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Riboswitches are natural RNA elements that posttranscriptionally regulate gene expression by binding small molecules and thereby autonomously control intracellular levels of these metabolites. Although riboswitch-based mechanisms have been examined extensively, the integration of their activity with global physiology and metabolism has been largely(More)
We present a novel approach to the problem of generating a polygon sequence that blends two simple polygons given a correspondence between their boundaries. Previous approaches to this problem, including direct vertex interpolation and an interpolation based on edge lengths and angles between edges, tend to produce self intersections and shape distortions.(More)
Riboswitches are natural RNA sensors that affect gene control via their capacity to bind small molecules. Their prevalence in higher eukaryotes is unclear. We discovered a post-transcriptional mechanism in plants that uses a riboswitch to control a metabolic feedback loop through differential processing of the precursor RNA 3' terminus. When cellular(More)
Red algae are extremely attractive for biotechnology because they synthesize accessory photosynthetic pigments (phycobilins and carotenoids), unsaturated fatty acids, and unique cell wall sulfated polysaccharides. We report a high-efficiency chloroplast transformation system for the unicellular red microalga Porphyridium sp. This is the first genetic(More)
Gene expression in Kinetoplastids is very unusual in that the open reading frames are arranged in long polycistronic arrays, monocistronic mRNAs being created by post-transcriptional processing. Thus the regulation of gene expression is post-transcriptional. We here discuss recent results concerning the enzymes required for mRNA degradation, and components(More)
All eukaryotic mRNAs possess a 5'-cap (m(7)GpppN) that is recognized by a family of cap-binding proteins. These participate in various processes, such as RNA transport and stabilization, as well as in assembly of the translation initiation complex. The 5'-cap of trypanosomatids is complex; in addition to 7-methyl guanosine, it includes unique modifications(More)
Trypanosomatids are ancient eukaryotic parasites that migrate between insect vectors and mammalian hosts, causing a range of diseases in humans and domestic animals. Trypanosomatids feature a multitude of unusual molecular features, including polycistronic transcription and subsequent processing by trans-splicing and polyadenylation. Regulation of protein(More)
DNA sequences, that control expression of the spliced leader (SL) RNA gene in the parasitic protozoan Leishmania amazonensis, were mapped by block substitution mutagenesis. In the absence of a functional in vitro system for transcription, no promoter elements have yet been identified in this organism. We therefore developed an alternative in vivo approach,(More)
Developmental gene regulation in trypanosomatids proceeds exclusively by post-transcriptional mechanisms. Stability and abundance of heat shock protein (HSP)70 and HSP83 transcripts in Leishmania increase at mammalian-like temperatures, and their translation is enhanced. Here we report that the 3'-untranslated region (UTR) of HSP83 (886 nucleotides) confers(More)
We previously proposed a mechanism for control of Rubisco expression and assembly during oxidative stress in Chlamydomonas reinhardtii. The N terminus of the large subunit (LSU) comprises an RNA recognition motif (RRM) that is normally buried in the protein, but becomes exposed under oxidizing conditions when the glutathione pool shifts toward its oxidized(More)