The Amazonian rainforest is arguably the most species-rich terrestrial ecosystem in the world, yet the timing of the origin and evolutionary causes of this diversity are a matter of debate. We review ...the geologic and phylogenetic evidence from Amazonia and compare it with uplift records from the Andes. This uplift and its effect on regional climate fundamentally changed the Amazonian landscape by reconfiguring drainage patterns and creating a vast influx of sediments into the basin. On this "Andean" substrate, a region-wide edaphic mosaic developed that became extremely rich in species, particularly in Western Amazonia. We show that Andean uplift was crucial for the evolution of Amazonian landscapes and ecosystems, and that current biodiversity patterns are rooted deep in the pre-Quaternary.
The Atlantic rainforest of Brazil is one of the global terrestrial hotspots of biodiversity. Despite having undergone large scale deforestation, forest cover has shown signs of increases in the last ...decades. Here, to understand the degradation and regeneration history of Atlantic rainforest remnants near São Paulo, we combine a unique dataset of very high resolution images from Worldview-2 and Worldview-3 (0.5 and 0.3m spatial resolution, respectively), georeferenced aerial photographs from 1962 and use a deep learning method called U-net to map (i) the forest cover and changes and (ii) two pioneer tree species, Cecropia hololeuca and Tibouchina pulchra. For Tibouchina pulchra, all the individuals were mapped in February, when the trees undergo mass-flowering with purple and pink blossoms. Additionally, elevation data at 30m spatial resolution from NASA Shuttle Radar Topography Mission (SRTM) and annual mean climate variables (Terraclimate datasets at ∼ 4km of spatial resolution) were used to analyse the forest and species distributions. We found that natural forests are currently more frequently found on south-facing slopes, likely because of geomorphology and past land use, and that Tibouchina is restricted to the wetter part of the region (southern part), which annually receives at least 1600 mm of precipitation. Tibouchina pulchra was found to clearly indicate forest regeneration as almost all individuals were found within or adjacent to forests regrown after 1962. By contrast, Cecropia hololeuca was found to indicate older disturbed forests, with all individuals almost exclusively found in forest fragments already present in 1962. At the regional scale, using the dominance maps of both species, we show that at least 4.3% of the current region's natural forests have regrown after 1962 (Tibouchina dominated, ∼ 4757 ha) and that ∼ 9% of the old natural forests have experienced significant disturbance (Cecropia dominated).
•Ultrasound is a promising technique in food technology with a low impact on the environment.•The application of high-energy ultrasound can be used to improve functional properties of proteins.•To ...obtain better results during its application, the optimal conditions must be standardized to each food.
In recent years, high-energy ultrasound has been used as an alternative to improve the functional properties of various proteins, such as from milk, eggs, soy and poultry. The benefits of implementing this technology depend on the inherent characteristics of the protein source and the intensity and amplitude of the ultrasound, as well as on the pH, temperature, ionic strength, time, and all of the variables that have an effect on the physicochemical properties of proteins. Therefore, it is necessary to establish the optimal conditions for each type of food. The use of ultrasound is a promising technique in food technology with a low impact on the environment, and it has thus become known as a green technology. Therefore, this review focuses on the application of high-energy ultrasound to food; its effects on the functional properties of proteins; and how different conditions such as the frequency, time, amplitude, temperature, and protein concentration affect the functional properties.
Graphene has exceptional electronic, optical, mechanical and thermal properties, which provide it with great potential for use in electronic, optoelectronic and sensing applications. The chemical ...functionalization of graphene has been investigated with a view to controlling its electronic properties and interactions with other materials. Covalent modification of graphene by organic diazonium salts has been used to achieve these goals, but because graphene comprises only a single atomic layer, it is strongly influenced by the underlying substrate. Here, we show a stark difference in the rate of electron-transfer reactions with organic diazonium salts for monolayer graphene supported on a variety of substrates. Reactions proceed rapidly for graphene supported on SiO(2) and Al(2)O(3) (sapphire), but negligibly on alkyl-terminated and hexagonal boron nitride (hBN) surfaces, as shown by Raman spectroscopy. We also develop a model of reactivity based on substrate-induced electron-hole puddles in graphene, and achieve spatial patterning of chemical reactions in graphene by patterning the substrate.
Microbial mats and microbialites are essential tools for reconstructing early life and its environments. To better understand microbial trace element cycling, a microbial mat was collected from the ...sinkhole systems of the western shores of the Dead Sea, a dynamic environment exhibiting diverse extreme environments. Intense arsenic enrichment was measured (up to 6.5 million times higher than current concentrations in water, and 400 times the bulk concentration in the mat). Arsenic was found predominantly as As(V) in organic molecules, as shown by XANES spectra and high‐resolution elemental mapping. Arsenic cycling genes obtained from metagenomic analysis were associated with arsenic detoxification, supporting an active mechanism of As(V) uptake, As(III) efflux and organoarsenic accumulation in the extracellular polymeric substances (EPS) of the mat. Thus, we propose that such localized As enrichment can be attributed to a transient increase in As(V) concentrations in the circulating subsurface water of the Dead Sea shore and its subsequent incorporation into organoarsenic molecules through microbial detoxification processes. Our data set supports the possibility of metalloid enrichment recorded in very localized facies due to rapid geogenic fluctuations in the chemistry of the water flowing over a biofilm. In this context, this example calls for caution in interpreting metal(loid) enrichment in organic matter‐rich layers and microbialites of Paleoproterozoic origin. Arsenic signatures in Precambrian organic matter and carbonate rocks may host biosignatures, including evidence for extracellular polymeric substances, As‐binding and detoxification processes, without supporting arsenotrophy. However, they provide clues to better assess the paleoenvironmental conditions at the time of microbial mat formation.
Plain Language Summary
Microbial mats and microbialites are like time machines helping us learn about ancient life and its environments. We collected a microbial mat from the unique Dead Sea’s sinkholes, where life thrives in extreme conditions. In this mat, we found for the first time in this area a staggering 6.5 million‐fold increase in arsenic, an element toxic to life. By closely studying the genes and chemistry of this microbial mat, we discovered that microbes were striving to clean up this excess arsenic in a sort of natural detoxification process. It seems that a temporary spike in arsenic levels in the Dead Sea water triggered this clean‐up work, which eventually stored the arsenic safely in the mat away from the microbial cells. Our findings suggest that in the past, when microbial mats were one of the only ecosystems on Earth, changes in the water flowing over mats like this one could have caused similar accumulations of metals. Therefore, when scientists study ancient fossilized microbial layers, these discoveries can help us look into the past and understand the chemical and biological conditions under which these ancient microbial mats formed.
Key Points
Intense arsenic enrichment is detected for the first time around the Dead Sea
Arsenic is accumulated in the organic matter of a microbial mat as methylated organoarsenic
The enrichment results from microbial detoxification and may be fossilized
Display omitted
•Cooperativity and flexibility play important roles in enzyme evolution.•Evolutionarily-important flexibility can be both structural or electrostatic.•Floppiness in ancestral ...scaffolds can promote the emergence of new activities.•Functional evolution requires an interplay between flexibility and specificity.•Flexibility can be harnessed to both understand and manipulate protein evolution.
Enzymes are flexible catalysts, and there has been substantial discussion about the extent to which this flexibility contributes to their catalytic efficiency. What has been significantly less discussed is the extent to which this flexibility contributes to their evolvability. Despite this, recent years have seen an increasing number of both experimental and computational studies that demonstrate that cooperativity and flexibility play significant roles in enzyme innovation. This review covers key developments in the field that emphasize the importance of enzyme dynamics not just to the evolution of new enzyme function(s), but also as a property that can be harnessed in the design of new artificial enzymes.
In many bacteria, including Vibrio cholerae, cyclic dimeric guanosine monophosphate (c-di-GMP) controls the motile to biofilm life style switch. Yet, little is known about how this occurs. In this ...study, we report that changes in c-di-GMP concentration impact the biosynthesis of the MshA pili, resulting in altered motility and biofilm phenotypes in V. cholerae. Previously, we reported that cdgJ encodes a c-di-GMP phosphodiesterase and a ΔcdgJ mutant has reduced motility and enhanced biofilm formation. Here we show that loss of the genes required for the mannose-sensitive hemagglutinin (MshA) pilus biogenesis restores motility in the ΔcdgJ mutant. Mutations of the predicted ATPase proteins mshE or pilT, responsible for polymerizing and depolymerizing MshA pili, impair near surface motility behavior and initial surface attachment dynamics. A ΔcdgJ mutant has enhanced surface attachment, while the ΔcdgJmshA mutant phenocopies the high motility and low attachment phenotypes observed in a ΔmshA strain. Elevated concentrations of c-di-GMP enhance surface MshA pilus production. MshE, but not PilT binds c-di-GMP directly, establishing a mechanism for c-di-GMP signaling input in MshA pilus production. Collectively, our results suggest that the dynamic nature of the MshA pilus established by the assembly and disassembly of pilin subunits is essential for transition from the motile to sessile lifestyle and that c-di-GMP affects MshA pilus assembly and function through direct interactions with the MshE ATPase.
A long-standing paradigm in astrophysics is that collisions- or mergers-of two neutron stars form highly relativistic and collimated outflows (jets) that power Y-ray bursts of short (less than two ...seconds) duration. The observational support for this model, however, is only indirect. A hitherto outstanding prediction is that gravitational-wave events from such mergers should be associated with Y-ray bursts, and that a majority of these bursts should be seen off-axis, that is, they should point away from Earth. Here we report the discovery observations of the X-ray counterpart associated with the gravitational-wave event GW170817. Although the electromagnetic counterpart at optical and infrared frequencies is dominated by the radioactive glow (known as a 'kilonova') from freshly synthesized rapid neutron capture (r-process) material in the merger ejecta, observations at X-ray and, later, radio frequencies are consistent with a short Y-ray burst viewed off-axis. Our detection of X-ray emission at a location coincident with the kilonova transient provides the missing observational link between short Y-ray bursts and gravitational waves from neutron-star mergers, and gives independent confirmation of the collimated nature of the Y-ray-burst emission.
Angiosperm mitochondrial genomes (mtDNA) exhibit variable quantities of alien sequences. Many of these sequences are acquired by intracellular gene transfer (IGT) from the plastid. In addition, ...frequent events of horizontal gene transfer (HGT) between mitochondria of different species also contribute to their expanded genomes. In contrast, alien sequences are rarely found in plastid genomes. Most of the plant-to-plant HGT events involve mitochondrion-to-mitochondrion transfers. Occasionally, foreign sequences in mtDNAs are plastid-derived (MTPT), raising questions about their origin, frequency, and mechanism of transfer. The rising number of complete mtDNAs allowed us to address these questions. We identified 15 new foreign MTPTs, increasing significantly the number of those previously reported. One out of five of the angiosperm species analyzed contained at least one foreign MTPT, suggesting a remarkable frequency of HGT among plants. By analyzing the flanking regions of the foreign MTPTs, we found strong evidence for mt-to-mt transfers in 65% of the cases. We hypothesize that plastid sequences were initially acquired by the native mtDNA via IGT and then transferred to a distantly-related plant via mitochondrial HGT, rather than directly from a foreign plastid to the mitochondrial genome. Finally, we describe three novel putative cases of mitochondrial-derived sequences among angiosperm plastomes.
We report on the hybrid inorganic–organic ammonium compound NH4Cd(HCOO)3, which displays a most unusual framework structure: instead of the expected 49·66 topology, it shows an ABX3 perovskite ...architecture with the peculiarity and uniqueness (among all the up-to-date reported hybrid metal formates) that the Cd ions are connected only by syn–anti formate bridges, instead of anti–anti ones. This change of the coordination mode of the formate ligand is thus another variable that can provide new possibilities for tuning the properties of these versatile functional metal–organic framework materials. The room-temperature crystal structure of NH4Cd(HCOO)3 is noncentrosymmetric (S.G.: Pna21) and displays a polar axis. DFT calculations and symmetry mode analysis show that the rather large polarization arising from the off-center shift of the ammonium cations in the cavities (4.33 μC/cm2) is partially canceled by the antiparallel polarization coming from the Cd(HCOO)3− framework, thus resulting in a net polarization of 1.35 μC/cm2. As shown by second harmonic generation studies, this net polarization can be greatly increased by applying pressure (P max = 14 GPa), an external stimulus that, in turn, induces the appearance of new structural phases, as confirmed by Raman spectroscopy.
PDF
