Changing Ecological Conditions in the Marine Environment Generate Different Microbial Food Web Structures in a Repeatable Manner

The mechanisms responsible for the development of various structural and functional features of the microbial food web (MFW) and their dynamics at spatial and temporal scales, which are important for predicting their responses to future environmental changes, are largely unknown. More than 3000 datasets of environmental and microbial variables collected over a decade on a seasonal and large spatial scale in the Adriatic Sea were analyzed. The sets of environmental variables were classified into four clusters (representing different environmental states) using Neural Gas analysis and the differences in MFW structure between the clusters were analyzed. Different variants of MFW evolve in the different clusters in terms of the abundance of MFW components, their ratios, growth and grazing rates, predator preference in prey selection, the strength of predator-prey interaction, and the relative importance of top-down and bottom-up control. However, these clusters are neither spatially nor temporally fixed; rather, the area studied represents a mosaic of different environmental conditions that alternate from one state to another on a time scale. In each of the environmental states, a distinct structure of MFW develops that shows consistent and repeatable changes that strictly follow the switching in environmental conditions from one state to another.

Apramycin overcomes the inherent lack of antimicrobial bactericidal activity in Mycobacterium abscessus

Antibiotic therapy of infections caused by the emerging pathogen Mycobacterium abscessus is challenging due to the organism’s inherent resistance towards clinically available antimicrobials. The low bactericidal potency of currently available treatment regimens is of concern and testifies to the poor therapeutic outcome in pulmonary M. abscessus infections. Mechanistically, we here demonstrate that the acetyltransferase Eis2 is responsible for the lack of bactericidal activity of amikacin, the standard aminoglycoside used in combination treatment. In contrast, the distinct structure aminoglycoside apramycin is not modified by any of the pathogen’s innate aminoglycoside resistance mechanisms nor is it affected by the multi-drug resistance regulator WhiB7. As a consequence, apramycin uniquely shows potent bactericidal activity against M. abscessus . This favourable feature of apramycin is reflected in a mouse model of M. abscessus lung infection, which demonstrates superior activity over amikacin. These findings encourage the development of apramycin for the treatment of M. abscessus infections and suggest that M. abscessus eradication in lung pulmonary disease may be within therapeutic reach.

Analytical Solution of Stress in a Transversely Isotropic Floor Rock Mass under Distributed Loading in an Arbitrary Direction

Rock masses with a distinct structure may present a transversely isotropic character; thus, the stress state in a transversely isotropic elastic half-plane surface is an important way to assess the behavior of the interaction between the distributed loading and the surroundings. Most previous theoretical analyses have considered a loading direction that is either vertical or horizontal, and the stress distribution that results from the effect of different loading directions remains unclear. In this paper, based on the transversely isotropic elastic half-plane surface theory, a stress solution that is applicable to distributed loading in any direction is proposed to further examine the loading effect. The consistency between the analytical solution and numerical simulations showed the effectiveness of the proposal that was introduced. Then, it was utilized to analyze the stress distribution rule by changing the Poisson’s ratio and Young’s modulus of the model. The effects of the formation dip angle on the stress state are also examined. The stress distribution, depending on the physical property parameters and relative angle, is predicted using an analytical solution, and the mechanisms associated with the transversely isotropic elastic half-plane surface subjected to the loading in any direction are clarified. Additionally, extensive analyses regarding this case study, with respect to the mechanical behavior associated with changes in the stress boundary, is available. Hence, the proposed analytical solution can more realistically account for the loading problem in many engineering practices.

Origin and Function of Structural Diversity in the Plant Specialized Metabolome

The plant specialized metabolome consists of a multitude of structurally and functionally diverse metabolites, variable from species to species. The specialized metabolites play roles in the response to environmental changes and abiotic or biotic stresses, as well as in plant growth and development. At its basis, the specialized metabolism is built of four major pathways, each starting from a few distinct primary metabolism precursors, and leading to distinct basic carbon skeleton core structures: polyketides and fatty acid derivatives, terpenoids, alkaloids, and phenolics. Structural diversity in specialized metabolism, however, expands exponentially with each subsequent modification. We review here the major sources of structural variety and question if a specific role can be attributed to each distinct structure. We focus on the influences that various core structures and modifications have on flavonoid antioxidant activity and on the diversity generated by oxidative coupling reactions. We suggest that many oxidative coupling products, triggered by initial radical scavenging, may not have a function in se, but could potentially be enzymatically recycled to effective antioxidants. We further discuss the wide structural variety created by multiple decorations (glycosylations, acylations, prenylations), the formation of high-molecular weight conjugates and polyesters, and the plasticity of the specialized metabolism. We draw attention to the need for untargeted methods to identify the complex, multiply decorated and conjugated compounds, in order to study the functioning of the plant specialized metabolome.

The hereditary mutation G51D unlocks a distinct fibril strain transmissible to wild-type α-synuclein

Abstractα-Synuclein (α-Syn) can form different fibril strains with distinct polymorphs and neuropathologies, which is associated with the clinicopathological variability in synucleinopathies. How different α-syn fibril strains are produced and selected under disease conditions remains poorly understood. In this study, we show that the hereditary mutation G51D induces α-syn to form a distinct fibril strain in vitro. The cryogenic electron microscopy (cryo-EM) structure of the G51D fibril strain was determined at 2.96 Å resolution. The G51D fibril displays a relatively small and extended serpentine fold distinct from other α-syn fibril structures. Moreover, we show by cryo-EM that wild-type (WT) α-syn can assembly into the G51D fibril strain via cross-seeding with G51D fibrils. Our study reveals a distinct structure of G51D fibril strain triggered by G51D mutation but feasibly adopted by both WT and G51D α-syn, which suggests the cross-seeding and strain selection of WT and mutant α-syn in familial Parkinson’s disease (fPD).

Increasing Buffering Capacity Enhances Rumen Fermentation Characteristics and Alters Rumen Microbiota Composition of High-Concentrate Fed Hanwoo Steers

This study determined the buffering capacity of buffer agents and its effect on in vitro and in vivo rumen fermentation characteristics and bacterial composition of a high-concentrate fed Hanwoo steers. Both BC0.9% and BC0.5% had significantly highest buffering capacity, pH, and ammonia-nitrogen (NH3-N) than BC0.3% and CON at 24 h incubation. Individual and total volatile fatty acids (VFA) were significantly lowest in CON. Phylum Bacteroidetes dominated all treatments but a higher abundance of Firmicutes in BC0.5% than others. Ruminoccocus bromii and Succiniclasticum ruminis were dominant in BC0.5% and Bacteroides massiliensis in BC0.3%. The normalized data of relative abundance of observed OTUs’ representative families have grouped the CON with BC0.3% in the same cluster, whereas BC0.5% and BC0.9% were clustered separately which indicates the effect of varying buffering capacity of buffer agents. Principal coordinate analysis (PCoA) on unweighted UniFrac distances revealed close similarity of bacterial community structures within and between treatments and control, in which BC0.9% and BC0.3% groups showed dispersed community distribution. Overall, the increasing buffering capacity enhances rumen fermentation parameters and affects rumen microbiome by altering bacterial community through distinct structure between high and low buffering capacity, thus an important factor to prevent ruminal acidosis during a high-concentrate diet.

Ab initio thermodynamics reveals the nanocomposite structure of ferrihydrite

Ferrihydrite is a poorly crystalline iron oxyhydroxide nanomineral that serves a critical role as the most bioavailable form of ferric iron for living systems. However, its atomic structure and composition remain unclear due in part to ambiguities in interpretation of X-ray scattering results. Prevailing models so far have not considered the prospect that at the level of individual nanoparticles multiple X-ray indistinguishable phases could coexist. Using ab initio thermodynamics we show that ferrihydrite is likely a nanocomposite of distinct structure types whose distribution depends on particle size, temperature, and hydration. Nanoparticles of two contrasting single-phase ferrihydrite models of Michel and Manceau are here shown to be thermodynamically equivalent across a wide range of temperature and pressure conditions despite differences in their structural water content. Higher temperature and water pressure favor the formation of the former, while lower temperature and water pressure favor the latter. For aqueous suspensions at ambient conditions, their coexistence is maximal for particle sizes up to 12 nm. The predictions inform and help resolve different observations in various experiments.

Highly Stretchable Fully Biomass Autonomic Self-Healing Polyamide Elastomers and Their Foam for Selective Oil Absorption

Renewable polymers with self-healing ability, excellent elongation, hydrophobicity, and selective oil absorption attributes are of interest for an extensive range of applications, such as e-skin, soft robots, wearable devices, and cleaning up oil spills. Herein, two fully renewable eco-friendly polyamide (PA)-based self-healing elastomers (namely, PA36,IA, and PA36,36) were prepared by a facile and green one-pot melt polycondensation of itaconic acid (IA), PripolTM 1009, and PriamineTM 1075 monomers. The molecular structures of these PAs were analyzed by FITR, 1H NMR, and 13C NMR. The distinct structure of these PAs shows superior strain values (above 2300%) and high ambient temperature autonomous self-healing ability. Interestingly, the synthesized renewable PA36,36 showed zero water absorption values and hydrophobic properties with a contact angle of θ = 91o compared to the synthesized PA36,IA and other previously reported PAs. These excellent attributes are due to the low concentration of amide groups, the highly entangled main chains, the intermolecular diffusion, the manifold dangling chains, and the numerous reversible physical bonds within the renewable PAs. Furthermore, the hydrophobic properties may aid in the selective oil absorption of the PA36,36-based foam, for which PA36,36 foam is produced by the green supercritical carbon dioxide (scCO2) batch foaming process. The PA36,36 foam with a microporous cellular structure showed better absorption capacity and high stability in repeated use. Due to these advantages, these bio-based PAs have potential for the production of eco-friendly self-healing materials, superabsorbent foams, and other polymeric materials.

Settler Colonial Structures of Domestication: British Home Children in Canada

There has been a surge of research on Home Children in the past several decades, as the phenomenon previously unknown to many came into the spotlight. However, much of the historical research has focused on either the psychological and physical impacts on the children at the hands of their new “families” (there were many reports of child abuse and neglect) or the ways they were saved from their poverty in Britain by being sent to the colonies. This article will put this existing historical research into conversation with theories of settler colonialism, considering Home Children as a tool of domestication for the social reproduction of Canadian white settler society, which was paired with the forced removal of Indigenous peoples from their lands. This analysis stems from and is intertwined with personal reflections on my own family history as a white settler woman descending from a Home Child to explore the gendered labour of social reproduction as a crucial pillar in creating and maintaining settler colonial Canada. Following Lorenzo Veracini’s argument that settler colonialism is a distinct structure that uses domestication as one of its key tenets and relies on its “regenerative capacity”, this paper will explore how British Home Children were a key component of settler colonialism in Canada and how this history has manifested in the current gendered, racialized, and classed politics of “settling”.

Diversified Crop Rotation: An Approach for Sustainable Agriculture Production

Diversified crop rotation (DCR) improves the efficiency of farming systems all over the world. It has the potentiality to improve soil condition and boost system productivity. Improved soil attributes such as increased soil water uptake and storage, and a greater number of beneficial soil organisms, may improve yield tolerance to drought and other hard growing conditions in a variety of crop rotations. Crop rotations with a variety of crops benefit the farmers,reduce production risk and uncertainty, and enhance soil and ecological sustainability. Farmers may be able to diversify their sources of income by adopting diversified crop rotations. Furthermore, because of the distinct structure, function, and relationship of plant community with soil in DCR, it contributes to the long-term development of soil health by decreasing insect, weed, and disease incidence and increasing the physical and chemical structure of the soil. DCR is becoming more popular approach for maintaining sustainable crop production. This review provides the evidence of the significance of DCR, challenges to adapt it, and possible way out to overcome the challenges.