Dual role of TLR2 and myeloid differentiation factor 88 in a mouse model of invasive group B streptococcal disease

Toll-like receptors (TLRs) are involved in pathogen recognition by the innate immune system. Different TLRs and the adaptor molecule myeloid differentiation factor 88 (MyD88) were previously shown to mediate in vitro cell activation induced by group B streptococcus (GBS). The present study examined the potential in vivo roles of TLR2 and MyD88 during infection with GBS. When pups were infected locally with a low bacterial dose, none of the TLR2- or MyD88-deficient mice, but all of the wild-type ones, were able to prevent systemic spread of GBS from the initial focus. Bacterial burden was higher in MyD88- than in TLR2-deficient mice, indicating a more profound defect of host defense in the former animals. In contrast, a high bacterial dose induced high level bacteremia in both mutant and wild-type mice. Under these conditions, however, TLR2 or MyD88 deficiency significantly protected mice from lethality, concomitantly with decreased circulating levels of TNF-alpha and IL-6. Administration of anti-TNF-alpha Abs to wild-type mice could mimic the effects of TLR2 or MyD88 deficiency and was detrimental in the low dose model, but protective in the high dose model. In conclusion, these data highlight a dual role of TLR2 and MyD88 in the host defense against GBS sepsis and strongly suggest TNF-alpha as the molecular mediator of bacterial clearance and septic shock.     

Bacterium-bacterium inhibitory interactions among psychrotrophic bacteria isolated from Antarctic seawater (Terra Nova Bay, Ross Sea)

One hundred and forty bacteria isolated from Antarctic seawater samples were examined for their ability to inhibit the growth of indigenous isolates and their sensitivity to antibacterial activity expressed by one another. On the basis of 16S rRNA gene sequencing and analysis, bacterial isolates were assigned to five phylogenetically different taxa, Actinobacteria, alpha and gamma subclasses of Proteobacteria, Bacillaceae, and Bacteroidetes. Twenty-one isolates (15%), predominantly Actinobacteria, exhibited antagonistic properties against marine bacteria of Antarctic origin. Members of Bacteroidetes and Firmicutes did not show any inhibitory activity. Differences were observed among inhibition patterns of single isolates, suggesting that their activity was more likely strain-specific rather than dependent on phylogenetic affiliation. A novel analysis based on network theory confirmed these results, showing that the structure of this population is probably robust to perturbations, but also that it depends strongly on the most active strains. The determination of plasmid incidence in the bacterial strains investigated revealed that there was no correlation between their presence and the antagonistic activity. The data presented here provide evidence for the antagonistic interactions within bacterial strains inhabiting Antarctic seawater and suggest the potential exploitation of Antarctic bacteria as a novel source of antibiotics.     

Enhanced micropropagation response and biocontrol effect of Azospirillum brasilense Sp245 on Prunus cerasifera L. clone Mr.S 2/5 plants

Inoculation with Azospirillum brasilense Sp245 exerts beneficial effects on micropropagated plants of Prunus cerasifera L. clone Mr.S 2/5, as seen in the results of a comparative analysis of inoculated and non-inoculated explants, during both the rooting and acclimatation phases. The presence of Azospirillum brasilense Sp245 increased root system, root hair biomass production and apical activity. Although the presence of the bacteria had a positive effect on rooting, the addition of indolebutyric acid (IBA) to Murashige and Skoog (MS) medium was seen as indispensable in order to promote the rooting of explants. Aside from the promotion of plant growth, A. brasilense Sp245 protects plants against pathogen attacks, such as Rhizoctonia spp., with a plant survival rate of nearly 100% vs. 0% as seen in the negative control. The biocontrol effect of A. brasilense Sp245 on the fungal rhizospheric community has been confirmed by denaturing gradient gel electrophoresis (DGGE) profiles of the rhizospheric microbial community. This study indicates that A. brasilense Sp245 could be employed as a tool in plant biotechnology.     

Extracts of black and brown rice powders improve hepatic lipid accumulation via the activation of PPARα in obese and diabetic model mice

Rice powder extract (RPE) from black and brown rice (Oryza sativa L. indica) improves hepatic lipid accumulation in obese and diabetic model mice via peroxisomal fatty acid oxidation. RPE showed PPARα agonistic activity which did not differ between black and brown RPE despite a higher anthocyanin content in black RPE.     

Effect of follicle-stimulating hormone on cyclic adenosine monophosphate level and on meiotic maturation in mouse cumulus cell-enclosed oocytes cultured in vitro

We have reported that in vitro treatment with follicle-stimulating hormone (FSH) delays by about 3 h spontaneous meiotic resumption in cumulus cell-enclosed mouse oocytes. In the present paper we show that the temporary meiotic block is accompanied by a transient increase of cAMP concentration in the oocyte. In cumulus cell-oocyte complexes stimulated with 1 microgram/ml FSH, cAMP significantly increases within 1 h both in the whole complex (from a basal value of 1.9 +/- 0.2 to 169 +/- 13 fmol) and in the enclosed oocyte (from 0.9 +/- 0.2 to 2.4 +/- 0.2 fmol), then progressively decreases to basal values. Stimulation by FSH does not cause any cAMP increase in denuded oocytes. As the concentration of cAMP in the cells decreases, the percentage of oocytes escaping the meiotic block imposed by FSH increases. If the complexes are cultured in the presence of 1 microgram/ml FSH plus 1 mM isobutyl-1-methylxanthine (1BMX), cAMP concentration increases approximately 250-fold in the complex, and 10-fold in the enclosed oocyte; the level of cAMP in the oocyte drops very rapidly (50% degradation in less than 2 min) if the oocyte is then transferred to IBMX-free medium. The data are discussed in terms of the possible role of cAMP transfer from cumulus cells to the oocyte in the regulation of meiotic progression in mouse oocytes.     

Cellular and molecular aspects of mouse primordial germ cell migration and proliferation in culture.

The development of mouse primordial germ cells is followed from their first appearance in the extraembryonic mesoderm of the posterior amniotic fold (7 dpc embryo) to their settlement in the genital ridges (12.5 dpc embryo). The role of fibronectin as adhesive substrate and/or in stimulating cell motility during PGC migration is discussed. Recent papers showing how PGCs migrate when cultured in vitro on cellular monolayers are reviewed. The process of PGC homing is proposed to be controlled by chemotaxis as well by developmentally regulated cell-to-cell interactions. Finally, evidence that survival and proliferation of PGCs is strictly dependent on growth factors such as LIF and MGF, and possibly on a cAMP-dependent mechanism is reported.     

In vitro plant regeneration of Vismia guianensis through organogenesis

A protocol for in vitro plant regeneration through organogenesis was established for Vismia guianensis(Hypericaceae), a species that produces an anti-cancer compound. The highest mean number of shoots per gram of callus (57.33) was obtained on Murashige and Skoog medium supplemented with 4.44 μM 6-benzyl-aminopurine, 5.70 μM indole-3-acetic acid and 12.88 μM gibberellic acid. Rooting was favoured by the addition of 10 μM indole-3-butyric acid, and by sucrose concentrations higher than 1%. This revised version was published online in June 2006 with corrections to the Cover Date.     

Nonisothermal bioreactors in the treatment of vegetation waters from olive oil: laccase versus syringic acid as bioremediation model

Laccase from Trametes versicolor was immobilized by diazotization on a nylon membrane grafted with glycidil methacrylate, using phenylenediamine as spacer and coupling agent. The behavior of these enzyme derivatives was studied under isothermal and nonisothermal conditions by using syringic acid as substrate, in view of the employment of these membranes in processes of detoxification of vegetation waters from olive oil mills. The pH and temperature dependence of catalytic activity under isothermal conditions has shown that these membranes can be usefully employed under extreme pH and temperatures. When employed under nonisothermal conditions, the membranes exhibited an increase of catalytic activity linearly proportional to the applied transmembrane temperature difference. Percentage activity increases ranging from 62% to 18% were found in the range of syringic acid concentration from 0.02 to 0.8 mM, when a difference of 1 degrees C was applied across the catalytic membrane. Because the percentage activity increase is strictly related to the reduction of the production times, the technology of nonisothermal bioreactors has been demonstrated to be an useful tool also in the treatment of vegetation waters from olive oil mills.