Transgenic Arabidopsis thaliana expressing a barley UDP-glucosyltransferase exhibit resistance to the mycotoxin deoxynivalenol

Fusarium head blight (FHB), caused by Fusarium graminearum, is a devastating disease of small grain cereal crops. FHB causes yield reductions and contamination of grain with trichothecene mycotoxins such as deoxynivalenol (DON). DON inhibits protein synthesis in eukaryotic cells and acts as a virulence factor during fungal pathogenesis, therefore resistance to DON is considered an important component of resistance against FHB. One mechanism of resistance to DON is conversion of DON to DON-3-O-glucoside (D3G). Previous studies showed that expression of the UDP-glucosyltransferase genes HvUGT13248 from barley and AtUGt73C5 (DOGT1) from Arabidopsis thaliana conferred DON resistance to yeast. Over-expression of AtUGt73C5 in Arabidopsis led to increased DON resistance of seedlings but also to dwarfing of transgenic plants due to the formation of brassinosteroid-glucosides. The objectives of this study were to develop transgenic Arabidopsis expressing HvUGT13248, to test for phenotypic changes in growth habit, and the response to DON. Transgenic lines that constitutively expressed the epitope-tagged HvUGT13248 protein exhibited increased resistance to DON in a seed germination assay and converted DON to D3G to a higher extent than the untransformed wild-type. By contrast to the over-expression of DOGT1 in Arabidopsis, which conjugated the brassinosteriod castasterone with a glucoside group resulting in a dwarf phenotype, expression of the barley HvUGT13248 gene did not lead to drastic morphological changes. Consistent with this observation, no castasterone-glucoside formation was detectable in yeast expressing the barley HvUGT13248 gene. This barley UGT is therefore a promising candidate for transgenic approaches aiming to increase DON and Fusarium resistance of crop plants without undesired collateral effects.     

Poly(2-dimethylamino ethylmethacrylate)-based polymers to camouflage red blood cell antigens

Poly(2-dimethylamino-ethylmethacrylate) (PDMAEMA) is a cationic polymer when dissolved in a 7.4 pH fluid. Owing to its ionic nature, this polycation interacts with the negatively charged cell membrane surface of red blood cells (RBCs). The electrostatic self-assembly of PDMAEMA on RBCs membrane can be employed for inducing the formation of a polymeric shield camouflaging blood group antigens on RBCs as a valuable strategy for developing "universal RBCs" for blood transfusion. The purpose of this research was to evaluate the camouflaging ability of PDMAEMA homopolymers and PDMAEMA-co-poly(ethylene glycol) copolymers differing in molecular weight and architecture. Surprisingly, the PDMAEMAs caused a partially masking, no masking, and sensitization of the same RBCs population. The MW and architecture of the polymers as well as temperature of PDMAEMA-RBCs treatment influenced the results observed. Herein, the very particular reactivity of PDMAEMAs and RBCs is analyzed and discussed.     

BDNF/TrkB signaling protects HT-29 human colon cancer cells from EGFR inhibition

The clinical success of targeted treatment of colorectal cancer (CRC) is often limited by resistance to anti-epidermal growth factor receptor (EGFR) therapy. The neurotrophin brain-derived neurotrophic factor (BDNF) and its receptor TrkB have recently emerged as anticancer targets, and we have previously shown increased BDNF levels in CRC tumor samples. Here we report the findings from in vitro experiments suggesting that BDNF/TrkB signaling can protect CRC cells from the antitumor effects of EGFR blockade. The anti-EGFR monoclonal antibody cetuximab reduced both cell proliferation and the mRNA expression of BDNF and TrkB in human HT-29 CRC cells. The inhibitory effect of cetuximab on cell proliferation and survival was counteracted by the addition of human recombinant BDNF. Finally, the Trk inhibitor K252a synergistically enhanced the effect of cetuximab on cell proliferation, and this effect was blocked by BDNF. These results provide the first evidence that increased BDNF/TrkB signaling might play a role in resistance to EGFR blockade. Moreover, it is possible that targeting TrkB could potentiate the anticancer effects of anti-EGFR therapy.     

Deletion of Complement Factor H–Related Genes CFHR1 and CFHR3 Is Associated with Atypical Hemolytic Uremic Syndrome

Atypical hemolytic uremic syndrome (aHUS) is associated with defective complement regulation. Disease-associated mutations have been described in the genes encoding the complement regulators complement factor H, membrane cofactor protein, factor B, and factor I. In this study, we show in two independent cohorts of aHUS patients that deletion of two closely related genes, complement factor H–related 1 (CFHR1) and complement factor H–related 3 (CFHR3), increases the risk of aHUS. Amplification analysis and sequencing of genomic DNA of three affected individuals revealed a chromosomal deletion of ~84 kb in the RCA gene cluster, resulting in loss of the genes coding for CFHR1 and CFHR3, but leaving the genomic structure of factor H intact. The CFHR1 and CFHR3 genes are flanked by long homologous repeats with long interspersed nuclear elements (retrotransposons) and we suggest that nonallelic homologous recombination between these repeats results in the loss of the two genes. Impaired protection of erythrocytes from complement activation is observed in the serum of aHUS patients deficient in CFHR1 and CFHR3, thus suggesting a regulatory role for CFHR1 and CFHR3 in complement activation. The identification of CFHR1/CFHR3 deficiency in aHUS patients may lead to the design of new diagnostic approaches, such as enhanced testing for these genes.     

Spreading of prions from the immune to the peripheral nervous system: a potential implication of dendritic cells

The implication of dendritic cells (DCs) in the peripheral spreading of prions has increased in the last few years. It has been recently described that DCs can transmit prions to primary neurons from the central nervous system. In order to improve the understanding of the earliest steps of prion peripheral neuroinvasion, we studied, using an in vitro model, the effect of exposing primary peripheral neurons to scrapie-infected lymphoid cells. Thanks to this system, there is evidence that bone marrow dendritic cells (BMDCs) are in connection with neurites of peripheral neurons via cytoplasmic extensions. BMDCs are competent to internalize prions independently from the expression of cellular prion protein (PrP^C) and have the capacity to transmit detergent-insoluble, relatively proteinase K-resistant prion protein (PrP^Sc) to peripheral neurons after 96 h of coculture. Furthermore, we confirmed the special status of the peripheral nervous system in front of prion diseases. Contrary to central neurons, PrP^Sc infection does not disturb survival and neurite outgrowth. Our model demonstrates that PrP^Sc-loaded dendritic cells and peripheral nerve fibers that are included in neuroimmune interfaces can initiate and spread prion neuroinvasion.     

Effect of Temperature on the Fatty Acid Composition of the Extreme Thermophiles, Bacillus caldolyticus and Bacillus caldotenax

Gas chromatographic analysis of extracts from Bacillus caldolyticus and Bacillus caldotenax grown at 60, 70, or 80 C showed that both contain branched-chain fatty acids as major constituents at all temperatures tested. With increasing temperature, a decrease of i-C15 and an increase of i-C17 fatty acids were observed in both strains, as well as a decrease of i-C16 fatty acids corresponding to an increase of n-C16 fatty acids. The most obvious difference was that the shifts observed with B. caldolyticus occurred mainly upon raising the temperature to 10 C above, and in B. caldotenax upon lowering the temperature to 20 C below, the optimal growth temperature.     

The effect of nutrients and precursors on the fatty acid composition of two thermophilic bacteria

Summary Growing the two strains B. caldolyticus and B. caldotenax on several substrates has shown that the fatty acid composition of both bacteria is not very significantly altered by the carbon source. The fatty acid pattern of B.caldolyticus was, however, drastically varied if the BHI-complex was omitted from the medium, resulting mainly in an increase of the br.-even, str.-even, str.-odd, and anteiso compounds, accompanied by a sharp decrease of the br.-odd fatty acids. Leucine, isoleucine, or valine were found to act as precursors for the corresponding fatty acids even with final concentrations as low as 0.05 mM, leading to the predominance of either iso-odd, anteiso-odd, or iso-even compounds. Simultaneously the activity of extracellular enzymes was found to vary. Along with the decrease of the n-even and iso-even fatty acids, and the increase of the iso-odd compounds as a result of increased amounts of leucine added to the medium, the growth of B.caldolyticus was found to decline.