Consequences of Piñon-Juniper Woodland Fuel Reduction: Prescribed Fire Increases Soil Erosion While Mastication Does Not

Ecosystems - Fire suppression has increased fuel load and the risk of catastrophic wildfire in forest and woodland ecosystems across the Western United States. In an effort to reduce fuel load and...     

Responses of Clostridia to oxygen: from detoxification to adaptive strategies

Clostridia comprise bacteria of environmental, biotechnological and medical interest and many commensals of the gut microbiota. Because of their strictly anaerobic lifestyle, oxygen is a major stress for Clostridia. However, recent data showed that these bacteria can cope with O₂ better than expected for obligate anaerobes through their ability to scavenge, detoxify and consume O₂. Upon O₂ exposure, Clostridia redirect their central metabolism onto pathways less O₂-sensitive and induce the expression of genes encoding enzymes involved in O₂-reduction and in the repair of oxidized damaged molecules. While Faecalibacterium prausnitzii efficiently consumes O₂ through a specific extracellular electron shuttling system requiring riboflavin, enzymes such as rubrerythrins and flavodiiron proteins with NAD(P)H-dependent O₂- and/or H₂O₂-reductase activities are usually encoded in other Clostridia. These two classes of enzymes play indeed a pivotal role in O₂ tolerance in Clostridioides difficile and Clostridium acetobutylicum. Two main signalling pathways triggering O₂-induced responses have been described so far in Clostridia. PerR acts as a key regulator of the O₂- and/or reactive oxygen species–defence machinery while in C. difficile, σ^B, the sigma factor of the general stress response also plays a crucial role in O₂ tolerance by controlling the expression of genes involved in O₂ scavenging and repair systems.     

The human tRNA-guanine transglycosylase displays promiscuous nucleobase preference but strict tRNA specificity

Base-modification can occur throughout a transfer RNA molecule; however, elaboration is particularly prevalent at position 34 of the anticodon loop (the wobble position), where it functions to influence protein translation. Previously, we demonstrated that the queuosine modification at position 34 can be substituted with an artificial analogue via the queuine tRNA ribosyltransferase enzyme to induce disease recovery in an animal model of multiple sclerosis. Here, we demonstrate that the human enzyme can recognize a very broad range of artificial 7-deazaguanine derivatives for transfer RNA incorporation. By contrast, the enzyme displays strict specificity for transfer RNA species decoding the dual synonymous NAU/C codons, determined using a novel enzyme-RNA capture-release method. Our data highlight the broad scope and therapeutic potential of exploiting the queuosine incorporation pathway to intentionally engineer chemical diversity into the transfer RNA anticodon.     

The Most Social of Maladies: Re-Thinking the History of Psychiatry From the Edges of Empire

Culture, Medicine, and Psychiatry - This paper argues that the colonial experience was never just “out there” but was a constitutive feature of the global development of psychiatry and,...     

Macroalgae exhibit diverse responses to human disturbances on coral reefs

Scientists and managers rely on indicator taxa such as coral and macroalgal cover to evaluate the effects of human disturbance on coral reefs, often assuming a universally positive relationship between local human disturbance and macroalgae. Despite evidence that macroalgae respond to local stressors in diverse ways, there have been few efforts to evaluate relationships between specific macroalgae taxa and local human-driven disturbance. Using genus-level monitoring data from 1205 sites in the Indian and Pacific Oceans, we assess whether macroalgae percent cover correlates with local human disturbance while accounting for factors that could obscure or confound relationships. Assessing macroalgae at genus level revealed that no genera were positively correlated with all human disturbance metrics. Instead, we found relationships between the division or genera of algae and specific human disturbances that were not detectable when pooling taxa into a single functional category, which is common to many analyses. The convention to use percent cover of macroalgae as an indication of local human disturbance therefore likely obscures signatures of local anthropogenic threats to reefs. Our limited understanding of relationships between human disturbance, macroalgae taxa, and their responses to human disturbances impedes the ability to diagnose and respond appropriately to these threats.     

FreshOmics: A manually curated and standardized –omics database for investigating freshwater microbiomes

Freshwater is a critical resource for human survival but severely threatened by anthropogenic activities and climate change. These changes strongly impact the abundance and diversity of the microbial communities which are key players in the functioning of these aquatic ecosystems. Although widely documented since the emergence of high-throughput sequencing approaches, the information on these natural microbial communities is scattered among thousands of publications and it is therefore difficult to investigate the temporal dynamics and the spatial distribution of microbial taxa within or across ecosystems. To fill this gap and in the FAIR principles context we built a manually curated and standardized microbial freshwater –omics database (FreshOmics). Based on recognized ontologies (ENVO, MIMICS, GO, ISO), FreshOmics describes 29 different types of freshwater ecosystems and uses standardized attributes to depict biological samples, sequencing protocols and article attributes for more than 2487 geographical locations across 71 countries around the world. The database contains 24,808 sequence identifiers (i.e., Run_Id / Exp_ID, mainly from SRA/DDBJ SRA/ENA, GSA and MG-RAST repositories) covering all sequence-based -omics approaches used to investigate bacteria, archaea, microbial eukaryotes, and viruses. Therefore, FreshOmics allows accurate and comprehensive analyses of microbial communities to answer questions related to their roles in freshwater ecosystems functioning and resilience, especially through meta-analysis studies. This collection also highlights different sort of errors in published works (e.g., wrong coordinates, sample type, material, spelling).     

Scale of population synchrony confirms macroecological estimates of minimum viable range size

Global ecosystems are facing a deepening biodiversity crisis, necessitating robust approaches to quantifying species extinction risk. The lower limit of the macroecological relationship between species range and body size has long been hypothesized as an estimate of the relationship between the minimum viable range size (MVRS) needed for species persistence and the organismal traits that affect space and resource requirements. Here, we perform the first explicit test of this assumption by confronting the MVRS predicted by the range-body size relationship with an independent estimate based on the scale of synchrony in abundance among spatially separated populations of riverine fish. We provide clear evidence of a positive relationship between the scale of synchrony and species body size, and strong support for the MVRS set by the lower limit of the range-body size macroecological relationship. This MVRS may help prioritize first evaluations for unassessed or data-deficient taxa in global conservation assessments.     

Palaeoenvironmental shifts drove the adaptive radiation of a noctuid stemborer tribe (lepidoptera, noctuidae, apameini) in the miocene

Between the late Oligocene and the early Miocene, climatic changes have shattered the faunal and floral communities and drove the apparition of new ecological niches. Grassland biomes began to supplant forestlands, thus favouring a large-scale ecosystem turnover. The independent adaptive radiations of several mammal lineages through the evolution of key innovations are classic examples of these changes. However, little is known concerning the evolutionary history of other herbivorous groups in relation with this modified environment. It is especially the case in phytophagous insect communities, which have been rarely studied in this context despite their ecological importance. Here, we investigate the phylogenetic and evolutionary patterns of grass-specialist moths from the species-rich tribe Apameini (Lepidoptera, Noctuidae). The molecular dating analyses carried out over the corresponding phylogenetic framework reveal an origin around 29 million years ago for the Apameini. Ancestral state reconstructions indicate (i) a potential Palaearctic origin of the tribe Apameini associated with a major dispersal event in Afrotropics for the subtribe Sesamiina; (ii) a recent colonization from Palaearctic of the New World and Oriental regions by several independent lineages; and (iii) an ancestral association of the tribe Apameini over grasses (Poaceae). Diversification analyses indicate that diversification rates have not remained constant during the evolution of the group, as underlined by a significant shift in diversification rates during the early Miocene. Interestingly, this age estimate is congruent with the development of grasslands at this time. Rather than clade ages, variations in diversification rates among genera better explain the current differences in species diversity. Our results underpin a potential adaptive radiation of these phytophagous moths with the family Poaceae in relation with the major environmental shifts that have occurred in the Miocene.