Beet necrotic yellow vein virus coat protein-mediated protection in sugarbeet (Beta vulgaris L.) protoplasts

Transformed Beta vulgaris L. suspension cultures were obtained after cocultivation of sugarbeet cells with Agrobacterium tumefaciens harbouring a binary vector containing the coat protein gene of beet necrotic yellow vein virus inserted between the kanamycin resistance gene and a ß-glucuronidase reporter gene. Protoplasts were isolated both from untransformed cells, and from transformed cells expressing the viral coat protein, and both were then infected with beet necrotic yellow vein virus. Comparison of the levels of infectivity shows that the expression of the coat protein gene in sugarbeet protoplasts mediates high levels of protection against infection by beet necrotic yellow vein virus.Abbreviations TMV Tobacco Mosaic Virus - CP Coat Protein - BNYVV Beet Necrotic Yellow Vein Virus - ß-Glu ß-glucuronidase - MS Murashige and Skoog (1962) - PEG Polyethylene glycol - npt neomycin phosphotransferase - nos nopaline synthase - FITC fluoresceine isothiocyanate - IAA indole acetic acid - BAP benzyl amino purine - MES 2-[N-Morpholino]ethane sulfonic acid - IgG Immunoglobulin G - nt nucleotide     

Combining laboratory and mathematical models to infer mechanisms underlying kinetic changes in macrophage susceptibility to an RNA virus

Background

Macrophages are essential to innate immunity against many pathogens, but some pathogens also target macrophages as routes to infection. The Porcine Reproductive and Respiratory Syndrome virus (PRRSV) is an RNA virus that infects porcine alveolar macrophages (PAMs) causing devastating impact on global pig production. Identifying the cellular mechanisms that mediate PAM susceptibility to the virus is crucial for developing effective interventions. Previous evidence suggests that the scavenger receptor CD163 is essential for productive infection of PAMs with PRRSV. Here we use an integrative in-vitro–in-silico modelling approach to determine whether and how PAM susceptibility to PRRSV changes over time, to assess the role of CD163 expression on such changes, and to infer other potential causative mechanisms altering cell susceptibility.

Results

Our in-vitro experiment showed that PAM susceptibility to PRRSV changed considerably over incubation time. Moreover, an increasing proportion of PAMs apparently lacking CD163 were found susceptible to PRRSV at the later incubation stages, thus conflicting with current understanding that CD163 is essential for productive infection of PAMs with PRRSV. We developed process based dynamic mathematical models and fitted these to the data to assess alternative hypotheses regarding potential underlying mechanisms for the observed susceptibility and biomarker trends. The models informed by our data support the hypothesis that although CD163 may have enhanced cell susceptibility, it was not essential for productive infection in our study. Instead the models promote the existence of a reversible cellular state, such as macrophage polarization, mediated in a density dependent manner by autocrine factors, to be responsible for the observed kinetics in cell susceptibility.

Conclusions

Our dynamic model–inference approach provides strong support that PAM susceptibility to the PRRS virus is transient, reversible and can be mediated by compounds produced by the target cells themselves, and that these can render PAMs lacking the CD163 receptor susceptible to PRRSV. The results have implications for the development of therapeutics aiming to boost target cell resistance and prompt future investigation of dynamic changes in macrophage susceptibility to PRRSV and other viruses.

     

Caldicoprobacter algeriensis sp. nov. a New Thermophilic Anaerobic, Xylanolytic Bacterium Isolated from an Algerian Hot Spring

A thermophilic anaerobic bacterium (strain TH7C1(T)) was isolated from the hydrothermal hot spring of Guelma in the northeast of Algeria. Strain TH7C1(T) stained Gram-positive, was a non-motile rod appearing singly, in pairs, or as long chains (0.7-1 × 2-6 μm(2)). Spores were never observed. It grew at temperatures between 55 and 75°C (optimum 65°C) and at pH between 6.2 and 8.3 (optimum 6.9). It did not require NaCl for growth, but tolerated it up to 5 g l(-1). Strain TH7C1(T) is an obligatory heterotroph fermenting sugars including glucose, galactose, lactose, raffinose, fructose, ribose, xylose, arabinose, maltose, mannitol, cellobiose, mannose, melibiose, saccharose, but also xylan, and pyruvate. Fermentation of sugars only occurred in the presence of yeast extract (0.1%). The end-products from glucose fermentation were acetate, lactate, ethanol, CO(2), and H(2). Nitrate, nitrite, thiosulfate, elemental sulfur, sulfate, and sulfite were not used as electron acceptors. The G+C content of the genomic DNA was 44.7 mol% (HPLC techniques). Phylogenetic analysis of the small-subunit ribosomal RNA (rRNA) gene sequence indicated that strain TH7C1(T) was affiliated to Firmicutes, order Clostridiales, family Caldicoprobacteraceae, with Caldicoprobacter oshimai (98.5%) being its closest relative. Based on phenotypic, phylogenetic, and genetic characteristics, strain TH7C1(T) is proposed as a novel species of genus Caldicoprobacter, Caldicoprobacter algeriensis, sp. nov. (strain TH7C1(T) = DSM 22661(T) = JCM 16184(T)).     

Levée de dormance de L'embryon de Pommier (Pirus malus L.) en l'absence d'oxygène et de froid

Summary The dormancy of apple embryos may be entirely broken without cold by keeping them in N₂-atmosphere. The breaking of dormancy under these conditions is more rapid than that obtained by cold treatment.     

The CH1α domain of mucosal gp41 IgA contributes to antibody specificity and antiviral functions in HIV-1 highly exposed Sero-Negative individuals

The antibody molecule comprises a variable domain conferring antigen specificity and affinity distinct from the heavy chain constant (CH) domains dictating effector functions. We here interrogate this paradigm by evaluating the unique influence of the CH1α domain on epitope specificity and functions using two mucosal gp41-specific Fab-IgAs (FabA) derived from HIV-1 highly-exposed but persistently seronegative individuals (HESN). These HESN develop selectively affinity-matured HIV-1-specific mucosal IgA that target the gp41 viral envelope and might provide protection although by unclear mechanisms. Isotype-switching FabAs into Fab-IgGs (FabGs) results in a >10-fold loss in affinity for HIV-1 clade A, B, and C gp41, together with reduced neutralization of HIV-1 cross-clade. The FabA conformational epitopes map selectively on gp41 in 6-Helix bundle and pre-fusion conformations cross-clade, unlike FabGs. Finally, we designed in silico, a 12 amino-acid peptide recapitulating one FabA conformational epitope that inhibits the FabA binding to gp41 cross-clade and its neutralizing activity. Altogether, our results reveal that the CH1α domain shapes the antibody paratope through an allosteric effect, thereby strengthening the antibody specificity and functional activities. Further, they clarify the mechanisms by which these HESN IgAs might confer protection against HIV-1-sexual acquisition. The IgA-specific epitope we characterized by reverse vaccinology could help designing a mucosal HIV-1 vaccine.     

High salinity helps the halophyte <Emphasis Type="Italic">Sesuvium portulacastrum</Emphasis> in defense against Cd toxicity by maintaining redox balance and photosynthesis

Main conclusion

NaCl alleviates Cd toxicity in Sesvium portulacastrum by maintaining plant water status and redox balance, protecting chloroplasts structure and inducing some potential Cd ²⁺ chelators as GSH and proline. It has been demonstrated that NaCl alleviates Cd-induced growth inhibition in the halophyte Sesuvium portulacastrum. However, the processes that mediate this effect are still unclear. In this work we combined physiological, biochemical and ultrastructural studies to highlight the effects of salt on the redox balance and photosynthesis in Cd-stressed plants. Seedlings were exposed to different Cd concentrations (0, 25 and 50 µM Cd) combined with low (0.09 mM) (LS), or high (200 mM) NaCl (HS) in hydroponic culture. Plant–water relations, photosynthesis rate, leaf gas exchange, chlorophyll fluorescence, chloroplast ultrastructure, and proline and glutathione concentrations were analyzed after 1 month of treatment. In addition, the endogenous levels of stress-related hormones were determined in plants subjected to 25 µM Cd combined with both NaCl concentrations. In plants with low salt supply (LS), Cd reduced growth, induced plant dehydration, disrupted chloroplast structure and functioning, decreased net CO₂ assimilation rate (A) and transpiration rate (E), inhibited the maximum potential quantum efficiency (Fv/Fm) and the quantum yield efficiency (Φ _PSII) of PSII, and enhanced the non-photochemical quenching (NPQ). The addition of 200 mM NaCl (HS) to the Cd-containing medium culture significantly mitigated Cd phytotoxicity. Hence, even at similar internal Cd concentrations, HS-Cd plants were less affected by Cd than LS-Cd ones. Hence, 200 mM NaCl significantly alleviates Cd-induced toxicity symptoms, growth inhibition, and photosynthesis disturbances. The cell ultrastructure was better preserved in HS-Cd plants but affected in LS-Cd plants. The HS-Cd plants showed also higher concentrations of reduced glutathione (GSH), proline and jasmonic acid (JA) than the LS-Cd plants. However, under LS-Cd conditions, plants maintained higher concentration of salicylic acid (SA) and abscisic acid (ABA) than the HS-Cd ones. We conclude that in S. portulacastrum alleviation of Cd toxicity by NaCl is related to the modification of GSH and proline contents as well as stress hormone levels thus protecting redox balance and photosynthesis.

     

Cd-induced growth reduction in the halophyte <Emphasis Type="Italic">Sesuvium portulacastrum</Emphasis> is significantly improved by NaCl

The effects of Cd²⁺ and NaCl, applied together or separately, on growth and uptake of Cd²⁺ were determined for the halophyte Sesuvium portulacastrum L. Seedlings were cultivated in the presence of 50 or 100 μmol L⁻¹ Cd²⁺ alone or combined with 100 or 400 mmol L⁻¹ NaCl. Data showed that alone, Cd²⁺ induced chlorosis, necrosis, and inhibited growth. Addition of NaCl to Cd²⁺-containing medium restored growth and alleviated the toxicity, however. NaCl also enhanced the amounts of Cd²⁺ accumulated in the shoots. All Cd²⁺ treatment reduced K⁺ and Ca²⁺ uptake and transport to the shoots. Accumulation of Na⁺ in the shoots was not affected by Cd²⁺, however. Thus S. portulacastrum maintained its halophytic characteristics in the presence of Cd²⁺. We suggest this halophyte could be used for phytoextraction of Cd²⁺ from salt-contaminated sites.     

Structure‐antigenicity of the V3 region of SIVmac envelope glycoprotein

The objective of this study was to analyze the immunogenicity and antigenicity of the V3 domain (Cys313–Cys346) of the external envelope glycoprotein gp125 of SIVmac251. The corresponding peptide was synthesized and characterized as linear and cyclic peptides. Our results showed that this region, as for HIV‐1, contained an immunodominant epitope. The antigenicity was similar for the linear and cyclic peptides when tested against a panel of 15 sera from SIV infected macaques. Similarly, both peptide structures presented similar immunogenicity as shown by the characterization of the anti‐peptide antibodies produced in rabbits against the cyclic and linear forms. But, unexpectedly, the antibodies produced against linear peptides recognized with a relatively higher intensity the native envelope gp140 than those produced against the cyclic structure. Furthermore, we showed that these antibodies recognized better the deglycosylated form of the glycoprotein. But, in contrast to the neutralizing activity obtained with anti‐V3 peptides from HIV‐1, no antiviral activity was obtained with antibodies generated against linear or cyclic SIVmac V3 peptides. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.     

Effect of prolonged administration of long-acting somatostatin on caerulein, CCK-8 and GRP induced pancreatic growth in the rat.

This work investigates the effects of the long-acting somatostatin analogue, octreotide also named SMS 201-995 or Sandostatin, on pancreatic growth in function of the dose and duration of treatment. Octreotide was administered s.c. twice daily, while pancreatico-trophic peptides, caerulein and CCK-8 (1.8 nmol/kg b.wt.) or GRP (3.6 nmol/kg b.wt.) were administered s.c. three times daily. Octreotide (1,10,20 micrograms/kg b.wt.) administered for 4 days reduced pancreatic growth induced by caerulein in a dose-dependent manner. This effect, significant from 10 micrograms/kg, was more obvious with 20 micrograms/kg. At this latter dose, octreotide inhibited significantly the increase in pancreatic weight and protein, RNA, DNA and enzyme content induced by a 4- or 10-day treatment with GRP. A similar effect was observed after a 4-day treatment with CCK-8, but after a 10-day treatment only protein and enzyme contents were reduced. Octreotide by itself did not affect pancreatic size and composition after a 10-day treatment, but decreased enzyme content after a 4-day treatment. It is concluded that octreotide exerts an antitrophic effect on the rat exocrine pancreas which depends on the dose and duration of treatment and can be modulated by the trophic factor applied for a long-term.     

Eubacterium aggreganssp. nov., a New Homoacetogenic Bacterium from Olive Mill Wastewater Treatment Digestor

A strictly anaerobic, homoacetogenic, Gram-positive, non spore-forming bacterium, designated strain SR12^T(T=type strain), was isolated from an anaerobic methanogenic digestor fed with olive mill wastewater. Yeast extract was required for growth but could also be used as sole carbon and energy source. Strain SR12^Tutilized a few carbohydrates (glucose, fructose and sucrose), organic compounds (lactate, crotonate, formate and betaine), alcohols (methanol), the methoxyl group of some methoxylated aromatic compounds, and H₂+CO₂. The end-products of carbohydrate fermentation were acetate, formate, butyrate, H₂and CO₂. End-products from lactate and methoxylated aromatic compounds were acetate and butyrate. Strain SR12^Twas non-motile, formed aggregates, had a G+C content of 55 mol % and grew optimally at 35°C and pH 7.2 on a medium containing glucose. Phylogenetically, strain SR12^Twas related toEubacterium barkeri, E. callanderi, andE. limosumwithE. barkerias the closest relative (similarity of 98%) with which it bears little phenotypic similarity or DNA homology (60%). On the basis of its phenotypic, genotypic, and phylogenetic characteristics, we propose to designate strain SR12^TasEubacterium aggreganssp. nov. The type strain is SR12^T(=DSM 12183).