Vocal imitations and the identification of sound events

International audienceIt is commonly observed that a speaker vocally imitates a sound that she or he intends to communicate to an interlocutor. We report on an experiment that examined the assumption that vocal imitations can e ffectively communicate a referent sound, and that they do so by conveying the features necessary for the identifi cation of the referent sound event. Subjects were required to sort a set of vocal imitations of everyday sounds. The resulting clusters corresponded in most of the cases to the categories of the referent sound events, indicating that the imitations enabled the listeners to recover what was imitated. Furthermore, a binary decision tree analysis showed that a few characteristic acoustic features predicted the clusters. These features also predicted the classi fication of the referent sounds, but did not generalize to the categorization of other sounds. This showed that, for the speaker, vocally imitating a sound consists of conveying the acoustic features important for recognition, within the constraints of human vocal production. As such vocal imitations prove to be a phenomenon potentially useful to study sound identifi cation

Spodoptera frugiperda (Lepidoptera: Noctuidae) host-plant variants: two host strains or two distinct species?

International audienceThe moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differences in their mating behavior, pheromone compositions, and show development variability according to the host-plant. Though the latter suggest that both strains are different species, this issue is still highly controversial because hybrids naturally occur in the wild, not to mention the discrepancies among published results concerning mating success between the two strains. In order to clarify the status of the two host-plant strains of S. frugiperda, we analyze features that possibly reflect the level of post-zygotic isolation: (1) first generation (F1) hybrid lethality and sterility; (2) patterns of meiotic segregation of hybrids in reciprocal second generation (F2), as compared to the meiosis of the two parental strains. We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny. Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field. Altogether these results provide additional evidence in favor of a sibling species status for the two strains

Lack of an Antibacterial Response Defect in Drosophila Toll-9 Mutant

Toll and Toll-like receptors represent families of receptors involved in mediating innate immunity response in insects and mammals. Although Drosophila proteome contains multiple Toll paralogs, Toll-1 is, so far, the only receptor to which an immune role has been attributed. In contrast, every single mammalian TLR is a key membrane receptor upstream of the vertebrate immune signaling cascades. The prevailing view is that TLR-mediated immunity is ancient. Structural analysis reveals that Drosophila Toll-9 is the most closely related to vertebrate TLRs and utilizes similar signaling components as Toll-1. This suggests that Toll-9 could be an ancestor of TLR-like receptors and could have immune function. Consistently, it has been reported that over-expression of Toll-9 in immune tissues is sufficient to induce the expression of some antimicrobial peptides in flies. These results have led to the idea that Toll-9 could be a constitutively active receptor that maintain significant levels of antimicrobial molecules and therefore provide constant basal protection against micro-organisms. To test theses hypotheses, we generated and analyzed phenotypes associated with a complete loss-of-function allele of Toll-9. Our results suggest that Toll-9 is neither required to maintain a basal anti-microbial response nor to mount an efficient immune response to bacterial infection

Perception of vocal imitations and identification of the imitated sounds

cote interne IRCAM: Lemaitre10bNone / NoneNational audienceWe report two studies investigating how vocal imitations enable the recognition of the imitated sounds. First, we asked couples of participants to listen to series of everyday sounds. One of the participants (the “speaker”) had then to describe a selected sound to the other one (the “listener”), so that he could “guess” the selected sound. The results showed that, spontaneously, the speakers used, among other para-linguistic cues, large numbers of vocal imitations. Moreover, they suggested that the identification performances were increased when vocal imitations were used, compared to only verbal descriptions. Second, we sampled twenty-eight sounds across an experimental taxonomy of kitchen sounds and required laypersons to vocally imitate these sounds. Another group of participants was then required to categorize these vocal imitations, according to what they thought was imitated. A hierarchical cluster analysis showed that, overall, the categories of vocal imitations fitted well with the categories of imitated sound sources. By using finer analysis techniques, we also showed that some imitations inconsistently clustered. On the other hand, the consistent clusters of imitations were perfectly predicted by a few acoustical descriptors. We therefore conclude that vocal imitations of sounds contain enough information for the recognition of the imitated sounds

Les imitations vocales de sons environnementaux permettent-elles leur reconnaissance ?

National audienceSi nous faisons l'hypothèse qu'au cours d'une conversation courante, l'emploi d'imitations vocales par un locuteur permet à son interlocuteur d'identifier le son imité, il est alors fondé de penser que l'étude de ces imitations peut beaucoup nous apprendre concernant les mécanismes psychologiques d'identification des sons environnementaux. Nous présentons ici deux études qui investiguent cette question. Dans une première étude, nous avons demandé à des paires de participants d'écouter des séries de sons. Un des participants avait alors à décrire à l'autre un son sélectionné, et le second participant avait alors à deviner ce son. Les participants étaient absolument libres d'utiliser tous les moyens nécessaires pour décrire le son. Les résultats montrent que dans plus de 50 % des cas, les participants ont spontanément utilisé des imitations vocales, et que l'emploi de ces imitations améliore les performances de reconnaissance. Dans une seconde expérience, nous avons enregistré des imitations vocales de sons environnementaux (bruits de cuisine). Ces sons présentaient l'intérêt d'avoir été étudiés dans un travail préalable, et leur catégorisation perceptive était donc connue. Nous avons alors demandé à des participants de classer ces imitations, en fonction de ce qu'ils croyaient être imité. Une analyse en clusters hiérarchique montre alors que les catégories d'imitations correspondent de manière remarquable aux catégories de sons imités. Ces catégories semblent définies par certaines caractéristiques acoustiques systématiques. Ce dernier point est confirmé, en montrant, à l'aide de techniques de classification automatique simples, que la catégorisation des imitations peut être prédite en se basant sur quelques descripteurs psychoacoustiques classiques. Ces résultats montrent donc que les imitations vocales contiennent l'information suffisante à la reconnaissance du son imité, et que cette information se caractérise simplement du point de vue acoustique. Ils laissent donc espérer que l'étude des imitations vocales de sons environnementaux va permettre de caractériser l'identification de ces sons

Do vocal imitations enable the identification of the imitated sounds?

cote interne IRCAM: Lemaitre09hNone / NoneNational audienceDo vocal imitations enable the identification of the imitated sounds

ATP-dependent activity and mitochondrial localization of drug efflux pumps in doxorubicin-resistant breast cancer cells.

International audienceBACKGROUND: We hypothesized that, among the mechanisms of drug-resistance acquired by doxorubicin (DOX)-resistant breast cancer cells to maintain cell survival, ATP-dependent drug efflux pumps could be expressed in their mitochondrial membranes and this might limit the accumulation of DOX in this subcellular compartment in relation to mitochondrial ATP production.Methods/results Mitochondrial DOX accumulation: the presence and the activity of mitochondrial efflux pumps and their relationship with mitochondrial ATP synthesis were analyzed in DOX-resistant (MCF-7doxR) and -sensitive (MCF-7S) breast cancer cells. Mitochondrial accumulation of DOX (autofluorescence) was decreased when ATP was produced, but only in MCF-7doxR. In these DOX-resistant cells, breast cancer resistance protein (BCRP) and multidrug resistance-associated protein (MRP1) were expressed and localized in mitochondria (confocal microscopy and confocal spectral imaging studies). In addition, mitochondrial accumulation of DOX was increased by BCRP and MRP1 inhibitors and, to a lower extent, by the mitochondrial ATP synthase inhibitor, oligomycin, in MCF-7doxR.CONCLUSIONS: Both BCRP and MRP1 were localized in mitochondria and participated to the reduction of mitochondrial accumulation of DOX in MCF-7doxR. This process was partly dependent of mitochondrial ATP synthesis.GENERAL SIGNIFICANCE: The present study provides novel insights in the involvement of mitochondria in the underlying mechanisms of DOX-resistance in breast cancer cells