Telomeric Trans-Silencing: An Epigenetic Repression Combining RNA Silencing and Heterochromatin Formation

The study of P-element repression in Drosophila melanogaster led to the discovery of the telomeric Trans-Silencing Effect (TSE), a repression mechanism by which a transposon or a transgene inserted in subtelomeric heterochromatin (Telomeric Associated Sequence or TAS) has the capacity to repress in trans in the female germline, a homologous transposon, or transgene located in euchromatin. TSE shows variegation among egg chambers in ovaries when silencing is incomplete. Here, we report that TSE displays an epigenetic transmission through meiosis, which involves an extrachromosomal maternally transmitted factor. We show that this silencing is highly sensitive to mutations affecting both heterochromatin formation (Su(var)205 encoding Heterochromatin Protein 1 and Su(var)3–7) and the repeat-associated small interfering RNA (or rasiRNA) silencing pathway (aubergine, homeless, armitage, and piwi). In contrast, TSE is not sensitive to mutations affecting r2d2, which is involved in the small interfering RNA (or siRNA) silencing pathway, nor is it sensitive to a mutation in loquacious, which is involved in the micro RNA (or miRNA) silencing pathway. These results, taken together with the recent discovery of TAS homologous small RNAs associated to PIWI proteins, support the proposition that TSE involves a repeat-associated small interfering RNA pathway linked to heterochromatin formation, which was co-opted by the P element to establish repression of its own transposition after its recent invasion of the D. melanogaster genome. Therefore, the study of TSE provides insight into the genetic properties of a germline-specific small RNA silencing pathway

Prospective study on a fast-track training in psychiatry for medical students: the psychiatric hat game

Abstract: Background: While medical students are losing interest in lectures in favor of other educational materials, many studies suggest the benefit of active learning, combined with gamified educational tools. The authors developed a psychiatric adaptation of the « Hat Game ». It was hypothesised that this game would increase both knowledge and motivation in medical students toward psychiatric semiology. The aim of the study was to assess the benefit of a Psychiatric Hat Game session for learning psychiatric symptoms in third-year medical students. Student performance was also evaluated at 3 months. Methods: This gamified fast-track training consists of two teams and each team has to guess as many psychiatric semiology terms as possible using different techniques (i.e. speech, mime). The study involved a pre- and post-evaluation of knowledge (Multiple Choice Questions) and a satisfaction survey. Baseline, post-immediate, and three-months scores were compared by using Friedman analysis for paired samples. Comparisons of mean scores at two different times were performed by using Wilcoxon test for paired samples. Results: One hundred and sixty-six students were proposed to take part in the study. Among them 129 completed the whole program (response rate = 77.7%). Mean scores measured at the three points in time were significantly different (p < 0.001, N = 129). Knowledge mean scores were significantly higher after the game than before (+ 28.6%, p < 0.001). Improvement was maintained 3 months after the game (+ 18.9%, p < 0.001). Satisfaction survey items highlighted that students enjoyed and would recommend this type of gamified training. Conclusions: The Psychiatric Hat Game improved knowledge of psychiatric semiology in medical students. Results suggest that it is a promising and efficient tool to playfully teach medical semiology, with transferable features, utility and acceptability from one medical field to another. This study contributes to the growing body of knowledge advocating for serious games and gamified training in medical education.Version of Recor

The Epigenetic Trans-Silencing Effect in Drosophila Involves Maternally-Transmitted Small RNAs Whose Production Depends on the piRNA Pathway and HP1

BACKGROUND: The study of P transposable element repression in Drosophila melanogaster led to the discovery of the Trans-Silencing Effect (TSE), a homology-dependent repression mechanism by which a P-transgene inserted in subtelomeric heterochromatin (Telomeric Associated Sequences, "TAS") has the capacity to repress in trans, in the female germline, a homologous P-lacZ transgene located in euchromatin. Phenotypic and genetic analysis have shown that TSE exhibits variegation in ovaries, displays a maternal effect as well as epigenetic transmission through meiosis and involves heterochromatin (including HP1) and RNA silencing. PRINCIPAL FINDINGS: Here, we show that mutations in squash and zucchini, which are involved in the piwi-interacting RNA (piRNA) silencing pathway, strongly affect TSE. In addition, we carried out a molecular analysis of TSE and show that silencing is correlated to the accumulation of lacZ small RNAs in ovaries. Finally, we show that the production of these small RNAs is sensitive to mutations affecting squash and zucchini, as well as to the dose of HP1. CONCLUSIONS AND SIGNIFICANCE: Thus, our results indicate that the TSE represents a bona fide piRNA-based repression. In addition, the sensitivity of TSE to HP1 dose suggests that in Drosophila, as previously shown in Schizosaccharomyces pombe, a RNA silencing pathway can depend on heterochromatin components

Telomeric Trans-Silencing in Drosophila melanogaster: Tissue Specificity, Development and Functional Interactions between Non-Homologous Telomeres

BACKGROUND: The study of P element repression in Drosophila melanogaster led to the discovery of the telomeric Trans-Silencing Effect (TSE), a homology-dependent repression mechanism by which a P-transgene inserted in subtelomeric heterochromatin (Telomeric Associated Sequences, "TAS") has the capacity to repress in trans, in the female germline, a homologous P-lacZ transgene located in euchromatin. TSE can show variegation in ovaries, displays a maternal effect as well as an epigenetic transmission through meiosis and involves heterochromatin and RNA silencing pathways. PRINCIPAL FINDINGS: Here, we analyze phenotypic and genetic properties of TSE. We report that TSE does not occur in the soma at the adult stage, but appears restricted to the female germline. It is detectable during development at the third instar larvae where it presents the same tissue specificity and maternal effect as in adults. Transgenes located in TAS at the telomeres of the main chromosomes can be silencers which in each case show the maternal effect. Silencers located at non-homologous telomeres functionally interact since they stimulate each other via the maternally-transmitted component. All germinally-expressed euchromatic transgenes tested, located on all major chromosomes, were found to be repressed by a telomeric silencer: thus we detected no TSE escaper. The presence of the euchromatic target transgene is not necessary to establish the maternal inheritance of TSE, responsible for its epigenetic behavior. A single telomeric silencer locus can simultaneously repress two P-lacZ targets located on different chromosomal arms. CONCLUSIONS AND SIGNIFICANCE: Therefore TSE appears to be a widespread phenomenon which can involve different telomeres and work across the genome. It can explain the P cytotype establishment by telomeric P elements in natural Drosophila populations

Urbanisation autonome : pour une autre action urbaine sur les quartiers précaires

International audienceNeighborhoods that are built autonomously and do not conform to public standards represent the largest form of urbanization in the world. With this in mind, Valérie Clerc, Laure Criqui and Guillaume Josse propose new ways to intervene on these spaces at the heart of the making of the urban.Les quartiers construits de façon autonome et non conforme aux normes publiques représentent la forme d'urbanisation majoritaire dans le monde. Forts de ce rappel, Valérie Clerc, Laure Criqui et Guillaume Josse proposent de nouvelles pistes pour intervenir sur ces espaces au coeur de la fabrique urbaine

Reconciliation between neontology and paleontology in the Gryllidea (Orthoptera, Ensifera): reinterpreting the venation of the stridulatory apparatus in crickets

International audienceThe Ensifera are famous for the diversity of their acoustic devices and have been intensively studied for their acoustic behaviour and evolution. They sing mostly by scrapping their forewings against each other. Their apparatus includes a stridulatory file and several broad areas that may play as sound resonators, which homology has been harshly debated. Most previous studies focussed on the functional parts, while the whole forewing venation has been less studied in a comparative context. Here, we extend recent observations with 3D-microtomography to study the venation of the forewing of both modern and fossil Ensifera, focussing more specifically on true crickets (Grylloidea Laicharting, 1781), mole crickets (Gryllotalpidae Leach, 1815) and their fossil allies (angstrom Baissogryllidae Gorochov, 1985, angstrom Protogryllidae Zeuner, 1937). We propose a complete pattern of forewing venation for the Gryllidea Laicharting, 1781, extending the paradigm proposed by Bethoux and Nel (2001, 2002) for fossils. This pattern defines the acoustic and non-acoustic structures using well-defined homologies through the whole Gryllidea. We put in evidence potential apomorphies for Gryllidea, Grylloidea and Gryllotalpidae, but none of the wing traits originally proposed to define the angstrom Baissogryllidae or the angstrom Protogryllidae are found exclusively in these taxa. Our observations support the hypothesis of convergence between crickets and mole crickets for the stridulatory file

First 3D reconstruction of a forewing of a fossil Orthoptera: Interpreting the venation pattern in the smallest known cricket with a stridulatory apparatus, Picogryllus carentonensis (Orthoptera, Grylloidea, Oecanthidae)

International audienceFossil insects are valuable indicators of the evolutionary history of the clades to which they belong. According to their state of preservation, fossil insects are often partially described for key morphological characters, such as forewing venation in crickets (Orthoptera, Grylloidea). In parallel, the use of 3D microtomography is increasingly becoming common for studying some fossils, which allowed here the precise reconstruction and interpretation of the venation pattern in the smallest known cricket with a stridulatory apparatus, dagger Picogryllus carentonensis, found in opaque amber. The 3D reconstructions have revealed the general structure of the venation of the forewing and have enabled the identification of all its veins and cells, validating its similarity with that of extant crickets. Putative homologies are established according to previous studies, and some particularities are observed, such as the presence of two crossveins in the mirror, a rare feature in extant crickets that is discussed in the frame of cricket venation evolution. These findings highlight the importance of 3D microtomography as a powerful tool for examining fossil insects and also provide crucial information for taxonomic identification and evolutionary studies, offering a validated morphological basis for future phylogenetic analyses incorporating fossils

First 3D reconstruction of the male genitalia of a Cretaceous fossil cricket: Diving into the evolutionary history of the Oecanthidae family (Orthoptera: Grylloidea) with the incorporation of new fossils in its phylogeny and a total-evidence dating approach

International audienceFossils are valuable indicators of the evolutionary history of the clades to which they belong to, especially when they are incorporated as terminal taxa in a total-evidence phylogeny. According to their state of preservation, fossils are often incompletely described for key morphological characters, such as genitalic structures. Here, the internal parts of the genitalia of a male fossil cricket from Cretaceous amber, dagger Picogryllus carentonensis Josse and Desutter-Grandcolas (Oecanthidae, Podoscirtinae), together with other key morphological characters (i.e., metanotal structures and tibial spurs), were reconstructed for the first time by 3D microtomography. Total-evidence phylogeny and dating combining morphological data (fossils and extant taxa), molecular data (extant taxa only) and time calibration (fossil dates) were performed to evaluate the tempo and mode of evolution of the cricket family Oecanthidae. Divergence time estimates were thus refined and the patterns of transformation for key morphological structures contrasted through the analysis of phylogenetic morphological partitions. Our results show that Oecanthidae date back to the Upper Jurassic (Oxfordian, around 162 Ma) and attest to the presence of the Podoscirtinae in Western Europe during the Lower Cretaceous. Morphological evolution may have been driven by the conquest of new resources (as shown by leg evolution in ancestral Oecanthidae) and/or the &#039;conquest of silence&#039; (as shown by repetitive and definitive losses of acoustic structures). By contrast, genitalia evolution proved more diffuse

The “Neurospeed” game: a fun tool to learn the neurological semiology

International audienceBackground: Neurological semiology is often considered by medical students as particularly difficult to learn. Finding alternative teaching methods may improve students' motivation and understanding of this field. Methods: We developed the "Neurospeed", a game to learn neurological syndromes. We assessed its efficiency on short-term learning of neurological syndromes in third-year medical students, through Multiple Choice Questions (MCQs) before and after the game session. Students' satisfaction was evaluated by a satisfaction survey. Results: Out of the 199 third-year medical students of the Faculty of Medicine Sorbonne Paris Nord, 180 attended the Neurospeed in December 2020, and 148 answered 20 Multiple Choice Questions before and after the game, with significant improvement of their score (p < 0.001). Most of the participants agreed that the game was playful, stimulating, and helpful to learn neurological semiology. Conclusions: Overall, our results show that the Neurospeed game is an interesting tool as a complement to traditional lectures. Further studies are necessary to compare the efficacy of different types of serious games on short-term and long-term learning of neurological semiology

New Cretaceous crickets of the subfamilies Nemobiinae and Podoscirtinae (Orthoptera, Grylloidea: Trigonidiidae, Oecanthidae) attest the antiquity of these clades

International audienceFossils are more and more used in phylogenetic evolutionary studies either for clade calibration, or as terminals in a dataset including morphological characters. The strength of these methodological advances relies however on the quality and completeness of the fossil record. For crickets (Insecta, Orthoptera, Gryllidea), few ancient (pre-Cenozoic) well-preserved fossils are known, except for isolated wings often classified in purely fossil groups and a few fossils found in Cretaceous amber. Here, we present two remarkable fossils from mid-Cretaceous amber of France, that were imaged using X-ray synchrotron microtomography and exhibit an exquisite preservation allowing description with a precision similar to that of extant taxa. Palaeonemobius occidentalis Laurent and Desutter-Grandcolas, gen. nov., sp. nov. and Picogryllus carentonensis Josse and Desutter-Grandcolas, gen. nov., sp. nov. are the oldest representatives of the Nemobiinae and Podoscirtinae subfamilies of the Trigonidiidae and Oecanthidae families respectively. P. carentonensis Josse and Desutter-Grandcolas, gen. nov., sp. nov. is also the smallest adult male with a full stridulatory apparatus ever documented in crickets (body length 3.3 mm), and the first taxon of the cricket clade for which male genitalia can be partly described. We discuss the significance of Cretaceous fossils of crickets for future evolutionary studies of this clade