第885回千葉医学会例会・千葉大学第二外科例会

<p><b>A</b>. NMDS ordination of 16S rRNA gene-derived microbial community structure. Similarity profile analysis, an <i>a priori</i> statistical approach that uses permutation to identify groups of communities that are more dissimilar than expected by chance, identified two distinct clusters of communities. Ellipses represent the 95% confidence intervals around the centroid for each cluster (the spatial mean in NMDS space of the communities belonging to each cluster). Lines emanating from the centroids indicate to which cluster each community belongs. Bacterial families well-correlated with the ordination (r² > 0.40) are displayed; vector length is proportional to the Pearson correlation coefficient for each family and vector direction corresponds to the direction of increasing abundance relative to the ordinated communities. Legend indicates the dune from which each ordinated community originated. Final 2-dimensional stress of the ordination is 0.12. <b>B</b>. Linear discriminant analysis (LDA) of bacterial classes indicates that the two clusters of microbial communities identified by similarity profile analysis are driven by the disparity between a high abundance of <i>Gammaproteobacteria</i> in one set of communities and more diverse population in the other set of communities. Only classes with effect size > 2.0 are displayed. <b>C</b>. NMDS ordination is based only on samples for which environmental parameters were measured. Parameters with r² > 0.1 are displayed. Final 2-dimensional stress of the ordination is 0.07.</p

The Metagenomics and Metadesign of the Subways and Urban Biomes (MetaSUB) International Consortium inaugural meeting report

The Metagenomics and Metadesign of the Subways and Urban Biomes (MetaSUB) International Consortium is a novel, interdisciplinary initiative comprised of experts across many fields, including genomics, data analysis, engineering, public health, and architecture. The ultimate goal of the MetaSUB Consortium is to improve city utilization and planning through the detection, measurement, and design of metagenomics within urban environments. Although continual measures occur for temperature, air pressure, weather, and human activity, including longitudinal, cross-kingdom ecosystem dynamics can alter and improve the design of cities. The MetaSUB Consortium is aiding these efforts by developing and testing metagenomic methods and standards, including optimized methods for sample collection, DNA/RNA isolation, taxa characterization, and data visualization. The data produced by the consortium can aid city planners, public health officials, and architectural designers. In addition, the study will continue to lead to the discovery of new species, global maps of antimicrobial resistance (AMR) markers, and novel biosynthetic gene clusters (BGCs). Finally, we note that engineered metagenomic ecosystems can help enable more responsive, safer, and quantified cities

Tetrahedral and square planar Ni[(SPR2)2N] 2 complexes, R = Ph &amp;amp;iPr revisited: Experimental and theoretical analysis of interconversion pathways, structural preferences, and spin delocalization

Sulfur-containing mono-or bidentate types of ligands, usually form square planar Ni(II)S4 complexes. However, it has already been established that the bidentate L- dithioimidodiphosphinato ligands, [R2P(S)NP(S)R′2]-, R, andR′ = aryl or alkyl, can afford both tetrahedral and square planar, NiS4- containing, homoleptic NiR,R′L2 complexes, owing to an apparent structural flexibility, which has not, so far, been probed. In this work, the literature tetrahedral Ni[R2P(S)NP(S)R2] 2 complexes, R = Ph (NiPh,PhL2, 1Td) and R = iPr (NiiPr,iPrL2, 2) as well as the newly synthesized Ni[iPr2P(S)NP(S)Ph2] 2 complex (NiiPr,PhL2, 3), have been studied by UV-vis, IR, and 31P NMR spectroscopy. Complex 3 was shown by X-ray crystallography to be square planar, and magnetic studies confirmed that it is diamagnetic in the solid state. However, it becomes paramagnetic in solution, as it shows a similar UV-vis spectrum to one of the tetrahedral 1Td and 2 complexes. The crystal structure of the potassium salt of the asymmetric ligand, [iPr2P(S)NP(S)Ph2]K, has also been determined and compared to those of the protonated iPr 2P(S)NHP(S)Ph2 ligand and complex 3. All three, 1 Td, 2, and3, NiR,R′L2 complexes show strong paramagnetic effects in their solution 31P NMRspectra. Themagnetic properties of paramagnetic complexes 1 and 2 in the solid state were investigated on oriented crystals, and their analysis afforded remarkably small values of the spin-orbit coupling constant (λ) and orbital reduction factor (k) parameters, implying significant delocalization of unpaired electronic density toward the ligands. The above experimental findings are combined with data from standard density functional theory and correlated multiconfiguration ab initio theoretical methods, in an effort to investigate the interplay between the square planar and tetrahedral geometries of the NiS4 core, the mechanistic pathway for the spin-state interconversion, the degree of covalency of the Ni-S bonds, and the distribution of the spin density in this type of system. The analysis provides justification for the structural flexibility of such ligands, affording Ni R,R′L2 complexes with variable metallacycle conformation and NiS4 core geometries. Of particular importance are the large zero-field splitting values estimated by both experimental and theoretical means, which have not, as yet, been verified by direct methods, such as electron paramagnetic resonance spectroscopy. The findings of our work confirm earlier observations on the feasibility of synthesizing either tetrahedral or square planar NiS4 complexes containing the same type of ligands. They can also form the basis of investigating structure-properties relationships in other NiS4-containing systems. © 2010 American Chemical Society

Tetrahedral and Square Planar Ni[(SPR₂)₂N]₂ complexes, R = Ph & ⁱPr Revisited: Experimental and Theoretical Analysis of Interconversion Pathways, Structural Preferences, and Spin Delocalization

Sulfur-containing mono- or bidentate types of ligands, usually form square planar Ni(II)S4 complexes. However, it has already been established that the bidentate L− dithioimidodiphosphinato ligands, [R2P(S)NP(S)R′2]−, R, and R′ = aryl or alkyl, can afford both tetrahedral and square planar, NiS4-containing, homoleptic NiR,R′L2 complexes, owing to an apparent structural flexibility, which has not, so far, been probed. In this work, the literature tetrahedral Ni[R2P(S)NP(S)R2]2 complexes, R = Ph (NiPh,PhL2, 1Td) and R = iPr (NiiPr,iPrL2, 2) as well as the newly synthesized Ni[iPr2P(S)NP(S)Ph2]2 complex (NiiPr,PhL2, 3), have been studied by UV−vis, IR, and 31P NMR spectroscopy. Complex 3 was shown by X-ray crystallography to be square planar, and magnetic studies confirmed that it is diamagnetic in the solid state. However, it becomes paramagnetic in solution, as it shows a similar UV−vis spectrum to one of the tetrahedral 1Td and 2 complexes. The crystal structure of the potassium salt of the asymmetric ligand, [iPr2P(S)NP(S)Ph2]K, has also been determined and compared to those of the protonated iPr2P(S)NHP(S)Ph2 ligand and complex 3. All three, 1Td, 2, and 3, NiR,R′L2 complexes show strong paramagnetic effects in their solution 31P NMR spectra. The magnetic properties of paramagnetic complexes 1 and 2 in the solid state were investigated on oriented crystals, and their analysis afforded remarkably small values of the spin−orbit coupling constant (λ) and orbital reduction factor (k) parameters, implying significant delocalization of unpaired electronic density toward the ligands. The above experimental findings are combined with data from standard density functional theory and correlated multiconfiguration ab initio theoretical methods, in an effort to investigate the interplay between the square planar and tetrahedral geometries of the NiS4 core, the mechanistic pathway for the spin-state interconversion, the degree of covalency of the Ni−S bonds, and the distribution of the spin density in this type of system. The analysis provides justification for the structural flexibility of such ligands, affording NiR,R′L2 complexes with variable metallacycle conformation and NiS4 core geometries. Of particular importance are the large zero-field splitting values estimated by both experimental and theoretical means, which have not, as yet, been verified by direct methods, such as electron paramagnetic resonance spectroscopy. The findings of our work confirm earlier observations on the feasibility of synthesizing either tetrahedral or square planar NiS4 complexes containing the same type of ligands. They can also form the basis of investigating structure−properties relationships in other NiS4-containing systems

Is Exposure to BMAA a Risk Factor for Neurodegenerative Diseases? : A Response to a Critical Review of the BMAA Hypothesis

In a literature survey, Chernoff et al. (2017) dismissed the hypothesis that chronic exposure to beta-N-methylamino-L-alanine (BMAA) may be a risk factor for progressive neurodegenerative disease. They question the growing scientific literature that suggests the following: (1) BMAA exposure causes ALS/PDC among the indigenous Chamorro people of Guam; (2) Guamanian ALS/PDC shares clinical and neuropathological features with Alzheimer's disease, Parkinson's disease, and ALS; (3) one possible mechanism for protein misfolds is misincorporation of BMAA into proteins as a substitute for L-serine; and (4) chronic exposure to BMAA through diet or environmental exposures to cyanobacterial blooms can cause neurodegenerative disease. We here identify multiple errors in their critique including the following: (1) their review selectively cites the published literature; (2) the authors reported favorably on HILIC methods of BMAA detection while the literature shows significant matrix effects and peak coelution in HILIC that may prevent detection and quantification of BMAA in cyanobacteria; (3) the authors build alternative arguments to the BMAA hypothesis, rather than explain the published literature which, to date, has been unable to refute the BMAA hypothesis; and (4) the authors erroneously attribute methods to incorrect studies, indicative of a failure to carefully consider all relevant publications. The lack of attention to BMAA research begins with the review's title which incorrectly refers to BMAA as a "non-essential" amino acid. Research regarding chronic exposure to BMAA as a cause of human neurodegenerative diseases is emerging and requires additional resources, validation, and research. Here, we propose strategies for improvement in the execution and reporting of analytical methods and the need for additional and well-executed inter-lab comparisons for BMAA quantitation. We emphasize the need for optimization and validation of analytical methods to ensure that they are fit-for-purpose. Although there remain gaps in the literature, an increasingly large body of data from multiple independent labs using orthogonal methods provides increasing evidence that chronic exposure to BMAA may be a risk factor for neurological illness

Comparison of the relative abundance of phyla between cultivation, deep 16S rRNA gene amplicon sequencing and metagenomics.

<p>Comparison of the relative abundance of phyla between cultivation, deep 16S rRNA gene amplicon sequencing and metagenomics.</p

Results of ANOVA and PERMANOVA analyses.

<p>P values less than 0.05 are bolded.</p

Heatmap showing the most abundant OTUs in all samples.

<p>OTU names are given at the lowest available taxonomic level; OTUs that could not be classified below the level of order are termed Unclassified. Dendrograms were generated using hierarchical clustering with complete linkage. Plot indicates the relative fraction of sequences in each sample that were classified as <i>Gammaproteobacteria</i> at the level of class. Sample key: dune name; location on dune face (C = crest, M = middle, B = base); sample number.</p