Macrophylloside, a flavone glucoside from Primula macrophylla

A new flavone glucoside macrophylloside has been isolated from the whole plant of Primula macrophylla and its structure was determined by spectroscopic methods as 2′-hydroxy-7-O-β- -glucopyranosyloxyflavone. Sitosterol glucoside was also isolated for the first time from this plant.     

Host-vector systems for the thermotolerant methanol-utilizing bacteriaMethylophilus spp. KISRI-Strains

Fourteen recombinant plasmids were constructed by inserting fragments of pSAS, a naturally occurring plasmid ofMethylophilus spp. KISRI-5, into the multiple cloning sites of pUC19. Six recombinants and three knownEscherichia coli plasmids were used to transform three thermotolerant methylotrophic KISRI strains by use of an optimized protocol of electroporation. Analysis of transformants for plasmid DNA showed that all plasmids were stable in the methylotrophic hosts. These studies offer opportunities to developMethylophilus spp. as host-vector systems.     

Role of verocytotoxigenic Escherichia coli in cattle and buffalo calf diarrhoea

Abstract 273 Strains of Escherichia coli isolated from diarrhoeic and healthy control cattle and buffalo calves in Sri Lanka, were tested for Verocytotoxin (VT) and for heat-stable (ST) and heat-labile (LT) enterotoxins. VT and ST toxigenic E. coli were significantly associated with diarrhoea, accounting for 28% and 18% of diarrhoeic episodes, respectively. LT toxigenic E. coli were not significantly associated with diarrhoea.     

Serotypes of verocytotoxigenic Escherichia coli isolated from cattle and buffalo calf diarrhoea

Abstract Parasporal crystals of the recently isolated Bacillus thuringiensis var. tenebrionis are toxic for coleopteran larvae. Unlike those of other strains they are soluble either in aqueous solutions of NaBr at neutral pH or in water after titration to pH values above pH 10.0. The dissolved crystal protein readily forms crystals after removal of the salt or neutralization. The crystal protein was not found to differ much in the amino acid composition from other crystal proteins. The parasporal crystals are composed of subunits of M _r 68 000 which are not linked by disulfide bridges.     

Identification of Staphylococcal Hemolysins by an Electrophoretic Localization Technique

A technique for identifying and characterizing staphylococcal hemolysins by first separating them electrophoretically in barbital-buffered agar gel (pH 8.4) at 5 ma/cm for 2 hr and then determining their hemolytic activities by exposing them to human, horse, rabbit, and sheep erythrocytes is described. The alpha-hemolysin produced by a White variant of the Wood 46 strain of Staphylococcus aureus migrated 18 mm towards the cathode, and it lysed horse, rabbit, and sheep erythrocytes, whereas a Clear variant of the Wood 46 strain of S. aureus produced a lysin which migrated similarly to the alpha-hemolysin but lysed only rabbit cells. This latter lysin was tentatively named alpha(1)-lysin. This strain of S. aureus also produced beta-hemolysin which migrated 36 mm towards the cathode and lysed sheep cells. beta-Hemolysin produced by some strains of S. aureus showed considerable tailing during electrophoresis, whereas beta-hemolysin produced by other strains of S. aureus migrated as a well-defined peak. A lysin migrating 11 mm towards the anode was probably delta-lysin. It was, however, not produced in sufficient concentration when the cultures were grown in semisolid medium.     

Purification and Properties of Staphylococcal δ-Hemolysin I. Production of δ-Hemolysin

Concentrated preparations of staphylococcal delta-hemolysin were obtained by growing selected hemolytic colonies from the 146P strain of Staphylococcus aureus on dialysis membranes laid over Brain Liver Heart agar plates at 37 C for 20 hr under 10% CO(2) and harvesting the growth from five such membranes in 1.0 ml of deionized distilled water. Incubation in a humid environment facilitated this harvesting procedure. Incubation longer than 40 hr or incubation under CO(2) higher than 10 to 20% gave lower yields of delta-lysin. Addition of a sugar, fermented by the organisms, resulted in lower yields of delta-hemolysin. Agar, although separated from the growing cells by the dialysis membrane, did potentiate delta-hemolysin production. Addition of 0.1% agar to the inoculum further enhanced this potentiation. delta-Hemolysin produced in broth or semisolid cultures was excessively diluted with the media. Dialysis membranes prevented this dilution and thus yielded concentrated preparations of delta-hemolysin.