RESUMO
Plant viruses encode suppressors of posttranscriptional gene silencing, an adaptive antiviral defense responses that confines virus infection. Previously, we identified single-stranded DNA satellite (also known as DNA-ß) of ~1,350 nucleotides in length associated with Croton yellow vein mosaic begomovirus (CYVMV) in croton plants. The expression of genes from DNA-ß requires the begomovirus for packaged, replication, insect transmission and movement in plants. The present study demonstrates the effect of the ßC1 gene on the silencing pathway as analysed by using both transgenic systems and transient Agrobacterium tumefaciens based delivery. Plants that carry an intron-hairpin construct covering the ßC1 gene accumulated cognate small-interfering RNAs and remained symptom-free after exposure to CYVMV and its satellite. These results suggest that ßC1 interferes with silencing mechanism.
Assuntos
Begomovirus/genética , Croton/genética , Croton/imunologia , Croton/virologia , DNA Satélite/genética , Interferência de RNA/imunologia , Agrobacterium tumefaciens , Begomovirus/imunologia , Northern Blotting , Southern Blotting , Primers do DNA/genética , Plasmídeos/genética , Reação em Cadeia da Polimerase , RNA Interferente Pequeno/genética , Transformação GenéticaRESUMO
The peritoneal MPhi in the immunological defense removes foreign particles, pathogenic or otherwise, by phagocytosis, and shows movement in search of the target. The macrophage (MPhi) appears in various shapes and sizes, spherical, flattened spindle-shaped, amoeboid, polygonal and with very long extension. On activation, the MPhi shows changes in cell shape, cytokinesis and development of intercellular contacts. A dynamic redistribution of cytoskeleton with cytoplasmic spread and/or extensions occurs with immunomodulators, like Mangiferin (1,3,6,7-tetrahydroxyxanthone-C(2)-beta-D-glucoside). The MPhi isolated from the peritoneal fluid of BALB/c mice pretreated with mangiferin and saline control, on challenge, shows redistribution of cytoplasm with variable morphology. Using the image analyses technique for pattern recognition of individual shapes of MPhi leads to the observation of clustering of cells in the coverslip culture. The stimulation in phagocytosis due to mangiferin, shows cytoplasmic spread, long extensions and intercellular contacts. The individual variations in the cytoplasmic redistribution are due to changes in the balance between the cellular surface area and the long extensions where the shape and nature of the phagocytic particle and the type of MPhi are determinants.
