172 research outputs found
Correction to: Brachypodium: 20 years as a grass biology model system; the way forward?:(Trends in Plant Science 27, 1002–1016, 2022)
It has been 20 years since Brachypodium distachyon was suggested as a model
grass species, but ongoing research now encompasses the entire genus. Extensive
Brachypodium genome sequencing programmes have provided resources to
explore the determinants and drivers of population diversity. This has been accompanied
by cytomolecular studies to make Brachypodium a platform to investigate
speciation, polyploidisation, perenniality, and various aspects of chromosome
and interphase nucleus organisation. The value of Brachypodium as a functional
genomic platform has been underscored by the identification of key genes for
development, biotic and abiotic stress, and cell wall structure and function. While
Brachypodium is relevant to the biofuel industry, its impact goes far beyond that
as an intriguing model to study climate change and combinatorial stress
Why Delannoy numbers?
This article is not a research paper, but a little note on the history of
combinatorics: We present here a tentative short biography of Henri Delannoy,
and a survey of his most notable works. This answers to the question raised in
the title, as these works are related to lattice paths enumeration, to the
so-called Delannoy numbers, and were the first general way to solve Ballot-like
problems. These numbers appear in probabilistic game theory, alignments of DNA
sequences, tiling problems, temporal representation models, analysis of
algorithms and combinatorial structures.Comment: Presented to the conference "Lattice Paths Combinatorics and Discrete
Distributions" (Athens, June 5-7, 2002) and to appear in the Journal of
Statistical Planning and Inference
Gradual polyploid genome evolution revealed by pan-genomic analysis of Brachypodium hybridum and its diploid progenitors
Our understanding of polyploid genome evolution is constrained because we cannot know the exact founders of a particular polyploid. To differentiate between founder effects and post polyploidization evolution, we use a pan-genomic approach to study the allotetraploid Brachypodium hybridum and its diploid progenitors. Comparative analysis suggests that most B. hybridum whole gene presence/absence variation is part of the standing variation in its diploid progenitors. Analysis of nuclear single nucleotide variants, plastomes and k-mers associated with retrotransposons reveals two independent origins for B. hybridum, ~1.4 and ~0.14 million years ago. Examination of gene expression in the younger B. hybridum lineage reveals no bias in overall subgenome expression. Our results are consistent with a gradual accumulation of genomic changes after polyploidization and a lack of subgenome expression dominance. Significantly, if we did not use a pan-genomic approach, we would grossly overestimate the number of genomic changes attributable to post polyploidization evolution
Challenge 6: Healthy planet: hazards, risk, management and solutions-oriented research
Our unsustainable use of nature is bringing the
Earth system and its capacity to recover from
global changes beyond the environmental
boundaries that supported us as a society. Here,
we discuss some urgent challenges that should
be addressed for the human species to live with
undesirable products resulting from its
development : sustainable use of nitrogen,
watersheds management for preserving water
resources and their quality, environmental
impact of plastics, increase of the resilience of
marine ecosystems, restoration of the
deteriorated marine coastal ecosystems, or the
early detection of emergence of diseases. We
advocate for the use of Nature based solutions
to mitigate environmental problems, and also
consider subjective wellbeing issues in the
governance of societies for a future healthy
planet.Peer reviewe
Characterizing trade at the largest wildlife market of Amazonian Peru
Wildlife exploitation has nutritional, medicinal, luxury, sociocultural, and financial significance for human societies. Yet, it also risks undesired outcomes for conservation, animal welfare, and public health. Although it is prohibited in urban markets, the wildlife trade in Peru is poorly monitored, and practiced openly. To identify those species most likely to be affected, we investigated the trade in live wild animals and their derivatives at the Belén Market, and additional smaller open-air markets, which together make Iquitos the largest and most important wildlife trade hubs in the Peruvian Amazon. Specifically, we asked what wild animals or animal products were most profitable, what were they used for, and which wild animals were perceived by vendors to have increased most in rarity. Vendors provided 44 local animal names, from which we inferred an estimated 205 species. Nine per cent (n = 19) of these inferred species are categorised on the IUCN Red List as threatened; 35% (n = 71) are categorised as declining. We found that wild meat/food was the most frequently stated purpose of sale of wildlife, followed by pets, spiritual/belief-based use, traditional medicine, and decorative use. The most commonly cited most profitable wildlife derivatives were ‘lowland paca’, ‘yellow footed tortoise’, and ‘collared peccary’. A significant positive correlation was found between the most profitable species and those that are becoming increasingly rare. Further research focused on the actual impacts on wildlife, the socio-economic importance of this trade, the societal pressures driving consumer demand, and the risks to public health is warranted
The Exopolysaccharide Matrix Modulates the Interaction between 3D Architecture and Virulence of a Mixed-Species Oral Biofilm
Virulent biofilms are responsible for a range of infections, including oral diseases. All biofilms harbor a microbial-derived extracellular-matrix. The exopolysaccharides (EPS) formed on tooth-pellicle and bacterial surfaces provide binding sites for microorganisms; eventually the accumulated EPS enmeshes microbial cells. The metabolic activity of the bacteria within this matrix leads to acidification of the milieu. We explored the mechanisms through which the Streptococcus mutans-produced EPS-matrix modulates the three-dimensional (3D) architecture and the population shifts during morphogenesis of biofilms on a saliva-coated-apatitic surface using a mixed-bacterial species system. Concomitantly, we examined whether the matrix influences the development of pH-microenvironments within intact-biofilms using a novel 3D in situ pH-mapping technique. Data reveal that the production of the EPS-matrix helps to create spatial heterogeneities by forming an intricate network of exopolysaccharide-enmeshed bacterial-islets (microcolonies) through localized cell-to-matrix interactions. This complex 3D architecture creates compartmentalized acidic and EPS-rich microenvironments throughout the biofilm, which triggers the dominance of pathogenic S. mutans within a mixed-species system. The establishment of a 3D-matrix and EPS-enmeshed microcolonies were largely mediated by the S. mutans gtfB/gtfC genes, expression of which was enhanced in the presence of Actinomyces naeslundii and Streptococcus oralis. Acidic pockets were found only in the interiors of bacterial-islets that are protected by EPS, which impedes rapid neutralization by buffer (pH 7.0). As a result, regions of low pH (<5.5) were detected at specific locations along the surface of attachment. Resistance to chlorhexidine was enhanced in cells within EPS-microcolony complexes compared to those outside such structures within the biofilm. Our results illustrate the critical interaction between matrix architecture and pH heterogeneity in the 3D environment. The formation of structured acidic-microenvironments in close proximity to the apatite-surface is an essential factor associated with virulence in cariogenic-biofilms. These observations may have relevance beyond the mouth, as matrix is inherent to all biofilms
Brief psychological therapies for anxiety and depression in primary care: meta-analysis and meta-regression
Psychological therapies provided in primary care are usually briefer than in secondary care. There has been no recent comprehensive review comparing their effectiveness for common mental health problems. We aimed to compare the effectiveness of different types of brief psychological therapy administered within primary care across and between anxiety, depressive and mixed disorders
Trophic Ecology of Atlantic Bluefin Tuna (Thunnus thynnus) Larvae from the Gulf of Mexico and NW Mediterranean Spawning Grounds: A Comparative Stable Isotope Study
The present study uses stable isotopes of nitrogen and carbon (δ15Nandδ13C) as trophic indicators for Atlantic bluefin tuna larvae (BFT) (6–10mm standard length) in the highly contrasting environmental conditions of the Gulf of Mexico (GOM) and the Balearic Sea (MED). These regions are differentiated by their temperature regime and relative productivity, with the GOM being significantly warmer and more productive. MED BFT larvae showed the highest δ15N signatures, implying an elevated trophic position above the underlyingmicrozooplankton baseline. Ontogenetic dietary shifts were observed in the BFT larvae from the GOM and MED which indicates early life trophodynamics differences between these spawning habitats. Significant trophic differences between the GOM and MED larvae were observed in relation to δ15N signatures in favour of the MED larvae, which may have important implications in their growth during their early life stages. These low δ15N levels in the zooplankton from the GOM may be an indication of a shifting isotopic baseline in pelagic food webs due to diatrophic inputs by cyanobacteria. Lack of enrichment for δ15N in BFT larvae compared to zooplankton implies an alternative grazing pathway from the traditional food chain of phytoplankton— zooplankton—larval fish. Results provide insight for a comparative characterization of the trophic pathways variability of the two main spawning grounds for BFT larvaeVersión del editor4,411
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