Abstract: 1. Motile gram-negative bacteria readily attach to and detach from glass slides, and may remain on them from a few seconds to a number of hours. They attach (a) at one end, (b) along their length showing slight Brownian movement, or (c) along their length remaining quite immobile. No differences were detected between fimbriate and non-fimbriate species. 2. Bacteria that attach at one end appear to do so by their polar flagella. When in this position they rotate in a clockwise or an anticlockwise direction. The rate of rotation is constant for a given time, but can switch to other rates. Rates of 1.7 to 11.7 rotations/sec have been recorded. The rotation of the cells may offer a method of documenting flagellar beat. 3. Bacteria killed by ultraviolet irradiation attach as readily as do living bacteria, but considerably fewer attach when killed by heat or formalin. 4. Bacteria resuspended in dilute solutions of the proteins salmine or albumin attach in fewer numbers than do bacteria resuspended in buffer, while bacteria resuspended in dilute solutions of the proteins casein or gelatin attach in larger numbers. 5. The ecological and cellular consequences of the results are briefly discussed.

Abstract: General characteristics of blue-green algal halotolerance were studied by growth experiments and selected analyses. Variation in NaCl concentration was used to mimic salinity. Marine isolates were more halotolerant (8–10% NaCl) than non-marine isolates (2% NaCl). The Na+ requirement for growth was saturated at 1 mg NaCl/l for non-marine isolates and 100mg NaCl/l for marine isolates. Intracellular Na+ values were affected by washing; however, bound-K+ values for both marine and fresh-water blue-green algae were fairly constant, 1–3 μg/mg cells. A specific Na+ function was implied by the retention after washing of 22Na+ (0.1 μg/mg cells) by Agmenellum quadruplicatum (PR-6), a marine coccoid blue-green alga.

Abstract: The relative ability of species of thermophilic fungi to degrade cellulose was measured using an agar-diffusion technique based on the clearing of acid-swollen cellulose.

Abstract: When filaments from a culture of Anabaena sp. growing photoautotrophically with nitrate as a nitrogen source are placed in a nitrate-free mineral medium and incubated anaerobically in the light, the formation of heterocysts and the synthesis of nitrogenase both begin after a lag of about 24 hours. During the lag period, about 70% of the phycocyanin is destroyed. Under an atmosphere of N2-CO2, the nitrogenase activity rises to a peak value, and then falls markedly as growth at the expense of N2 begins. Phycocyanin synthesis resumes concomitantly with growth. Under an atmosphere of Ar-CO2, the formation of heterocysts and the synthesis of nitrogenase proceed to higher levels than those observed under N2-CO2, and the nitrogenase level is thereafter maintained. Under these conditions, neither growth nor resynthesis of phycocyanin occurs, and phycocyanin eventually falls to about 10% of its initial level in the filaments; however, growth can be promptly initiated if N2 is admitted to the system. The implications of these findings are discussed.

Abstract: The ability of some unicellular blue-green algae to grow at the expense of N2 under aerobic conditions has been confirmed and the distribution of this property in the Chroococcaceae has been investigated. It appears to be confined to strains with spherical cells enclosed by the multilaminate sheaths characteristic of the genus Gloeocapsa. Only two unicellular blue-green algae of this type are now available in pure culture; and their properties are so similar that they may well be independent isolates of the same species.

Abstract: An der Gametenverschmelzung bei der heterothallischen, isogamen Grunalge Chlamydomonas reinhardii ist, wie an der Befruchtung bei hoheren Organismen, ein lytischer Faktor beteiligt. Wahrend des Kontaktes von ⊕ und ⊝ Gameten oder wahrend einer, Isoagglutination von Gameten des einen Paarungstyps mit den isolierten Geiseln vom entgegengesetzten Paarungstyp wurde ein hitzelabiler, lytischer Faktor ins Nahrmedium abgegeben. Auch Extrakte aus vegetativen und generativen Zellen von C. reinhardii enthielten lytische Aktivitat. Unter der Einwirkung des extrahierten oder des sekretierten Autolysins fand eine partielle Lyse der Zellwande von Gameten und Zoosporen statt, die mit der Freisetzung von Protoplasten verbunden war. Die Praparate mit lytischer Aktivitat losten auserdem die Wande der Zoosporangien von C. reinhardii vollstandig auf und setzten dabei Zoosporen frei.

Abstract: 5 to 6% of the total cellular protein was released into the medium from Escherichia coli B which was harvested from a logarithmically growing culture in a glycerol-salts medium, suspended in 014 M NaCl, pH 73, at a tenfold cell density (about 15×1010/ml or 16 mg protein/ml) and treated for 1 min at 37° C with 200 μg polymyxin B/ml The protein patterns of this material obtained by polyacrylamide gel electrophoresis were identical with those derived from an osmotic shock supernatant according to Neu and Heppel (1965) Periplasmic enzyme activities found in the polymyxin-supernatant included 5′-nucleotidase, 3′-nucleotidase, ribonuclease I, acid phosphatase and alkaline phosphatase Upon further incubation with polymyxin B (up to 60 min), cell autolysis occurred with a concomitant release of 68% of total protein and up to 100% of cytoplasmic enzyme activities like β-galactosidase, inorganic pyrophosphatase and aldolase This autolysis was not observed with stationary phase cells or with cells grown in a complex yeast extract-glucose broth The mechanism of action of polymyxin B leading to the specific release of periplasmic proteins in discussed

Abstract: 0768 09 1. An axenic culture of a species of Nostoc from the coralloid roots of the cycad Macrozamia lucida, grows heterotrophically in complete darkness at measurable and reproducible rates. 2. Heterotrophic growth was supported by glucose, fructose and sucrose over the pH range 6 to 9. The growth rate with glucose was increased if casamino acids were added. 3. Heterotrophic growth on glucose proceeded under both aerobic and anaerobic conditions. 4. Cultures grown in the dark were pigmented. There was no significant difference in the ultrastructure of photoautotrophically-grown and dark heterotrophically grown cells.

Abstract: Vigorous agitation caused the zoospores of Phytophthora palmivora to undergo rapid synchronous encystment. The rate of encystment was determined by counting the number of cells with an alkali-resistant cyst wall. 50% of the zoospores formed an alkali-resistant cyst wall within 60 sec of agitation; after 120 sec, essentially all zoospores had encysted. The rate of spontaneous encystment in nonagitated suspensions was much slower. The flagella of nearly all zoospores disappeared within 30 sec of agitation, i.e. prior to the formation of an alkali-resistant cyst wall. Zoospores depend on internal reserves for synthesizing their cyst walls. Approximately 70% of the total carbohydrate in motile zoospores was extracted with water after treating the cells with 70% ethnol. During synchronous encystment, this carbohydrate fraction composed largely of glucans decreased markedly while the insoluble carbohydrate fraction (cyst wall glucan) increased correspondingly. Clearly, the conversion of cytoplasmic glucan into wall glucan plays a major role in zoospore encystment.

Abstract: Whole cells of Rhodospirillum rubrum were cultivated in a malate medium lacking bound nitrogen under N2 and tested for their nitrogenase activity by measuring the disappearance of nitrogen manometrically.

Abstract: Nitrosospira briensis was isolated from the soils of Crete, the Greek mainland and Switzerland. This is only the second report of the reisolation of a member of this genus since it was described by the Winogradskys in 1933. N. briensis, studied in the present investigation, is so tightly coiled that the cells appear as rods or cylinders rather than spirals when examined with the phase- contrast microscope. On occasion the cells partially uncoil and the spirals are clearly evident even with a phase-contrast microscope. When the cells were thin-sectioned, shadowed, negatively-stained or freeze-etched and viewed with the electron microscope, the spirals were visible even in tightly coiled cells. The tightly coiled cells which appear as rods or cylinders are 1.5–2.5 μ long and 0.8–1.0 μ wide. The cells moved erratically and are propelled by 1–6 flagella which were 3–5 μ long.

Abstract: A 0.2 M mixture of L-leucine and L-lysine, a pair of amino acids which Machlis (1969) had shown could attract the zoospores of Allomyces in much lower concentrations, was found to immobilize zoospores by stopping flagellar motion. While the age of the spores does not affect the response to the amino acid mixture, the time for 100% immobilization does increase with increasing numbers of spores. Viability of the spores is not altered by treatment with the mixture of L-leucine and L-lysine and subsequent germling development is highly synchronized.

Abstract: A nitrate reductase from the thermophilic acidophilic alga, Cyanidium caldarium, was studied. The enzyme utilises the reduced forms of benzyl viologen and flavins as well as both NADPH2 and NADH2 as electron donors to reduce nitrate.

Abstract: Walls from cysts, hyphae and sporangia of Phytophthora palmivora consist chiefly (ca. 90% dry wt) of β-glucans with 1,3-, 1,4- and 1,6-links. The glucans are predominatly β-1,3-linked but there are significant differences in the relative proportion of 1,3-, 1,6- and 1,4-linked glucosyl residues among the three wall types. There are also differences in protein content, susceptibility to degradation by various β-glucanases, and surface texture. The isolated cyst wall consists solely of a thin fabric of long, tightly interwoven, randomly oriented microfibrils. Both inner and outer surfaces of the cyst wall are distinctly microfibrillar. The hyphal wall has two different textures; the internal surface is distinctly microfibrillar while the external surface is non-fibrillar. In a germinated cyst, there is a zone of demarcation where the microfibrils of the cyst wall disappear into the smooth outer texture of the germ tube wall. An exo-β-1,3-glucanase preferentially removed the amorphous material of the outer surface of the germ tube leaving exposed a continuous microfibrillar fabric from cyst to hyphal tube. Conceivably, the textural and structural differentiation of the cell wall may play a decisive role in cellular morphogenesis.

Abstract: The two types of scales of the coccolithophorid Hymenomonas (= Cricosphaera) carterae have been studied with the negative staining technique. Both types of scales, including the non-mineralized circular ones and the larger, mineralized elliptical ones are made up of a highly ordered network of radial and concentric fibrils. Both fibrils are ribbon shaped and have dimensions of 10–22×30–75 A in cross-sections. The margin of the scales is composed of two closely associated fibrillar ribbons which are observed occasionally in edge view. In the elliptical scales, the periphery of the fibrillar network often is obscured by a deposition of the coccolith calcium carbonate. The substructure of the fibrils, the occurrence of kinking sites, and the fibrillar resistance to alkaline and weak acid treatments strongly resemble the scales of Pleurochrysis scherffelii. In relation to the recent findings of Brown and co-workers (Brown et al., 1969, 1970) on scale formation processes, it is hypothesized that the fibrillar network of the scales of both species is structurally and chemically identical, and that the fibrillar material consists of a cellulose-like polysaccharide.

Abstract: 1. Mycelial extracts and culture filtrates of two species of Trametes have been assayed for various enzymatic activities. The tests performed after 3 and 10 days of mycelial growth on 3% malt extract have revealed that the spectra of external enzymes secreted by both strains differ markedly from their intracellular equivalents. A great part of the external isozyme bands, shown in disc electrophoresis and isoelectric focusing, have no equivalent acting within the cell. 2. These findings are discussed on the basis of special functional properties which have to be attributed to external enzymes. It is concluded that a great number of them are not simply internal enzymes which happen to be active outside the cell but that they are synthesized or at least modified especially for extracellular action under these special conditions. 3. A comparison between the two species of Trametes has shown that both produce enzymes with identical function. This indicates their strong relationship, though the electrophoretic mobility of most of the enzymes is not comparable. The consequences of these findings for chemical taxonomy are discussed.

Abstract: Anabaena flos-aquae was grown in chemostats with phosphate-limiting growth and dilution rate of 0.015–0.03 h-1. The yields of cells were dependent on dilution rate and a two-fold increase obtained by growth in the presence of 15 mM KNO3. Alkaline phosphatase activity varied 20-fold, lowest activity with excess phosphate light-limited cells and the highest activity with cells grown in the presence of 15 mM KNO3. There was no correlation between hot water soluble phosphate of cells and alkaline phosphatase activity.

Abstract: Two closely similar phycoerythrins were purified from Cryptomonas sp. The two proteins were indistinguishable with respect to native molecular weight, subunit structure, photolability and immunological specificity, and differed only in their isoelectric points (pH 5.74 and 6.35), as determined by isoelectric focussing in polyacrylamide gels. Each protein consisted of two unequal subunits, α (mol. wt. 11,800) and β (mol. wt. 19,000), and each subunit contained covalently bound chromophore. In contrast to the blue-green and red algal phycoerythrins studied thus far, the Cryptomonas sp. phycoerythrins are extremely photolabile; exposure of the purified proteins to relatively short periods of intense illumination with visible light produces a marked decrease in fluorescence and in absorbance at 567 mμ.

Abstract: Treponema denticola was grown in serum-containing media to which 14C-labelled compounds were added. Determinations of radioactivity in the products formed indicated that the organism fermented alanine, cysteine, glycine, serine, and glucose. Fermentation products included acetate, lactate, succinate, formate, pyruvate, ethanol, CO2, H2S, and NH3. The products formed from glucose constituted a small portion of the total products. Assays of enzymatic activities in cell extracts indicated that the organism degraded glucose via the Embden-Meyerhof pathway. T. denticola possessed a coenzyme A-dependent CO2-pyruvate exchange activity associated with a clostridial-type clastic system for pyruvate metabolism. Phosphotransacetylase and acetate kinase activities were present in cell extracts. Acetyl phosphate formation and benzyl viologen reduction were detected when cell extracts were incubated with pyruvate, serine or cysteine. The data indicate that T. denticola is an amino acid fermenter and that it possesses the enzymes needed for the fermentation of glucose. However, glucose does not serve as the primary substrate when the organism grows in media including both this carbohydrate and amino acids.

Abstract: In exponentially growing cultures of the blue-green alga Microcystis aeruginosa the number of gas vacuoles per cell decreases and reaches a value of 4.5×103 at 1.2×107 cells per ml. The assembly of gas vacuoles with respect to number and length was followed after the organelles were caused to collapse by a pulse of ultrasound. The change in the number N of gas vacuoles per cell is N=224.8×t0.757, 0