Electron microscopic study of meningococci in stab cultures

The study of the ultrastructure of meningococci (strain C0638) in the process of submerged batch cultivation permitted the authors to follow changes in the fine structure of these microorganisms in different phases of the growth of the culture. Thus, the meningococcal populations retained their ultrastructure most intact during the exponential phase and the growth rate deceleration phase. During these growth phases a faintly pronounced reaction of the surface structures with ruthenium red was observed. In the stationary phase and in the atrophy phase this reaction was completely absent. The accumulation of exotoxin bubbles in the membrane was shown to achieve its maximum in the atrophy phase; besides, these structures regularly appeared at the death of the cells under the action of alkali. A hypothesis explaining the appearance of these bubbles is put forward.     

Genomic changes arising in long-term stab cultures of Escherichia coli

Genomic scans of clones isolated from long-term stab cultures of Escherichia coli K-12 showed the loss of two large segments of the genome, with each lost segment being approximately 20 kb long. A detailed analysis of one of the deletions, located between 5.4 and 5.9 min, revealed that similar deletions had arisen in several other stab cultures. All deletions of this type exhibited a right terminus ending precisely at an IS5A element and a left terminus that varied over an approximately 5-kb range but was bordered in all but two cases by sequences belonging to the preferred consensus target sequence for IS5, YTAR. The ubiquity of such deletions in independent stab cultures and the increase in their frequency over time argue that they have a selective advantage. It is speculated that the loss of the crl locus is responsible for the selective advantage of the deletions.     

Oxygen or glucose deprivation-induced neuronal injury in cortical cell cultures is reduced by tetanus toxin.

We examined glutamate-mediated neurotoxicity in cortical cell cultures pretreated with 1-5 micrograms/ml tetanus toxin to attenuate the Ca(2+)-dependent release of neurotransmitters. Efficacy of the tetanus toxin pretreatment was suggested by blockade of electrical burst activity induced by Mg2+ removal and by reduction of glutamate efflux induced by high K+. Tetanus toxin reduced neuronal injury produced by brief exposure to elevated extracellular K+ or to glutamate, situations in which release of endogenous excitatory neurotransmitter is likely to play a role. Furthermore, although glutamate efflux evoked by anoxic conditions may occur largely via Ca(2+)-independent transport, tetanus toxin attenuated both glutamate efflux and neuronal injury following combined oxygen and glucose deprivation. With prolonged exposure periods, the neuroprotective efficacy of tetanus toxin was comparable to that of NMDA receptor antagonists. Presynaptic inhibition of Ca(2+)-dependent glutamate release may be a valuable approach to attenuating hypoxic-ischemic brain injury.     

The effect of cholera toxin on myogenesis in rat skeletal muscle cultures

Cholera toxin, when added to rat primary embryonic muscle cultures, stimulates intracellular cyclic AMP and cell fusion. The effect on cell fusion can be mimicked by daily addition of dibutyryl cyclic AMP, but not by choleragenoid, which like cholera toxin binds to the ganglioside G_M1, but does not stimulate adenyl cyclase. The effects on fusion of three other agents known to affect intracellular cyclic AMP levels, indomethacin, isobutylmethyl xanthine, and isoproterenol were also studied. It is concluded that intracellular cyclic AMP levels are important in the control of rat skeletal muscle cell fusion.     

Limited controlled trial of the reactogenic properties of ADTP vaccines containing stab cultures as the pertussis component

The reactogenic properties of adsorbed DPT vaccine containing Bordetella pertussis cultures, grown by submerged cultivation, as the pertussis component were studied. The study revealed that the vaccine was low-reactogenic: no severe postvaccinal reactions were recorded in immunized children. The frequency and intensity of febrile and local reactions in children immunized with adsorbed DPT vaccine under trial and the commercial preparation commonly used in the USSR were identical, but considerably less pronounced than in children immunized with foreign vaccines having similar composition.     

Production of the chlorosis inducing toxin in liquid cultures ofPseudomonas phaseolicola (Burkh.) Dowson

Amino acids affected amount and time course of the toxin production on complex as well as on chemically defined media. With glutamic acid the toxin content was high in the early growth stage but decreased later on, while the reverse was true with cysteine as single amino acid.Toxin production was highest at temperatures below 20°C. Generally, the toxin production started during the rapid growth phase and reached its maximum shortly after growth ceased. Chloramphenicolinhibited bacteria did not produce much toxin. Bacterial cells contained relatively low amounts of the toxin. Conditions for toxin production in large quantities are described. The feasibility to produce tritiummarked toxin was studied.Comparison of different strains showed that avirulent or weakly virulent halo-less strains do not produce detectable amounts of toxin. However, there was no correlation of the toxin production to the grouping of the bacterial strains in race 1 or the more virulent race 2.