Rapid Identification by Polymerase Chain Reaction of Staphylococcal Exfoliative Toxin Serotype A and B Genes

A new system was designed to detect staphylococcal exfoliative toxin A (ETA) and B (ETB) genes by the polymerase chain reaction (PCR). The primer pairs for the ETA gene (eta) were 20 and 20-mer, and its PCR product was a 741-bp eta fragment, while the primer pairs for the ETB gene (etb) were also 20 and 20-mer, and its PCR product was a 629-bp etb fragment. When these primers were simultaneously used in the PCR, the two types of ET were clearly detected as two bands in an ETA and ETB double-producer using only one colony within 3 hr. We examined 66 strains of Staphylococcus aureus isolated from patients with staphylococcal scalded skin syndrome (SSSS) and compared the results obtained by ELISA and PCR. The same results were obtained for 56 of the strains, i.e., 30 strains were ETA producers, 20 strains were ETB producers, and 6 strains were double-producers. However, positive results were obtained for 5 of the 10 non-ET-producing strains. Two of these strains were judged by PCR as ETA producers and three as ETB producers. Thus, PCR is very sensitive and rapid in detecting ETA and ETB gene fragments in colonies isolated from patients with SSSS.     

Role of water receptor in the frog

To elucidate the role of the water receptor in the frog (Rana catesbeiana), reflex activities elicited by its excitation were studied. Application of tap water to the oral mucosa depressed the rhythmical movement of gorge (buccal) respiration, accompanied by an elevation of the inner pressure of the oral cavity (buccal pressure). Tonic reflex discharges were elicited in the nerves innervating the submental and submaxillary muscles, which close the nostrils, the pterygoid and the profound portion of the major masseter muscles, which produce a strong bite, and the geniohyoid and hyoglossus muscles, which elevate buccal pressure. These muscles, except for the pterygoid, also participate in the rhythmical movement of gorge respiration as expiratory muscles. Rhythmical movements in the minor masseter and sternohyoid muscles, which act as inspiratory muscles in gorge respiration, were depressed by the water stimulation of the oral mucosa. These findings indicate that the water receptor plays a role in the interruption of gorge respiratory movements, accompanied by an elevation of buccal pressure.     

A specific microbial sensor for formic acid

Summary A microbial sensor consisting of immobilized Clostridium butyricum, two gas permeable Teflon membranes and fuel cell type electrode was suitable for the determination of formic acid. When the sensor was inserted into the sample solution containing formic acid, the current increases to a steady state with a response time of 20 min. The relationship between the steady state current and the formic acid concentration is linear up to 1 000 mg l^–1. The currents are reproducible with an average relative error of 5%. Selectivity of the sensor is satisfactory. Results obtained with this sensor and by gas chromatography were in good agreement (regression coefficient; 0.98) when the cultivation medium of Aeromonas formicans was employed. Immobilized Clostridium butyricum is stable for more than 20 days.     

The crystallization of mitochondrial cytochrome oxidase-cytochrome c complex

Conditions are described under which crystals are formed with equimolar complex of mitochondrial cytochrome oxidase and cytochrome c. Characteristic absorption bands of the solubilized crystals could be attributed to the cytochrome oxidase-cytochrome c complex with heme a:c ratio of 2:1. Activity of crystals shows more close heme-heme interaction between two cytochromes than that of the mixture.     

Cytochrome oxidase of Nitrobacter agilis: isolation by hydrophobic interaction chromatography

Cytochrome oxidase has been purified from Nitrobacter agilis using hydrophobic interaction chromatography. The purified preparation contained 3-5% phospholipid and migrated as a single band during polyacrylamide gel electrophoresis under nondissociating conditions, but appeared as three bands in the presence of sodium dodecyl sulfate and 6 M urea. These three bands corresponded to molecular weights of 37 000, 25 000, and 13 000. The absorption spectra of cytochrome oxidase isolated from Nitrobacter were similar to those reported for a-type cytochrome oxidase from other sources and exhibited absorption maxima at 420 and 600 nm when oxidized and 443 and 606 nm when reduced. The purified enzyme reacted both with horse heart and Nitrobacter cytochrome c. The enzymatic activity depended upon the pH of reaction mixture, with the maximum activity at pH 6.5 and 7.5 for Nitrobacter and horse heart cytochrome c, respectively. The activity of the purified enzyme was inhibited by cyanide, azide, and diethyl dithiocarbamate.     

1,4-Methylhistamine is a specific substrate for type B monoamine oxidase

1,4-Methylhistamine was characterized as substrate for monoamine oxidase (MAO) in rat liver mitochondria. The $\text{K}$_m and $\text{V}$_max values were 38.8 μM and 6.33 nmoles/mg protein/60 min, respectively. The inhibition experiments with clorgyline and deprenyl, the selective inhibitors for type A and type B MAO, showed that 1,4-methylhistamine was specific for type B MAO.