Comparative transcriptomics reveal a novel tardigrade-specific DNA-binding protein induced in response to ionizing radiation

: Tardigrades are microscopic animals renowned for their ability to withstand extreme conditions, including high doses of ionizing radiation (IR). To better understand their radio-resistance, we first characterized induction and repair of DNA double- and single-strand breaks after exposure to IR in the model species Hypsibius exemplaris. Importantly, we found that the rate of single-strand breaks induced was roughly equivalent to that in human cells, suggesting that DNA repair plays a predominant role in tardigrades' radio-resistance. To identify novel tardigrade-specific genes involved, we next conducted a comparative transcriptomics analysis across three different species. In all three species, many DNA repair genes were among the most strongly overexpressed genes alongside a novel tardigrade-specific gene, which we named Tardigrade DNA damage Response 1 (TDR1). We found that TDR1 protein interacts with DNA and forms aggregates at high concentration suggesting it may condensate DNA and preserve chromosome organization until DNA repair is accomplished. Remarkably, when expressed in human cells, TDR1 improved resistance to Bleomycin, a radiomimetic drug. Based on these findings, we propose that TDR1 is a novel tardigrade-specific gene conferring resistance to IR. Our study sheds light on mechanisms of DNA repair helping cope with high levels of DNA damage inflicted by IR

Identification and characterization of a meiotic driver in Drosophila simulans

Les distorteurs de ségrégation méiotiques sont des éléments génétiques égoïstes qui favorisent leur propre transmission en manipulant la méiose à leur avantage. La diffusion dans les populations d’un distorteur lié au chromosome X (Sex-Ratio) provoque un excès de femelles et cela conduit à un conflit entre le chromosome X et les autres chromosomes. Ces conflits intra-génomiques sont d’importants moteurs de l’évolution des génomes. Mais, peu de choses sont connues sur la nature moléculaire et la fonction des éléments égoïstes Sex-Ratio. Le premier chapitre de cette thèse présente une synthèse actualisée sur les distorteurs de ségrégation méiotiques liés à un chromosome sexuel. Le second chapitre est consacré à l’identification et la caractérisation d’un élément distorteur du système Sex-Ratio « Paris » de Drosophila simulans, dans lequel deux éléments distorteurs liés au chromosome X provoquent ensemble la misségrégation des chromatides sœurs du chromosome Y lors de la méiose II. J’identifie à travers une cartographie génétique par recombinaison un des loci distorteur et je conduis une validation fonctionnelle de son implication dans la distorsion. Il s’agit d’un jeune gène qui évolue rapidement et appartient à une famille de gènes bien connus, impliquée dans la constitution de l’hétérochromatine. Ce gène a émergé par duplication il y a environ 15-22 millions d’années et a connu de façon indépendante de multiples duplications en cis, pseudogenizations, ou bien directement sa perte tout au long de son histoire évolutive. Cela suggère que ce gène pourrait avoir été impliquée dans de multiples conflits génétiques. Le dernier chapitre est consacré à une étude exploratoire de la diversité structurale des chromosomes Y en relation avec la distorsion de ségrégation méiotique du système « Paris ». Les résultats présentés dans ce manuscrit contribuent à augmenter les connaissances sur l’origine moléculaire des conflits génétiques et sur leur impact évolutif.Segregation distorters are selfish genetic elements that promote their own transmission by subverting the meiotic process to their advantage. The spread of an X-linked distorter (Sex-Ratio) in populations results in an excess of females, which triggers a genetic conflict between the X chromosome and the rest of the genome. Such conflicts are important drivers of genome evolution, but little is known about the molecular nature and the function of the Sex Ratio selfish elements. The first chapter of this manuscript is a review of the current knowledge about X-linked segregation distorters. Then, I present my work on the « Paris » Sex Ratio system of Drosophila simulans, in which two distorter elements on the X chromosome co-operate to prevent Y chromosome sister chromatids segregation during meiosis II. I mapped a gene in one of the distorter loci and achieved the functional validation of its involvement in sex-ratio distortion. It is a young and rapidly evolving gene that belongs to a well-known gene family involved in chromatin state regulation. It emerged through duplication about 15-22 Myrs ago and has experienced multiple independant cis-duplications, loss or pseudogenization throughout its evolutionary history. This suggests that this gene could have been involved in multiple genetic conflicts. Finally, the last chapter is about an opening study of the strucural diversity of Y chromosomes in relation to « Paris » segregation distorter. These findings should help understanding the molecular basis of genetic conflicts and the evolutionary impact of heterochromatin regulation during meiosis

Les NFT dans le sport : analyse marketing d'acteurs français

International audienceAs unique digital identifiers based on blockchain technology, NFTs help record ownership of sports memorabilia in a virtual space. Until now, consumers could only own non-digital items, such as trading cards, branded clothing and various types of print content (Wilson et al., 2021). Blockchain technology applied to non-fungible tokens (NFTs), is revolutionizing the way content is created, exchanged, stored and authenticated for content creators and their fans (Malhotra et al., 2021). Sport offers exceptional ground from the point of view of supply and demand from collectors and brands. We interviewed five major players in the French NFT market in 2023. As a new marketing tool, they offer an additional avenue to explore to boost the relationship with consumers while promoting different innovative sports experiences based on a deeper digital engagement with fans. Each community being different, the challenge remains to articulate an NFT strategy with the marketing approach of the brand.Les NFT, identifiants numériques uniques basés sur la technologie blockchain, permettent d'enregistrer la propriété des souvenirs sportifs dans un espace virtuel. Jusqu'ici, les consommateurs ne pouvaient posséder que des articles non numériques, tels que les cartes à collectionner, vêtements de marque et divers types de contenus imprimés (Wilson et al., 2021). La technologie blockchain appliquée aux jetons non fongibles (NFT), révolutionne la façon dont le contenu est créé, échangé, stocké et authentifié pour les créateurs de contenu et leurs fans (Malhotra et al., 2021). Le sport offre un terrain singulier du point de vue de l’offre et de la demande des collectionneurs. Nous avons interrogé cinq acteurs majeurs du marché français des NFT en 2023. En tant que nouvel outil marketing, les NFT constituent une option supplémentaire pour dynamiser la relation avec les consommateurs. Ils valorisent aussi différentes expériences sportives innovantes basées sur un engagement numérique plus poussé avec les fans. Chaque communauté étant différente, l’enjeu reste d’articuler une stratégie NFT avec l’approche marketing de la marque

Rapid evolution of a Y-chromosome heterochromatin protein underlies sex chromosome meiotic drive

International audienceSex chromosome meiotic drive, the non-Mendelian transmission of sex chromosomes, is the expression of an intragenomic conflict that can have extreme evolutionary consequences. However, the molecular bases of such conflicts remain poorly understood. Here, we show that a young and rapidly evolving X-linked heterochromatin protein 1 (HP1) gene, HP1D2, plays a key role in the classical Paris sex-ratio (SR) meiotic drive occurring in Drosophila simulans Driver HP1D2 alleles prevent the segregation of the Y chromatids during meiosis II, causing female-biased sex ratio in progeny. HP1D2 accumulates on the heterochromatic Y chromosome in male germ cells, strongly suggesting that it controls the segregation of sister chromatids through heterochromatin modification. We show that Paris SR drive is a consequence of dysfunctional HP1D2 alleles that fail to prepare the Y chromosome for meiosis, thus providing evidence that the rapid evolution of genes controlling the heterochromatin structure can be a significant source of intragenomic conflicts

Sex-Ratio Meiotic Drive Shapes the Evolution of the Y Chromosome in Drosophila simulans

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Ant phylogenomics reveals a natural selection hotspot preceding the origin of complex eusociality

International audienceThe evolution of eusociality has allowed ants to become one of the most conspicuous and ecologically dominant groups of organisms in the world. A large majority of the current ~14,000 ant species belong to the formicoids1, a clade of nine subfamilies which exhibit the most extreme forms of reproductive division of labour, large colony size2, worker polymorphism3 and extended queen longevity4. The eight remaining non-formicoid subfamilies are less well studied, with few genomes having been sequenced so far and unclear phylogenetic relationships5. By sequencing 65 genomes, we provide a robust phylogeny of the 17 ant subfamilies, retrieving high support to the controversial leptanillomorph clade (Leptanillinae and Martialinae) as the sister-group to all other extant ants. Moreover, our genomic analyses revealed that the emergence of the formicoids was accompanied by an elevated number of positive selection events. Importantly, the top three gene functions under selection are linked to key features of complex eusociality with histone acetylation being implicated in caste differentiation, gene silencing by RNA in worker sterility and autophagy in longevity. These results show that key pathways associated with eusociality have been under strong selection during the Cretaceous, suggesting that the molecular foundations of complex eusociality may have evolved rapidly in less than 20 Ma

Targeted treatment of injured nestmates with antimicrobial compounds in an ant society

Abstract Infected wounds pose a major mortality risk in animals. Injuries are common in the ant Megaponera analis, which raids pugnacious prey. Here we show that M. analis can determine when wounds are infected and treat them accordingly. By applying a variety of antimicrobial compounds and proteins secreted from the metapleural gland to infected wounds, workers reduce the mortality of infected individuals by 90%. Chemical analyses showed that wound infection is associated with specific changes in the cuticular hydrocarbon profile, thereby likely allowing nestmates to diagnose the infection state of injured individuals and apply the appropriate antimicrobial treatment. This study demonstrates that M. analis ant societies use antimicrobial compounds produced in the metapleural glands to treat infected wounds and reduce nestmate mortality