Dynamics of Molecular Evolution and Phylogeography of Barley yellow dwarf virus-PAV

Barley yellow dwarf virus (BYDV) species PAV occurs frequently in irrigated wheat fields worldwide and can be efficiently transmitted by aphids. Isolates of BYDV-PAV from different countries show great divergence both in genomic sequences and pathogenicity. Despite its economical importance, the genetic structure of natural BYDV-PAV populations, as well as of the mechanisms maintaining its high diversity, remain poorly explored. In this study, we investigate the dynamics of BYDV-PAV genome evolution utilizing time-structured data sets of complete genomic sequences from 58 isolates from different hosts obtained worldwide. First, we observed that BYDV-PAV exhibits a high frequency of homologous recombination. Second, our analysis revealed that BYDV-PAV genome evolves under purifying selection and at a substitution rate similar to other RNA viruses (3.158×10−4 nucleotide substitutions/site/year). Phylogeography analyses show that the diversification of BYDV-PAV can be explained by local geographic adaptation as well as by host-driven adaptation. These results increase our understanding of the diversity, molecular evolutionary characteristics and epidemiological properties of an economically important plant RNA virus

Silencing

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Développement du RNA interférence chez les strongles gastro-intestinaux

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In vivo approach to elucidate the functionality of nicotinic receptors in <em>Haemonchus contortus</em> using RNA interference

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Resistencia de ovinos frente a infestacion experimental por estrongilidos y su relacion con resistencia a los antihelminticos

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Host eosinophil granules interact with Haemonchus contortus P-glycoproteins: A novel insight in to the role of ABC transporters in host-parasite interaction

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Rhodamine Rh123 efflux assay performed on <i>Haemonchus contortus</i> eggs stimulated with eosinophil granule proteins.

<p>The regression line was obtained from the log agonist (granule proteins) versus response variable-slope model using Prism software. A significant effect of eosinophil granule products on Pgp activation was observed (P<0.0069).</p

Expression of Pgp mRNAs in xL3 larvae of <i>H. contortus</i> after 24 hours stimulation with increasing concentrations of eosinophil granule proteins.

<p>Real-time RT-PCR experiments were performed in triplicate for each sample using two distinct cDNA preparations per sample. mRNA expression levels were normalized using non-stimulated xL3. The mRNA fold changes were calculated using three distinct reference genes (<i>gapdh, actin</i> and <i>β-tubulin</i>). ** Significant difference from control values after Man-Whitney test analyses (<i>P<0.01</i>).</p

Expression of Pgp mRNAs during <i>H. contortus</i> life cycle.

<p>Real-time RT-PCR experiments were performed in triplicate for each developmental stage: Eggs (E) and third stage larvae (L3) corresponding to the free-living stages as well as in fourth stage larvae (L4) and adult males (A) corresponding to parasitic stages. The mRNA expression levels observed in the eggs was normalized to 1. The mRNA fold changes were calculated using three distinct reference genes (<i>gapdh, actin</i> and <i>β-tubulin</i>). For each sample, real-time RT-PCR were performed in triplicate and repeated twice using two independent cDNAs templates. * Significant difference from control values after Bonferroni's Multiple Comparison Test (* P<0.05; ** P<0.01; *** P<0.001).</p

Purification of eosinophil cells from sheep infected with <i>H. contortus</i>.

<p>Granulocyte cell populations were isolated from the leukocyte population by flow cytometry using Forward Scatter (FS) and Size Scatter (SS) parameters. The dot-plot histograms with total leukocyte population (A) and dot-plot histogram after Percoll density separation (B) highlight the R2 enriched cell population correponding to eosinophils. Purity of eosinophil cell population was further checked by Giemsa May-Grunwald (GMG) staining (C). The GMG stains the eosinophil cell nuclei in purple and cytoplasmic granules in orange. Total eosinophil lysate (1) and purified eosinophil granule proteins (2) were separated by 10% polyacrylamide gel electrophoresis and stained with Coomassie blue (D).</p