Rampant polyuridylylation of plastid gene transcripts in the dinoflagellate Lingulodinium

Dinoflagellate plastid genes are believed to be encoded on small generally unigenic plasmid-like minicircles. The minicircle gene complement has reached saturation with an incomplete set of plastid genes (18) compared with typical functional plastids (60–200). While some of the missing plastid genes have recently been found in the nucleus, it is still unknown if additional genes, not located on minicircles, might also contribute to the plastid genome. Sequencing of tailed RNA showed that transcripts derived from the known minicircle genes psbA and atpB contained a homogenous 3′ polyuridine tract of 25–40 residues. This unusual modification suggested that random sequencing of a poly(dA) primed cDNA library could be used to characterize the plastid transcriptome. We have recovered only 12 different polyuridylylated transcripts from our library, all of which are encoded on minicircles in several dinoflagellate species. The correspondence of all polyuridylylated transcripts with previously described minicircle genes thus supports the dinoflagellate plastid as harbouring the smallest genome of any functional chloroplast. Interestingly, northern blots indicate that the majority of transcripts are modified, suggesting that polyuridylylation is unlikely to act as a degradation signal as do the heterogeneous poly(A)-rich extensions of transcripts in cyanobacteria and other plastids

Expression of the plastid genome in the dinoflagellate Gonyaulax polyedra

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

The QKI-6 RNA Binding Protein Localizes with the MBP mRNAs in Stress Granules of Glial Cells

Background: The quaking viable (qk v) mouse has several developmental defects that result in rapid tremors in the hind limbs. The qkI gene expresses three major alternatively spliced mRNAs (5, 6 and 7 kb) that encode the QKI-5, QKI-6 and QKI-7 RNA binding proteins that differ in their C-terminal 30 amino acids. The QKI isoforms are known to regulate RNA metabolism within oligodendrocytes, however, little is known about their roles during cellular stress. Methodology/Principal Findings: In this study, we report an interaction between the QKI-6 isoform and a component of the RNA induced silencing complex (RISC), argonaute 2 (Ago2). We show in glial cells that QKI-6 co-localizes with Ago2 and the myelin basic protein mRNA in cytoplasmic stress granules. Conclusions: Our findings define the QKI isoforms as Ago2-interacting proteins. We also identify the QKI-6 isoform as a new component of stress granules in glial cells

Lexical tone perception in Mandarin Chinese speakers with aphasia

The brain localization debate of lexical tone processing concerns functional hypothesis that lexical tone, owing to its strong linguistic features, is dominant in the left hemisphere, and acoustic hypothesis that all pitch patterns, including lexical tone, are dominant in the right hemisphere due to their acoustic features. Lexical tone as a complex signal contains acoustic components that carry linguistic, paralinguistic, and nonlinguistic information. To examine these two hypotheses, the current study adopted triplet stimuli including Chinese characters, their corresponding pinyin with a diacritic, and the four diacritics representing Chinese lexical tones. The stimuli represent the variation of lexical tone for its linguistic and acoustic features. The results of a listening task by Mandarin Chinese speakers with and without aphasia support the functional hypothesis that pitch patterns are lateralized to different hemispheres of the brain depending on their functions, with lexical tone to the left hemisphere as a function of linguistic features

Synthesis of Hollow ZnSnO 3

Hollow ZnSnO3 nanospheres were synthesized by a hydrothermal method using ZnO nanospheres as the hard template and raw material simultaneously. The combined characterizations of X-ray diffraction (XRD), scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HRTEM) confirmed the successful preparation of hollow ZnSnO3 nanospheres. The gas-sensing results indicated that the sensor made from hollow ZnSnO3 nanospheres exhibited high sensitivity, good selectivity, and stability to ethanol at a low operating temperature of 200°C. The sensitivity was about 32 and the response and recovery time were about 4 s and 30 s for 100 ppm ethanol, respectively. The enhancement in gas-sensing properties was attributed to the hollow nanostructures and high specific surface areas of ZnSnO3