Metabolic and miRNA Profiling of TMV Infected Plants Reveals Biphasic Temporal Changes

Plant viral infections induce changes including gene expression and metabolic components. Identification of metabolites and microRNAs (miRNAs) differing in abundance along infection may provide a broad view of the pathways involved in signaling and defense that orchestrate and execute the response in plant-pathogen interactions. We used a systemic approach by applying both liquid and gas chromatography coupled to mass spectrometry to determine the relative level of metabolites across the viral infection, together with a miRs profiling using a micro-array based procedure. Systemic changes in metabolites were characterized by a biphasic response after infection. The first phase, detected at one dpi, evidenced the action of a systemic signal since no virus was detected systemically. Several of the metabolites increased at this stage were hormone-related. miRs profiling after infection also revealed a biphasic alteration, showing miRs alteration at 5 dpi where no virus was detected systemically and a late phase correlating with virus accumulation. Correlation analyses revealed a massive increase in the density of correlation networks after infection indicating a complex reprogramming of the regulatory pathways, either in response to the plant defense mechanism or to the virus infection itself. Our data propose the involvement of a systemic signaling on early miRs alteration

Frication noise modulated by voicing, as revealed by pitch-scaled decomposition

A decomposition algorithm that uses a pitch-scaled harmonic filter was evaluated using synthetic signals and applied to mixed-source speech, spoken by three subjects, to separate the voiced and unvoiced parts. Pulsing of the noise component was observed in voiced frication, which was analyzed by complex demodulation of the signal envelope. The timing of the pulsation, represented by the phase of the anharmonic modulation coefficient, showed a step change during a vowel-fricative transition corresponding to the change in location of the sound source within the vocal tract. Analysis of fricatives //[phonetic beta], v, [edh], z, [yog], [vee with swirl], [backward glottal stop]// demonstrated a relationship between steady-state phase and place, and f0 glides confirmed that the main cause was a place-dependent delay

Dynamic Magnetic Resonance Imaging: new tools for speech research

A multiplanar Dynamic Magnetic Resonance Imaging (MRI) technique that extends our earlier work on single-plane Dynamic MRI is described. Scanned images acquired while an utterasne is repeated are recombined to form pseudo-time-varying images of the vocal tract using a simultaneously recorded audio signal. There is no technical limit on the utterance length or number of slices that can be so imaged, though the number of repetitions required may be limited by the subject's stamina. An example of [pasi] imaged in three sagittal planes is shown; with a Signa GE 0.5T MR scanner, 360 tokens were reconstructed to form a sequence of 39 3-slice 16ms frames. From these, a 3-D volume was generated for each time frame, and tract surfaces outlined manually. Parameters derived from these include: palate-tongue distances for [a,s,i]; estimates of tongue volume and of the area function using only the midsagittal, and then all three slices. These demonstrate the accuracy and usefulness of the technique