Molecular and functional characterization of a novel sodium channel TipE-like auxiliary subunit from the American cockroach Periplaneta americana

In Drosophila melanogaster, the functions of voltage-gated sodium (Nav) channels are modulated by TipE and its orthologs. Here, we describe a novel TipE homolog of the American cockroach, Periplaneta americana, called PaTipE. Like DmTipE, PaTipE mRNAs are ubiquitously expressed. Surprisingly, PaTipE mRNA was undetectable in neurosecretory cells identified as dorsal unpaired median neurons. Phylogenetic analysis placed this new sequence in TipE clade, indicating an independent evolution from a common ancestor. Contrary to previous reports, our data indicate that the auxiliary subunits of insect Nav channels are very distant from the mammalian BKCa auxiliary subunits. To decipher the functional roles of PaTipE, we characterized the gating properties of DmNav1-1 channels co-expressed with DmTipE or PaTipE, in Xenopus oocytes. Compared to DmTipE, PaTipE increased Na(+) currents by a 4.2-fold. The voltage-dependence of steady-state fast inactivation of DmNav1-1/PaTipE channels was shifted by 5.8 mV to more negative potentials than that of DmNav1-1/DmTipE channels. DmNav1-1/PaTipE channels recovered 3.2-fold slower from the fast-inactivated state than DmNav1-1/DmTipE channels. In conclusion, this study supports that the insect Nav auxiliary subunits share functional features with their mammalian counterparts, although structurally and phylogenetically distant

L’inclusion financière en Afrique sub-saharienne : faits stylisés et déterminants

L’inclusion financière favorise le développement économique en permettant à une part croissante des ménages et desPMEd’accéder à une large palette de services financiers pour un coût raisonnable. Elle apparaît la plus faible en Afrique subsaharienne (AfSS) et en particulier en Zone franc, tant en termes de bancarisation, d’intensité d’utilisation des comptes bancaires que d’accès au crédit. La prévalence de l’exclusion financière en AfSS reflète des facteurs structurels provenant tant des insuffisances de l’offre (coût, gestion des asymétries d’information), de la demande des services financiers (revenus et éducation financière, phénomènes d’auto-exclusion) que de l’environnement réglementaire et du climat des affaires. L’inclusion financière implique, comme tout développement des activités financières, de nouveaux risques pour la stabilité financière et donc un renforcement des réglementations et de la supervision bancaire de façon à ce que la confiance du public et l’accès croissant aux services financiers aillent de pair avec une croissance économique stable et durable

L'aide internationale est-elle affectée par les cycles économiques et les politiques budgétaires des pays donateurs ?

Cet article présente les principaux résultats d'une étude en cours qui analyse l'effet des cycles économiques sur les flux - publics et privés - d'aide au développement. Les résultats préliminaires (sur la période 1976-2006) montrent que l'aide publique au développement est à la fois faiblement procyclique et sensible aux variations du solde budgétaire structurel (hors cycle). Cependant, l'effet procyclique est significatif uniquement pour les " petits " bailleurs (non G7) et asymétrique. L'aide privée (hors transferts des migrants) apparait également procyclique, mais selon des canaux de transmission différents. La conjonction de l'inertie de l'aide publique et du caractère cyclique de l'aide privée suggère trois axes pour améliorer l'efficacité de l'aide au développement : une aide publique au développement plus contracyclique, des financements innovants ayant une base peu cyclique, et un recours aux financements privé

Développement d’un traceur de caractéristiques de quadripôles et son utilisation en séance de travaux pratiques

Dans le cadre d’un projet d’études techniques, deux étudiants en 2ème du cycle ingénieur à l’ENSIL-ENSCI à Limoges ont réalisé un traceur automatique de caractéristiques de transistors (à effet de champ et bipolaire). Cet outil permet aujourd’hui aux étudiants en travaux pratiques d’électronique analogique de disposer des caractéristiques courant-tension et des paramètres dynamiques petit signal basse fréquence réalistes du composant utilisé en séance lors de la synthèse de leur circuit afin de répondre au cahier des charges spécifié. Ce papier présentera d’une part la construction de ce traceur de caractéristique (matériel utilisé, éléments de programmation …) et d’autre part l’utilisation de ces courbes lors de la synthèse d’un circuit amplificateur de tension à base d’un transistor bipolaire

Développement d’un traceur de caractéristiques de quadripôles et son utilisation en séance de travaux pratiques

Dans le cadre d’un projet d’études techniques, deux étudiants en 2ème du cycle ingénieur à l’ENSIL-ENSCI à Limoges ont réalisé un traceur automatique de caractéristiques de transistors (à effet de champ et bipolaire). Cet outil permet aujourd’hui aux étudiants en travaux pratiques d’électronique analogique de disposer des caractéristiques courant-tension et des paramètres dynamiques petit signal basse fréquence réalistes du composant utilisé en séance lors de la synthèse de leur circuit afin de répondre au cahier des charges spécifié. Ce papier présentera d’une part la construction de ce traceur de caractéristique (matériel utilisé, éléments de programmation …) et d’autre part l’utilisation de ces courbes lors de la synthèse d’un circuit amplificateur de tension à base d’un transistor bipolaire

Attractive serial dependence in numerosity perception in dogs (Canis familiaris).

Recent literature in humans has described a perceptual phenomenon called serial dependence, by which the current stimulus appears similar to the previous one. It has been interpreted as an active stabilization process, integrating stimulus features over time for a stable and seamless conscious experience. Despite the growing number of studies investigating serial dependence across several visual domains in humans, it is not known if the phenomenon extends also to other species. In the current study we aim to fill this gap of knowledge by exploring the behavioral signature of serial dependence in numerosity perception in dogs. We enrolled 5 dogs, who were trained on quantity discrimination prior to being presented with a set of test trials. Simultaneously presented test stimuli included a variable probe (4-16 dots) and a reference (8 dots), which was preceded by a task-irrelevant inducer stimulus (4 or 16) in the identical location. We hypothesized that if dogs are susceptible to the serial dependence, the reference would be perceived either smaller or larger depending on the inducer numerosity. For each dog we fitted a psychometric curve based on the probability of choosing the reference and defined the point of subjective equality (PSE) for the reference preceded by either of the inducer, (PSE(4)=7.10; PSE(16)=10.07). To compare the perceptual effect of the two inducers, we performed an ANOVA, which revealed a significant effect of the inducer (F(2)=23.87; p<0.001), with both of theconditions being significantly different from the control condition (p(4)=0.35; p(16)=0.02, sequential Bonferroni corrections applied). This result suggests an attractive bias in consecutively presented stimuli in dogs, providing the first evidence that the phenomenon of serial dependence extends also to non-human animals. Moreover, the finding expands the similarities between humans and dogs in processing visual stimuli

Object connectedness affects quantity perception in dogs.

Research in humans has shown that connecting a collection of dots with task-irrelevant lines leads to a robust numerical underestimation. To date, this paradigm has not been explored in other animal species. We assessed if connectedness results in an underestimation of quantity in dogs. Dogs (N=30) underwent an initial task, where they were presented with two plates containing different numbers of food items, and were trained to choose the stimulus containing the larger amount of food. Once they reached the learning criterion, dogs were presented with two arrays, each of which contained 30 food pieces, arranged in identical locations. On one array the food pieces were connected by thin inedible lines, forming three clusters of ten elements each. On the other array, identical lines were arranged randomly amongst food elements without being in contact with them. Each dog was presented with the test condition four times, and were expected to maximize food intake, choosing the stimulus where food items appeared more numerous. Thirteen dogs completed the test, the rest of the dogs did not reach the learning criterion in the training phase. An intercept-only GLMM model on dogs’ choice in test trials (connected or unconnected stimulus) revealed that dogs chose the unconnected stimulus more often than expected by chance (35/52, p=0.015). This suggests that connectedness affects quantity judgements by dogs in a similar way to humans. The result is of particular relevance in view of the fact that previous research generally failed to find effects of non-numerical cues on quantity estimation by dogs. Furthermore, dogs are the first non-human species in which the illusion has been assessed. In the light of the scarce susceptibility to quantity illusions by many animal species, it would be interesting to know if susceptibility to this illusion applies also to other species

G-protein-mediated desensitization of metabotropic glutamatergic and muscarinic responses in CA3 cells in rat hippocampus.

1. Desensitization of a metabotropic response was investigated in CA3 pyramidal neurons in hippocampal slice cultures using the patch-clamp technique. 2. 1S,3R-1-aminocyclopentane-1,3-dicarboxylate (1S,3R-ACPD), an agonist at metabotropic glutamate receptors (mGluRs), and metacholine (MCh), an agonist at muscarinic receptors, induced a cationic current that appears to be activated through a G-protein-independent transduction process, as previously shown. Prolonged or repetitive bath application of agonists led to rapid desensitization of the cationic current with a time constant of approximately 20 s. 3. Complete recovery from desensitization was observed within 6 min. 4. These responses mediated by mGluRs and muscarinic receptors cross-desensitized. 5. Preventing the activation of G-proteins by loading cells with GDP beta S strongly reduced or suppressed desensitization, and resulted in a sustained inward cationic current. When cells were filled with GTP gamma S to irreversibly activate G-proteins, the desensitization process was enhanced such that a first application of agonist caused a markedly reduced response. 6. These results show that a cationic current induced by metabotropic agonists in hippocampal pyramidal cells undergoes apparent desensitization and suggests that this process occurs through a G-protein-mediated inhibition of the underlying membrane conductance