Sorbistin, a new aminoglycoside antibiotic complex of bacterial origin. I. Production, isolation and properties

A strain of a new Pseudomonas species produced the aminoglycoside antibiotic complex, sorbistin, which was separated by ion-exchange chromatography into three bio-active components A1, A2 and B, and two bio-inactive components C and D. Sorbistins A1, A2 and B showed moderate intrinsic activity against a wide range of bacterial species and inhibited most of the aminoglycoside-resistant organisms. Sorbistin A1 exhibited the highest activity among the three bio-active components. Sorbistins showed low order of acute toxicity in mice.     

Circadian rhythms of digestive enzymes in the small intestine of the rat. II. Effects of fasting and refeeding

The effects of fasting were examined on the rhythmic changes in the activities of maltase [EC 3.2.1.20] and leucine aminopeptidase [EC 3.4.11.1] in the small intestine of rats which has been kept under scheduled feeding conditions. Irrespective of whether the rats had been kept on a daytime or nighttime feeding schedule, the rhythms of maltase and leucine aminopeptidase persisted when the animals were starved. However, the amplitude of the leucine aminopeptidase rhythm began to decrease from the first day of fasting, while that of maltase did not. Conspicuous rhythms persisted for at least 2 days during fasting, but they gradually became vague and disappeared after 5 days. When rats were refed after fasting, the leucine aminopeptidase activity increased within a few hours, but the maltose activity did not. It is suggested that the rhythms of the digestive enzymes in the small intestine of rats are not a direct consequence of food intake, but are triggered off by the anticipatory mechanism which operates when rats expect to be fed. The rhythmic change of leucine aminopeptidase seemed to be intensified by food intake.     

Condensation of 7 H -Benzo[ de ]naphthacene-7-one (9,10-Dibenzanthrone)

We have synthesized undecacyclic aromatic hydrocarbons using condensation of dibenzoanthrones. For example, dibenzo[ a,o ]dinaphtho[3,2,1- cd ;1,2,3- lm ]perylene, diphenanthra[1,2,3- cd ; 3,2,1- lm ]perylene and diphenanthra[2,3,4- cd ;4,3,2- lm ]perylene were produced from 5,6-, 8,9- and 10,11-dibenzoanthrones, respectively. In the present study, we have extended our work and aimed to synthesize new undecacyclic aromatic hydrocarbons by the use of 9,10-dibenzoanthrone (7 H -benzo[ de ]naphthacene-7-one) as a starting material. 9,10-Dibenzoanthrone was prepared by the cyclization of 1,2'-dinaphthylketone in aluminum chloride anhydride and sodium chloride, and the structure was confirmed by NMR measurements. It dissolves into ethanol and crystallizes in pale yellow needles; its melting point is 198.2-199.3°. The condensation of 9,10-dibenzoanthrone should give undecacyclic aromatic hydrocarbons such as benzo[ vwx ]naphtha[12,1,2- cde ] hexaphene.     

On the torque mechanism of Savonius rotors

The aerodynamic performance and the flow fields of Savonius rotors at various overlap ratios have been investigated by measuring the pressure distributions on the blades and by visualizing the flow fields in and around the rotors with and without rotation. Experiments have been performed on four rotors having two semicircular blades but with different overlap ratios ranging 0 to 0.5. The static torque performance is improved by increasing the overlap ratio especially on the returning blade, which is due to the pressure recovery effect by the flow through the overlap. On the other hand, the torque and the power performance of the rotating rotor reaches a maximum at an overlap ratio of 0.15. This effect is largely created by the Coanda-like flow on the convex side of the advancing blade, which is strengthened by the flow through the overlap at this small overlap ratio. However, this phenomenon is weakened as the overlap ratio is further increased suggesting a deteriorated performance of the rotor. Observations of the flow inside the rotor indicate an increased recirculating region at such large overlap ratios, which also suggests a reduced aerodynamic efficiency for rotors with large overlap.     

Evaluation of sorbitol-salicin MacConkey medium containing cefixime and tellurite (CT-SSMAC medium) for isolation of Escherichia coli O157:H7 from raw vegetables

The utility of CT-SSMAC medium (sorbitol-salicin MacConkey medium containing cefixime and tellurite) for the isolation of Escherichia coli O157:H7 from raw vegetables was investigated. The colonies of all E. coli O157:H7 and O157:NM strains tested were colorless and beta-galactosidase-positive on CT-SSMAC medium. Furthermore, the number of colorless colonies on the CT-SSMAC medium was less than that on the sorbitol MacConkey medium containing cefixime and tellurite (CT-SMAC medium) from several raw vegetable samples. All colorless colonies grown on CT-SSMAC medium from raw vegetable samples were beta-galactosidase-negative. These findings suggest that the CT-SSMAC medium is useful for the isolation of E. coli O157:H7 from raw vegetable samples.     

Organic sulfur compounds and polycyclic hydrocarbons transferred to oyster and mussel from petroleum suspension: Identification by gas chromatography and capillary mass chromatography

An attempt was made to determine the organic sulfur compounds usually contained in crude oil as markers of oil pollution in shellfish. The oyster (Crassostrea gigas) and mussel (Mytilus edulis) were maintained in a controlled laboratory environment and in water with a suspension of crude oil. Capillary column gas chromatography-mass chromatography of extracts showed the presence of organic sulfur compounds of alkyl benzothiophene (C₂C₄), dibenzothiophene and alkyl dibenzothiophene (C₁C₄). Coexistence of polycyclic aromatic hydrocarbons with organic sulfur compounds was found in oyster and mussel. The time courses of concentration ratios of organic sulfur compounds in the oyster and the mussel were determined by gas chromatography connected with flame photometric detector.     

Gene A product of phi X174 is required for site-specific endonucleolytic cleavage during single-stranded DNA synthesis in vivo

A DNA protein complex that is a precursor of mature phi X174 phage was isolated. The complex sedimented with an S value of 50 in a sucrose gradient and contained phage DNA consisting of a replicative form molecule with an extended tail of single-stranded viral DNA. The viral-strand DNA ranged from one to two genomes in length. Proteins coded on the phi X174 genome as well as the host genome were associated with the viral DNA in the 50S precursor complex. Our results indicated that both viral DNA synthesis and cleavage of the growing viral-strand DNA occurred in the 50S complex.