A genome-wide comprehensive analysis of nucleosome positioning in yeast.

In eukaryotic cells, the one-dimensional DNA molecules need to be tightly packaged into the spatially constraining nucleus. Folding is achieved on its lowest level by wrapping the DNA around nucleosomes. Their arrangement regulates other nuclear processes, such as transcription and DNA repair. Despite strong efforts to study nucleosome positioning using Next Generation Sequencing (NGS) data, the mechanism of their collective arrangement along the gene body remains poorly understood. Here, we classify nucleosome distributions of protein-coding genes in Saccharomyces cerevisiae according to their profile similarity and analyse their differences using functional Principal Component Analysis. By decomposing the NGS signals into their main descriptive functions, we compared wild type and chromatin remodeler-deficient strains, keeping position-specific details preserved whilst considering the nucleosome arrangement as a whole. A correlation analysis with other genomic properties, such as gene size and length of the upstream Nucleosome Depleted Region (NDR), identified key factors that influence the nucleosome distribution. We reveal that the RSC chromatin remodeler-which is responsible for NDR maintenance-is indispensable for decoupling nucleosome arrangement within the gene from positioning outside, which interfere in rsc8-depleted conditions. Moreover, nucleosome profiles in chd1Δ strains displayed a clear correlation with RNA polymerase II presence, whereas wild type cells did not indicate a noticeable interdependence. We propose that RSC is pivotal for global nucleosome organisation, whilst Chd1 plays a key role for maintaining local arrangement.

Multiple genomic solutions for local adaptation in two closely related species (sheep and goats) facing the same climatic constraints.

The question of how local adaptation takes place remains a fundamental question in evolutionary biology. The variation of allele frequencies in genes under selection over environmental gradients remains mainly theoretical and its empirical assessment would help understanding how adaptation happens over environmental clines. To bring new insights to this issue we set up a broad framework which aimed to compare the adaptive trajectories over environmental clines in two domesticated mammal species co-distributed in diversified landscapes. We sequenced the genomes of 160 sheep and 161 goats extensively managed along environmental gradients, including temperature, rainfall, seasonality and altitude, to identify genes and biological processes shaping local adaptation. Allele frequencies at putatively adaptive loci were rarely found to vary gradually along environmental gradients, but rather displayed a discontinuous shift at the extremities of environmental clines. Of the 430 candidate adaptive genes identified, only 6 were orthologous between sheep and goats and those responded differently to environmental pressures, suggesting different putative mechanisms involved in local adaptation in these two closely related species. Interestingly, the genomes of the 2 species were impacted differently by the environment, genes related to signatures of selection were most related to altitude, slope and rainfall seasonality for sheep, and summer temperature and spring rainfall for goats. The diversity of candidate adaptive pathways may result from a high number of biological functions involved in the adaptations to multiple eco-climatic gradients, and a differential role of climatic drivers on the two species, despite their co-distribution along the same environmental gradients. This study describes empirical examples of clinal variation in putatively adaptive alleles with different patterns in allele frequency distributions over continuous environmental gradients, thus showing the diversity of genetic responses in adaptive landscapes and opening new horizons for understanding genomics of adaptation in mammalian species and beyond.

Integrative omics framework for characterization of coral reef ecosystems from the Tara Pacific expedition.

Coral reef science is a fast-growing field propelled by the need to better understand coral health and resilience to devise strategies to slow reef loss resulting from environmental stresses. Key to coral resilience are the symbiotic interactions established within a complex holobiont, i.e. the multipartite assemblages comprising the coral host organism, endosymbiotic dinoflagellates, bacteria, archaea, fungi, and viruses. Tara Pacific is an ambitious project built upon the experience of previous Tara Oceans expeditions, and leveraging state-of-the-art sequencing technologies and analyses to dissect the biodiversity and biocomplexity of the coral holobiont screened across most archipelagos spread throughout the entire Pacific Ocean. Here we detail the Tara Pacific workflow for multi-omics data generation, from sample handling to nucleotide sequence data generation and deposition. This unique multidimensional framework also includes a large amount of concomitant metadata collected side-by-side that provide new assessments of coral reef biodiversity including micro-biodiversity and shape future investigations of coral reef dynamics and their fate in the Anthropocene.

Functional interplay between Mediator and RSC chromatin remodeling complex controls nucleosome-depleted region maintenance at promoters.

Chromatin organization is crucial for transcriptional regulation in eukaryotes. Mediator is an essential and conserved co-activator thought to act in concert with chromatin regulators. However, it remains largely unknown how their functions are coordinated. Here, we provide evidence in the yeast Saccharomyces cerevisiae that Mediator establishes physical contact with RSC (Remodels the Structure of Chromatin), a conserved and essential chromatin remodeling complex that is crucial for nucleosome-depleted region (NDR) formation. We determine the role of Mediator-RSC interaction in their chromatin binding, nucleosome occupancy, and transcription on a genomic scale. Mediator and RSC co-localize on wide NDRs of promoter regions, and specific Mediator mutations affect nucleosome eviction and TSS-associated +1 nucleosome stability. This work shows that Mediator contributes to RSC remodeling function to shape NDRs and maintain chromatin organization on promoter regions. It will help in our understanding of transcriptional regulation in the chromatin context relevant for severe diseases.

The complete plastome of Glandora prostrata subsp. lusitanica (Samp.) D.C.Thomas (Boraginaceae), the first chloroplast genome belonging to the Glandora genus.

Glandora prostrata (Loisel.) D.C.Thomas (Thomas et al., 2008), besides being a common plant of western and south-western Europe and north-western Africa, is a species with a wealth of reported uses in traditional and folk medicine. The chloroplast genome of Glandora prostrata subsp. lusitanica (Samp.) D.C.Thomas (Thomas et al., 2008) isolate BPTPS049 described in this study is the first publicly available complete plastome belonging to the Glandora genus. The chloroplast genome (GenBank accession number: ON641304) is 150,041 bp in length with 37.5% GC content, displaying a quadripartite structure that contains a pair of inverted repeat regions (25,833 bp each), separated by a large (81,222 bp) and small (17,153 bp) single-copy regions. It has 131 annotated genes including 86 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The phylogenetic analysis performed confirms that G. prostrata subsp. lusitanica is placed under the Boraginaceae family, which belongs to the Boraginales order. This study will contribute to conservation, phylogenetic, and evolutionary studies that comprise this traditional species relevant to the landscape of aromatic, medicinal, and condiment plants from Portugal.

The complete plastome of Centaurium erythraea subsp. majus (Hoffmanns. & Link) M.Laínz (Gentianaceae), the first chloroplast genome belonging to the Centaurium genus.

Despite having many historically reported ethnomedicinal uses, Centaurium erythraea Rafn (Rafn and Buchs, 1800; common centaury) also produces cytotoxic secondary metabolites, and its presence should be carefully monitored. In this study, the complete chloroplast of Centaurium erythraea subsp. majus (Hoffmanns. & Link) M.Laínz (Laínz, 1971) isolate BPTPS121 is described, being the first available plastome belonging to the Centaurium genus. The chloroplast genome (GenBank accession number: ON641347) is 153,107 bp in length with 37.9% GC content, displaying a quadripartite structure that contains a pair of inverted repeat regions (25,166 bp each), separated by a large single-copy (84,388 bp) and small single-copy (18,387 bp) regions. A total of 129 genes were predicted, including 37 tRNA genes, eight rRNA genes, and 84 protein-coding genes. The phylogenetic analysis showed that isolate BPTPS121 is placed under the Gentianaceae family, belonging to the Gentianales order. The maximum-likelihood tree supports the already described lineage divergence in the Gentianaceae family, with C. erythraea subsp. majus belonging to the Chironieae tribe positioned below the Exaceae tribe and above the Potalieae and the entire Gentianeae tribes. This study will contribute to conservation, phylogenetic, and evolutionary studies, as well as DNA barcoding applications for food, feed, and supplements safety purposes.

Genomic adaptation of the picoeukaryote Pelagomonas calceolata to iron-poor oceans revealed by a chromosome-scale genome sequence.

The smallest phytoplankton species are key actors in oceans biogeochemical cycling and their abundance and distribution are affected with global environmental changes. Among them, algae of the Pelagophyceae class encompass coastal species causative of harmful algal blooms while others are cosmopolitan and abundant. The lack of genomic reference in this lineage is a main limitation to study its ecological importance. Here, we analysed Pelagomonas calceolata relative abundance, ecological niche and potential for the adaptation in all oceans using a complete chromosome-scale assembled genome sequence. Our results show that P. calceolata is one of the most abundant eukaryotic species in the oceans with a relative abundance favoured by high temperature, low-light and iron-poor conditions. Climate change projections based on its relative abundance suggest an extension of the P. calceolata habitat toward the poles at the end of this century. Finally, we observed a specific gene repertoire and expression level variations potentially explaining its ecological success in low-iron and low-nitrate environments. Collectively, these findings reveal the ecological importance of P. calceolata and lay the foundation for a global scale analysis of the adaptation and acclimation strategies of this small phytoplankton in a changing environment.

Postglacial species arrival and diversity buildup of northern ecosystems took millennia.

What drives ecosystem buildup, diversity, and stability? We assess species arrival and ecosystem changes across 16 millennia by combining regional-scale plant sedimentary ancient DNA from Fennoscandia with near-complete DNA and trait databases. We show that postglacial arrival time varies within and between plant growth forms. Further, arrival times were mainly predicted by adaptation to temperature, disturbance, and light. Major break points in ecological trait diversity were seen between 13.9 and 10.8 calibrated thousand years before the present (cal ka BP), as well as break point in functional diversity at 12.0 cal ka BP, shifting from a state of ecosystem buildup to a state where most habitat types and biotic ecosystem components were in place. Trait and functional diversity stabilized around 8 cal ka BP, after which both remained stable, although changes in climate took place and species inflow continued. Our ecosystem reconstruction indicates a millennial-scale time phase of formation to reach stable and resilient levels of diversity and functioning.

Diversity and ecological footprint of Global Ocean RNA viruses.

DNA viruses are increasingly recognized as influencing marine microbes and microbe-mediated biogeochemical cycling. However, little is known about global marine RNA virus diversity, ecology, and ecosystem roles. In this study, we uncover patterns and predictors of marine RNA virus community- and "species"-level diversity and contextualize their ecological impacts from pole to pole. Our analyses revealed four ecological zones, latitudinal and depth diversity patterns, and environmental correlates for RNA viruses. Our findings only partially parallel those of cosampled plankton and show unexpectedly high polar ecological interactions. The influence of RNA viruses on ecosystems appears to be large, as predicted hosts are ecologically important. Moreover, the occurrence of auxiliary metabolic genes indicates that RNA viruses cause reprogramming of diverse host metabolisms, including photosynthesis and carbon cycling, and that RNA virus abundances predict ocean carbon export.

Tempo and drivers of plant diversification in the European mountain system.

There is still limited consensus on the evolutionary history of species-rich temperate alpine floras due to a lack of comparable and high-quality phylogenetic data covering multiple plant lineages. Here we reconstructed when and how European alpine plant lineages diversified, i.e., the tempo and drivers of speciation events. We performed full-plastome phylogenomics and used multi-clade comparative models applied to six representative angiosperm lineages that have diversified in European mountains (212 sampled species, 251 ingroup species total). Diversification rates remained surprisingly steady for most clades, even during the Pleistocene, with speciation events being mostly driven by geographic divergence and bedrock shifts. Interestingly, we inferred asymmetrical historical migration rates from siliceous to calcareous bedrocks, and from higher to lower elevations, likely due to repeated shrinkage and expansion of high elevation habitats during the Pleistocene. This may have buffered climate-related extinctions, but prevented speciation along elevation gradients as often documented for tropical alpine floras.

Long-read and chromosome-scale assembly of the hexaploid wheat genome achieves high resolution for research and breeding.

BACKGROUND: The sequencing of the wheat (Triticum aestivum) genome has been a methodological challenge for many years owing to its large size (15.5 Gb), repeat content, and hexaploidy. Many initiatives aiming at obtaining a reference genome of cultivar Chinese Spring have been launched in the past years and it was achieved in 2018 as the result of a huge effort to combine short-read sequencing with many other resources. Reference-quality genome assemblies were then produced for other accessions, but the rapid evolution of sequencing technologies offers opportunities to reach high-quality standards at lower cost. RESULTS: Here, we report on an optimized procedure based on long reads produced on the Oxford Nanopore Technology PromethION device to assemble the genome of the French bread wheat cultivar Renan. CONCLUSIONS: We provide the most contiguous chromosome-scale assembly of a bread wheat genome to date. Coupled with an annotation based on RNA-sequencing data, this resource will be valuable for the crop community and will facilitate the rapid selection of agronomically important traits. We also provide a framework to generate high-quality assemblies of complex genomes using ONT.

Cryptic and abundant marine viruses at the evolutionary origins of Earth's RNA virome.

Whereas DNA viruses are known to be abundant, diverse, and commonly key ecosystem players, RNA viruses are insufficiently studied outside disease settings. In this study, we analyzed ≈28 terabases of Global Ocean RNA sequences to expand Earth's RNA virus catalogs and their taxonomy, investigate their evolutionary origins, and assess their marine biogeography from pole to pole. Using new approaches to optimize discovery and classification, we identified RNA viruses that necessitate substantive revisions of taxonomy (doubling phyla and adding >50% new classes) and evolutionary understanding. "Species"-rank abundance determination revealed that viruses of the new phyla "Taraviricota," a missing link in early RNA virus evolution, and "Arctiviricota" are widespread and dominant in the oceans. These efforts provide foundational knowledge critical to integrating RNA viruses into ecological and epidemiological models.

Estado de ánimo, emociones y conductas de los niños durante la pandemia de COVID-19 en la Ciudad Autónoma de Buenos Aires / Mood, emotions, and behaviors of children during the COVID-19 pandemic in Autonomous City of Buenos Aires

Introducción. Los cambios en la rutina y en el entramado social que generó la pandemia por COVID-19 afectaron a los niños, niñas y adolescentes (NNyA). El objetivo de este trabajo fue conocer el estado de ánimo, las emociones y las conductas de los NNyA durante el aislamiento por COVID-19. Población y métodos . Estudio prospectivo, descriptivo y transversal. Se preguntó a los padres y/o cuidadores de niños de 3 a 15 años de edad, de la Ciudad Autónoma de Buenos Aires, cómo percibían el estado de ánimo, las conductas y las emociones de los NNyA durante el período de aislamiento. Resultados. Se incluyeron 1080 cuestionarios. El 81 % de los padres y/o cuidadores advirtió algún cambio en la salud emocional de los NNyA. El 76 % refirió que los niños de 3-5 años se mostraban aburridos, enojados y angustiados. Además, observaron un aumento de los episodios de llanto (52 %) y regresión a comportamientos ya superados (29 %). En el grupo de 6-11 años, el 43 % presentó dificultad en mantener la concentración. En 3 de cada 10 adolescentes, de 12 a 15 años de edad, los adultos percibieron abandono de actividades que antes disfrutaban, preocupación y tristeza. Conclusión. La pandemia de COVID-19 impactó en el estado de ánimo, las conductas y las emociones de los NNyA. Predominaron los sentimientos negativos, como aburrimiento, tristeza, angustia y preocupación.

Introduction. Changes in daily routine and social fabric resulting from the COVID-19 pandemic had an effect on children and adolescents. The objective of this study was to know the mood, emotions, and behaviors of children and adolescents during the COVID-19 lockdown. Population and methods. This was a prospective, descriptive, cross-sectional study. Parents and/or caregivers of children and adolescents aged 3-15 years in the Autonomous City of Buenos Aires were asked about their perceptions of the mood, behaviors, and emotions of children and adolescents during the lockdown. Results. A total of 1080 questionnaires were included. Results showed that 81% of parents and/or caregivers observed changes in children and adolescents emotional health; 76% referred that children aged 3-5 years were bored, angry, and upset. They also observed an increase in crying spells (52%) and regression to behaviors that had been outgrown (29%). In the 6-11-year-old group, 43% showed difficulty focusing. Adults noticed that 3 out of 10 adolescents aged 12-15 years discontinued activities they used to enjoy and were sad and worried. Conclusion. The COVID-19 pandemic impacted on the mood, behaviors, and emotions of children and adolescents. Negative feelings prevailed, such as boredom, sadness, anxiety, and worry.

Mood, emotions, and behaviors of children during the COVID-19 pandemic in Autonomous City of Buenos Aires. / Estado de ánimo, emociones y conductas de los niños durante la pandemia de COVID-19 en la Ciudad Autónoma de Buenos Aires.

INTRODUCTION: Changes in daily routine and social fabric resulting from the COVID-19 pandemic had an effect on children and adolescents. The objective of this study was to know the mood, emotions, and behaviors of children and adolescents during the COVID-19 lockdown. POPULATION AND METHODS: This was a prospective, descriptive, cross-sectional study. Parents and/ or caregivers of children and adolescents aged 3-15 years in the Autonomous City of Buenos Aires were asked about their perceptions of the mood, behaviors, and emotions of children and adolescents during the lockdown. RESULTS: A total of 1080 questionnaires were included. Results showed that 81% of parents and/or caregivers observed changes in children and adolescents emotional health; 76% referred that children aged 3-5 years were bored, angry, and upset. They also observed an increase in crying spells (52%) and regression to behaviors that had been outgrown (29%). In the 6-11-year-old group, 43% showed difficulty focusing. Adults noticed that 3 out of 10 adolescents aged 12-15 years discontinued activities they used to enjoy and were sad and worried. CONCLUSIONS: The COVID-19 pandemic impacted on the mood, behaviors, and emotions of children and adolescents. Negative feelings prevailed, such as boredom, sadness, anxiety, and worry.

Introducción. Los cambios en la rutina y en el entramado social que generó la pandemia por COVID-19 afectaron a los niños, niñas y adolescentes (NNyA). El objetivo de este trabajo fue conocer el estado de ánimo, las emociones y las conductas de los NNyA durante el aislamiento por COVID-19. Población y métodos. Estudio prospectivo, descriptivo y transversal. Se preguntó a los padres y/o cuidadores de niños de 3 a 15 años de edad, de la Ciudad Autónoma de Buenos Aires, cómo percibían el estado de ánimo, las conductas y las emociones de los NNyA durante el período de aislamiento. Resultados. Se incluyeron 1080 cuestionarios. El 81 % de los padres y/o cuidadores advirtió algún cambio en la salud emocional de los NNyA. El 76 % refirió que los niños de 3-5 años se mostraban aburridos, enojados y angustiados. Además, observaron un aumento de los episodios de llanto (52 %) y regresión a comportamientos ya superados (29 %). En el grupo de 6-11 años, el 43 % presentó dificultad en mantener la concentración. En 3 de cada 10 adolescentes, de 12 a 15 años de edad, los adultos percibieron abandono de actividades que antes disfrutaban, preocupación y tristeza. Conclusión. La pandemia de COVID-19impactó en el estado de ánimo, las conductas y las emociones de los NNyA. Predominaron los sentimientos negativos, como aburrimiento, tristeza, angustia y preocupación.

VarGoats project: a dataset of 1159 whole-genome sequences to dissect Capra hircus global diversity.

BACKGROUND: Since their domestication 10,500 years ago, goat populations with distinctive genetic backgrounds have adapted to a broad variety of environments and breeding conditions. The VarGoats project is an international 1000-genome resequencing program designed to understand the consequences of domestication and breeding on the genetic diversity of domestic goats and to elucidate how speciation and hybridization have modeled the genomes of a set of species representative of the genus Capra. FINDINGS: A dataset comprising 652 sequenced goats and 507 public goat sequences, including 35 animals representing eight wild species, has been collected worldwide. We identified 74,274,427 single nucleotide polymorphisms (SNPs) and 13,607,850 insertion-deletions (InDels) by aligning these sequences to the latest version of the goat reference genome (ARS1). A Neighbor-joining tree based on Reynolds genetic distances showed that goats from Africa, Asia and Europe tend to group into independent clusters. Because goat breeds from Oceania and Caribbean (Creole) all derive from imported animals, they are distributed along the tree according to their ancestral geographic origin. CONCLUSIONS: We report on an unprecedented international effort to characterize the genome-wide diversity of domestic goats. This large range of sequenced individuals represents a unique opportunity to ascertain how the demographic and selection processes associated with post-domestication history have shaped the diversity of this species. Data generated for the project will also be extremely useful to identify deleterious mutations and polymorphisms with causal effects on complex traits, and thus will contribute to new knowledge that could be used in genomic prediction and genome-wide association studies.

Late Quaternary dynamics of Arctic biota from ancient environmental genomics.

During the last glacial-interglacial cycle, Arctic biotas experienced substantial climatic changes, yet the nature, extent and rate of their responses are not fully understood1-8. Here we report a large-scale environmental DNA metagenomic study of ancient plant and mammal communities, analysing 535 permafrost and lake sediment samples from across the Arctic spanning the past 50,000 years. Furthermore, we present 1,541 contemporary plant genome assemblies that were generated as reference sequences. Our study provides several insights into the long-term dynamics of the Arctic biota at the circumpolar and regional scales. Our key findings include: (1) a relatively homogeneous steppe-tundra flora dominated the Arctic during the Last Glacial Maximum, followed by regional divergence of vegetation during the Holocene epoch; (2) certain grazing animals consistently co-occurred in space and time; (3) humans appear to have been a minor factor in driving animal distributions; (4) higher effective precipitation, as well as an increase in the proportion of wetland plants, show negative effects on animal diversity; (5) the persistence of the steppe-tundra vegetation in northern Siberia enabled the late survival of several now-extinct megafauna species, including the woolly mammoth until 3.9 ± 0.2 thousand years ago (ka) and the woolly rhinoceros until 9.8 ± 0.2 ka; and (6) phylogenetic analysis of mammoth environmental DNA reveals a previously unsampled mitochondrial lineage. Our findings highlight the power of ancient environmental metagenomics analyses to advance understanding of population histories and long-term ecological dynamics.