ALBERT

Description: The title compound AgS 2 CN R 2 was prepared from an aqueous alcoholic solution by reaction of dicyanoargentate [Ag(CN) 2 ] – with excess ammoniumdithiocarbamate. It crystallizes in the tetragonal space group I 2 d (No. 122) with a = 7.9898(4) and c = 12.1072(7) Å, V = 772.89(7) Å 3 , Z = 8. The crystal structure comprises a 3D tetrahedral network of distorted AgS 4 units connected via all vertices thus forming the β-cristobalite structure type. The dithiocarbaramate ligands extend into the hollow space of the framework. Thermal decomposition starts above 125 °C and proceeds with a complex reaction to give finally Ag 2 S (acanthite).

Description: Abstract Increasing glacial discharge can lower salinity and alter organic matter (OM) supply in fjords, but assessing the biogeochemical effects of enhanced freshwater fluxes requires understanding of microbial interactions with OM across salinity gradients. Here, we examined microbial enzymatic capabilities—in bulk waters (nonsize‐fractionated) and on particles (≥ 1.6 μm)—to hydrolyze common OM constituents (peptides, glucose, polysaccharides) along a freshwater–marine continuum within Tyrolerfjord‐Young Sound. Bulk peptidase activities were up to 15‐fold higher in the fjord than in glacial rivers, whereas bulk glucosidase activities in rivers were twofold greater, despite fourfold lower cell counts. Particle‐associated glucosidase activities showed similar trends by salinity, but particle‐associated peptidase activities were up to fivefold higher—or, for several peptidases, only detectable—in the fjord. Bulk polysaccharide hydrolase activities also exhibited freshwater–marine contrasts: xylan hydrolysis rates were fivefold higher in rivers, while chondroitin hydrolysis rates were 30‐fold greater in the fjord. Contrasting enzymatic patterns paralleled variations in bacterial community structure, with most robust compositional shifts in river‐to‐fjord transitions, signifying a taxonomic and genetic basis for functional differences in freshwater and marine waters. However, distinct dissolved organic matter (DOM) pools across the salinity gradient, as well as a positive relationship between several enzymatic activities and DOM compounds, indicate that DOM supply exerts a more proximate control on microbial activities. Thus, differing microbial enzymatic capabilities, community structure, and DOM composition—interwoven with salinity and water mass origins—suggest that increased meltwater may alter OM retention and processing in fjords, changing the pool of OM supplied to coastal Arctic microbial communities.

Description: The gut hormone ghrelin is involved in numerous metabolic functions, such as the stimulation of growth hormone secretion, gastric motility, and food intake. Ghrelin is modified by ghrelin O-acyltransferase ( GOAT) or membrane-bound O-acyltransferase domain-containing 4 ( MBOAT4 ) enabling action through the growth hormone secretagogue receptors ( GHS-R ). During the course of evolution, initially strong ligand/receptor specificities can be disrupted by genomic changes, potentially modifying physiological roles of the ligand/receptor system. Here, we investigated the coevolution of ghrelin, GOAT, and GHS-R in vertebrates. We combined similarity search, conserved synteny analyses, phylogenetic reconstructions, and protein structure comparisons to reconstruct the evolutionary history of the ghrelin system. Ghrelin remained a single-gene locus in all vertebrate species, and accordingly, a single GHS-R isoform was identified in all tetrapods. Similar patterns of the nonsynonymous ( dN ) and synonymous ( dS ) ratio ( dN/dS ) in the vertebrate lineage strongly suggest coevolution of the ghrelin and GHS-R genes, supporting specific functional interactions and common physiological pathways. The selection profiles do not allow confirmation as to whether ghrelin binds specifically to GOAT , but the ghrelin dN/dS patterns are more similar to those of GOAT compared to MBOAT1 and MBOAT2 isoforms. Four GHS-R isoforms were identified in teleost genomes. This diversification of GHS-R resulted from successive rounds of duplications, some of which remained specific to the teleost lineage. Coevolution signals are lost in teleosts, presumably due to the diversification of GHS-R but not the ghrelin gene. The identification of the GHS-R diversity in teleosts provides a molecular basis for comparative studies on ghrelin's physiological roles and regulation, while the comparative sequence and structure analyses will assist translational medicine to determine structure–function relationships of the ghrelin/ GHS-R system. We investigated the coevolution of ghrelin, GOAT , and GHS - R s, and we found similar patterns of selection profiles in amphibian, reptiles, and birds, which strongly suggest coevolution of ghrelin and GHS - R genes, supporting specific functional interaction and common physiological pathways. By contrast, coevolution signals are lost in teleosts, presumably due to the diversification of GHS - R s. Our results allowed to clarify the evolutionary history of ghrelin receptors and provide further insights into studies on structure–function relationships, also allowing to mechanistically understand and presumably therapeutically target the ghrelin/ GHS - R system.

Description: The title compound AuS 2 CNH 2 was prepared from an aqueous solution by reaction of dicyanidoaurate [Au(CN) 2 ] – with excess of ammoniumdithiocarbamate NH 4 S 2 CN H 2 at pH ≈ 2. The compound crystallizes in the orthorhombic space group Cmma with a = 6.4597(2), b = 12.6556(3), and c = 5.3235(1) Å. The crystal structure comprises linear S–Au–S dumbbells forming unbranched zigzag chains in combination with the dithiocarbamate ligands. The three-dimensional arrangement of the molecules is realized by aurophilic Au I –Au I and hydrogen bonding interactions, respectively. AuS 2 CNH 2 presents orange luminescence due to a broad emission band between 12000 cm –1 and 23000 cm –1 (ν = 26316 cm –1 ).

Description: Bisphenols, anthropogenic pollutants, leach from consumer products and have potential to be ingested and are excreted in waste. The endocrine disrupting effects of highly manufactured bisphenols (BPA, BPS, and BPF) are known, however the activities of others are not. Here, the estrogenic and androgenic activities of a series of 4,4'-bisphenols that vary at the inter-connecting bisphenol bridge were determined (BPA, BPB, BPBP, BPC2, BPE, BPF, BPS, and BPZ) and compared to in silico binding to estrogen receptor-alpha and the androgen receptor. Bioassay results showed the order of estrogenicity (BPC2 (strongest) 〉 BPBP 〉 BPB 〉 BPZ 〉 BPE 〉 BPF 〉 BPA 〉 BPS, r 2  = 0.995) and anti-androgenicity (BPC2 (strongest) 〉 BPE, BPB, BPA, BPF, and BPS, r 2  = 0.996) correlated to nuclear receptor binding affinities. Like testosterone and the anti-androgen hydroxyflutamide, bisphenol fit in the ligand-binding domain through hydrogen-bonding at residues Thr877 and Asn705, but also interacted at either Cys784/Ser778 or Gln711 through the other phenol ring. This suggests the 4,4'-bisphenols, like hydroxyflutamide, are androgen receptor antagonists. Hydrogen-bond trends between ERα and the 4,4'-bisphenols were limited to residue Glu353, which interacted with the –OH of one phenol and the –OH of the A ring of 17β-estradiol; hydrogen-bonding varied at the –OH of ring D of 17β-estradiol and the second phenol –OH group. While both estrogen and androgen bioassays correlated to in silico results, conservation of hydrogen-bonding residues in the androgen receptor provides a convincing picture of direct antagonist binding by 4,4'-bisphenols.

Description: Abstract Volatile fatty acids (VFAs) and alcohols are key intermediates of anaerobic carbon metabolism, yet their biogeochemical cycling remains poorly constrained in hydrothermal systems. We investigated the abundance, stable carbon isotopic composition, and metabolic cycling of VFAs and alcohols to elucidate their generation and utilization pathways in hydrothermally influenced sediments (4 °C to 90 °C) from the Guaymas Basin. Acetate (up to 229 μM) and methanol (up to 37 μM) were abundant in porewaters. The δ13C values of acetate varied between −35.6‰ and −18.1‰. Carbon isotopic signatures, thermodynamic predictions, and experimental incubations suggested biological sources such as fermentation and acetogenesis for acetate. Acetate and methanol were predominantly consumed by nonmethanogenic processes (e.g., sulfate reduction), as reflected in high oxidation rates versus low methanogenesis rates, and further evidenced through inhibition experiments with molybdate. These results reveal an important role for VFAs and alcohols as energy sources for diverse chemoheterotrophs in organic‐rich hydrothermally influenced sediments.

Description: Abstract Anaerobic oxidation of methane (AOM), a central process in the carbon cycle of anoxic environments, moderates the release of methane from soils and sediments to water bodies and, ultimately, the atmosphere. The regulation of AOM in the environment remains poorly constrained. Here we quantified AOM and sulfate reduction (SR) rates in diverse deep seafloor samples at in situ pressure and methane concentration and discovered that, in some cases, AOM exceeded SR rates by more than 4 times when methane concentrations were above 5 mM. Methane concentration also affected other carbon‐cycling processes (e.g., carbon assimilation) in addition to SR. These results illustrate that substantial amounts of methane may be oxidized independent of sulfate reduction under in situ conditions, reshaping our view of the capacity and mechanism of AOM in methane rich environments, including the deep biosphere, where sulfate availability is considered to limit AOM.

Description: The cover picture shows a partial view of the crystal structure of AuS 2 CNH 2 which was solved and refined using X-ray powder diffraction data. Au(I) is twofold coordinated by sulfur atoms (S) in the shape of a stretched dumbbell. The dithiocarbamate acts as a monodentate ligand forming zigzag chains [-S-Au-S-C(N)-S-Au-S-] running along [010]. The gold atoms are arranged linearly along [100] with Au-Au separations of 3.2299(1) Å, indicative of a relatively weak aurophilic bonding interaction. The hydrogen atoms of the S 2 CNH 2 ligand could not be located but they are obviously situated in the same planes parallel to (100) together with the other atoms. Therefore, the cohesion of the zigzag chains within these planes clearly occurs via hydrogen bonding interactions (N–H⋯S). Cooperative aurophilic and hydrogen bonding of similar strength are responsible for the observed structural arrangement in the crystal structure of AuS 2 CNH 2 . The aurophilic interactions cause light emission in the orange spectral range marked by a star in the CIE color coordinates. More details can be found in the article by Christoph Ludwig Teske et al. on page 466 ff .