SINE RNA Induces Severe Developmental Defects in Arabidopsis thaliana and Interacts with HYL1 (DRB1), a Key Member of the DCL1 Complex

The proper temporal and spatial expression of genes during plant development is governed, in part, by the regulatory activities of various types of small RNAs produced by the different RNAi pathways. Here we report that transgenic Arabidopsis plants constitutively expressing the rapeseed SB1 SINE retroposon exhibit developmental defects resembling those observed in some RNAi mutants. We show that SB1 RNA interacts with HYL1 (DRB1), a double-stranded RNA-binding protein (dsRBP) that associates with the Dicer homologue DCL1 to produce microRNAs. RNase V1 protection assays mapped the binding site of HYL1 to a SB1 region that mimics the hairpin structure of microRNA precursors. We also show that HYL1, upon binding to RNA substrates, induces conformational changes that force single-stranded RNA regions to adopt a structured helix-like conformation. Xenopus laevis ADAR1, but not Arabidopsis DRB4, binds SB1 RNA in the same region as HYL1, suggesting that SINE RNAs bind only a subset of dsRBPs. Consistently, DCL4-DRB4-dependent miRNA accumulation was unchanged in SB1 transgenic Arabidopsis, whereas DCL1-HYL1-dependent miRNA and DCL1-HYL1-DCL4-DRB4-dependent tasiRNA accumulation was decreased. We propose that SINE RNA can modulate the activity of the RNAi pathways in plants and possibly in other eukaryotes

Contribution à l'étude de l'impact des conditions géologiques sur la karstification quaternaire de la bordure nord du Causse de Limogne Quercy, Lot

The northern half of the «causse de Limogne» (Quercy, France) : the part of the geological conditions on the quaternary karstification. The geological characteristics (lithologie succession and structural frame-work) of the Northern half of the «Causse de Limogne » (Quercy) are briefly described and compared with the distribution of the quaternary karstic phenomena. From this comparison, a very clear dependence of the karstitication to this various factors is proved. The practical consequences fot the speleological prospections and explorations are succinctly emphasized.La description succincte des conditions géologiques (série lithologique et cadre structural) de la moitié nord du causse de Limogne (Quercy) est mise en parallèle avec la répartition des phénomènes karstiques quaternaires. Il en ressort une dépendance très nette de la karstification vis-à-vis de ces divers facteurs. Les conséquences pratiques pour la prospection et l'exploration spéléologique sont sommairement dégagées.Pélissier Thierry. Contribution à l'étude de l'impact des conditions géologiques sur la karstification quaternaire de la bordure nord du Causse de Limogne Quercy, Lot . In: Karstologia : revue de karstologie et de spéléologie physique, n°5, 1er semestre 1985. pp. 23-28

Glue for Jumping Elements: Epigenetic Means for Controlling Transposable Elements in Plants

International audienc

Éditorial

Douat Michel, Maire Richard, Pélissier Thierry. Éditorial. In: Karstologia : revue de karstologie et de spéléologie physique, n°29, 1er semestre 1997. Formation des réseaux karstiques et creusement des vallées (Larzac, Hérault) p. 2

Éditorial

Douat Michel, Maire Richard, Pélissier Thierry. Éditorial. In: Karstologia : revue de karstologie et de spéléologie physique, n°29, 1er semestre 1997. Formation des réseaux karstiques et creusement des vallées (Larzac, Hérault) p. 2

DNA methylation in an intron of the IBM1 histone demethylase gene stabilizes chromatin modification patterns

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Arabidopsis eIF2α kinase GCN2 is essential for growth in stress conditions and is activated by wounding

International audiencePhosphorylation of eIF2alpha provides a key mechanism for down-regulating protein synthesis in response to nutrient starvation or stresses in mammalian and yeast cells. However, this process has not been well characterized in plant