Remote sensing enables the quantification of tropical deforestation with high spatial resolution. This in-depth mapping has led to substantial advances in the analysis of continent-wide fragmentation ...of tropical forests. Here we identified approximately 130 million forest fragments in three continents that show surprisingly similar power-law size and perimeter distributions as well as fractal dimensions. Power-law distributions have been observed in many natural phenomena such as wildfires, landslides and earthquakes. The principles of percolation theory provide one explanation for the observed patterns, and suggest that forest fragmentation is close to the critical point of percolation; simulation modelling also supports this hypothesis. The observed patterns emerge not only from random deforestation, which can be described by percolation theory, but also from a wide range of deforestation and forest-recovery regimes. Our models predict that additional forest loss will result in a large increase in the total number of forest fragments-at maximum by a factor of 33 over 50 years-as well as a decrease in their size, and that these consequences could be partly mitigated by reforestation and forest protection.
Covering: 2005 to 2020Phenol coupling is a key reaction in the biosynthesis of important biopolymers such as lignin and melanin and of a plethora of biarylic secondary metabolites. The reaction ...usually leads to several different regioisomeric products due to the delocalization of a radical in the reaction intermediates. If axial chirality is involved, stereoisomeric products are obtained provided no external factor influences the selectivity. Hence, in non-enzymatic organic synthesis it is notoriously difficult to control the selectivity of the reaction, in particular if the coupling is intermolecular. From biosynthesis, it is known that especially fungi, plants, and bacteria produce biarylic compounds regio- and stereoselectively. Nonetheless, the involved enzymes long evaded discovery. First progress was made in the late 1990s; however, the breakthrough came only with the genomic era and, in particular, in the last few years the number of relevant publications has dramatically increased. The discoveries reviewed in this article reveal a remarkable diversity of enzymes that catalyze oxidative intermolecular phenol coupling, including various classes of laccases, cytochrome P450 enzymes, and heme peroxidases. Particularly in the case of laccases, the catalytic systems are often complex and additional proteins, substrates, or reaction conditions have a strong influence on activity and regio- and atroposelectivity. Although the field of (selective) enzymatic phenol coupling is still in its infancy, the diversity of enzymes identified recently could make it easier to select suitable candidates for biotechnological development and to approach this challenging reaction through biocatalysis.
Some of the recent developments in enzymatic asymmetric CC bond formation are described in this review. The close relationship of biocatalysis and biosynthesis is highlighted with a special emphasis ...on diversity and biogenesis. One focus of this review is the creation of tetrasubstituted carbon stereocenters. Members of the supposedly well‐known aldolase and hydroxynitrile lyase enzyme families possess the ability to catalyze the formation of tertiary alcohols. In the case of aldolases, this can occur through intramolecular cyclization or intermolecular asymmetric CC bond formation. Thiamine diphosphate‐dependent YerE has been identified as a potent catalyst for the acyloin condensation with ketones as acceptor substrates. C1 transformations such as methylation or carboxylation are catalyzed in an asymmetric manner by enzymes from different classes, for example S‐adenosylmethionine‐dependent (radical) enzymes or NADPH‐dependent oxidoreductases. Insights from biosynthetic and mechanistic studies of enzymatic reactions proceeding via radical intermediates give valuable hints towards possible applications in biocatalysis. Still, the oxygen sensitivity of many of these biocatalysts poses a considerable challenge for practical applications.
The application of mineral phosphate (P) fertilizers leads to an unintended Cd input into agricultural systems, which might affect soil fertility and quality of crops. The Cd fluxes at three arable ...sites in Switzerland were determined by a detailed analysis of all inputs (atmospheric deposition, mineral P fertilizers, manure, and weathering) and outputs (seepage water, wheat and barley harvest) during one hydrological year. The most important inputs were mineral P fertilizers (0.49 to 0.57 g Cd ha–1 yr–1) and manure (0.20 to 0.91 g Cd ha–1 yr–1). Mass balances revealed net Cd losses for cultivation of wheat (−0.01 to −0.49 g Cd ha–1 yr–1) but net accumulations for that of barley (+0.18 to +0.71 g Cd ha–1 yr–1). To trace Cd sources and redistribution processes in the soils, we used natural variations in the Cd stable isotope compositions. Cadmium in seepage water (δ114/110Cd = 0.39 to 0.79‰) and plant harvest (0.27 to 0.94‰) was isotopically heavier than in soil (−0.21 to 0.14‰). Consequently, parent material weathering shifted bulk soil isotope compositions to lighter signals following a Rayleigh fractionation process (ε ≈ 0.16). Furthermore, soil-plant cycling extracted isotopically heavy Cd from the subsoil and moved it to the topsoil. These long-term processes and not anthropogenic inputs determined the Cd distribution in our soils.
Natural biaryls typically occur as one regio- and atropisomeric variant in a given organism. Here, we report on the identification of biosynthetic genes of aurasperone- and bifonsecin-type biaryls in ...several Aspergillus species. The genes of the tailoring enzymes form a gene cluster that is separate from the polyketide synthase gene. Dimerization of naphthopyrone monomers is catalyzed by members of an undescribed subfamily of cytochrome P450 enzymes. The stereoselectivity of these enzymes is influenced by the two natural monomeric substrates; homodimerization of one monomer yields a stereochemically pure biaryl, while the other monomer yields a mixture of enantiomers.
Abstract
WormBase (www.wormbase.org) is the central repository for the genetics and genomics of the nematode Caenorhabditis elegans. We provide the research community with data and tools to ...facilitate the use of C. elegans and related nematodes as model organisms for studying human health, development, and many aspects of fundamental biology. Throughout our 22-year history, we have continued to evolve to reflect progress and innovation in the science and technologies involved in the study of C. elegans. We strive to incorporate new data types and richer data sets, and to provide integrated displays and services that avail the knowledge generated by the published nematode genetics literature. Here, we provide a broad overview of the current state of WormBase in terms of data type, curation workflows, analysis, and tools, including exciting new advances for analysis of single-cell data, text mining and visualization, and the new community collaboration forum. Concurrently, we continue the integration and harmonization of infrastructure, processes, and tools with the Alliance of Genome Resources, of which WormBase is a founding member.
We documented the adjunctive bacteriophage therapy to treat a chronic relapsing periprosthetic joint infection of the knee and chronic osteomyelitis of the femur caused by multidrug-resistant
The ...combined antibiotic-phage treatment eradicated the infection, and no side effects to phages were observed.
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