Isolation of Propionibacterium acnes from central nervous system infections

Propionibacterium acnes is a common skin colonizer and its involvement in central nervous system (CNS) infections may be related with previous neurosurgical procedures. P. acnes was isolated in pure or mixed cultures from ten patients with CNS infections during a 5-year period. The clinical presentation, treatment and outcome were retrospectively reviewed. Nine out of 11 patients had CNS infections after a neurosurgical procedure. The clinical presentation was: brain abscess (five patients), subdural or epidural empyema (four patients) and shunt meningitis (one patient). Three patients had also secondary meningitis. All patients received antibiotic therapy and all abscesses and empyemas were drained. The patient with shunt meningitis cured without catheter removal. Only one patient with a brain abscess by P. acnes died, but several months thereafter and as a consequence of a Gram-negative superinfection. P. acnes is a pathogen for the CNS and infections must be surgically managed under adequate antibiotic treatment.     

Some rumen ciliates have endosymbiotic methanogens

Abstract Most of the small ciliate protozoa, including Dasytricha ruminantium and Entodinium spp. living in the rumen of sheep, were found to have intracellular bacteria. These bacteria were not present in digestive vacuoles. They showed characteristic coenzyme F₄₂₀ autofluorescence and they were detected with a rhodamine-labelled Archaea-specific oligonucleotide probe. The measured volume percent of autofluorescing bacteria (1%) was close to the total volume of intracellular bacteria estimated from TEM stereology. Thus it is likely that all of the bacteria living in the cytoplasm of these ciliates were endosymbiotic methanogens, using H₂ evolved by the host ciliate to form methane. Intracellular methanogens appear to be much more numerous than those attached to the external cell surface of ciliates.     

Vegetation heterogeneity and diversity in flat and mountain landscapes of Patagonia (Argentina)

Abstract. We studied floristic and diversity patterns and their environmental controls in two landscapes of contrasting topography in the Patagonian steppe. The analyses were focused on the effects of water availability gradients and landscape configuration on plant species distribution and coexistence. Floristic variation was investigated using Correspondence Analysis. The relationship between floristic and environmental variation was analyzed using Canonical Correspondence Analysis and correlation tests. We explored diversity patterns by relating spatial distance to floristic dissimilarities. The floristic gradient was determined by shrub and grass species and was related to precipitation in the flat area, and to precipitation, elevation and potential radiation in the mountain area. Site species richness increased with water availability in both areas. Mean site species richness and species turnover in space was higher in the mountain than in the flat area. Landscape species richness and floristic gradients were more concentrated in the mountain than in the flat area. In contrast to shrubs and grasses, forb species distributions were uncoordinated and probably independent of any environmental gradient. Our results suggest (1) that landscape configuration affects species composition and diversity through its direct effect on abiotic environmental heterogeneity, and (2) that the environmental controls of the community composition vary depending on the plant functional type considered.     

Ehrlich cell plasma membrane redox system is modulated through signal transduction pathways involvingcGMP and Ca2+ as second messengers

Ehrlich cell plasma membrane ferricyanide reductase activity increased in the presence of mastoparan, a generic activator of G proteins, using either whole cells or isolated plasma membrane fractions. Agents that increase intracellularcAMP also increased the rate of ferricyanide reduction by Ehrlich cells. For the first time, evidence is shown on a modulation of plasma membrane redox system bycGMP. In fact, permeant analogs ofcGMP, dibutyrylcGMP, and 8-bromo-cGMP increased the rate of ferricyanide reduction by the Ehrlich cell plasma membrane redox system. Furthermore, specific inhibition ofcGMP-phosphodiesterases by dipyridamole was also accompanied by an enhancement in the rate of ferricyanide reduction. On the other hand, treatments expected to increase cytoplasmic Ca²⁺ concentrations were accompanied by a remarkable stimulation of the reductase activity. Taking all these data together, it seems that the Ehrlich cell plasma membrane redox system is under a multiple and complex regulation by different signal transduction pathways involving G proteins, cyclic nucleotides, and Ca²⁺ ions.     

Evolution of the nucleotide sequence of influenza virus RNA segment 7 during drift of the H3N2 subtype

The complete genetic information contained in the influenza virus RNA segment 7 of the A/Bangkok/ $\text{1}\text{79}$ (H3N2) strain has been cloned by in vitro synthesis of the complementary dsDNA and its insertion into plasmid pBR322. The nucleotide sequence of the viral RNA segment has been determined from the cDNA insert. It is 1027 nucleotides long, and contains two open reading frames, as shown for other influenza virus strains. When compared with the previously published sequence for the A/Udorn/72 (H3N2) strain, 15 nucleotide exchanges are observed, most of them silent mutations, and only two causing amino acid changes in each of the M1 and M2 protein sequences.     

Beclin1-binding UVRAG targets the class C Vps complex to coordinate autophagosome maturation and endocytic trafficking

Autophagic and endocytic pathways are tightly regulated membrane rearrangement processes that are crucial for homeostasis, development and disease. Autophagic cargo is delivered from autophagosomes to lysosomes for degradation through a complex process that topologically resembles endosomal maturation. Here, we report that a Beclin1-binding autophagic tumour suppressor, UVRAG, interacts with the class C Vps complex, a key component of the endosomal fusion machinery. This interaction stimulates Rab7 GTPase activity and autophagosome fusion with late endosomes/lysosomes, thereby enhancing delivery and degradation of autophagic cargo. Furthermore, the UVRAG-class-C-Vps complex accelerates endosome-endosome fusion, resulting in rapid degradation of endocytic cargo. Remarkably, autophagosome/endosome maturation mediated by the UVRAG-class-C-Vps complex is genetically separable from UVRAG-Beclin1-mediated autophagosome formation. This result indicates that UVRAG functions as a multivalent trafficking effector that regulates not only two important steps of autophagy - autophagosome formation and maturation - but also endosomal fusion, which concomitantly promotes transport of autophagic and endocytic cargo to the degradative compartments.