Haemagglutination and tissue culture adhesion of Gardnerella vaginalis

Six strains of Gardnerella vaginalis were studied to examine the adhesin-receptor mechanism involved in their attachment to human red blood cells and an epithelial tissue culture cell line (McCoy). The adhesins involved in the attachment of the bacteria to each of these cells were proteinaceous but showed marked differences after various chemical or physical treatments, indicating that separate adhesins were present. Haemagglutinating strains were more hydrophobic than tissue-culture-adherent strains. Haemagglutination of human red blood cells by strains of G. vaginalis was inhibited by galactose, lactose, N-acetylneuraminic acid and phosphatidylserine. In contrast, the tissue-culture adherence of strains was not inhibited by these substances.     

Faded shaker, a lethal pigment and neurological mutation in the chicken

Faded shaker (fs) is a lethal condition in chickens resulting in a congenital tremor and a dilution of down and feather melanin. It is inherited as an autosomal recessive gene with the homozygote showing incomplete penetrance, the apparent result of a single dominant gene masking the effects of the fs/fs genotype. Mortality of the mutants occurred between 18 days of incubation and three months of age; most died before one week of age with half of the mutants dying before hatching. No specific cause of death was observed. The tremor had a frequency of 6 to 10 vibrations per second, was more pronounced in the posterior end of the bird and was constant over time within an individual. Weight of the faded shaker cerebellum was reduced by 7.6%, presumably due to an observed deficiency of myelin. The down and feather color of faded shakers ranged from almost normal to near white, but was constant over several feather generations within an individual. Faded shaker melanosomes were both deficient in number and incompletely melanized. Melanocyte dendrition and melanosome distribution were both normal. Skin transplants showed that the dilution was a result of a defect located in the fs/fs skin. Pigmentation of the retinal pigment epithelium also was abnormal.     

Reduced pH causes structural changes in the potent mitogenic toxin of Pasteurella multocida

Pasteurella multocida toxin is a potent mitogen that is believed to act intracellularly. On transverse urea gradient gels at pH 8.0 the toxin displayed one major unfolding transition at 4 M urea. However, at pH 6.1 the unfolding transition took place at 3.5 M urea. Circular dichroism spectra also indicated that a structural change took place at acidic pH. In addition it was found that the toxin that had been denatured in 8 M urea refolded in solution with a high recovery of biological activity. These findings are discussed in terms of the likely domain structure of the P. multocida toxin.     

Stimulation of human neutrophil phagocytosis of Candida albicans by a beta-glucan synthase inhibitor, cilofungin.

The effect of a lipopeptide antifungal agent, cilofungin, on serum opsonization and phagocytosis of Candida albicans yeast phase cells in human neutrophil monolayer assays was investigated. Simultaneous addition of fungicidal concentrations of cilofungin did not enhance or inhibit phagocytosis of C. albicans. Pretreatment of Candida blastospores with cilofungin in the absence of serum complement for 1 h did not affect phagocytosis. However, pretreatment of blastospores with cilofungin and complement promoted a significant increase in ingestion. Pretreatment of neutrophils with cilofungin in serum-free media did not affect neutrophil viability. In contrast, pre-exposure of neutrophils to cilofungin in the presence of complement inhibited ingestion of blastospores.