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Wood density is a key control on tree biomass, and understanding its spatial variation improves estimates of forest carbon stock. Sullivan et al. measure >900 forest plots to quantify wood density and produce high resolution maps of its variation across South American tropical forests.

Analysing >1,700 inventory plots from the Amazon Tree Diversity Network, the authors show that the majority of Amazon tree species can occupy floodplains and that patterns of species turnover are closely linked to regional flood patterns.

Employing pharmacology, genetics and all-optical approaches in zebrafish, Braaker et al. find that neuronal activity influences the growth of myelin sheaths along axons by signaling through metabotropic glutamate receptor 5 on oligodendrocytes.

Tree mortality has been shown to be the dominant control on carbon storage in Amazon forests, but little is known of how and why Amazon forest trees die. Here the authors analyse a large Amazon-wide dataset, finding that fast-growing species face greater mortality risk, but that slower-growing individuals within a species are more likely to die, regardless of size.

Inventory data from more than 1 million trees across African, Amazonian and Southeast Asian tropical forests suggests that, despite their high diversity, just 1,053 species, representing a consistent ~2.2% of tropical tree species in each region, constitute half of Earth’s 800 billion tropical trees.

The Amazon rainforest is dominated by relatively few tree species, yet the degree to which this hyperdominance influences carbon cycling remains unknown. Here, the authors analyse 530 forest plots and show that ∼1% of species are responsible for 50% of the aboveground carbon storage and productivity.

Using 13 functional traits we characterize the Amazonian trees and the communities they form. Amazonian tree communities are distributed along a fast-slow-spectrum. This results in clear differences in traits among these forests, as well as their biomass and biomass productivity.

An analysis of 24,202 critical cases of COVID-19 identifies potentially druggable targets in inflammatory signalling (JAK1), monocyte–macrophage activation and endothelial permeability (PDE4A), immunometabolism (SLC2A5 and AK5), and host factors required for viral entry and replication (TMPRSS2 and RAB2A).

The authors analyse tree responses to an extreme heat and drought event across South America to understand long-term climate resistance. While no more sensitive to this than previous lesser events, forests in drier climates showed the greatest impacts and thus vulnerability to climate extremes.

The VGLUT3-p.T8I mutation was identified in patients with SUDs and EDs and introduced in a mouse line. Here, authors show that mutant mice have an imbalanced DA signaling in the dorsal striatum associated with maladaptive cocaine and food consumption.

Renewable energy from reservoir-based hydropower plants can have high GHG emissions. Integrating floating solar photovoltaics on hydropower reservoirs can help offset GHG emissions from a large proportion of hydropower facilities.

Emerging variants of SARS-CoV-2 raise concerns about vaccine efficiency. Here, the authors present a post-hoc analysis for the ChAdOx1 nCoV-19 (AZD1222) vaccine trial in Brazil and provide efficacy against symptomatic COVID-19 caused by the Zeta (P.2) and other variants.

Even evergreen tropical forests can have seasonal dynamics, which may be sensitive to disturbance. Here, the authors combine high-resolution remote sensing observations and microclimate data to show that forest fragmentation impacts canopy phenology dynamics in the Amazon forest.

The protein Galectin-3 modulates host immunity and plays roles during infections. Here, Almeida et al. show that this protein contributes to host defence against infection with the fungal pathogen Cryptococcus neoformans by inhibiting fungal growth and inducing lysis of fungal extracellular vesicles.

A global network of researchers was formed to investigate the role of human genetics in SARS-CoV-2 infection and COVID-19 severity; this paper reports 13 genome-wide significant loci and potentially actionable mechanisms in response to infection.

A diverse, multidisciplinary panel of 386 experts in COVID-19 response from 112 countries provides health and social policy actions to address inadequacies in the pandemic response and help to bring this public health threat to an end.

Bacillus anthracis causes the infectious disease anthrax. Here, the authors synthesized deoxy glycosides that are effective against B. anthracis and related bacteria and found that these amphiphilic compounds kill bacteria via an unusual mechanism of action.

Tree species turnover across Amazonian forests unveils sharp floristic transitional zones, that are linked with changes in soil fertility and climate.

Genomic surveillance has been important for tracking the evolution and spread of SARS-CoV-2. Here, the authors analyse ~300,000 SARS-CoV-2 genomes from two years of sequencing in the Latin America and Caribbean regions and describe the emergence and spread of different lineages over time.

A pan-Amazon study of forests shows large variations in drought tolerance traits and finds that forests in regions of pronounced climate change are losing biomass and may be operating beyond their hydraulic limits.

As sea levels rise, coasts are being increasingly  threatened by overtopping caused by the combination of sea level rise, storm surge and wave runup. Here the authors find that global coastal overtopping has increased by over 50% in the last two decades, and under a RCP 8.5 scenario this could increase up to 50 times by 2100 compared to today.

Deciphering the relationship between prolonged topographic growth and temporary earthquake uplift is challenging due to the mismatch in their deformation patterns. Zhang et al. introduce a novel model to address this highly hotly-debated discrepancy.

A study mapping the tree species richness in Amazonian forests shows that soil type exerts a strong effect on species richness, probably caused by the areas of these forest types. Cumulative water deficit, tree density and temperature seasonality affect species richness at a regional scale.

Understanding myelination is important for CNS plasticity and disease. Here the authors show exocytosis mediated by the vesicular SNARE proteins VAMP2/3 is involved in oligodendrocyte membrane expansion.

Whole-genome sequencing, transcriptome-wide association and fine-mapping analyses in over 7,000 individuals with critical COVID-19 are used to identify 16 independent variants that are associated with severe illness in COVID-19.

The aquaculture sector in the Amazon is an important source of food and livelihood provision; however, it is associated with environmental and ecological risks. This Review assesses aquaculture in the Amazon, offering insights into the challenges and opportunities for its sustainable growth.

Genetic and Structural analysis of COVID patients cohort reveals a correlation between mitochondrial haplogroup and SARS-CoV-2 severity.

Here, the authors present results of the ZiBRA-2 project (https://www.zibra2project.org) which is an arbovirus surveillance project, across the Midwest of Brazil using a mobile genomics laboratory, combined with a genomic surveillance training program that targeted post-graduate students, laboratory technicians, and health practitioners in universities and laboratories.

Shallow parts of megathrusts up-dip of locked patches generally have a high slip rate deficit, which could mean tsunami hazard has been underestimated, according to a stress-constrained inversion of geodetic data.

Dendritic cells initiate and regulate adaptive immunity and differ according to gut anatomical ___location. Here the authors show that DC residing in the upper and lower intestines show differential PD-L1 and XCR1 expression and drive specific T cell responses to prevent gut inflammation.

Brazil has one of the fastest-growing COVID-19 epidemics in the world. De Souza et al. report epidemiological, demographic and clinical findings for COVID-19 cases in the country during the first 3 months of the epidemic.

Some dams produce large amounts of GHGs and it is important to see whether future dams will satisfy sustainable energy goals. Here the authors estimate the range of GHG emission intensities expected for 351 proposed and 158 existing Amazon dams and find that existing Amazon hydropower reservoirs collectively emit 14 Tg CO₂eq per year, and that if all proposed Amazon dams are built, annual emissions would increase 5-fold.

Most Amazon tree species are rare but a small proportion are common across the region. The authors show that different species are hyperdominant in different size classes and that hyperdominance is more phylogenetically restricted for larger canopy trees than for smaller understory ones.

This Registered Report presents evidence from 87 countries and regions showing that brief emotion-regulation interventions consistently reduced negative emotions and increased positive emotions during the COVID-19 pandemic.

It is unclear whether the emergence of new infectious diseases can be predicted. Here, Anthony et al. investigate viral communities in faeces of wild macaques and show that viral diversity is inherently structured, suggesting that it should be possible to forecast some changes in viral communities.