Vacuolation induced by VacA toxin of Helicobacter pylori requires the intracellular accumulation of membrane permeant bases, Cl(-) and water.

The protein vacuolating toxin A (VacA) of Helicobacter pylori converts late endosomes into large vacuoles in the presence of permeant bases. Here it is shown that this phenomenon corresponds to an accumulation of permeant bases and Cl(-) in HeLa cells and requires the presence of extracellular Cl(-). The net influx of Cl(-) is due to electroneutral, Na(+), K(+), 2Cl(-) cotransporter-mediated transport. Cell vacuolation leads to cell volume increase, consistent with water flux into the cell, while hyper-osmotic media decreased vacuole formation. These data represent the first evidence that VacA-treated cells undergo an osmotic unbalance, reinforcing the hypothesis that the VacA chloride channel is responsible for cell vacuolation.     

Rouleau formation of erythrocytes: A dynamical model

A model is presented for the nonBrownian motion of living erythrocytes suspended in their own plasma as observed by Rowlands et al. On the basis of this model, the formation of rouleaux (contractile fibrils among interacting erythrocytes) can be described in terms of an organization of the molecules (mainly fibrinogen) present in blood plasma; this organization is sustained by the nonlinear propagation of electric vibrations generated by red blood cells (coherent electric vibrations of the Fröhlich type).A number of peculiar experimental features otherwise unexplained can also be taken into account in the framework of the model.     

Immobilization of white-tailed deer with xylazine hydrochloride and ketamine hydrochloride and antagonism by tolazoline hydrochloride

Fourteen penned and 17 free-ranging white-tailed deer (Odocoileus virginianus Rafinesque) were singularly or repeatedly immobilized with 100 mg xylazine hydrochloride (HCl) and 300 mg ketamine HCl. The mean times from intravenous injection to ambulation for 1.0, 2.0, and 4.0 mg/kg body weight doses of tolazoline HCl were 13.5, 10.5, and 9.2 min. Deer not receiving tolazoline HCl recovered in an average of 168 min. Heart rates significantly (P less than 0.001) increased from 47 to 83 beats/min after tolazoline HCl administration, representing a return to normal rate. Tolazoline HCl had no effect on respiratory rate. A total of 85 reversals with tolazoline HCl resulted in no apparent adverse reactions.     

Immunological comparison of desmosomal components from several bovine tissues

A panel of monoclonal antibodies and conventional antisera directed against desmosomal proteins from bovine muzzle epidermis was used to identify immunologically related proteins from two other bovine stratified squamous epithelia, cornea and esophagus. Desmosome-enriched tissue fractions were prepared from epidermis, cornea, and esophagus. These tissue extracts were electrophoresed on sodium dodecyl sulfate (SDS)-polyacrylamide gels, blotted onto nitrocellulose paper, and labeled using an indirect immunoperoxidase technique. Labeling with the conventional antisera demonstrates that each of the previously characterized epidermal desmosomal proteins or protein families has an immunologically cross-reacting counterpart in cornea and esophagus. However, chemical differences between homologous desmosomal proteins in these three tissues have also been detected. The corresponding proteins in the different tissues have similar but not always identical apparent molecular weights. Moreover, tissue-restricted antigenic determinants were detected in two of the desmosomal proteins families using four monoclonal antibodies, each of which recognizes a distinct antigenic determinant.     

Absence of VA colonization in Oxalis pes-caprae inoculated with Glomus mosseae

Although members of the Oxalidaceae family have been described as host plants of vesicular-arbuscular mycorrhizal fungi, Oxalis pes-caprae did not become colonized by Glomus mosseae. Extracts of Ox. pes-caprae root inhibited the germination of G. mosseae spores. However, the presence of G. mosseae in the rhizosphere of Ox. pes-caprae produced browning of the roots, which was interpreted as a hypersensitivity response of the plant to the presence of VA fungus.     

Cultivation of formerly noncultivable strains ofMycoplasma hyorhinis

Growth on axenic agar medium is one of several characters by which mycoplasmas are defined. In apparent contradiction of the definition, DBS 1050 and other noncultivable strains ofMycoplasma hyorhinis do not grow on axenic medium but grow in cell culture. Our results show that BHK-21 cell extracts support DBS 1050 growth in appropriate medium. An inhibition assay, based on a virus neutralization format, shows that a variety of common medium ingredients inhibit DBS 1050 growth. The most potent activity was found in yeast extract. All other noncultivable strains ofM. hyorhinis tested have a yeast extract sensitivity, while cultivable strains do not. The apparent cell dependence of DBS 1050 can be attributed to growth inhibition due to factors present in a wide variety of peptones and extracts commonly used in medium; preferential growth in cell cultures is due to the absence of effective levels of these factors. Data are not available to determine if cell cultures provide growth factors not found in standard medium. The infraspecific taxon,M. hyorhinis cultivar α, is proposed for formerly noncultivable strains ofM. hyorhinis.     

Promotion of uniparental inheritance of mitochondrial drug resistance by delayed division of yeast zygotes

Summary Uniparental inheritance of mitochondrial markers conferring resistance to 3 (3,4-dichlorphenyl)-1,1-dimethylurea (diuron or DCMU) and antimycin in the fission yeast Schizosaccharomyces pombe is promoted by delaying first division of zygotes.