Outdoor mass culture of Spirulina maxima in sea-water

Summary The results of a whole year experiment on the outdoor mass culture of Spirulina maxima strain 4Mx on fertilized sea-water are reported. Carbonate and phosphate precipitation in the sea-water media was prevented by maintaining a low concentration of phosphate and by controlling the pH in the range of 8.0–8.3. The mean annual yield of biomass on sea-water plus urea as nitrogen source was 7.35 g (dry weight) m^-2· day^-1, a value slightly lower than that obtained on the standard bicarbonate medium (8.14 g · m^-2 · day^-1). On sea-water plus nitrate the yield was only 5.2 g·m^-2·day^-1. The nitrogen content of the biomass was higher in summer and lower in winter. The seasonal effect was more evident when nitrate was the nitrogen source.     

Host receptor sites involved in the attachment of Bdellovibrio bacteriovorus and Bdellovibrio stolpii

Abstract The location of lipoteichoic acid and 3 cell wall-associated protein antigens in fresh isolates of Streptococcus mutans (serotype c ) and in variants derived from these parental strains by repeated subculture in vitro has been examined by electrophoretic and dot-immunobinding techniques. Following subculture there was a marked shift in the distribution of all four antigens from the cell wall to the extracellular culture supernatants. It is therefore apparent that that the decreased hydrophobicity and the impaired ability of the subcultured variants to colonise in vivo, as observed by others, cannot be correlated with changes in a single surface molecule.     

NMR studies in solution of poly-L-proline

The isomerization of poly-L -proline in different solvents has been studied by NMR spectroscopy. Different resonance signals for the CH_α protons have been obtained for the two different helical conformations of thus compound, namely form I and form II.     

Determination of transference numbers from membrane potential data

A system composed of two ionic solutions, solution () and solution (), which are isotonic and separated by a membrane permeable to the solvent and to at most two of the ionic components present in the solutions, is considered. The variations of the difference of electric potential between solution () and solution (), in the steady state and for zero electric current, corresponding to variations in the composition of e.g. solution (), are found to depend only on the properties of the membrane phase at the boundary with solution (). This result is deducible under loose assumptions as to the dependence of the properties of transport and absorption of the permeant components in the membrane on their activities in solution. It can therefore be particularly useful for the study of systems, like biological membranes, whose structural and chemical composition is so poorly known that any assumption about that dependence is hardly justifiable.     

Germination of Single Bacterial Spores

Changes in refractility and optical density occurring in individual spores of Bacillus cereus T and B. megaterium QM B1551 during germination were investigated by use of a Zeiss microscope photometer. The curves revealed that the germination process in single spores had two distinct phases; an initial rapid phase was followed by a second slower phase. Under the experimental condition employed, the first phase of germination of B. cereus spores lasted for approximately 75 +/- 15 sec, whereas the second phase lasted for 3 to 4.5 min. In B. megaterium spores, the first phase was observed to last for approximately 2 min and the second phase for more than 7 min. The duration of the second phase was dependent on conditions employed for germination. The kinetics of the first phase were strikingly similar under all conditions of physiological germination. Time-lapse phase-contrast microscopy of germinating spores also revealed the biphasic nature of germination. It was postulated that the first phase represents changes induced by an initial partial hydration of the spore and release into the medium of dipicolinic acid, whereas the second phase reflects degradation of the cortex and hydration of the core.     

THE ULTRASTRUCTURE OF PORPHYRIDIUM CRUENTUM

An electron microscopic examination of Porphyridium cruentum revealed the presence of mitochondria which had been reported absent in this aerobic organism. The chloroplast in this red alga was found to contain small granules (about 320 A) regularly arranged along the parallel chloroplast lamellae. The chloroplast granules differ in size and staining intensity from the ribosomes located in the cytoplasm. Two tubular elements are described. One type (450 to 550 A) is associated with the Golgi bodies. Another type (350 A), in the cell periphery, is believed to connect the endoplasmic reticulum and the cell membrane. Daughter nuclei were found to be positioned at opposite ends of the cell prior to commencement of cell division. Cytokinesis is accomplished by an annular median constriction causing the gradual separation of the chloroplast, pyrenoid, and other cell organelles, resulting in two equal daughter cells. No appreciable differences were observed between cells grown in high light (400 ft-c) and low light (40 ft-c). Structural differences between young and old cells were compared.     

The ATP-bioluminescence method for a rapid evaluation of the microbial activity in the stone materials of monuments

The examination of the state of conservation of works of art in stone includes the assessment of the presence of microbiological agents on the surface of the decayed monuments. These microorganisms can accelerate, via their metabolic activity, the decay process of the stone surface. At present this assessment is made with the traditional techniques for the microbiological examination of the soil, provides results only after a delay of 30 days. A bioluminescent ATP assay should provide rapid quantitation of actively growing organisms on the surface of a stone monument, and the applicability of this technique was verified on some samples of sandstone (Pietraforte) collected from a historic building (the Strozzi Palace) in Florence. These samples were evaluated for the amount of the ATP and the total number of microorganisms. The results obtained suggest that the bioluminescent assay could be suitable for detecting and quantitating the presence of microorganisms in a sample of stone.     

A rat Sertoli cell factor similar to basic fibroblast growth factor increases c-fos messenger ribonucleic acid in cultured Sertoli cells

We have shown that the cultured Sertoli cell from the immature rat contains a fibroblast growth factor (FGF)-like factor. It behaves as a cationic peptide, is a potent competence factor for BALB/c3T3 mouse embryo fibroblasts, and displays a high affinity for heparin. Both bovine basic FGF and Sertoli cell FGF-like factor rapidly increase c-fos mRNA in cultured Sertoli cells. FSH, serum, and phorbol esters individually stimulate c-fos in cultured Sertoli cells whereas platelet-derived growth factor, epidermal growth factor, and insulin-like growth factor-I have little affect. However, unlike FSH, basic FGF does not stimulate an increase in cAMP and unlike either serum or phorbol esters, basic FGF does not stimulate phosphoinositol turnover or intracellular calcium changes. When Sertoli cell protein kinase C activity is suppressed by preexposure to phorbol ester, basic FGF continues to be a potent stimulator of c-fos, indicating that the calcium/phospholipid pathway is not involved in FGF induction. Basic FGF and FSH also increase jun-B mRNA levels in cultured Sertoli cells. In response to FGF, jun-B is more transiently increased than c-fos. In contrast, in response to FSH, jun-B persists longer than c-fos. These results indicate that cultured Sertoli cells contain a FGF-like factor that increases c-fos mRNA via a mechanism not involving cAMP and the calcium/phospholipid pathways. The different responsiveness of c-fos and jun-B to FSH and basic FGF may explain differences in the ultimate actions of these two ligands.