Rareté et changements globaux : tolérance aux changements globaux et capacité pour la plasticité transgénérationnelle chez une espèce rare et une espèce commune de polychètes marins

RÉSUMÉ: La variation au sein de la répartition géographique des espèces est observée depuis longtemps, et il a été reconnu, qu'à l'intérieur d'un groupe taxonomique, la majorité des espèces ont une distribution géographique restreinte (espèce rare), alors que peu sont largement distribuée (espèce commune). L'explication la plus acceptée quant à la variation du niveau de biodiversité à travers le monde est la différence au niveau de la « niche » des espèces, qui ultimement définit l'amplitude de leur distribution géographique. La variation des traits physiologiques joue un rôle pivot dans la définition de la niche des espèces, et par le fait même leur distribution géographique. Ainsi les espèces rares auront de plus petites fenêtres de tolérance physiologique et des niveaux de plasticité plus faibles, faisant d'elles des espèces plus à risque à l'extinction locale dans le contexte des changements globaux. En considérant que les espèces rares sont les plus nombreuses, leurs réponses face aux changements rapides en cours dans leur environnement vont avoir des impacts sur la diversité taxonomique au sein du règne animal, ainsi que sur la structure et les fonctions des futurs écosystèmes. Le réchauffement et l'acidification des océans vont avoir des répercussions sur un grand nombre de processus cellulaires. Par les changements au niveau du métabolisme énergétique, puis l'altération des traits d'histoire de vie, c'est toute la structure et le fonctionnement des écosystèmes qui seront bouleversé. La plasticité phénotypique peu rapidement aider à rétablir et maximiser les performances des organismes à l'intérieur d'une (intra-générationnelle) ou plusieurs générations (transgénérationnelle) lors de changements dans leur environnement. Par conséquent, le but de notre étude était d'investiguer si des espèces rare et commune répondent différemment aux scénarios de changements globaux en environnement marin, et si leur tolérance et capacité pour la plasticité transgénérationnelle sont différentes. Pour répondre à ces questions, deux espèces de polychètes du genre Ophryotrocha, une rare (O. robusta) et une commune (O. japonica), ont été exposées à quatre scénarios de changements globaux prédits pour la fin du siècle sur deux générations, soit des conditions de contrôle (C), d'acidification des océans (AO), de réchauffement des océans (RO) et un scénario combiné (RAO)). Les traits d'histoire de vie (croissance, fécondité, volume des œufs) ont été mesurés sur une période de quatre mois, après quoi les profiles métabolomiques des individus ont été analysés pour mettre en évidence les métabolites liés aux changements des traits d'histoire de vie. En général, la température élevée a été le facteur principal affectant négativement les performances de l'espèce rare. L'augmentation de la température a eu un impact négatif sur le fitness et la survie de O. robusta. À l'opposé, le fitness de l'espèce commune, mesurés en termes de taux de survie et de capacité à contribuer à la prochaine génération, est demeuré plutôt élevé dans tous les scénarios et générations. L'espèce commune a été l'espèce la plus performante dans les différents scénarios, probablement par le bénéfice des mécanismes de plasticité intra et transgénérationnelle. Ce qui mène à la conclusion que l'espèce rare possède une fenêtre de tolérance plus étroite que l'espèce commune et qu'elle aura plus de difficulté à faire face aux futures conditions de changements climatiques. Ces résultats ont une portée importante au niveau de la conservation de la biodiversité marine, considérant que les espèces rares sont communes dans le règne animal et ont un rôle clé en ce qui a trait aux fonctions des écosystèmes. -- Mot(s) clé(s) en français : Distribution géographique, tolérance, changements globaux, plasticité transgénérationnelle, histoire de vie, métabolomique, biodiversité. -- ABSTRACT: Variation in the geographical range of species has long been observed, and it well established that most species have a restricted geographic distribution (rare species), whilst few are geographically widespread (common species). One explanation for the variation in biodiversity levels across the globe is that difference in species' 'niche' ultimately defines the breadth of their geographical distribution. Variation in physiological traits is considered to play a pivotal role in defining species niche, and thus their geographical distribution and local abundance, predicting that rare species will have smaller physiological tolerance windows and plasticity levels. Rare species' responses to rapid ongoing changes in their environment will then greatly define taxonomic diversity across the tree of life, as well as the functions of future ecosystems. Ocean warming and acidification will have impacts on a number of cellular processes. Through shifts in metabolic energy and alteration of life-history traits, all the ecosystem's structure and functions will be affected. Phenotypic plasticity can rapidly help re-establishing and maximising organisms' performances within and between generations when environmental changes occur. Consequently, the aim of our study was to determine if rare and common species respond differently to global changes scenarios in a marine environment, and if their tolerance and capacity for transgenerational plasticity are different. To answer this, two species of polychaete of the genus Ophryotrocha, one rare (O. robusta) and one common (O. japonica), were exposed to four different climate change scenarios predict to occur by the end of the century for two generations (control (C), ocean acidification (OA), ocean warming (OW) and a combined scenario (OAW)). Life history traits (growth, fecundity and eggs volume) were measured on a four months period, after which metabolomics profiles were analysed to highlight molecular pattern (energetic metabolism) linked to life history traits' changes. Overall, the high temperature was the main factor negatively affecting the rare species' performances. The increase in temperature impacted the physiology of O. robusta, ultimately affecting its reproduction and survival. On the other hand, the common species' reproduction, measured in terms of survival success and capacity to contribute to the next generation, remained quite high for all scenarios and generations. The common species was also the most tolerant species under global change scenarios, likely benefiting from both within- and transgenerational plasticity mechanisms. Hence the rare species appear to possess a narrower tolerance window than the common species, and might will have more difficulties to cope with future climatic conditions. These results will likely have important impacts on marine biodiversity levels and conservation, considering that rare species are common in the animal kingdom and have key role in ecosystem functions. -- Mot(s) clé(s) en anglais : Geographic distribution, tolerance, global changes, transgenerational plasticity, life history, metabolomics, biodiversity

Draft Genome Sequences of Four Aeromonas salmonicida subsp. achromogenes Strains, 23051, 23053, 23055, and 23056, Isolated from Senegalese Sole ( Solea senegalensis )

International audienceThe bacterial species Aeromonas salmonicida officially has five subspecies. A large majority of the currently available sequences come from Aeromonas salmonicida subsp. salmonicida, which causes furunculosis in salmonids. We present the genomic sequences of four Aeromonas salmonicida subsp. achromogenes strains. This will help increase the robustness of genomic analyses for this subspecies

The Importance of adapting functional test instructions for older adults with neurocognitive disorders

The assessment of the risk of falling in geriatric rehabilitation is often using standardized functional tests, which may be more complex but less representative in older adults with a neurocognitive disorder. The conceptual aim of this manuscript was thus to discuss the impact of adapted instructions on physical performance during standardized functional tests for older with neurocognitive disorders (NCD). Six topics were addressed: 1) current and global profile of falls in older, 2) fall assessment, 3) neurocognitive disorders in the older adults, 4) relationship between cognitive impairment and functional performance, 5) impact of the instructions on functional assessments in an older population, and finally 6) an overview of the future perspectives on possible adaptations for functional assessments in older adults with NCD. We believe that it is realistic and feasible to address adapted instructions to patients with NCD in clinical settings to optimize their assessment of their risk of falling

Blood contains circulating cell-free respiratory competent mitochondria.

Mitochondria are considered as the power-generating units of the cell due to their key role in energy metabolism and cell signaling. However, mitochondrial components could be found in the extracellular space, as fragments or encapsulated in vesicles. In addition, this intact organelle has been recently reported to be released by platelets exclusively in specific conditions. Here, we demonstrate for the first time, that blood preparation with resting platelets, contains whole functional mitochondria in normal physiological state. Likewise, we show, that normal and tumor cultured cells are able to secrete their mitochondria. Using serial centrifugation or filtration followed by polymerase chain reaction-based methods, and Whole Genome Sequencing, we detect extracellular full-length mitochondrial DNA in particles over 0.22 µm holding specific mitochondrial membrane proteins. We identify these particles as intact cell-free mitochondria using fluorescence-activated cell sorting analysis, fluorescence microscopy, and transmission electron microscopy. Oxygen consumption analysis revealed that these mitochondria are respiratory competent. In view of previously described mitochondrial potential in intercellular transfer, this discovery could greatly widen the scope of cell-cell communication biology. Further steps should be developed to investigate the potential role of mitochondria as a signaling organelle outside the cell and to determine whether these circulating units could be relevant for early detection and prognosis of various diseases

The BAF complex inhibitor pyrimethamine reverses HIV-1 latency in people with HIV-1 on antiretroviral therapy

Reactivation of the latent HIV-1 reservoir is a first step toward triggering reservoir decay. Here, we investigated the impact of the BAF complex inhibitor pyrimethamine on the reservoir of people living with HIV-1 (PLWH). Twenty-eight PLWH on suppressive antiretroviral therapy were randomized (1:1:1:1 ratio) to receive pyrimethamine, valproic acid, both, or no intervention for 14 days. The primary end point was change in cell-associated unspliced (CA US) HIV-1 RNA at days 0 and 14. We observed a rapid, modest, and significant increase in (CA US) HIV-1 RNA in response to pyrimethamine exposure, which persisted throughout treatment and follow-up. Valproic acid treatment alone did not increase (CA US) HIV-1 RNA or augment the effect of pyrimethamine. Pyrimethamine treatment did not result in a reduction in the size of the inducible reservoir. These data demonstrate that the licensed drug pyrimethamine can be repurposed as a BAF complex inhibitor to reverse HIV-1 latency in vivo in PLWH, substantiating its potential advancement in clinical studies.</p

Impact of Anti-Inflammatory Agents on the Gene Expression Profile of Stimulated Human Neutrophils: Unraveling Endogenous Resolution Pathways

Adenosine, prostaglandin E2, or increased intracellular cyclic AMP concentration each elicit potent anti-inflammatory events in human neutrophils by inhibiting functions such as phagocytosis, superoxide production, adhesion and cytokine release. However, the endogenous molecular pathways mediating these actions are poorly understood. In the present study, we examined their impact on the gene expression profile of stimulated neutrophils. Purified blood neutrophils from healthy donors were stimulated with a cocktail of inflammatory agonists in the presence of at least one of the following anti-inflammatory agents: adenosine A2A receptor agonist CGS 21680, prostaglandin E2, cyclic-AMP-elevating compounds forskolin and RO 20-1724. Total RNA was analyzed using gene chips and real-time PCR. Genes encoding transcription factors, enzymes and regulatory proteins, as well as secreted cytokines/chemokines showed differential expression. We identified 15 genes for which the anti-inflammatory agents altered mRNA levels. The agents affected the expression profile in remarkably similar fashion, suggesting a central mechanism limiting cell activation. We have identified a set of genes that may be part of important resolution pathways that interfere with cell activation. Identification of these pathways will improve understanding of the capacity of tissues to terminate inflammatory responses and contribute to the development of therapeutic strategies based on endogenous resolution

The s230r integrase substitution associated with virus load rebound during dolutegravir monotherapy confers low-level resistance to integrase str

Background. Dolutegravir (DTG) is an integrase strand-transfer inhibitor (INSTI) used for treatment of human immunodeficiency virus (HIV)–infected individuals. Owing to its high genetic barrier to resistance, DTG has been clinically investigated as maintenance monotherapy to maintain viral suppression and to reduce complication and healthcare costs. Our study aims to explain the underlying mechanism related to the emergence of a S230R substitution in patients who experienced virologic failure while using DTG monotherapy. Methods. We evaluated the effect of the S230R substitution in regard to integrase enzyme activity, viral infectivity, replicative capacity, and susceptibility to different INSTIs by biochemical and cell-based assays. Results. The S230R substitution conferred a 63% reduction in enzyme efficiency. S230R virus was 1.29-fold less infectious than wild-type virus but could replicate in PM1 cells without significant delay. Resistance levels against DTG, cabotegravir, raltegravir, and elvitegravir in tissue culture were 3.85-, 3.72-, 1.52-, and 1.21-fold, respectively, in virus with the S230R substitution. Conclusions. Our data indicate that the S230R substitution is comparable to the previously reported R263K substitution in some respects. Virologic failure during DTG monotherapy can occur through the development of the S230R or R263K mutation, without the need for high-level DTG resistance

A global experiment on motivating social distancing during the COVID-19 pandemic

Finding communication strategies that effectively motivate social distancing continues to be a global public health priority during the COVID-19 pandemic. This cross-country, preregistered experiment (n = 25,718 from 89 countries) tested hypotheses concerning generalizable positive and negative outcomes of social distancing messages that promoted personal agency and reflective choices (i.e., an autonomy-supportive message) or were restrictive and shaming (i.e., a controlling message) compared with no message at all. Results partially supported experimental hypotheses in that the controlling message increased controlled motivation (a poorly internalized form of motivation relying on shame, guilt, and fear of social consequences) relative to no message. On the other hand, the autonomy-supportive message lowered feelings of defiance compared with the controlling message, but the controlling message did not differ from receiving no message at all. Unexpectedly, messages did not influence autonomous motivation (a highly internalized form of motivation relying on one’s core values) or behavioral intentions. Results supported hypothesized associations between people’s existing autonomous and controlled motivations and self-reported behavioral intentions to engage in social distancing. Controlled motivation was associated with more defiance and less long-term behavioral intention to engage in social distancing, whereas autonomous motivation was associated with less defiance and more short- and long-term intentions to social distance. Overall, this work highlights the potential harm of using shaming and pressuring language in public health communication, with implications for the current and future global health challenges

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe