Gene expression in Xenopus laevis embryos after Triadimefon exposure

The triazole derivative Triadimefon (FON) is a systemic fungicide used to control powdery mildews, rusts, and other fungal pests. Some data have already been published about the teratogenic activity of this compound: craniofacial malformations were found in mouse, rat, and Xenopus laevis embryos exposed to FON. These alterations were correlated to defective branchial arch development possibly caused by abnormal neural crest cell (NCC) migration into the branchial mesenchyme. As the migration of NCCs is controlled by the HOX code and by an anteroposterior retinoic acid (RA) gradient, we analyzed the expression of CYP26, a key enzyme in RA metabolism, following FON exposure. The increased expression of this gene and the ability of citral (a RA inhibitor) to reduce the teratogenic effects of the fungicide support the notion that endogenous RA is involved in the mechanism of action of FON. Moreover, by in situ hybridization, we studied the effects of FON exposure at gastrula stage on the expression of some genes involved in craniofacial development, hindbrain patterning, and NCC migration. We observed abnormal localization of xCRABP, Hoxa2 and Xbap signal expression at the level of migrating NCC domains, whereas in the hindbrain, we did not find any alteration in Krox20 and Hoxa2 expression.     

The non-flavonoid inducible nodA3 and the flavonoid regulated nodA1 genes of Rhizobium tropici CIAT 899 guarantee nod factor production and nodulation of different host legumes

Plant and Soil - Previous studies have shown that pH, rather than calcium (Ca), is the main reason why some Lupinus species are sensitive to nutrient solutions mimicking calcareous soils; however,...     

TNFα activation of PKCδ, mediated by NFκB and ER stress,cross-talks with the insulin signaling cascade

TNFα plays key roles in the regulation of inflammation, cell death, and proliferation and its signaling cascade cross-talks with the insulin signaling cascade. PKCδ, a novel PKC isoform, is known to participate in proximal TNFα signaling events. However, it has remained unclear whether PKCδ plays a role in distal TNFα signaling events. Here we demonstrate that PKCδ is activated by TNFα in a delayed fashion that is temporally associated with JNK activation. To investigate the signaling pathways activating PKCδ and JNK, we used pharmacological and genetic inhibitors of NFκB. We found that inhibition of NFκB attenuated PKCδ and JNK activations. Further analysis revealed that ER stress contributes to TNFα-stimulated PKCδ and JNK activations. To investigate the role of PKCδ in TNFα action, we used 29-mer shRNAs to silence PKCδ expression. A reduction of ~90% in PKCδ protein levels reduced TNFα-stimulated stress kinase activation, including JNK. Further, PKCδ was necessary for thapsigargin-stimulated JNK activation. Because thapsigargin is a potent inducer of ER stress, we determined whether PKCδ was necessary for induction of the UPR. Indeed, a reduction in PKCδ protein levels reduced thapsigargin-stimulated CHOP induction, a hallmark of the UPR, but not BiP/GRP78 induction, suggesting that PKCδ does not globally regulate the UPR. Next, the role of PKCδ in TNFα mediated cross-talk with the insulin signaling pathway was investigated in cells expressing human IRS-1 and a 29-mer shRNA to silence PKCδ expression. We found that a reduction in PKCδ protein levels reversed the TNFα-mediated reduction in insulin-stimulated IRS-1 Tyr phosphorylation, Akt activation, and glycogen synthesis. In addition, TNFα-stimulated IRS protein Ser/Thr phosphorylation and degradation were blocked. Our results indicate that: 1) NFκB and ER stress contribute in part to PKCδ activation; 2) PKCδ plays a key role in the propagation of the TNFα signal; and 3) PKCδ contributes to TNFα-induced inhibition of insulin signaling events.     

Inducible expression of inflammatory chemokines in respiratory syncytial virus-infected mice: role of MIP-1alpha in lung pathology

Lower respiratory tract disease caused by respiratory syncytial virus (RSV) is characterized by profound airway mucosa inflammation, both in infants with naturally acquired infection and in experimentally inoculated animal models. Chemokines are central regulatory molecules in inflammatory, immune, and infectious processes of the lung. In this study, we demonstrate that intranasal infection of BALB/c mice with RSV A results in inducible expression of lung chemokines belonging to the CXC (MIP-2 and IP-10), CC (RANTES, eotaxin, MIP-1beta, MIP-1alpha, MCP-1, TCA-3) and C (lymphotactin) families. Chemokine mRNA expression occurred as early as 24 h following inoculation and persisted for at least 5 days in mice inoculated with the highest dose of virus (10(7) PFU). In general, levels of chemokine mRNA and protein were dependent on the dose of RSV inoculum and paralleled the intensity of lung cellular inflammation. Immunohisthochemical studies indicated that RSV-induced expression of MIP-1alpha, one of the most abundantly expressed chemokines, was primarily localized in epithelial cells of the alveoli and bronchioles, as well as in adjoining capillary endothelium. Genetically altered mice with a selective deletion of the MIP-1alpha gene (-/- mice) demonstrated a significant reduction in lung inflammation following RSV infection, compared to control littermates (+/+ mice). Despite the paucity of infiltrating cells, the peak RSV titer in the lung of -/- mice was not significantly different from that observed in +/+ mice. These results provide the first direct evidence that RSV infection may induce lung inflammation via the early production of inflammatory chemokines.     

Cardiolipin and its metabolites move from mitochondria to other cellular membranes during death receptor-mediated apoptosis

We previously reported that during death receptor-mediated apoptosis, cardiolipin (CL) relocates to the cell surface, where it reacts with autoantibodies from antiphospholipid syndrome sera. Here, we analysed the intracellular distribution of CL and its metabolites during the early phase of cell death signalling triggered by Fas stimulation in U937 cells and mouse liver. We found a redistribution of mitochondrial CL to the cell surface by using confocal microscopy and flow cytometry. Mass spectrometry revealed that CL and its metabolites relocated from mitochondria to other intracellular organelles during apoptosis, with a conversion into non-mitochondrial lipids. Concomitantly, cytosolic Bid relocated to the light membranes comprised in fraction P100, including the plasma membrane and associated vesicular systems. A direct Bid-CL interaction was demonstrated by the observation that CL and monolysoCL coimmunoprecipitated with Bid especially after Fas stimulation, suggesting a dynamic interaction of the protein with CL and its metabolites.     

The FAR protein family of the nematode Caenorhabditis elegans. Differential lipid binding properties,structural characteristics,and developmental regulation

Parasitic nematodes of humans and plants secrete a structurally novel type of fatty acid- and retinol-binding protein, FAR, into the tissues they occupy. These proteins may interfere with intercellular lipid signaling to manipulate the defense reactions of the host or acquire essential lipids for the parasites. The genome of the nematode Caenorhabditis elegans encodes eight FAR-like proteins (Ce-FAR-1 to -8). These fall into three discrete groups as indicated by phylogenetic sequence comparisons and intron positions, the proteins from parasitic nematodes falling into group A. Recombinant Ce-FAR-1 to -7 were produced in Escherichia coli and tested for lipid binding in fluorescence-based assays. Ce-FAR-1 to -6 bound DAUDA (11-((5-dimethylaminonaphthalene-1-sulfonyl)amino)undecanoic acid), cis-parinaric acid, and retinol with dissociation constants in the micromolar range, whereas Ce-FAR-7 bound the latter two lipids relatively poorly. Each protein produced a characteristic shift in peak fluorescence emission of DAUDA, and one (Ce-FAR-5) produced a shift greater than has been observed previously for any lipid-binding protein. Selected Ce-FAR proteins were analyzed by circular dichroism (CD) and differential scanning calorimetry, were found to be helix-rich, and exhibited high thermal stability (transition midpoint, 82.7 degrees C). CD and secondary structure predictions, however, both indicated that Ce-FAR-7 possesses substantially less helix than the other FAR proteins. The genes encoding the Ce-FAR proteins were found to be transcribed differentially through the life cycle of C. elegans, such that Ce-far-4 was transcribed at highest levels in the fourth larval stage, and Ce-far-3 and -7 predominated in males.