Dendritic Spine Morphology Determines Membrane-Associated Protein Exchange between Dendritic Shafts and Spine Heads

The purpose of this study was to examine whether variability in the shape of dendritic spines affects protein movement within the plasma membrane. Using a combination of confocal microscopy and the fluorescence loss in photobleaching technique in living hippocampal CA1 pyramidal neurons expressing membrane-linked GFP, we observed a clear correlation between spine shape parameters and the diffusion and compartmentalization of membrane-associated proteins. The kinetics of membrane-linked GFP exchange between the dendritic shaft and the spine head compartment were slower in dendritic spines with long necks and/or large heads than in those with short necks and/or small heads. Furthermore, when the spine area was reduced by eliciting epileptiform activity, the kinetics of protein exchange between the spine compartments exhibited a concomitant decrease. As synaptic plasticity is considered to involve the dynamic flux by lateral diffusion of membrane-bound proteins into and out of the synapse, our data suggest that spine shape represents an important parameter in the susceptibility of synapses to undergo plastic chang

Predicting where a radiation will occur: Acoustic and molecular surveys reveal overlooked diversity in Indian Ocean Island crickets (Mogoplistinae: Ornebius)

Recent theory suggests that the geographic location of island radiations (local accumulation of species diversity due to cladogenesis) can be predicted based on island area and isolation. Crickets are a suitable group for testing these predictions, as they show both the ability to reach some of the most isolated islands in the world, and to speciate at small spatial scales. Despite substantial song variation between closely related species in many island cricket lineages worldwide, to date this characteristic has not received attention in the western Indian Ocean islands; existing species descriptions are based on morphology alone. Here we use a combination of acoustics and DNA sequencing to survey these islands for Ornebius crickets. We uncover a small but previously unknown radiation in the Mascarenes, constituting a three-fold increase in the Ornebius species diversity of this archipelago (from two to six species). A further new species is detected in the Comoros. Although double archipelago colonisation is the best explanation for species diversity in the Seychelles, in situ cladogenesis is the best explanation for the six species in the Mascarenes and two species of the Comoros. Whether the radiation of Mascarene Ornebius results from intra- or purely inter- island speciation cannot be determined on the basis of the phylogenetic data alone. However, the existence of genetic, song and ecological divergence at the intra-island scale is suggestive of an intra-island speciation scenario in which ecological and mating traits diverge hand-in-hand. Our results suggest that the geographic location of Ornebius radiations is partially but not fully explained by island area and isolation. A notable anomaly is Madagascar, where our surveys are consistent with existing accounts in finding no Ornebius species present. Possible explanations are discussed, invoking ecological differences between species and differences in environmental history between islands. (Résumé d'auteur

Dissecting the autism-associated 16p11.2 locus identifies multiple drivers in neuroanatomical phenotypes and unveils a male-specific role for the major vault protein

Background Using mouse genetic studies and systematic assessments of brain neuroanatomical phenotypes, we set out to identify which of the 30 genes causes brain defects at the autism-associated 16p11.2 locus. Results We show that multiple genes mapping to this region interact to regulate brain anatomy, with female mice exhibiting far fewer brain neuroanatomical phenotypes. In male mice, among the 13 genes associated with neuroanatomical defects (Mvp, Ppp4c, Zg16, Taok2, Slx1b, Maz, Fam57b, Bola2, Tbx6, Qprt, Spn, Hirip3, and Doc2a), Mvp is the top driver implicated in phenotypes pertaining to brain, cortex, hippocampus, ventricles, and corpus callosum sizes. The major vault protein (MVP), the main component of the vault organelle, is a conserved protein found in eukaryotic cells, yet its function is not understood. Here, we find MVP expression highly specific to the limbic system and show that Mvp regulates neuronal morphology, postnatally and specifically in males. We also recapitulate a previously reported genetic interaction and show that Mvp+/−;Mapk3+/− mice exhibit behavioral deficits, notably decreased anxiety-like traits detected in the elevated plus maze and open field paradigms. Conclusions Our study highlights multiple gene drivers in neuroanatomical phenotypes, interacting with each other through complex relationships. It also provides the first evidence for the involvement of the major vault protein in the regulation of brain size and neuroanatomy, specifically in male mice

Présence de Xiphidiopsis lita Hebard, 1922, aux Mascareignes et aux Seychelles (Orthoptera, Ensifera)

Occurence of Xiphidiopsis lita Hebard, 1922, on Mascarene and Seychelles islands (Orthoptera, Ensifera). Xiphidiopsis lita Hebard, 1922, was described from Hawaii and is widely distributed on Pacific islands. This species is recorded for the first time on Mascarene islands (Mauritius, Rodriguez and Réunion). X. lita is also present on Seychelles where it was recorded as Amytta sp. A diagnosis of this widely distributed species is given, its world distribution is reviewed, and possible factors favouring this distribution are discussed.Décrit de Hawaii, Xiphidiopsis lita Hebard, 1922, est largement répandu sur les îles du Pacifique. Cette espèce est recensée pour la première fois aux Mascareignes (Maurice, Rodrigues et Réunion). X. lita est également présent aux Seychelles où il avait été recensé comme Amytta sp. Une diagnose de cette espèce à large répartition est donnée, le point sur sa répartition mondiale est fait et les éléments pouvant favoriser cette large répartition sont discutés.Hugel Sylvain. Présence de Xiphidiopsis lita Hebard, 1922, aux Mascareignes et aux Seychelles (Orthoptera, Ensifera). In: Bulletin de la Société entomologique de France, volume 115 (2),2010. pp. 167-173

Redécouverte du genre Pyrgacris à l'île de la Réunion : description du mâle de P. descampsi Kevan, 1975 (Orthoptera, Caelifera)

Rediscoveiy of the genus Pyrgacris to the Réunion island : description of the male of P. descampsi Kevan, 1975 (Orthoptera, Caelifera). Until now, only two original specimens belonging to the Pyrgacris genus were known : one male from Mauritius, described as P. relictus Descamps, 1968, and one female from Réunion. In spite of the lack of distinguishing traits between these two specimens, the female was subsequently named P. descampsi Kevan, 1975. The recent discovery of a Pyrgacris population in Réunion allows to show that the Pyrgacris from Réunion and Mauritius are clearly distinct species and that P. descampsi must be kept. The justification for higher rank taxa, created to include the Pyrgacris genus, is discussed. The extinction threat to this remarkable genus and more generally to the palmicolous entomofauna of Mascarene Islands is emphasized.A ce jour, le genre Pyrgacris Descamps, 1968, n'était connu que par deux spécimens anciens : un mâle provenant de l'île Maurice et décrit sous le nom de P. relictus Descamps, 1968, et une femelle provenant de l'île de la Réunion. En dépit de l'absence de caractères discriminant le mâle de la femelle, cette dernière a été nommée P. descampsi Kevan, 1975. La récente découverte d'une population de Pyrgacris à la Réunion permet aujourd'hui d'établir que les Pyrgacris de cette île sont bien distincts de ceux de l'île Maurice. Il semble justifié de conserver le nom de Kevan, P. descampsi, pour désigner cette espèce. La justification des taxons d'ordre supérieur érigés pour contenir le genre Pyrgacris est discutée. Enfin, la situation particulièrement critique de ce genre remarquable et des autres espèces palmicoles endémiques des Mascareignes est évoquée.Hugel Sylvain. Redécouverte du genre Pyrgacris à l'île de la Réunion : description du mâle de P. descampsi Kevan, 1975 (Orthoptera, Caelifera). In: Bulletin de la Société entomologique de France, volume 110 (2), juin 2005. pp. 153-159

First record of shield-backed katydids in Madagascar with the description of a new genus and three new species (Orthoptera: Ensifera: Tettigoniidae: Tettigoniinae Arytropteridini)

Hugel, Sylvain (2019): First record of shield-backed katydids in Madagascar with the description of a new genus and three new species (Orthoptera: Ensifera: Tettigoniidae: Tettigoniinae Arytropteridini). Zootaxa 4706 (4): 546-560, DOI: 10.11646/zootaxa.4706.4.

Endemic grasshoppers from the Mascarene Islands: a critically endangered island fauna

International audienc

Redécouverte du genre Pyrgacris à l'île de la Réunion : description du mâle de P. descampsi Kevan, 1975 (Orthoptera, Caelifera)

Rediscoveiy of the genus Pyrgacris to the Réunion island : description of the male of P. descampsi Kevan, 1975 (Orthoptera, Caelifera). Until now, only two original specimens belonging to the Pyrgacris genus were known : one male from Mauritius, described as P. relictus Descamps, 1968, and one female from Réunion. In spite of the lack of distinguishing traits between these two specimens, the female was subsequently named P. descampsi Kevan, 1975. The recent discovery of a Pyrgacris population in Réunion allows to show that the Pyrgacris from Réunion and Mauritius are clearly distinct species and that P. descampsi must be kept. The justification for higher rank taxa, created to include the Pyrgacris genus, is discussed. The extinction threat to this remarkable genus and more generally to the palmicolous entomofauna of Mascarene Islands is emphasized.A ce jour, le genre Pyrgacris Descamps, 1968, n'était connu que par deux spécimens anciens : un mâle provenant de l'île Maurice et décrit sous le nom de P. relictus Descamps, 1968, et une femelle provenant de l'île de la Réunion. En dépit de l'absence de caractères discriminant le mâle de la femelle, cette dernière a été nommée P. descampsi Kevan, 1975. La récente découverte d'une population de Pyrgacris à la Réunion permet aujourd'hui d'établir que les Pyrgacris de cette île sont bien distincts de ceux de l'île Maurice. Il semble justifié de conserver le nom de Kevan, P. descampsi, pour désigner cette espèce. La justification des taxons d'ordre supérieur érigés pour contenir le genre Pyrgacris est discutée. Enfin, la situation particulièrement critique de ce genre remarquable et des autres espèces palmicoles endémiques des Mascareignes est évoquée.Hugel Sylvain. Redécouverte du genre Pyrgacris à l'île de la Réunion : description du mâle de P. descampsi Kevan, 1975 (Orthoptera, Caelifera). In: Bulletin de la Société entomologique de France, volume 110 (2), juin 2005. pp. 153-159

Un nouvel Agraecia de Martinique et présence de Agraecia viridipennis en Guyane française (Orthoptera, Ensifera, Conocephalinae)

A new Agraecia from Martinique and record of Agraecia viridipennis in French Guyana (Orthoptera, Ensifera, Conocephalinae). A new species of Agraecia Serville, 1831, is described from Martinique : H. cesairei n. sp. The song of this new species is described and biological data are given. Agraecia viridipennis Redtenbacher, 1891, is recorded for the first time in French Guyana. The specimens collected there allow synonymising Agraecia malkini Piza, 1978, with A. viridipennis which is redescribed. The probable synonymy of A. pulchella Hebard, 1927, with A. vittata Redtenbacher, 1891, is pointed out, and the homogeneity of Agraecia is discussed.Une nouvelle espèce du genre Agraecia Serville, 1831, est décrite de Martinique : A. cesairei n. sp. La stridulation de cette espèce est décrite et des éléments de biologie sont donnés. Agraecia viridipennis Redtenbacher, 1891, est signalé pour la première fois de Guyane française. La série de spécimens collectés sur ce territoire permet d’établir la synonymie d''Agraecia malkini Piza, 1978, avec A. viridipennis, qui est redécrit. La probable synonymie d'A. pulchella Hebard, 1927, avec A. vittata Redtenbacher, 1891, est évoquée, et l’homogénéité du genre Agraecia est discutée.Hugel Sylvain. Un nouvel Agraecia de Martinique et présence de Agraecia viridipennis en Guyane française (Orthoptera, Ensifera, Conocephalinae). In: Bulletin de la Société entomologique de France, volume 114 (2),2009. pp. 129-140

Note synonymique sur Myrmecophilus americanus Saussure, 1877, et présence de M. quadrispina Perkins, 1899, à l'île Maurice (Orth., Myrmecophilinae)

Hugel Sylvain. Note synonymique sur Myrmecophilus americanus Saussure, 1877, et présence de M. quadrispina Perkins, 1899, à l'île Maurice (Orth., Myrmecophilinae). In: Bulletin de la Société entomologique de France, volume 111 (4), décembre 2006. p. 448