCTURE IN PINUS STROBUS

The immature sieve cell of Pinus strobus contains all of the protoplasmic components commonly encountered in young cell types. In addition, it contains slime bodies with distinct double-layered limiting membranes. The mature sieve cell is lined by a narrow layer of cytoplasm consisting of a plasmalemma, one or more layers of anastomosing tubules of endoplasmic reticulum, numerous mitochondria, starch granules and crystal-like bodies. Each mature cell contains a necrotic nucleus. Ribosomes and dictyosomes are lacking. Strands derived ontogenetically from the slime bodies of the immature cell traverse the central cavity and are continuous with those of neighboring sieve cells through the plasmalemma-lined pores of the sieve areas. Sieve-area pores are also traversed by numerous endoplasmic membranes. A membrane was not found separating the parietal layer of cytoplasm from the large central cavity.     

Ultrastructure of the capsule of Klebsiella pneumoniae and slime of Enterobacter aerogenes revealed by freeze etching

Summary The capsule of Klebsiella pneumoniae type I and slime of Enterobacter aerogenes strain A3 (SL) was examined by electron microscopy using the freeze etch technique. The capsules of K. pneumoniae were found to be composed of several layers of polysaccharide 10 nm thick; while the polysaccharide slime of E. aerogenes strain A3 (SL) was found to be composed of a diffuse network of fibrils. This work represents the first effort to visualize the replica of the unfixed, partially hydrated bacterial capsule or slime in the electron microscope. The slime of E. aerogenes strain A3 (SL) which was purified, and then freeze etched, resembled the layered structure of the capsule of K. pneumoniae. It is suggested that the charge or dielectric constant of the slime polysaccharide polymers was altered during purification, thereby permitting the layering to occur.Paper presented at the Annual Meeting of the American Society for Microbiology, Philadelphia, Pa. (U.S.A.), 1972.     

The fine structure of the sieve tubes of Salix caprea (L.) and its relation to the electroosmotic theory

Summary The sieve plate pores of Salix caprea in preparations fixed in glutaraldehyde are normally found to be occupied by slime fibrils showing periodic banding such as occur in a number of other species. Arguments are put forward to suggest that the occurence of fibrils in this position is natural and not an artefact of preparation. The sieve tubes further possess prominent and persistent nucleoli showing a radiating structure of tubules. The endoplasmic reticulum often occurs in parietal stacks reminiscent of other species.This evidence is discussed in relation to the electroosmotic theory of translocation.This work formed part of that submitted for the degree of Ph. D. of the University of London by U. Mishra.     

Ultrastructural study of Saffron pollen

Abstract

Pollen of Saffron (Crocus sativus L.), a sterile autotriploid plant was studied using scanning and transmission electron microscopy. The pollen of mature anthers had grains not containing pores or furrows, a discontinuous thin exine and a very thick intine crossed by tubules containing granular electron-dense material. Electron transparent material and lipid bodies were abundant in the cytoplasm which also contained a large number of vesicles. A high percentage of pollen grains showed anomalies.     

Bacterial canker of poplars in Britain: The cause of the disease and the role of leaf-scars in infection

Bacterial canker and die-back of poplars in Britain is caused by Aplano-bacterium populi Ridé. Pseudomonas syringae (van Hall), which has been suggested as the causal agent, plays at most only a minor role in canker lesions. It may cause a shoot blight in spring, a distinct pathological condition frequently associated with bacterial canker. Marked variation in infectivity of bacterial slime between seasons and at different dates of collection within one year appears to be the main cause for situations in which varieties, resistant in trials to inoculation with slime, have proved susceptible in the field. Leaf scars afford the main avenues for infection but their infectibility declines rapidly during October. The implications of the temporal separation of availability of natural inoculum and available infection sites are discussed.     

Characterisation of the slime gland secretion from the peripatus, Euperipatoides kanangrensis (Onychophora: Peripatopsidae)

The Onychophora display a distinctive mechanism of feeding that involves the entanglement of prey in a sticky secretion. This secretion is produced in the slime glands and ejected as adhesive threads from a pair of oral papillae on either side of the head. Biochemical analyses of the secretion reveals it to be a composite material containing protein, sugar, lipid and a surfactant, nonylphenol. The identification of nonylphenol in the secretion is significant in that this is the first report of this compound from a natural source. The proteins are the principal component of the slime and the amino acid composition of the crude secretion suggests the presence of collagen or a ‘collagen-like’ domain. One or more of the high molecular weight proteins are O-glycosylated where the predominant modification is a single N-acetylgalactosamine (GalNAc). This study adds to our understanding of the chemical and biochemical composition of the unusual onycophoran slime gland secretion.     

Nanoscale uniformity of pore architecture in diatomaceous silica: a combined small and wide angle x-ray scattering study

Combined small and wide angle X‐ray scattering (SAXS and WAXS) analysis was applied to purified biogenic silica of cultured diatom frustules and of natural populations sampled on marine tidal flats. The overall WAXS patterns did not reveal crystalline phases (WAXS domain between 0.07 to 0.5 nm) in this biogenic silica, which is in line with previous reports on the amorphous character of the SiO₂ matrix of diatom frustules. One exception was the silica of the pennate species Cylindrotheca fusiformis Reimann et Lewin, which revealed wide peaks in the WAXS spectra. These peaks either indicate the presence of a yet unknown crystalline phase with a repetitive distance (d‐value ≈0.06 nm) or are caused by the ordering of the fibrous silica fragments; numerous girdle bands. The SAXS spectra revealed the size range of pores (diameter d between 3.0 and 65 nm), the presence of distinct pores (slope transitions), and structure factors (oscillation of the spectra). All slopes varied in the range of ?4.0 to ?2.5, with two clear common regions among species: d < 10 nm (slopes –4, denoted as region I and also called the Porod region), and 10.0 < d < 40.0 nm (slopes ?2.9 to ?3.8, denoted as region II). The existence of these common regions suggests the presence of comparable form (region I) and structure (region II) factors, respectively the shape of the primary building units of the silica and the geometry of the pores. Contrast variation experiments using dibromomethane to fill pores in the SiO₂ matrix showed that scattering was caused by pores rather than silica particles. Electron microscopic analysis confirmed the presence of circular, elliptical, and rectangular pores ranging in size from 3 to 65 nm, determining the structure factor. The fine architecture (length/width ratio of pore diameters) and distribution of the pores, however, seemed to be influenced by environmental factors, such as the salinity of and additions of AlCl₃ to the growth medium. The results indicate that diatoms deposit silica with pores <50 nm in size and are highly homologous with respect to geometry. Consequently, it is suggested that in diatoms, whether pennate or centric, the formation of silica at a nanoscale level is a uniform process.     

Immunological examination of the glycocalyces ofStaphylococcus aureus strains Wiley and Smith

The immunological examination of the glycocalyces ofStaphylococcus aureus has been concerned with capsular elements while essentially neglecting slime layers. We have found bacterial slime layers to be prevalent in many natural bacterial environments and, in particular, in recently isolatedS. aureus strains Wiley and Smith [1]. Growth in modified staphylococcus 110 medium induces slime layer production in these strains, and investigation of this material has revealed the two slime layers to be immunogenically and antigenically identical. The slime layer of the Smith strain is immunologically distinct from the tight, integral capsule that also comprises the glycocalyx of this strain. The Wiley strain glycocalyx is composed of only a slime layer.     

The Inhibitory Effect of Staphylococcus epidermidis Slime on the Phagocytosis of Murine Peritoneal Macrophages Is Interferon-Independent

The extracellular slime produced by Staphylococcus epidermidis has been shown to interfere with several human neutrophil functions in vitro, such as chemotaxis, degranulation and phagocytosis. Slime production has been suggested as a useful marker for clinically significant infections with coagulase-negative Staphylococcus. Since the main role of macrophages in defense mechanisms is phagocytosis, the effect of slime on the phagocytic activity of macrophages was investigated. The phagocytic activity of murine peritoneal macrophages treated with slime in vitro decreased in a dose-dependent fashion. A similar decrease was also observed in macrophages isolated from mice that had previously received intraperitoneal injection of slime. To investigate whether interferon also plays a role in this process, mice were treated with interferon or an interferon inducer, polyinosinic-polycytidylic acid (poly I:C), together with slime before macrophage isolation. The slime-suppressed phagocytic activity of macrophages was partially relieved by both agents, and the recovery effect of poly I:C in slime-suppressed phagocytosis of macrophages in vivo might be attributed to the increased interferon level in peritoneal fluid and sera. However, when slime was given to poly I:C-pretreated mice, the phagocytic activity remained suppressed. Thus, it appears that slime is able to suppress the phagocytic activity of macrophages regardless of the state of macrophage activation by poly I:C. The results suggest that the inhibition of phagocytosis by S. epidermidis slime may be independent from the activation of interferon.     

Ultrastructure of the plasmodial slime moldPerichaena vermicularis

Summary The development of the peridium ofPerichaena vermicularis has been examined using light and electron microscopy and acid phosphatase localization. A newly formed fruiting body consists of undifferentiated protoplasm which is enveloped by a slime coat. Almost immediately after formation of the plasmodiocarp, the protoplasm differentiates into autolytic and fruiting regions. The autolytic region is located at irregular intervals between the slime coat and the fruiting region and separated from both of them by membranes.Soon after the autolytic region has formed, additional signs of degeneration appear in the autolytic region including unusual appearance of nuclei, increase in autophagic vacuoles, and the presence of clear areas in the ground substance. The plasma membrane, which once completely separated the slime coat from the autolytic region, is no longer continuous. Electron micrographs of the autolytic region from later developmental stages show formation of extensive channels which contain protoplasm in various stages of degradation. Acid phosphatase is present in the channels of the autolytic region. The morphological evidence and the presence of hydrolytic enzyme suggest the region is being digested and re-adsorbed.After the autolytic region has been digested, an even layer of peridial wall material is laid down, and at regular intervals additional wall material is produced. The additional wall material forms the reticulation on the inside of the peridial wall.This work was supported by National Sciences Foundation grants (GB-5883 and GB-8537) to Dr.Ian K.Ross and an NSF Traineeship (GZ 445 and 796) to I.Charvat.This constitutes a portion of a thesis presented to the Regents of the University of California by the first author in partial fulfillment of the requirements for the Ph. D. degree.     

Structure and Composition of Biological Slimes on Paper and Board Machines

Biological slimes (biofilms) collected from the wet end of paper and board machines were examined by electron microscopy and analyzed for fatty acid composition, neutral sugar composition, and ATP. Electron microscopy revealed minuscule prokaryotic organisms (diameter, 0.2 to 0.4 μm). Larger cells morphologically resembling Sphaerotilus and Leptothrix spp. were found in slimes from machines using recycled fiber or unbleached pulp. The bacteria were embedded in a slimy matrix and often contained reserve materials microscopically resembling poly-β-hydroxybutyrate and glycogen. Fatty acid analysis of the slimes revealed bacterial signature fatty acids in concentrations equivalent to the presence of 2 × 10¹⁰ to 2.6 × 10¹² (average, 7 × 10¹¹) bacterial cells (live and dead) per g (dry weight) of slime. The slimes contained several known components of bacterial polysaccharides in addition to glucose, indicating that the slime body consisted of bacterial polysaccharides. The slimes contained uronic acids equivalent to a binding capacity of 12.5 to 50 μmol of divalent cations per g (dry weight) of slime. The uronic acid-containing polysaccharides may be responsible for the accumulation of heavy metals in the slime. Calculation of the ATP contents of the slimes resulted in an estimate of 5 × 10¹² cells per g (dry weight) of slime when calibrated with pure bacterial cultures isolated from the slimes. From electron micrographs, an estimate ranging from 1 × 10¹⁰ to 1.5 × 10¹² (average, 4 × 10¹¹) cells per g (dry weight) of slime was obtained.     

A NATURALLY OCCURRING DEVELOPMENTAL SYNERGISM BETWEEN THE CELLULAR SLIME MOLD,DICTYOSTELIUM MUCOROIDES AND THE FUNGUS,MUCOR HIEMALIS

We here report the second record of a developmentally aberrant strain of a cellular slime mold from natural populations and demonstrate that this Dictyostelium mucoroides variant is capable of undergoing normal morphogenesis in the presence of the phycomycete fungus, Mucor hiemalis. The synergism is induced by an extracellular product(s) which is diffusable through thin agar membranes and is released by the fungus. The presence of the fungus not only induces stalk formation in this stalkless variant, but also increases the rate of sorocarp formation in 3 of 5 additional species of cellular slime molds assayed.     

Über die Oberflächenstruktur von Myxobakterien

Zusammenfassung Zellen von Cytophaga hutchinsonii und vegetativer Sporocytophaga myxococcoides produzieren während der Submerskultur in belüftetem Glucose-Medium große Mengen hochviscoser, extracellulärer Schleimstoffe. Im elektronenmikroskopischen Bild erscheint die Schleimhülle der Bakterien nach Negativkontrastierung mit Natriumphosphorwolframat als dichtes, weit verzweigtes Netzwerk fibrillärer Elemente, die an der Zelloberfläche entspringen und sich ohne erkennbare äußere Abgrenzung im Substrat ausbreiten. Feinste Elementarfibrillen der Schleimsubstanz haben eine Dicke von etwa 30 Å. Demgegenüber wird völlige Abwesenheit einer Schleimhülle bei den Mikrocysten festgestellt, die aus den vegetativen Zellen von Sp. myxococcoides nach Beendigung des logarithmischen Wachstums gebildet werden. Gleichzeitig mit der Mikrocystenbildung wird starke Abnahme der Viscosität im Kulturmedium festgestellt. Mikrocystenbildung scheint mit dem enzymatischen Abbau der Schleimsubstanz einherzugehen. Die Schleime von C. hutchinsonii und Sp. myxococcoides sind wahrscheinlich anionische Heteropolysaccharide. Cytophaga-Schleim enthält die vier Neutralzucker Glucose, Mannose, Arabinose und Xylose; bei Sporocytophaga ist zusätzlich Galaktose vorhanden. Einziger anionischer Baustein ist in beiden Fällen Glucuronsäure, die möglicherweise über Xylose mit den Polymeren verknüpft ist.

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On the surface-structure of myxobacteriaII. Anionic heteropolysaccharides as components of the extracellular slimes of Cytophaga hutchinsonii and Sporocytophaga myxococcoides

Summary Cells of Cytophaga hutchinsonii and vegetative Sporocytophaga myxococcoides produce copious amounts of extracellular slime during active growth in liquid, aerated glucose-medium, imparting a high degree of viscosity to the culture. Electron microscopy following negative staining with sodium phosphotungstate reveals the slime substance as densely interwoven network of filamentous material originating on the cell surface and extending far into the medium without any discernable boundary. Elementary fibrils of the slime substance have a thickness of about 30 Å. The surrounding layer of filamentous slime is completely absent from the surface of microcysts formed from vegetative cells of Sp. myxococcoides after cessation of logarithmic growth, and the original high viscosity of the cell suspension is greatly reduced. It is concluded that microcyst formation is accompanied by enzymatic breakdown of the extracellular slime substance.Isolated slime materials from both organisms are tentatively identified as anionic heteropolysaccharides. Neutral sugar components of the substance from C. hutchinsonii are glucose, mannose, arabinose and xylose. Sp. myxococcoides slime contains the same sugars and also galactose. Glucuronic acid is the only anionic component in the heteropolysaccharides of both organisms. Preliminary evidence suggests that the uronic acid is linked to the polymers via xylose.