Vigorous atmospheric motion in the red supergiant star Antares.

Red supergiant stars represent a late stage of the evolution of stars more massive than about nine solar masses, in which they develop complex, multi-component atmospheres. Bright spots have been detected in the atmosphere of red supergiants using interferometric imaging. Above the photosphere of a red supergiant, the molecular outer atmosphere extends up to about two stellar radii. Furthermore, the hot chromosphere (5,000 to 8,000 kelvin) and cool gas (less than 3,500 kelvin) of a red supergiant coexist at about three stellar radii. The dynamics of such complex atmospheres has been probed by ultraviolet and optical spectroscopy. The most direct approach, however, is to measure the velocity of gas at each position over the image of stars as in observations of the Sun. Here we report the mapping of the velocity field over the surface and atmosphere of the nearby red supergiant Antares. The two-dimensional velocity field map obtained from our near-infrared spectro-interferometric imaging reveals vigorous upwelling and downdrafting motions of several huge gas clumps at velocities ranging from about -20 to +20 kilometres per second in the atmosphere, which extends out to about 1.7 stellar radii. Convection alone cannot explain the observed turbulent motions and atmospheric extension, suggesting that an unidentified process is operating in the extended atmosphere.

Catabolite inactivation, cyclic AMP and protein phosphorylation in the methylotrophic yeast Hansenula polymorpha.

The inactivation of the peroxisomal enzyme alcohol oxidase and the cytoplasmic enzymes fructose-1,6-bisphosphatase, malate dehydrogenase and phosphoenolpyruvate carboxykinase was found to occur after addition of glucose to methanol-grown cells of the yeast Hansenula polymorpha. The concentration of cyclic AMP increased nearly twofold within 3 min under the same conditions. In crude extracts of H. polymorpha about 20 proteins are phosphorylated by cyclic AMP dependent protein kinases, among them also fructose-1,6-bisphosphatase. No phosphorylation of the alcohol oxidase protein could be detected. From this fact, it was concluded that the inactivation of the peroxisomal alcohol oxidase is independent of cyclic AMP-dependent protein phosphorylation.

Degradation and dehalogenation of monochlorophenols by the phenol-assimilating yeast Candida maltosa.

The phenol-assimilating yeast Candida maltosa is able to degrade monochlorophenols but cannot grow on these substrates. 3- and 4-chlorophenol were broken down very rapidly by phenol-grown cells under the formation of 4-chlorocatechol, 5-chloropyrogallol and 4-carboxymethylenebut-2-en-4-olide with concomitant release of chloride. 2-Chlorophenol was partially converted into cis,cis-2-chloromuconic acid via 3-chlorocatechol which was also obtained from 3-chlorophenol in low amounts. No further metabolites containing chloride were found. The dehalogenation step in the chlorophenol degradation is the cycloisomerization of the cis,cis-chloromuconic acid to 4-carboxymethylenebut-2-en-4-olide in the ortho fission pathway.

Amplification of pBR322 plasmid DNA in Escherichia coli relA strains during batch and fed-batch fermentation.

Fermenter studies under batch and fed-batch conditions were carried out to test the possibility of plasmid pBR322 production in large amounts by using E. coli relA strains. High amplification rates of pBR322 plasmid DNA were observed in E. coli CP79 (relA) and E. coli CP143 (relA) in both batch and fed-batch cultivation after exhaustion of the amino acid arginine. The concentrations of plasmid DNA per unit of biomass were nearly the same in batch and in fed-batch fermentations of E. coli CP79 and E. coli CP143. Therefore, the significantly higher biomass concentration of the two strains after fed-batch fermentation gave a dramatic increase in the yield of plasmid DNA per litre of medium in comparison to the batch process. The results support the suggestion that E. coli relA strains are suitable hosts for production of large amounts of ColE1-derived plasmids for recombinant DNA research.

[Activities of gluconeogenetic enzymes in the yeast Candida maltosa during growth on glucose or ethanol]. / Aktivitäten gluconeogenetischer Enzyme in der Hefe Candida maltosa bei Wachstum auf Glucose und Ethanol.

The activities of fructose-1,6-bisphosphatase, malate dehydrogenase and PEP carboxykinase were tested during discontinuous growth of the n-alkane-assimilating yeast Candida maltosa on glucose or ethanol. As expected, the highest activities of the enzymes were measured in the early log phase of growth on ethanol and the lowest in the early log phase of growth on glucose. However, the differences in the activities are much smaller than in Saccharomyces cerevisiae and other yeasts under similar conditions. Therefore, we conclude that catabolite repression does not play an essential role in the control of gluconeogenesis in Candida maltosa.

Cyclic AMP-dependent phosphorylation of fructose-1,6-bisphosphatase and other proteins in the yeast Candida maltosa.

In crude extracts of Candida maltosa, about 12 proteins are phosphorylated in the presence of cAMP or of a catalytic subunit of cAMP-dependent protein kinase. A strongly labelled protein spot occurred in the position of fructose-1,6-bisphosphatase both after electrophoresis of crude extracts incubated with cAMP and of a partially purified fructose-1,6-bisphosphatase incubated with a catalytic subunit of cAMP-dependent protein kinase. No phosphorylation of the cytoplasmic malate dehydrogenase could be detected. From these results it was concluded that cAMP-dependent phosphorylation plays an important role in the catabolite inactivation of fructose-1,6-bisphosphatase in Candida maltosa, as described for Saccharomyces cerevisiae.

Utilization of phenol by hydrocarbon assimilating yeasts.

77 Ascomycetous, basidiomycetous as well as imperfect yeast strains of 46 different species and 20 genera were tested for growth with the substrates n-octane, n-hexadecane, and phenol. Of 59 yeast strains with ascomycetous cell wall structure 33 grew on hydrocarbons and 32 on phenol. No yeast strain out of 26 which are unable to use n-alkanes as a source of carbon and energy grew on phenol. In comparison with the latter 32 out of 33 n-hexadecane assimilating yeasts were also capable of using phenol. All n-octane utilizing yeasts of this group also assimilate phenol as a carbon source for growth. The correlation of the hydrocarbon assimilation with the phenol assimilation seems to be not so strong in the basidiomycetous yeasts. 7 out of 18 strains from this group grew on n-hexadecane and 13 on phenol. Furthermore, it could be shown that the use of hydrocarbons and phenol (as well as methanol) is strongly correlated with the coenzyme Q structure of the respective yeast strain. The results are discussed with respect to the particular chemical properties of the substrates used and the fact that coenzyme Q structure is considered to be an important marker of evolutionary relationships among yeasts.

Optical long-baseline interferometry: signal-to-noise ratio of Image reconstruction by optical phase-closure imaging and by speckle masking.

Optical multiple-mirror interferometers in space can yield fascinating angular resolution. For example, at lambda ~100 nm and with an interferometer diameter of 20 m, a resolution of 0.001 sec of arc can be obtained. From the speckle interferograms recorded with ground-based interferometers or space interferometers, diffraction-limited images can be reconstructed by various methods. In this paper the signal-to-noise ratio of the two image reconstruction methods, optical phase-closure imaging and speckle masking (triple correlation), will be investigated. The results show that (1) phase-closure imaging yields images with higher signal to noise ratio than speckle masking for bright objects and (2) speckle masking yields images with higher signal-to-noise ratio than phase-closure imaging for faint objects.

Astronomical speckle masking: image reconstruction by cross triple correlation.

Speckle masking is a speckle method that is capable of reconstructing true diffraction-limited images from astronomical speckle interferograms. Image degradation caused by the atmosphere and by telescope aberrations can be overcome completely. Speckle masking is a solution of the phase problem in speckle interferometry. We propose a new, modified version of speckle masking that is based on cross triple correlation processing (or cross bispectrum processing) instead of autotriple correlation processing. The advantage of cross triple correlation processing is the fact that undesired photon bias terms in the average bispectrum of the speckle interferograms are overcome completely. We show computer simulations (astronomical magnitude of ~16(m)) that illustrate the feasibility of the method.

Oxidation of naphthalene by Saccharomyces cerevisiae and Candida utilis.

The yeasts Saccharomyces cerevisiae 118 and Candida utilis 128 were examined for their ability to metabolize the polycyclic aromatic hydrocarbons naphthalene and anthracene. The two yeasts tested oxidized these aromatics. Metabolites were extracted and analyzed by thin layer chromatography and gas chromatography. The predominant oxidation product of naphthalene found in the culture medium was 1-naphthol.

Dihydroxyacetone kinase of methanol-assimilating yeasts. II. Partial purification and some properties of dihydroxyacetone kinase from Candida methylica.

Dihydroxyacetone kinase (DHAK) from the cell-free extract of methanol-grown Candida methylica was partially purified about 100-fold by a procedure employing streptomycin sulfate fractionation, ammonium sulfate fractionation, negative absorption on Cibacron blue F3G-A sephadex G 200 and DEAE-cellulose column chromatography. The enzyme was stable in 50 mM Tris-HCl buffer pH 7.5 containing 60% glycerol at -18 degrees C. The pH optimum for the activity of DHAK from C. methylica was 7.5. The purified enzyme phosphorylated dihydroxyacetone four times faster than D,L-glyceraldehyde. The apparent MICHAELIS-MENTEN constants for dihydroxyacetone and D,L-glyceraldehyde were 0.011 mM and 0.024 mM. Other C3 compounds including glycerol were not phosphorylated. ITP and UTP were used as phosphate donors with a reaction rate of 11% and 3.1%, respectively, in relation to ATP, whereas the reaction rates of DHAK from C. methylica with CTP or GTP were much lower than 1%. The reaction of DHAK depends upon the presence of divalent cations in the assay. The highest activity was found with Mg2+ ions. The reaction rates with Co2+ or Ca2+ ions were only 57.3% and 30.3%, respectively, in relation to the assay with magnesium ions. Manganese chloride in the assay led to a complete loss of activity.

Dihydroxyacetone kinase of methanol-assimilating yeast. I. Regulation of dihydroxyacetone kinase from Candida methylica in situ.

In order to investigate the control behaviour of dihydroxyacetone kinase of methanol-grown Candida methylica under nearly physiological conditions kinetic and regulatory studies were carried out in situ. Yeast cells were made permeable to substrate and reaction products by treatment with Triton X-100. Normal Michaelis-Menten kinetics resulted in dependence upon the dihydroxyacetone concentration, both at the pH optimum of 7.6 and near the physiological pH-value of 6.5. The Km obtained for dihydroxyacetone was 0.02 mM, independent of the pH-value. The plots of dihydroxyacetone kinase activity as a function of the ATP concentration revealed complex kinetic characteristics with plateau regions. The maximum reaction rate was reached only after a lag time both at pH 7.6 and concentrations of ATP higher than 5 mM and at pH 6.5 and concentrations of ATP higher than 1.25 mM. Among a great number of tested metabolites no inhibitors of dihydroxyacetone kinase were found. Dihydroxyacetone kinase activity depending upon energy charge according to Atkinson exhibited curves of the U-type. These results and further data concerning the regulation of other enzymes obtained with C. methylica and other yeasts were the basis to propose a preliminary overall model of fine control of the carbon and energy metabolism of methanol-utilizing yeasts.

Regulation of NAD+- and NADP+-linked isocitrate dehydrogenase in the obligate methylotrophic bacterium Pseudomonas W6.

Cell-free extracts of the obligate methanol-utilizing bacterium Pseudomonas W6 catalyze the oxydation of isocitrate to alpha-ketoglutarate in the presence of NAD+ and NADP+. After electro-focusing of the crude extract of Pseudomonas W6 actually two distinct bands each of NAD+-linked isocitrate dehydrogenase (NAD+-IDH) and of NADP+-linked isocitrate dehydrogenase (NADP+-IDH) could be observed. The NAD+-IDH was completely separated from the NADP+-IDH by employing DEAE ion exchange chromatography and further purified by affinity chromatography using Cibacron blue F 3G-A. The NAD+-IDH was inhibited by a high energy charge, whereas the NADP+-IDH was found to be independent of energy charge. Consequently the NAD+-IDH showed the control behaviour of an enzyme of an energy-generating sequence which, however, equally fulfils a catabolic and an anabolic function. With respect to the inhibition by reduced pyridine nucleotides and alpha-ketoglutarate differences between NAD+-IDH and NADP+-IDH were also found. Only the NADP+-linked enzyme exhibited a feedback inhibition by its reaction products alpha-ketoglutarate and NADPH. This control behaviour gives evidence for the biosynthetic function of the NADP+-IDH. These results confer an amphibolic character to the sequence from citrate to alpha-ketoglutarate in the incomplete citric-acid cycle of Pseudomonas W6.

[Fe59 studies on the question of rabbit erythrocyte life-span]. / Untersuchungen mit 59Fe zur Frage der Lebensdauer von Kaninchen-Erythrozyten.

The present paper demonstrates a method to separate red cells of different age. The erythrocytes were separated by ultracentrifugation. The validity of this method was examined with radioactive iron (59Fe). During seventy days kinetic studies were performed in liver and spleen. A body scan was used to distinguish liver and spleen by radioactive iron.