Jean-Pierre Perreault

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This paper attributes a novel function, namely, that of transcriptional promoter, to the self-complementary, self-cleaving hammerhead RNA sequences found in RNA derived from the peach latent mosaic viroid (PLMVd). The features of this RNA promoter, which adopts a hairpin structure that can be utilized by Escherichia coli RNA polymerase (RNAP) for in vitro(More)
BACKGROUND It has been observed that following viroid infection, there is an accumulation of viroid-derived siRNAs in infected plants. Some experimental results suggest that these small RNAs may be produced by the plant defense system to protect it from infection, indicating that viroids can elicit the RNA-silencing pathways. The objective of this study is(More)
Given that greater than 90% of the human genome is expressed, it is logical to assume that post-transcriptional regulatory mechanisms must be the primary means of controlling the flow of information from mRNA to protein. This report describes a robust approach that includes in silico, in vitro and in cellulo experiments permitting an in-depth evaluation of(More)
G-quadruplexes (G4) are tetrahelical structures formed from planar arrangement of guanines in nucleic acids. A simple, regular motif was originally proposed to describe G4-forming sequences. More recently, however, formation of G4 was discovered to depend, at least in part, on the contextual backdrop of neighboring sequences. Prediction of G4 folding is(More)
Guanine-rich RNA sequences can fold into non-canonical, four stranded helical structures called G-quadruplexes that have been shown to be widely distributed within the mammalian transcriptome, as well as being key regulatory elements in various biological mechanisms. That said, their role within the 3'-untranslated region (UTR) of mRNA remains to be(More)
We report the characterization in the human genome of 966 pseudogenes derived from the four human Y (hY) RNAs, components of the Ro/SS-A autoantigen. About 95% of the Y RNA pseudogenes are found in corresponding locations on the chimpanzee and human chromosomes. On the contrary, Y pseudogenes in mice are both infrequent and found in different genomic(More)
In order to revisit the architecture of the catalytic center of the antigenomic hepatitis delta virus (HDV) ribozyme we developed an unbiased in vitro selection procedure that efficiently selected novel variants from a relatively small set of sequences. Using this procedure we examined all possible variants from a pool of HDV ribozymes that had been(More)
Ribozymes, RNA molecules that catalyze the cleavage of RNA substrates, provide an interesting alternative to the RNA interference (RNAi) approach to gene inactivation, especially given the fact that RNAi seems to trigger an immunological response. Unfortunately, the limited substrate specificity of ribozymes is considered to be a significant hurdle in their(More)
We describe here the establishment of an online database containing a large number of sequences and related data on viroids, viroid-like RNAs and human hepatitis delta virus (vHDV) in a customizable and user-friendly format. This database is available on the World Wide Web at http://penelope.med.usherb.ca/subviral.
G-quadruplexes (G4s) are non-canonical structures involved in many important cellular processes. To date, the prediction of potential G-quadruplex structures (PG4s) has been based almost exclusively on the sequence of interest agreeing with the algorithm Gx-N-1-7-Gx-N1-7-Gx-N1-7-Gx (where x ≥ 3 and N = A, U, G or C). However, many sequences agreeing with(More)