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The Schlafen family belongs to the interferon-stimulated genes and its members are involved in cell cycle regulation, T cell quiescence, inhibition of viral replication, DNA-repair and tRNA processing. Here, we present the cryo-EM structure of full-length human Schlafen 5 (SLFN5) and the high-resolution crystal structure of the highly conserved N-terminal core domain. We show that the core domain does not resemble an ATPase-like fold and neither binds nor hydrolyzes ATP. SLFN5 binds tRNA as well as single- and double-stranded DNA, suggesting a potential role in transcriptional regulation. Unlike rat Slfn13 or human SLFN11, human SLFN5 did not cleave tRNA. Based on the structure, we identified two residues in proximity to the zinc finger motif that decreased DNA binding when mutated. These results indicate that Schlafen proteins have divergent enzymatic functions and provide a structural platform for future biochemical and genetic studies.

The capture and use of water are critically important in drylands, which collectively constitute Earth's largest biome. Drylands will likely experience lower and more unreliable rainfall as climatic conditions change over the next century. Dryland soils support a rich community of microphytic organisms (biocrusts), which are critically important because they regulate the delivery and retention of water. Yet despite their hydrological significance, a global synthesis of their effects on hydrology is lacking. We synthesized 2,997 observations from 109 publications to explore how biocrusts affected five hydrological processes (times to ponding and runoff, early [sorptivity] and final [infiltration] stages of water flow into soil, and the rate or volume of runoff) and two hydrological outcomes (moisture storage, sediment production). We found that increasing biocrust cover reduced the time for water to pond on the surface (−40%) and commence runoff (−33%), and reduced infiltration (−34%) and sediment production (−68%). Greater biocrust cover had no significant effect on sorptivity or runoff rate/amount, but increased moisture storage (+14%). Infiltration declined most (−56%) at fine scales, and moisture storage was greatest (+36%) at large scales. Effects of biocrust type (cyanobacteria, lichen, moss, mixed), soil texture (sand, loam, clay), and climatic zone (arid, semiarid, dry subhumid) were nuanced. Our synthesis provides novel insights into the magnitude, processes, and contexts of biocrust effects in drylands. This information is critical to improve our capacity to manage dwindling dryland water supplies as Earth becomes hotter and drier. This work was conducted as part of the Powell Working Group “Completing the dryland puzzle: creating a predictive framework for biological soil crust function and response to climate change” supported by the John Wesley Powell Center for Analysis and Synthesis, funded by the US Geological Survey. J.B. and S.R. were funded by USGS Ecosystems and Land Use Change Mission Areas, by the US Department of Energy (DESC-0008168), and by the Strategic Environmental Research and Development Program (RC18-1322). J.D. is supported by grants from the Holsworth Wildlife Research Endowment & The Ecological Society of Australia, and a scholarship from China Scholarship Council (No. 201706040073). B.C. is supported by grants from the National Science Foundation (award DEB-1844531) and DePaul University. M.A.B. is supported by a grant from the National Science Foundation (award DEB-1638966). B.W. was supported by the Max Planck Society and a Paul Crutzen Nobel Laureate Fellowship. E.H.-S. was supported by CONACYT grant 251388 B. F.T.M. was supported by the European Research Council (ERC grant agreement 647038 [BIODESERT]) and Generalitat Valenciana (CIDEGENT/2018/041).

Studies of biological soil crusts (biocrusts) have proliferated over the last few decades. The biocrust literature has broadened, with more studies assessing and describing the function of a variety of biocrust communities in a broad range of biomes and habitats and across a large spectrum of disciplines, and also by the incorporation of biocrusts into global perspectives and biogeochemical models. As the number of biocrust researchers increases, along with the scope of soil communities defined as ‘biocrust’, it is worth asking whether we all share a clear, universal, and fully articulated definition of what constitutes a biocrust. In this review, we synthesize the literature with the views of new and experienced biocrust researchers, to provide a refined and fully elaborated definition of biocrusts. In doing so, we illustrate the ecological relevance and ecosystem services provided by them. We demonstrate that biocrusts are defined by four distinct elements: physical structure, functional characteristics, habitat, and taxonomic composition. We describe outgroups, which have some, but not all, of the characteristics necessary to be fully consistent with our definition and thus would not be considered biocrusts. We also summarize the wide variety of different types of communities that fall under our definition of biocrusts, in the process of highlighting their global distribution. Finally, we suggest the universal use of the Belnap, Büdel & Lange definition, with minor modifications: Biological soil crusts (biocrusts) result from an intimate association between soil particles and differing proportions of photoautotrophic (e.g. cyanobacteria, algae, lichens, bryophytes) and heterotrophic (e.g. bacteria, fungi, archaea) organisms, which live within, or immediately on top of, the uppermost millimetres of soil. Soil particles are aggregated through the presence and activity of these often extremotolerant biota that desiccate regularly, and the resultant living crust covers the surface of the ground as a coherent layer. With this detailed definition of biocrusts, illustrating their ecological functions and widespread distribution, we hope to stimulate interest in biocrust research and inform various stakeholders (e.g. land managers, land users) on their overall importance to ecosystem and Earth system functioning. This work was conducted as part of the “Completing the dryland puzzle: creating a predictive framework for biological soil crust function and response to climate change” Working Group supported by the John Wesley Powell Center for Analysis and Synthesis, funded by the U.S. Geological Survey. V.B.C. is funded by the National Science Foundation (DEB-1844531). F.T.M. acknowledges support from the European Research Council (ERC Grant Agreement 647038 [BIODESERT]) and Generalitat Valenciana (CIDEGENT/2018/041). K.E.Y. and A.D.-N. were supported by the National Science Foundation (#1557162 & #1557135). E.R.-C. was supported by the Ramon y Cajal fellowship (RYC2020-030762-I) and the REBIOARID Project (2018-101921-B-I00) founded by FEDER/Ministerio de Ciencia e Inovacion-Agencia estatal de investigacion, and the BIOCOST project (Conservación debiocostras como estrategia de adaptación al cambio climático: alineando avances científicos con la gestión y sociedad) supported by the Biodiversity Foundation of the Ministry for the Ecological Transition and the Demographic Challenge. S.C.R. was supported by USGS Ecosystems Mission Area. E.H.-S. acknowledges financial support from CONACYT grant SEP-CB-2015-01-251388.

Dentro de las aves, las de pastizal son de las más amenazadas en el mundo. En México, estos ecosistemas se han visto afectados por el sobre-apacentamiento con ganado doméstico y la conversión a la agricultura. Para desarrollar planes de conservación es necesario evaluar las poblaciones y utilizar herramientas precisas que permitan conocer el estado de éstas. El objetivo del estudio fue comparar el conteo de aves por transecto y el puntual, para contrastar su efectividad al estimar la riqueza de especies y densidad de poblaciones, mediante cuatro diferentes distancias de detección en tres tipos de hábitats: pastizal mediano abierto, sabana y áreas agrícolas, las cuales diferían en su cubierta vegetal. La cuantificación se realizó en el periodo invierno-primavera 2004 - 2005. Las densidades más altas se obtuvieron con la técnica del conteo puntual en los intervalos de 0 - 25 y 25 - 50 m. El mayor número de especies se detectó con ambos métodos en las distancias de 0 a 75 m. Los resultados son consistentes para las dos estaciones y los tres hábitats, por lo que es posible combinar los métodos probados cuando se realicen inventarios referentes a la diversidad de aves de los pastizales semiáridos de México.

Biological soil crusts (biocrusts) are a complex community of algae, cyanobacteria, lichens, bryophytes, and assorted bacteria, fungi, archaea, and bacteriophages that colonize the soil surface. Biocrusts are particularly common in drylands and are found in arid and semiarid ecosystems worldwide. While diminutive in size, biocrusts often cover large terrestrial areas, provide numerous ecosystem benefits, enhance biodiversity, and are found in multiple configurations and assemblages across different climate and disturbance regimes. Biocrusts have been a focus of many ecologists, especially those working in semiarid and arid lands, as biocrusts are foundational community members, play fundamental roles in ecosystem processes, and offer rare opportunities to study biological interactions at small and large spatial scales. Due to these same characteristics, biocrusts have the potential to serve as an excellent teaching tool. The purpose of this paper is to demonstrate the utility of biocrust communities as a model system in science education. Functioning as portable, dynamic mini ecosystems, biocrusts can be used to teach about organisms, biodiversity, biotic interactions, abiotic controls, ecosystem processes, and even global change, and can be easy to use in nearly every classroom setup. For example, education principles, such as evolution and adaptation to stress, or structure and function (patterns and processes) can be applied by bringing biocrusts into the classroom as a teaching tool. In addition, discussing the utility of biocrusts in the classroom – including theory, hypothesis testing, experimentation, and hands-on learning – this document also provides tips and resources for developing education tools and activities geared toward impactful learning.

Theories attempting to explain species coexistence in plant communities have argued in favour of species' capacities to occupy a multidimensional niche with spatial, temporal and biotic axes. We used the concept of hydrological niche segregation to learn how ecological niches are structured both spatially and temporally and whether small scale humidity gradients between adjacent niches are the main factor explaining water partitioning among tree species in a highly water-limited semiarid forest ecosystem. By combining geophysical methods, isotopic ecology, plant ecophysiology and anatomical measurements, we show how coexisting pine and oak species share, use and temporally switch between diverse spatially distinct niches by employing a set of functionally coupled plant traits in response to changing environmental signals. We identified four geospatial niches that turned into nine, when considering the temporal dynamics of the wetting/drying cycles in the substrate and the particular plant species adaptations to garner, transfer, store and use water. Under water scarcity, pine and oak exhibited water use segregation from different niches, yet under maximum drought when oak trees crossed physiological thresholds, niche overlap occurred. The identification of niches and mechanistic understanding of when and how species use them will help unify theories of plant coexistence and competition.

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Non-targeted mass spectrometry (MS) has become an important method over recent years in the fields of metabolomics and environmental research. While more and more algorithms and workflows become available to process a large number of non-targeted data sets, there still exist few manually evaluated universal test data sets for refining and evaluating these methods. The first step of non-targeted screening, peak detection and refinement of it is arguably the most important step for non-targeted screening. However, the absence of a model data set makes it harder for researchers to evaluate peak detection methods. In this Data Descriptor, we provide a manually checked data set consisting of 255,000 EICs (5000 peaks randomly sampled from across 51 samples) for the evaluation on peak detection and gap-filling algorithms. The data set was created from a previous real-world study, of which a subset was used to extract and manually classify ion chromatograms by three mass spectrometry experts. The data set consists of the converted mass spectrometry files, intermediate processing files and the central file containing a table with all important information for the classified peaks.

The phenomenon of poverty and its impact on environmental pollution of urban spaces in West Africa. On the relation between environmental awareness and living conditions. Die Autorin untersucht in ihrer Studie die Möglichkeiten umweltgerechten Handelns der ärmeren städtischen Bevölkerungsschichten im urbanen Raum Westafrikas. Dazu analysiert sie die Praktiken der Abfall- und Abwasserentsorgung in Bamako (Mali) und Ouagadougou (Burkina Faso) unter den dafür relevanten ökonomischen, sozialen und kulturellen Bedingungen. Neben der Erörterung von Armut anhand monetärer Aspekte, fehlender Verwirklichungschancen sowie familiärer und nachbarschaftlicher Solidaritätsstrategien stellt sie die Frage nach dem Zusammenhang von Umweltbewusstsein, Umweltverschmutzung, Umweltschutz, Wohn- und Lebensbedingungen, Infrastruktur und dem "Recht auf Stadt".

Win-win solutions might be short-lived. Government permission for smallholder farmers to extract and sell resin from a pine savanna biosphere-reserve in Mexico has settled a long dispute among different stakeholders in the short-term; however, forest production and conservation beyond 20 years are compromised due to low pine recruitment caused by competition with exotic grasses. Grass control practiced by farmers through grazing and fire has previously been discouraged by conservation authorities, which inadvertently limits long-term pine conservation and use. We describe the participatory design, rationale and simulation attributes of an educational, interactive, agent-based model that explores suites of management options and their economic and ecological outputs. We present and analyze the outcomes of four simulation workshops, where farmers and external-actors better grasped the complex ecological interactions involved in conserving and using pines in grazed pine savanna with exotic grasses, and discussed these findings with a long-term vision and tradeoff analysis approach.

Examination of the effects of altered precipitation and atmospheric temperature patterns on ecosystem processes are an active area of research. Influences of these climate factors may change when plant cover and species composition are disturbed as a consequence of land use change altering ecosystem processes, such as soil respiration. We addressed the following question: how does experimentally manipulated reduction in the size of each precipitation event influence soil respiration fluxes (Rs) in a tropical semiarid grassland with different plant cover and species composition? Rainout shelters were installed over eight yr old planted monospecific plots (4 m 2 ) of Bouteloua gracilis, the keystone species of the grassland biome, and over mixed grassland plots in sites that recovered from abandoned agricultural land, allowing full or a 50% reduction of ambient precipitation. Soil respiration rates as well soil temperature (T soil ) and soil water content (SWC), as controlling factors, were monitored. Overall, SWC was the most important control for Rs explaining ∼70% of its variability, followed by T soil which explained ∼25% and plant cover type having a minor effect (3%) explaining Rs variability. Still, Rs exhibited differential responses when comparing plant cover types; SWC in the mixed grassland had up to 90% relative influence on Rs as compared to 10% by Tsoil. In contrast, Rs rates in monospecific B. gracilis plots exhibited less overall variability considering SWC (55–60%) and T soil (40–45%), suggesting that grasslands dominated by the keystone species are more resilient and better buffer the effects of extreme climatic drought conditions on ecosystem processes.

Las zonas áridas cubren 40% de la superficie terrestre en donde habita el 40% de la población humana. Tras el desarrollo de las zonas áridas estas evolucionaron como sistemas socio-ecológicos (SSE) altamente vulnerables al cambio climático y a la desertificación. Para cumplir con los Objetivos de Desarrollo Sostenible (ODS), se requieren nuevas formas de generar conocimiento útil. Una opción es la coproducción de marcos de acción basados en una gestión integral de los SSE, porque se tejen sistemas de conocimiento en alianzas con sectores clave. La Red Internacional para la Sostenibilidad de las Zonas Áridas (RISZA) aborda los grandes retos que emergen en las zonas áridas de manera transdisciplinaria. Nuestra finalidad es proteger la diversidad biótica y cultural como base esencial del desarrollo sostenible. Un modus operandi de RISZA son los Observatorios Participativos Socio-Ecológicos (OPSE), entendidos como laboratorios en un territorio real, donde se exploran de manera participativa las rutas de acción y se aplican metodologías participativas como “participatory rural appraisal”. El fin de los OPSE es desarrollar planes de acción para implementar innovaciones sociales y facilitar la cogestión de conocimiento de cada SSE. Los OPSE son sitios/espacios presenciales y virtuales donde se recopila, intercambia y cogenera nuevo conocimiento como un “hub” de innovación para el desarrollo sostenible en las zonas áridas.

Human induced savannas in subtropical regions are often favored by small-holder farmers for livestock production and extraction of wood or non-wood products. Frequent burning and grazing are required to maintain the savanna vegetation structure. However, in conservation areas, fire suppression is promoted to avoid wildfires; whereas domestic livestock grazing is considered a strong interfering factor for tree establishment, due to trampling and browsing. In tropical forests which were converted to savannas, competitive exotic grasses have often replaced the native grasses. Where exotic grasses are present, aboveground biomass accumulation and thus man-induced fire risk are high and potentially undermine tree recruitment. On the long-term, the savanna state may shift into a grass-dominated state with little tree cover, generating unfavorable conditions from a livelihood perspective. We examined this problem in a human-induced pine savanna in the La Sepultura Biosphere Reserve in Chiapas, Mexico. Smallholder farmers highly valued this savanna for both livestock production and resin extraction from the fire resistant pine Pinus oocarpa. However, fire suppression and the presence of exotic grasses are reducing the tree recruitment. The main research question was to what degree can cattle grazing replace fire in its role of biomass removal and thereby stimulate pine recruitment and maintain the desired savanna state. We determined current savanna extension in the region and interviewed farmers to reconstruct past savannazation processes and expansion of exotic grasses. We related adult species-specific tree density to the herbaceous-grass cover, and pine and oak seedling and sapling densities to understory vegetation cover, canopy closure, and cattle grazing history. Finally, a field experiment was conducted to examine the effects of livestock grazing on survival and growth of planted pine saplings. The savanna currently covers 20% of the study site; it is the result of past slash-and-burn agriculture and selective logging, which have favored the expansion of several exotic grass species. In savannas where exotic grasses are abundant, sapling density was lower compared to sites with a native grass cover. While livestock grazing seemed to increase pine seedling density likely as a consequence of reduced grass cover, pine sapling survival however, was significantly reduced by livestock trampling. By seeking a balance between the livestock’s benefits and adverse effects on pine recruitment, farmers may develop an integrated management system adapted to their specific biotic rangeland conditions. It should allow forage production, while controlling the negative effects of exotic grasses on pine recruitment, thus maintaining a productive pine savanna system.

To allow bone defect regeneration, autologous bone grafting still represents the gold standard. However, autograft harvesting has limitations, including an additional surgery, donor site morbidity, and limited availability. Demineralized bone matrix (DBM) would represent an alternative, yet lacks sufficient osteoinductive properties. Combining DBM with a potent agent, such as bone morphogenetic protein-2 (BMP-2) might be a feasible alternative approach, optimizing an established grafting material with strong osteoinductive properties. A unique mixing device has been developed that enables perioperative handling to reach a homogeneous and standardized paste for bone defect filling. DBM proved in vitro to be a suitable carrier for BMP-2, with a documented release over 56 days at concentrations sufficient to stimulate osteogenic differentiation. At the end of the elution experiment, 56 days, bioactive BMP was still captured within the DBM. Using a sheep drill hole defect model, DBM perioperatively mixed with...

To date it is not well-understood how seasonality and human-induced habitat change may affect haemosporidian prevalence and parasitaemia in bird hosts in dryland habitats. We compared haemosporidian prevalence and parasitaemia between habitat types, including Yucca-dominated scrublands (closed habitat) and creosotebush scrublands (open habitat), and between seasons, including non-breeding (dry) and breeding (wet) in the Black-throated sparrow (Amphispiza bilineata) at semi-arid scrublands of Central Mexico. This bird species has different habitat preferences in comparison to other, previously studied species in the region; it shows higher abundances in open than in closed habitats and avoids urban areas. Overall haemosporidian prevalence was 22.1%. Prevalence and parasitaemia were higher for Haemoproteus sp. (Parahaemoproteus sp.) than Plasmodium. Variation in haemoparasitism was not associated with habitat type. This response differs from the previously recorded response in other bird species in the region for which haemoparasitism increases with increasing habitat degradation. Seasonality seems to be the most important driver of parasite infection for this sparrow as prevalence and parasitaemia were higher during the breeding than the non-breeding season. Two new lineages of Haemoproteus sp. that had not been reported before in any avian species were found through molecular diagnosis. A high diversity of haemosporidian lineages is shared among sites. More study is needed to understand the mechanisms that associate parasitaemia, prevalence, and specific environmental factors.

To the editor: Allogeneic bone marrow (BM) transplantation (alloBMT) is a unique curative therapy for diverse diseases. However, its use is limited by the development of severe treatment-related complications, most importantly, the occurrence of acute graft-versus-host-disease (aGVHD). Despite the

In this paper we will analyze the dynamics of a social-ecological system (SES), which requires an integrated understanding of both the interrelatedness of biophysical and socioeconomic components and the adaptive capacity of these system’s components to external drivers. Social-ecological resilience, the adaptive cycle metaphor and livelihood development are presented as the guiding conceptual framework to analyze local strategies, aiming towards the sustainable use of natural resources and to encourage the participation of the community in the management of ecosystem services, thereby improving human well-being. Furthermore, in the light of recurring unpredictable changes, adaptive capacity building and a high responsiveness to these changes may serve as fundamental assets to increase both ecological resilience, including the protection of biodiversity, and social resilience, including social and human capital and institutional capacity. An integrated analysis of SESs considers i) the interplay of internal and external factors and their role in SES dynamics, ii) potential thresholds whose crossing may shift the system into an undesirable state, and iii) cross-scale spatial and temporal interactions. Ultimately, an SES approach favors ecosystem stewardship in that it enhances the sustainable use of natural resources and ecosystem services, and simultaneously resilient livelihood development.