The preservation of medically important fungi.

Details are given of a method, first described in 1962, for preservation of fungi in anhydrous silica gel. It is shown that the procedure is suitable for use with dermatophytes, yeasts and other fungi of medical importance and that they may be preserved for periods of 5 years or more.     

The Sirius Passet Lagerstätte: silica death masking opens the window on the earliest matground community of the Cambrian explosion

The Sirius Passet Lagerstätte (SP), Peary Land, North Greenland, occurs in black slates deposited at or just below storm wave base. It represents the earliest Cambrian microbial mat community with exceptional preservation, predating the Burgess Shale by 10 million years. Trilobites from the SP are preserved as complete, three‐dimensional, concave hyporelief external moulds and convex epirelief casts. External moulds are shown to consist of a thin veneer of authigenic silica. The casts are formed from silicified cyanobacterial mat material. Silicification in both cases occurred shortly after death within benthic cyanobacterial mats. Pore waters were alkali, silica‐saturated, high in ferric iron but low in oxygen and sulphate. Excess silica was likely derived from remobilized biogenic silica. The remarkable siliceous death mask preservation opens a new window on the environment and location of the Cambrian Explosion. This window closed with the appearance of abundant mat grazers later as the Cambrian Explosion intensified.     

The Preservation of Bacteria and Fungi on anhydrous Silica Gel: an Assessment of Survival over Four years

The preservation method of Perkins (1962) using suspensions in skim-milk was used to preserve 33 bacteria and 22 fungi on anhydrous silica gel. During storage at room temperature, 64% of the bacteria and 77% of the fungi survived 1 year or more. Storage at 4° often increased the survival period c. 2- to 3-fold: 73% of the bacteria and all 12 of the fungi tested at 4° survived > 1 year. At the last testing, 60% of the bacteria and 36% of the fungi were still viable after storage at 4° for periods between 3 and 4 years. The Gram positive bacilli tended to survive the silica gel preservation process better than most Gram negative bacilli. Some factors influencing survival after preservation on silica gel are discussed; the results support the use of a closed storage tube.     

STUDIES ON THE BIOCHEMISTRY AND FINE STRUCTURE OF SILICA SHELL FORMATION IN DIATOMS. II. THE STRUCTURE OF THE CELL WALL OF NAVICULA PELLICULOSA (BRÉB.) HILSE

The cell wall of the freshwater diatom Navicula pelliculosa (Bréb.) Hilse is composed of the silica shell and an organic skin which surrounds it. Isolated skins can be prepared by first removing the contents of the cell by mechanical shaking, followed by a posttreatment of these isolated cell walls with HF vapor to remove the silica shell. T h e skins can also be seen in sections, particularly well after the silica shell has been removed B y H. F; vapor. The origin and morphological composition of the shin in N. pelliculosa are not yet completely ascertaincd. As parts of the cell wn11, both the silica shell and the skin are extracellularly located. The growth of the silica shell, however, occurs intracellularly inside a vesicle delimited by a triple-layered membrane, the silicalemma. This membrane or secondary excreted organic material or both in various proportions may compose the skin.     

Carcinocythemia. Report of two cases, one simulating a Burkitt lymphoma

Carcinocythemia is a rare complication of metastatic carcinoma, characterized by the presence of carcinoma cells in the peripheral blood, which may mimic acute leukemia. Two cases are reported in which the patients developed carcinocythemia several years after being treated for carcinoma of the breast. Cytologic examination of peripheral blood smears in both cases showed the presence of numerous large abnormal cells; in one case the cells simulated those of a Burkitt lymphoma. Cytochemical and/or immunologic marker studies ruled out a hematopoietic origin of the malignant cells in both cases and confirmed a diagnosis of carcinocythemia. The rapidly fatal outcome observed in these two cases was in accordance with the poor prognosis usually encountered with this rare phenomenon.     

Systematic significance of cell inclusions in Haemodoraceae and allied families: silica bodies and tapetal raphides

This paper presents the first record of silica deposits in tissues of Haemodoraceae and adds new records of tapetal raphides in this family. Within the order Commelinales, silica is present in leaves of three families (Hanguanacaeae, Haemodoraceae and Commelinaceae), but entirely absent from the other two (Pontederiaceae and Philydraceae). Presence or absence of characteristic cell inclusions may have systematic potential in commelinid monocotyledons, although the existing topology indicates de novo gains and losses in individual families. Silica sand was observed in leaves of five out of nine genera examined of Haemodoraceae, predominantly in vascular bundle sheath cells and epidermal cells. Within Haemodoraceae, silica is limited to subfamily Conostylidoideae. The occurrence of silica in Phlebocarya supports an earlier transfer of this genus from Haemodoroideae to Conostylidoideae. The presence of raphides (calcium oxalate crystals) in the anther tapetum represents a rare character, only reported in a few monocot families of the order Commelinales, and possibly representing a mechanism for regulation of cytoplasmic free calcium levels. Tapetal raphides were observed here in Anigozanthus and Conostylis (both Haemodoraceae), and Tradescantia (Commelinaceae), thus supplementing two earlier records in Haemodoraceae, Philydraceae and Commelinaceae.     

Immunostaining free oligosaccharides directly on thin-layer chromatograms

Oligosaccharides are chromatographed on amino-bonded high-performance thin-layer chromatography silica gel plates and after chromatography the aldehydes on the reducing ends of the oligosaccharides react with the amino groups on the silica gel. Bound oligosaccharides are immunostained directly on the chromatograms by monoclonal antibodies. The binding of antibodies is detected by autoradiography after a second incubation with 125I-labeled goat anti-mouse immunoglobulin. Using this method, 10 pmol of lacto-N-difucopentaose I (Leb hapten) and lacto-N-fucopentaose III (Lex hapten) are detected directly on the thin-layer chromatograms by monoclonal antibodies 10c17 and 534F8, respectively. Previously undescribed larger oligosaccharides containing these epitopes are also detected in human milk. This method may be used to identify and characterize antibody-binding oligosaccharides liberated from glycoconjugates by hydrazinolysis, by trifluoroacetolysis, by ozonolysis, or by treatment with endoglycosidases. This technique may also be used to determine the structural specificity of other carbohydrate-binding proteins such as lectins, toxins, and hormones or of bacteria and viruses that bind to cell surface glycoproteins.     

Experimental fossilization of the Thermophilic Gram-positive Bacterium Geobacillus SP7A: A Long Duration Preservation Study

Recent experiments to fossilize microorganisms using silica have shown that the fossilization process is far more complex than originally thought; microorganisms not only play an active role in silica precipitation but may also remain alive while silica is precipitating on their cell wall. To better understand the mechanisms that lead to the preservation of fossilized microbes in recent and ancient rocks, we experimentally silicified a Gram-positive bacterium, Geobacillus SP7A, over a period of five years. The microbial response to experimental fossilization was monitored with the use of LIVE/DEAD staining to assess the structural integrity of the cells during fossilization. It documented the crucial role of silicification on the preservation of the cells and of their structural integrity after several years. Electron microscopy observations showed that initial fossilization of Gram-positive bacteria was extremely rapid, thus allowing very good preservation of Geobacillus SP7A cells. A thick layer of silica was deposited on the outer surface of cell walls in the earliest phase of silicification before invading the cytoplasmic space. Eventually, the cell wall was the only recognizable feature. Heavily mineralized cells thus showed morphological similarities with natural microfossils found in the rock record.     

Collagenolytic activity in several species of deuteromycetes under various storage conditions

The ability of deuteromycetes of the genera Penicillium, Aspergillus, and Botrytis to retain collagenolytic activity was studied after both 2 and 10 years of storage on a Czapek medium under a layer of mineral oil at 4 degrees C, as well as in silica gel granules at 20 and -60 degrees C. The enzymatic activity of several species, including Botrytis terrestris, Penicillium janthinellum, Penicillium chrysogenum, and Penicillium citrinum, was retained under both conditions of storage. Aspergillus repens retained enzymatic activity only if stored under a layer of mineral oil. The viability of conidia and the collagenolytic activity of Botrytis terrestris, P. janthinellum, P. chrysogenum, and Penicillium citrinum, maintained on silica gel for 10 years, depended on the storage temperature. The viability of the test strains improved after storage on a silica gel at -60 degrees C. A strain of Aspergillus repens lost its ability to dissolve collagen at various storage temperatures on the silica gel. The index of lysis for three strains of Penicillium deuteromycetes (Penicillium janthinellum, Penicillium chrysogenum, and Penicillium citrinum) increased after a 10-year storage on silica gel at -60 degrees C.     

Biogeochemical silica mass balances in Lake Michigan and Lake Superior

Silica budgets for Lake Michigan and Lake Superior differ in several respects. Mass balance calculations for both lakes agree with previous studies in that permanent burial of biogenic silica in sediments may be only about 5% of the biogenic silica produced by diatoms. Because dissolution rates are large, good estimates of permanent burial of diatoms can not be obtained indirectly from the internal cycle of silica (silica uptake by diatoms and subsequent dissolution) but must be obtained from the sediment stratigraphy. The annual net production of biogenic silica in Lake Michigan requires 71% of the winter maximum silica reservoir which must be maintained primarily by internal cycling in this large lake whereas the comparable silica demand in Lake Superior is only 8.3%. The greater silica demand in Lake Michigan is the result of phosphorus enrichment which has increased diatom production. It is hypothesized that steady-state silica dynamics in Lake Michigan were disrupted by increased diatom production between 1955 and 1970 and that a new steady state based on silica-limited diatom production developed after 1970. Mass balance calculations for Lake Michigan show in contrast with previous work that the hypothesized water column silica depletion of 3.0 g · m^–3 could have occurred even though 90% or more of the biogenic silica production is recycled.     

Silica deposition in abaxial epidermis before the opening of leaf blades of Pleioblastus chino (Poaceae, Bambusoideae)

BACKGROUND AND AIMS Silica deposition is one of the important characteristics of the family Poaceae. The distribution, deposition process and physiology of silica in this family have been extensively investigated. Bamboos among members of Poaceae have leaves with a fairly long life span, and the leaves continuously accumulate silica in their tissues throughout their life, not only during the course of leaf opening, but also after opening. It has been revealed that the silica deposition process in relation to ageing of the bamboo leaf after opening differed depending on the cell types comprising the tissues. However, silica deposition has never been examined during the development and maturation periods of bamboo leaves. Hence, to clarify the silica deposition process in a developmental stage of the bamboo leaf, distribution of silica was observed in the abaxial epidermis before the opening of the leaf blades of Pleioblastus chino. METHODS: Abaxial epidermal tissues of leaves were examined using a scanning electron microscope equipped with an energy dispersive X-ray microanalyser. KEY RESULTS: Among seven cell types comprising the abaxial epidermis, three types of cells, guard cells, prickle hairs and silica cells, deposited silica conspicuously, and another four types, cork cells, long cells, micro hairs and subsidiary cells, deposited only a little silica. Among the former group of cell types, silica cells and guard cells deposited silica over their entire surfaces, while prickle hairs deposited silica only in the point-tips. Silica deposition was detected firstly in prickle hairs, and then in silica cells and guard cells. Only silica cells were assumed to deposit silica conspicuously before leaf opening but not conspicuously after opening. CONCLUSIONS: Cell types in leaf epidermis of bamboo are classified into three groups according to the silica deposition pattern. Silica deposition in silica cells may be positive as a part of the physiological activities of leaves.     

Regulation of B-lymphocyte production in the bone marrow: role of macrophages and the spleen in mediating responses to exogenous agents

B-Lymphocyte production in mouse bone marrow can be stimulated by administering a variety of foreign materials in vivo. The nature and location of cells mediating this effect have now been studied, using assays of lymphocyte renewal and pre-B-cell proliferation. Pretreatment of mice with silica, to depress macrophage function, abolished the stimulation of small lymphocyte renewal produced by administering either sheep red blood cells (SRBC) or mineral oil and reduced the response to bovine serum albumin. The response was still abolished when silica was given 6 or 24 hr, but not 48 hr, after SRBC. Splenectomy prevented the stimulation of marrow lymphocyte renewal when performed either 4 weeks before or up to 72 hr after SRBC injection. The stimulation of pre-B-cell proliferation was similarly prevented by pretreatment with either silica or splenectomy. The results indicate that the wave of increased B-lymphocyte production after SRBC injection depends for the first 2-3 days upon silica-sensitive, spleen-dependent mechanisms, suggesting an early mediation by splenic macrophages. Primary B-lymphocyte production in vivo may thus normally be stimulated by exposure to external environmental agents acting indirectly on bone marrow B-cell progenitors via cellular reactions in peripheral lymphoid tissues.     

Spicules of hexactinellid sponges (Hexactinellida: Porifera) as natural composite materials

This paper reviews studies on the hexactinellid glass sponges (Hexactinellida: Porifera) that have organic silica spicules. According to its physical properties (microdensity, Young’s modulus, and light transmission), the material of the spicules is similar to amorphous silica; however, sponge spicules are birefringent, which suggests that they have a highly ordered crystal-like nature. Mineralized remnants of siliceous spicules composed of chemically inert materials are preserved in sedimentary rocks and provide evidence of the ecological state of the ancient biosphere. Sponges occur in waters with low temperatures; therefore, they grow very slowly and live for hundreds of years. The organic silica spicules exhibit the capacity for triboluminescence. The generated light emission may be used by symbiotic bacteria on the spicule surface.     

The experimental silicification of Aquificales and their role in hot spring sinter formation

Archean microfossils provide some of the earliest physical evidence for life on Earth, yet there remains a great deal of uncertainty regarding which micro‐organisms were actually preserved. Because of the limited cellular detail remaining, interpretation of those microfossils has been based solely on size and morphology. This has led to significant controversy surrounding the presence or absence of cyanobacteria as early as 3.5 billion years. Accordingly, there has been an experimental bias towards studying their silicification. Here we report the very first findings on thermophilic bacteria–silica interactions, and investigate how Sulfurihydrogenibium azorense, a representative of the Aquificales often found as prominent members of modern hot spring vent communities, interacts with highly siliceous hydrothermal fluids. We show that adsorption of silica is limited to silica polymers and colloids, and that the magnitude of silica adsorption is dependent on its chemolithoautotrophic pathway. Intriguingly, when S. azorense is grown as a H₂‐oxidizer, it responds to increasing silica concentrations by producing a protein‐rich biofilm that may afford the cells protection against cell wall silicification. Although the biofilms of Aquificales could potentially contribute to or accelerate siliceous sinter formation under certain growth conditions, the cells themselves show a low preservation potential and are unlikely to have been preserved in the ancient rock record, despite phylogenetic analyses suggesting that they represent one of the most primordial life forms.     

Phytoliths of Indian grasses and their potential use in identification

Phytoliths are amorphous silicon dioxide (SiO₂.nH₂O) inclusions abundant in leaves, in-ternodes and glumes in members of Poaceae. They may occur as inclusions filling the entire lumen of the silica cells, bulliform cells and trichomes or may be part of the outer epidermal cell walls. Since phytoliths are resistant to fungal or animal digestive juices, a large quantity of phytoliths accumulate in the soil where grasses grow. Compared with the pollen grains of grasses which tend to be uniform, phytoliths vary in sue and morphology and can be of value in identification at different taxonomic levels and in the dating of past vegetation. The size and shape of phytoliths of about 100 species of grasses from Tamil Nadu, India, have been determined. Silica bodies were observed either after isolation or in cleared leaf blades. Size and shape of phytoliths were determined under a microscope or from micrographs of the specimens. Size and shape can be used to assign the phytoliths to their respective subfamilies and to distinguish some of the grasses at the generic level. Drawings of silica cells and an identification key are provided for 80 species.     

The Formation and Preservation of Synechococcus elongatus Cell Molds in Simulated Silica Sinter: Implications for the Identification of Microfossils

Siliceous sinters that precipitate around modern hot spring systems are able to fossilize the indigenous microbial communities, forming molds that accurately outline the shape of the microorganisms. Over time, the biomass decays, and only silica molds or their infill may remain as evidence of the former living cells. However, little is known regarding the fidelity of such silica molds in terms of size and morphology, and the preservation of critical parameters for the identification of ancient silicified microorganisms by silica molds remains untested. Here we report experiments examining the formation of microbial molds of the cyanobacterium Synechococcus elongatus in silica gel. We demonstrate that post-depositional processes, primarily desiccation, are crucial for obtaining accurate and robust molds, and that initial desiccation acts to strengthen cell molds against further alteration. However, all silica gel treatments systematically created preservational biases (changes in size, additional structures) that may be misleading and may complicate the identification of fossil microorganisms.     

Amino-terminal and midmolecule parathyroid hormone-related protein,phosphatidylcholine, and type II cell proliferation in silica-injured lung

Acute silica lung injury is marked by alveolar phospholipidosis and type II cell proliferation. Parathyroid hormone-related protein (PTHrP) 1-34 could have a regulatory role in this process because it stimulates phosphatidylcholine secretion and inhibits type II cell growth. Other regions of the PTHrP molecule may have biological activity and can also exert pulmonary effects. This study examined the temporal pattern for expression of several regions of PTHrP after silica lung injury and evaluated the effects of changes in expression on cell proliferation and lung phospholipids. Expression of all PTHrP regions fell at 4 days after injury. Reversing the decline in PTHrP 1-34 or PTHrP 67-86 with one intratracheal dose and four daily subcutaneous doses of PTHrP 1-34 or PTHrP 67-86 stimulated bronchoalveolar lavage disaturated phosphatidylcholine (DSPC) levels. Cell culture studies indicate that the peptides exerted direct effects on DSPC secretion by type II cells. Neither peptide affected type II cell proliferation with this dosing regimen, but addition of an additional intratracheal dose resulted in significant inhibition of growth, consistent with previous effects of PTHrP 1-34 in hyperoxic lung injury. These studies establish a regulatory role for PTHrP 1-34 and PTHrP 67-86 in DSPC metabolism and type II cell proliferation in silica injury. Growth inhibitory effects of PTHrP could interact with phospholipid stimulation by affecting type II cell numbers. Further studies are needed to explore the complex interactions of PTHrP-derived peptides and the type II cell response at various stages of silica lung injury.