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The factors shaping host–parasite interactions and epibiont communities in the variable rocky intertidal zone are poorly understood. California mussels, Mytilus californianus , are colonized by endolithic cyanobacterial parasites that erode the host shell. These cyanobacteria become mutualistic under certain abiotic conditions because shell erosion can protect mussels from thermal stress. How parasitic shell erosion affects or is affected by epibiotic microbial communities on mussel shells and the context dependency of these interactions is unknown. We used transplant experiments to characterize assemblages of epibiotic bacteria and endolithic parasites on mussel shells across intertidal elevation gradients. We hypothesized that living mussels, and associated epibacterial communities, could limit colonization and erosion by endolithic cyanobacteria compared with empty mussel shells. We hypothesized that shell erosion would be associated with compositional shifts in the epibacterial community and tidal elevation. We found that living mussels experienced less shell erosion than empty shells, demonstrating potential biotic regulation of endolithic parasites. Increased shell erosion was not associated with a distinct epibacterial community and was decoupled from the relative abundance of putatively endolithic taxa. Our findings suggest that epibacterial community structure is not directly impacted by the dynamic symbiosis between endolithic cyanobacteria and mussels throughout the rocky intertidal zone. [ABSTRACT FROM AUTHOR]

Incarcerated pregnant people face significant barriers when seeking health care services in prisons and jails, but little is known about their transitions from state prison health care systems to outside hospitals. This project analyzed current policies and procedures for care transitions for incarcerated people and presents policy recommendations to address issues of concern. We conducted in-depth interviews with stakeholders at a state prison, academic hospital, and private hospital to identify the barriers and facilitators to care transitions. Themes emerging from these interviews were operational, including medical records, communication, and education; and structural, including implicit biases and care of marginalized groups. These findings are likely applicable to similar facilities throughout the United States. A multipronged, interdisciplinary approach is needed to address challenges of care transitions. [ABSTRACT FROM AUTHOR]

Kelp are important primary producers that are colonized by diverse microbes that can have both positive and negative effects on their hosts. The kelp microbiome could support the burgeoning kelp cultivation sector by improving host growth, stress tolerance, and resistance to disease. Fundamental questions about the cultivated kelp microbiome still need to be addressed before microbiome‐based approaches can be developed. A critical knowledge gap is how cultivated kelp microbiomes change as hosts grow, particularly following outplanting to sites that vary in abiotic conditions and microbial source pools. In this study we assessed if microbes that colonize kelp in the nursery stage persist after outplanting. We characterized microbiome succession over time on two species of kelp, Alaria marginata and Saccharina latissima, outplanted to open ocean cultivation sites in multiple geographic locations. We tested for host‐species specificity of the microbiome and the effect of different abiotic conditions and microbial source pools on kelp microbiome stability during the cultivation process. We found the microbiome of kelp in the nursery is distinct from that of outplanted kelp. Few bacteria persisted on kelp following outplanting. Instead, we identified significant microbiome differences correlated with host species and microbial source pools at each cultivation site. Microbiome variation related to sampling month also indicates that seasonality in host and/or abiotic factors may influence temporal succession and microbiome turnover in cultivated kelps. This study provides a baseline understanding of microbiome dynamics during kelp cultivation and highlights research needs for applying microbiome manipulation to kelp cultivation. [ABSTRACT FROM AUTHOR]

Seaweed‐associated microbiota are essential for the health and resilience of nearshore ecosystems, marine biogeochemical cycling, and host health. Yet much remains unknown about the ecology of seaweed–microbe symbioses. In this study, we quantified fine‐scale patterns of microbial community structure across distinct anatomical regions of the kelp Laminaria setchellii. These anatomical regions represent a gradient of tissue ages: perennial holdfasts can be several years old, whereas stipe epicortex and blades are younger annual structures. Within blades, new growth occurs at the base, while the blade tips may be several months old and undergoing senescence. We hypothesized that microbial communities will differ across anatomical regions (holdfast, stipe, blade base, and blade tip), such that younger tissues will harbor fewer microbes that are more consistent across replicate individuals. Our data support this hypothesis, with the composition of bacterial (16S rRNA gene) and microeukaryote (18S rRNA gene) communities showing significant differences across the four anatomical regions, with the surfaces of older tissues (holdfast and blade tips) harboring significantly greater microbial richness compared to the younger tissues of the meristematic region. Additional samples collected from the surfaces of new L. setchellii recruits (<1y old) also showed differences in microbial community structure across anatomical regions, which demonstrates that these microbial differences are established early. We also observed this pattern in two additional algal species, suggesting that microbial community structure across host anatomy may be a common feature of the seaweed microbiome. [ABSTRACT FROM AUTHOR]

Seaweed‐associated microbiota are essential for the health and resilience of nearshore ecosystems, marine biogeochemical cycling, and host health. Yet much remains unknown about the ecology of seaweed–microbe symbioses. In this study, we quantified fine‐scale patterns of microbial community structure across distinct anatomical regions of the kelp Laminaria setchellii. These anatomical regions represent a gradient of tissue ages: perennial holdfasts can be several years old, whereas stipe epicortex and blades are younger annual structures. Within blades, new growth occurs at the base, while the blade tips may be several months old and undergoing senescence. We hypothesized that microbial communities will differ across anatomical regions (holdfast, stipe, blade base, and blade tip), such that younger tissues will harbor fewer microbes that are more consistent across replicate individuals. Our data support this hypothesis, with the composition of bacterial (16S rRNA gene) and microeukaryote (18S rRNA gene) communities showing significant differences across the four anatomical regions, with the surfaces of older tissues (holdfast and blade tips) harboring significantly greater microbial richness compared to the younger tissues of the meristematic region. Additional samples collected from the surfaces of new L. setchellii recruits (<1y old) also showed differences in microbial community structure across anatomical regions, which demonstrates that these microbial differences are established early. We also observed this pattern in two additional algal species, suggesting that microbial community structure across host anatomy may be a common feature of the seaweed microbiome. [ABSTRACT FROM AUTHOR]

Summary: It is unclear how host‐associated microbial communities will be affected by future environmental change. Characterizing how microbiota differ across sites with varying environmental conditions and assessing the stability of the microbiota in response to abiotic variation are critical steps towards predicting outcomes of environmental change. Intertidal organisms are valuable study systems because they experience extreme variation in environmental conditions on tractable timescales such as tide cycles and across small spatial gradients in the intertidal zone. Here we show a widespread intertidal macroalgae, Fucus distichus, hosts site‐specific microbiota over small (meters to kilometres) spatial scales. We demonstrate stability of site‐specific microbial associations by manipulating the host environment and microbial species pool with common garden and reciprocal transplant experiments. We hypothesized that F. distichus microbiota would readily shift to reflect the contemporary environment due to selective filtering by abiotic conditions and/or colonization by microbes from the new environment or nearby hosts. Instead, F. distichus microbiota was stable for days after transplantation in both the laboratory and field. Our findings expand the current understanding of microbiota dynamics on an intertidal foundation species. These results may also point to adaptations for withstanding short‐term environmental variation, in hosts and/or microbes, facilitating stable host–microbial associations. [ABSTRACT FROM AUTHOR]

Dietary fibers are potent modulators of immune responses that can restrain inflammation in multiple disease contexts. However, dietary fibers encompass a biochemically diverse family of carbohydrates, and it remains unknown how individual fiber sources influence immunity. In a direct comparison of four different high-fiber diets, we demonstrate a potent ability of guar gum to delay disease and neuroinflammation in experimental autoimmune encephalomyelitis, a T cell-mediated mouse model of multiple sclerosis. Guar gum-specific alterations to the microbiota are limited, and disease protection appears to be independent of fiber-induced increases in short-chain fatty acid levels or regulatory CD4+ T cells. Instead, CD4+ T cells of guar gum-supplemented mice are less encephalitogenic due to reduced activation, proliferation, Th1 differentiation, and altered migratory potential. These findings reveal specificity in the host response to fiber sources and define a pathway of fiber-induced immunomodulation that protects against pathologic neuroinflammation. [Display omitted] • Individual dietary fiber sources have distinct impacts on T cell subsets • The dietary fiber guar gum impairs Th1 polarization and alters migratory potential • Guar gum elevates short-chain fatty acids but does not impact regulatory T cells • Guar gum supplementation significantly delays autoimmune neuroinflammation Fettig et al. provide evidence that a specific dietary fiber, guar gum, can delay onset of MS-like symptoms in mice via impaired Th1 polarization and CD4+ T cell recruitment to the central nervous system. [ABSTRACT FROM AUTHOR]

In the excitement of the wake of the United States Supreme Court's 2013 Kiobel v. Royal Dutch Petroleum Co. decision, one less-addressed matter is the unresolved status of customary international law in American courts. This Comment highlights a lack of literature engaging comparative study of federally structured nations ' experiences implementing customary international law within their state and federal courts, and proposes that such a study may aid in resolving the American dilemma. This Comment studies Australian and Indian experiences, then uses the findings to look back toward the American experience for possible solutions for the status of customary international law. While not endeavoring to resolve the entire issue of customary international law status, this Comment finds three helpful implications in the comparative study. Two are meta principles, and one is a concrete canon suggestion that would diffuse a subset of problem areas for customary international law implementation in American courts. First, the American solution need not be as extreme as American theorists argue, given that multiple other federal nations successfully engage and implement customary international law within state and federal courts alike without resorting to such absolute strategies. Second, demonstrating that multiple other federal nations have similar reservations toward any sweeping implementation of customary international law, popular condemnations of America's isolationism and exceptionalism from customary international law should be more tightly correlated to a benign and unavoidable function of federalism than to a malicious and uniquely American elitism. Finally, borrowing from an Indian state court decision, this Comment proposes a customary international law equivalent of a Charming Betsy canon for interpreting municipal, state and federal laws. Under such a canon, when there exist multiple possible constructions of a municipal, state, or federal law, the construction conforming to customary international law would be used. Ultimately, this Comment finds that a look outside American borders for resolution of domestic customary international law status provides a fresh perspective to re-focus the standing polarized discourse. [ABSTRACT FROM AUTHOR]

It is well-known that biologicalsamples undergo X-ray-induceddegradation. One of the fastest occurring X-ray-induced processesinvolves redox modifications (reduction or oxidation) of redox-activecofactors in proteins. Here we analyze room-temperature data on thephotoreduction of Mn ions in the oxygen-evolving complex (OEC) ofphotosystem II, one of the most radiation damage-sensitive proteinsand a key constituent of natural photosynthesis in plants, green algae,and cyanobacteria. Time-resolved X-ray emission spectroscopy withwavelength-dispersive detection was used to collect data on the progressionof X-ray-induced damage. A kinetic model was developed to fit experimentalresults, and the rate constant for the reduction of OEC MnIIIand MnIVions by solvated electrons was determined. Fromthis model, the possible kinetics of X-ray-induced damage at a varietyof experimental conditions, such as different rates of dose depositionas well as different excitation wavelengths, can be inferred. We observeda trend of increasing dosage threshold prior to the onset of X-ray-induceddamage with increasing rates of dose deposition. This trend suggeststhat experimentation with higher rates of dose deposition is beneficialfor measurements of biological samples sensitive to radiation damage,particularly at pink beam and X-ray free electron laser sources. [ABSTRACT FROM AUTHOR]

Enzymes are biological catalysts whose dynamics enable their reactivity. Visualizing conformational changes, in particular, is technically challenging, and little is known about these crucial atomic motions. This is especially problematic for understanding the functional diversity associated with the radical S-adenosyl-L-methionine (SAM) superfamily whose members share a common radical mechanism but ultimately catalyze a broad range of challenging reactions. Computational chemistry approaches provide a readily accessible alternative to exploring the time-resolved behavior of these enzymes that is not limited by experimental logistics. Here, we review the application of molecular docking, molecular dynamics, and density functional theory, as well as hybrid quantum mechanics/molecular mechanics methods to the study of these enzymes, with a focus on understanding the mechanistic dynamics associated with turnover. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented which discusses various articles within the issues on topics including the Transatlantic Trade and Investment Partnership, the significance of international criminal courts, and the food scarcity issues focused on the right to international migration.

Reviewed: The American Avant-Garde Tradition: William Carlos Williams, Postmodern Poetry, and the Politics of Cultural Memory. Lowney, John.

There is a growing recognition of the roles of marine microenvironments as reservoirs of biodiversity and as sites of enhanced biological activity and in facilitating biological interactions. Here, we examine the bacterial community inhabiting free-living and particle-associated seawater microenvironments at the Pivers Island Coastal Observatory (PICO). 16S rRNA gene libraries from monthly samples (July 2013 to August 2014) were used to identify microbes in seawater in four size fractions: >63 μm (zooplankton and large particles), 63 to 5 μm(particles), 5 to 1 μm(small particles/dividing cells), and <1 μm(free-living prokaryotes). Analyses of microbial community composition highlight the importance of the microhabitat (e.g., particle-associated versus free-living lifestyle) as communities cluster by size fraction, and the microhabitat explains more of the community variability than measured environmental parameters, including pH, particle concentration, projected daily insolation, nutrients, and temperature. While temperature is statistically associated with community changes in the <1-μmand 5- to 1-μmfractions, none of the measured bulk seawater environmental variables are statistically significant in the larger-particle-associated fractions. These results, combined with high particle-associated community variability, especially in the largest size fraction (i.e., >63 μm), suggest that particle composition, including eukaryotes and their associated microbiomes, may be an important factor in selecting for specific particle-associated bacteria. [ABSTRACT FROM AUTHOR]

In aquatic foundation species, composition and abundance of associated epibionts can change substantially over small spatial distances. Such spatial variation can reflect top-down control by consumers, bottom-up control by abiotic factors or facilitation, or a combination of processes. We used visual and molecular surveys to describe spatial patterns in the abundance and distribution of the epiphytic red macroalga Smithora naiadum in a meadow of the seagrass Zostera marina on the Central Coast of British Columbia. We detected Smithora using 18 S ribosomal RNA molecular marker throughout the seagrass meadow at both interior and edge sites, even in the absence of macroscopic Smithora. We used a reciprocal transplant experiment to test two hypotheses: that patterns in Smithora abundance reflect local environmental conditions, or alternately, that patterns reflect spatial variation in the host plant attributes, microbiota and grazers. Zostera shoots hosted more Smithora at meadow edges relative to meadow interior sites, and shoots with Smithora were associated with distinct invertebrate grazer and bacterial communities relative to shoots 5 m in from the meadow edge without Smithora. Macroscopic Smithora grew on shoots experimentally transplanted from the interior to the meadow edge and shoots hosting Smithora that were transplanted to the interior did not lose Smithora. Our survey and experimental results suggest that presence of macroscopic Smithora blades on Zostera shoots changes the Zostera microbiota. Altogether, we conclude that environmental variation, not host plant attributes or dispersal limitation, affects Smithora colonization on Zostera , and once established, Smithora alters the microbiota on Zostera. [Display omitted] • The seagrass Zostera marina hosts microbial, algal and animal biodiversity. • Smithora is a red algae that grows on Zostera, potentially competing for light. • Smithora is very abundant on some seagrass shoots and absent on others. • Abundant at seagrass meadow edges, Smithora persists when moved to meadow interior. • Smithora presence appears to influence seagrass associated bacterial assemblages. [ABSTRACT FROM AUTHOR]

Burkholderia thailandensis has emerged as a nonpathogenic surrogate for Burkholderia pseudomallei , the causative agent of melioidosis, and an important Gram-negative model bacterium for studying the biosynthesis and regulation of secondary metabolism. We recently reported that subinhibitory concentrations of trimethoprim induce vast changes in both the primary and secondary metabolome of B. thailandensis . In the current work, we show that the folate biosynthetic enzyme FolE2 is permissive under standard growth conditions but essential for B. thailandensis in the presence of subinhibitory doses of trimethoprim. Reasoning that FolE2 may serve as an attractive drug target, we screened for and identified ten inhibitors, including dehydrocostus lactone (DHL), parthenolide, and β-lapachone, all of which are innocuous individually but form a chemical-synthetic lethal combination with subinhibitory doses of trimethoprim. We show that DHL is a mechanism-based inhibitor of FolE2 and capture the structure of the covalently inhibited enzyme using X-ray crystallography. In vitro, the combination of subinhibitory trimethoprim and DHL is more potent than Bactrim, the current standard of care against melioidosis. Moreover, unlike Bactrim, this combination does not affect the growth of most commensal and beneficial gut bacteria tested, thereby providing a degree of specificity against B. pseudomallei . Our work provides a path for identifying antimicrobial drug targets and for utilizing binary combinations of molecules that form a toxic cocktail based on metabolic idiosyncrasies of specific pathogens., Competing Interests: Competing interests statement:M.R.S. is a consultant to Merck Co, which had no role in this study. M.R.S. is a co-founder of Cryptyx Bioscience, Inc, which had no role in this study. Some of the authors have filed a patent application related to the research reported in this article.

Background: The most significant treatment complication for patients with hemophilia A is the development of neutralizing immunoglobin G (IgG), termed inhibitors, against factor VIII (FVIII) which prevent FVIII replacement therapy. Low titers of FVIII-specific immunoglobin M (IgM) have been identified in hemophilia A patients with and without inhibitors, as well as healthy individuals. However, the duration and influence of IgM on the immune response to FVIII remains unclear., Objective: To characterize the binding interactions of persistently secreted FVIII-specific IgM in hemophilia A mice and assess their effect on IgG antibody development., Methods: Splenic-derived monoclonal antibodies (MAbs) from immunized FVIII knockout mice were isolated and purified using hybridoma technology. Binding interactions were assessed utilizing a novel fluid-phase ELISA and computational modeling with HADDOCK to account for weak IgM binding., Results: Sixteen porcine cross-reactive and non-inhibitory FVIII-specific IgM MAbs were identified. RNA sequencing of FVIII-specific IgM revealed 13 unique VDJ/VJ sequences indicating derivation from 13 unique B cell clones. IgM demonstrated polyclonal and polyreactive binding to FVIII in vitro and in silico. Molecular docking studies with reconstructed IgM VDJ/VJ regions identified frequent IgM interactions with amino acid residues K376, T381, K437, R2215 or K2249 within the FVIII A2 and C2 domains. Injections of individual IgM prior to FVIII exposure and co-injection of FVIII/IgM immune complexes did not affect de novo FVIII antibody production., Conclusion: Persistent FVIII-specific IgM are polyclonal but preferentially bind the A2 and C2 domains and FVIII/IgM immune complex formation do not significantly alter inhibitor development., (Copyright © 2024. Published by Elsevier Inc.)

Hydroxyalkylquinolines (HAQs) are ubiquitious natural products but their interactions with associated protein targets remain elusive. We report X-ray crystal structures of two HAQs in complex with dihydroorotate dehydrogenase (DHODH). Our results reveal the structural basis of DHODH inhibition by HAQs and open the door to downstream structure-activity relationship studies., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Seaweed-associated microbiota are essential for the health and resilience of nearshore ecosystems, marine biogeochemical cycling, and host health. Yet much remains unknown about the ecology of seaweed-microbe symbioses. In this study, we quantified fine-scale patterns of microbial community structure across distinct anatomical regions of the kelp Laminaria setchellii. These anatomical regions represent a gradient of tissue ages: perennial holdfasts can be several years old, whereas stipe epicortex and blades are younger annual structures. Within blades, new growth occurs at the base, while the blade tips may be several months old and undergoing senescence. We hypothesized that microbial communities will differ across anatomical regions (holdfast, stipe, blade base, and blade tip), such that younger tissues will harbor fewer microbes that are more consistent across replicate individuals. Our data support this hypothesis, with the composition of bacterial (16S rRNA gene) and microeukaryote (18S rRNA gene) communities showing significant differences across the four anatomical regions, with the surfaces of older tissues (holdfast and blade tips) harboring significantly greater microbial richness compared to the younger tissues of the meristematic region. Additional samples collected from the surfaces of new L. setchellii recruits (<1y old) also showed differences in microbial community structure across anatomical regions, which demonstrates that these microbial differences are established early. We also observed this pattern in two additional algal species, suggesting that microbial community structure across host anatomy may be a common feature of the seaweed microbiome., (© 2021 Phycological Society of America.)

Host-associated microbiota composition can be conserved over evolutionary time scales. Indeed, closely related species often host similar microbiota; i.e., the composition of their microbiota harbors a phylogenetic signal, a pattern sometimes referred to as "phylosymbiosis." Elucidating the origins of this pattern is important to better understand microbiota ecology and evolution. However, this is hampered by our lack of theoretical expectations and a comprehensive overview of phylosymbiosis prevalence in nature. Here, we use simulations to provide a simple expectation for when we should expect this pattern to occur and then review the literature to document the prevalence and strength of phylosymbiosis across the host tree of life. We demonstrate that phylosymbiosis can readily emerge from a simple ecological filtering process, whereby a given host trait (e.g., gut pH) that varies with host phylogeny (i.e., harbors a phylogenetic signal) filters preadapted microbes. We found marked differences between methods used to detect phylosymbiosis, so we proposed a series of practical recommendations based on using multiple best-performing approaches. Importantly, we found that, while the prevalence of phylosymbiosis is mixed in nature, it appears to be stronger for microbiotas living in internal host compartments (e.g., the gut) than those living in external compartments (e.g., the rhizosphere). We show that phylosymbiosis can theoretically emerge without any intimate, long-term coevolutionary mechanisms and that most phylosymbiosis patterns observed in nature are compatible with a simple ecological process. Deviations from baseline ecological expectations might be used to further explore more complex hypotheses, such as codiversification. IMPORTANCE Phylosymbiosis is a pattern defined as the tendency of closely related species to host microbiota whose compositions resemble each other more than host species drawn at random from the same tree. Understanding the mechanisms behind phylosymbiosis is important because it can shed light on rules governing the assembly of host-associated microbiotas and, potentially, their coevolutionary dynamics with hosts. For example, is phylosymbiosis a result of coevolution, or can it be generated by simple ecological filtering processes? Beyond qualitative theoretical models, quantitative theoretical expectations can provide new insights. For example, deviations from a simple baseline of ecological filtering may be used to test more-complex hypotheses (e.g., coevolution). Here, we use simulations to provide evidence that simple host-related ecological filtering can readily generate phylosymbiosis, and we contrast these predictions with real-world data. We find that while phylosymbiosis is widespread in nature, phylosymbiosis patterns are compatible with a simple ecological model in the majority of taxa. Internal compartments of hosts, such as the animal gut, often display stronger phylosymbiosis than expected from a purely ecological filtering process, suggesting that other mechanisms are also involved.

Photosynthetic water oxidation is a fundamental process that sustains the biosphere. A Mn 4 Ca cluster embedded in the photosystem II protein environment is responsible for the production of atmospheric oxygen. Here, time-resolved x-ray emission spectroscopy (XES) was used to observe the process of oxygen formation in real time. These experiments reveal that the oxygen evolution step, initiated by three sequential laser flashes, is accompanied by rapid (within 50 μs) changes to the Mn Kβ XES spectrum. However, no oxidation of the Mn 4 Ca core above the all MnIV state was detected to precede O-O bond formation, and the observed changes were therefore assigned to O-O bond formation dynamics. We propose that O-O bond formation occurs prior to the transfer of the final (4th) electron from the Mn 4 Ca cluster to the oxidized tyrosine Y Z residue. This model resolves the kinetic limitations associated with O-O bond formation, and suggests an evolutionary adaptation to avoid releasing of harmful peroxide species.

Light-driven water oxidation is a fundamental reaction in the biosphere. The Mn 4 Ca cluster of photosystem II cycles through five redox states termed S 0 -S 4 , after which oxygen is evolved. Critically, the timing of O-O bond formation within the Kok cycle remains unknown. By combining recent crystallographic, spectroscopic, and DFT results, we demonstrate an atomistic S 3 state model with the possibility of a low barrier to O-O bond formation prior to the final oxidation step. Furthermore, the associated one electron oxidized S 4 state does not provide more advantages in terms of spin alignment or the energy of O-O bond formation. We propose that a high energy peroxide isoform of the S 3 state can preferentially be oxidized by Tyr z ox in the course of final electron transfer leading to O 2 evolution. Such a mechanism may explain the peculiar kinetic behavior of O 2 evolution as well as serve as an evolutionary adaptation to avoid release of the harmful peroxides.

This corrects the article DOI: 10.1038/ismej.2017.4.

Understanding the function of Mn ions in biological and chemical redox catalysis requires precise knowledge of their electronic structure. X-ray emission spectroscopy (XES) is an emerging technique with a growing application to biological and biomimetic systems. Here, we report an improved, cost-effective spectrometer used to analyze two biomimetic coordination compounds, [Mn IV (OH) 2 (Me 2 EBC)] 2+ and [Mn IV (O)(OH)(Me 2 EBC)] + , the second of which contains a key Mn IV ═O structural fragment. Despite having the same formal oxidation state (Mn IV ) and tetradentate ligands, XES spectra from these two compounds demonstrate different electronic structures. Experimental measurements and DFT calculations yield different localized spin densities for the two complexes resulting from Mn IV -OH conversion to Mn IV ═O. The relevance of the observed spectroscopic changes is discussed for applications in analyzing complex biological systems such as photosystem II. A model of the S 3 intermediate state of photosystem II containing a Mn IV ═O fragment is compared to recent time-resolved X-ray diffraction data of the same state.

Phytoplankton often both provision and depend on heterotrophic bacteria. In order to investigate these relationships further, we sequenced draft genomes of three bacterial isolates from cultures of the marine diatom Thalassiosira rotula to identify metabolic functions that may support interactions with T. rotula ., (Copyright © 2017 Garcia et al.)