Metagenomic Evidence for Sulfide Oxidation in Extremely Acidic Cave Biofilms

<div><p>Snottites are extremely acidic (pH 0–2) biofilms that form on the walls and ceilings of hydrogen sulfide-rich caves. Recent work suggests that microbial communities including snottites and related cave wall biofilms accelerate cave formation by oxidizing sulfide to sulfuric acid. Therefore, we used full-cycle rRNA methods and metagenomics to explore the community composition and sulfur metabolism of snottites from the sulfidic Frasassi and Acquasanta cave systems, Italy. Acquasanta snottites were dominated by strains of <i>Acidithiobacillus thiooxidans</i>, with a smaller population of <i>Ferroplasma</i> sp. Frasassi snottites were also dominated by <i>At. thiooxidans</i> but with a more diverse community including relatives of ‘G-plasma’ (Thermoplasmatales), <i>Acidimicrobium</i>, and rare taxa. We identified diverse homologues of sulfide:quinone oxidoreductase (SQR) in the metagenomic datasets. Based on phylogenetic analysis, the numerically dominant <i>At. thiooxidans</i> populations have four different types of SQR, while <i>Ferroplasma</i> has two and <i>Acidimicrobium</i> and G-plasma each have one. No other genetic evidence for sulfur oxidation was detected for either <i>Acidimicrobium</i> or G-plasma, suggesting that they do not generate sulfuric acid. Our results confirm earlier findings that <i>At. thiooxidans</i> is the dominant primary producer and sulfide oxidizer in sulfidic cave snottites.</p> </div

Ball and Socket Assembly of Binary Superatomic Solids Containing Trinuclear Nickel Cluster Cations and Fulleride Anions

The superlattice structures of hierarchical cluster solids are dictated by short-range interactions between constituent building blocks. Here we show that shape complementary sites, as well as halogen and chalcogen bonding between exposed capping ligands and fullerides, govern the packing arrangement of the resulting binary solids. Four new superatomic solids, [Ni₃(μ₃-I)₂(μ₂-dppm)₃⁺]­(C₆₀^•‑) (<b>1·</b>C₆₀), [Ni₃(μ₃-I)₂(μ₂-dppm)₃⁺]­(C₇₀^–)₂ (<b>1·</b>C₇₀), [Ni₃(μ₃-Te)₂(μ₂-dppm)₃⁺]­(C₆₀^•‑) (<b>2·</b>C₆₀), and [Ni₃(μ₃-Te)₂(μ_2‑dppm)₃]­(C₇₀^–)₂ (<b>2·</b>C₇₀), (dppm = Ph₂PCH₂PPh₂) were prepared and crystallized from solution. All four compounds were characterized by single crystal X-ray diffraction, IR spectroscopy, and SQUID magnetometry. Charge transfer between the molecular clusters is confirmed via optical spectroscopy and structural data. Compounds <b>1·</b>C₆₀ and <b>2·</b>C₆₀ are paramagnetic and 100 times more conductive than the constituent cluster precursors. The obtained solids exhibit close contacts, indicative of halogen/chalcogen bonds, between the fulleride anions and the nickel cluster capping ligands (I/Te) in the solid-state

Thiazolothiazole Fluorophores Exhibiting Strong Fluorescence and Viologen-Like Reversible Electrochromism

The synthesis, electrochemical, and photophysical characterization of <i>N</i>,<i>N</i>′-dialkylated and <i>N</i>,<i>N</i>′-dibenzylated dipyridinium thiazolo­[5,4-<i>d</i>]­thiazole derivatives are reported. The thiazolothiazole viologens exhibit strong blue fluorescence with high quantum yields between 0.8–0.96. The dioctyl, dimethyl, and dibenzyl derivatives also show distinctive and reversible yellow to dark blue electrochromism at low reduction potentials. The fused bicyclic thiazolo­[5,4-d]­thiazole heterocycle allows the alkylated pyridinium groups to remain planar, strongly affecting their electrochemical properties. The singlet quantum yield is greatly enhanced with quaternarization of the peripheral 4-pyridyl groups (Φ_F increases from 0.22 to 0.96) while long-lived fluorescence lifetimes were observed between 1.8–2.4 ns. The thiazolothiazole viologens have been characterized using cyclic voltammetry, UV–visible absorbance and fluorescence spectroscopy, spectroelectrochemistry, and time-resolved photoluminescence. The electrochromic properties observed in solution, in addition to their strong fluorescent emission properties, which can be suppressed upon 2 e^– reduction, make these materials attractive for multifunctional optoelectronic, electron transfer sensing, and other photochemical applications

<i>NF-YB2-EDLL</i>, but not <i>NF-YB2</i>^<i>E65R</i><i>-EDLL</i>, rescues late flowering in an <i>FT</i>-dependent manner.

<p>Flowering time quantification for 15–20 randomly selected T1 plants of <i>p35S</i>:<i>NF-YB2</i>, <i>p35S</i>:<i>NF-YB2-EDLL</i>, and <i>p35S</i>:<i>NF-YB2</i>^<i>E65R</i><i>-EDLL</i> in A) Col-0 B) <i>co-2</i> C) <i>b2b3</i> D) short days E) <i>ft-10</i>. Asterisks represent significant differences derived from one-way ANOVA (P < 0.05) followed by Bonferroni’s multiple comparison tests (_*** P < 0.001; * P < 0.05).</p

NF-YA2 and NF-YA6 bind the <i>FT</i> -5.3kb <i>CCAAT</i> box as a trimer with NF-YB2 and NF-YC3.

<p>NF-Y trimerization and <i>FT CCAAT</i> binding was assessed by EMSA analysis. An <i>FT CCAAT</i> probe was incubated with wild type (WT, lanes 2–8; 20) or E65R mutant (B2^E65R, lanes 15–18; 21) NF-YB2/NF-YC3 dimers (60 nM) in the presence of NF-YA2 (lanes 3–5; 16–18), or NF-YA6 (lanes 6–8) at increasing molar ratios (3, 4.5 or 6 fold), or CO (lanes 20, 21; 6 fold molar ratio). As controls, NF-YA2 (lane 9), NF-YA6 (lane 10), or CO (lane 22) were incubated alone with the probe, at the highest concentration of the dose curve (360 nM), in the absence of NF-YB2/NF-YC3. Lanes 1, 11, 14, 19: probe alone, without protein additions; lanes 12, 13: empty lanes. The NF-Y/DNA complex is indicated by a labelled arrowhead. fp: free probe.</p

NF-YA2 is a positive regulator of photoperiod dependent flowering.

<p>A) Flowering time quantification of two independent plant lines each (plant lines 1 and 2) for <i>p35S</i>:<i>NF-YA2</i> (white bars), <i>p35S</i>:<i>NF-YA7</i> (light grey bars), <i>p35S</i>:<i>NF-YA8</i> (grey bars), and <i>p35S</i>:<i>NF-YA9</i> (dark grey bars) (n≥12/line). B) Flowering time quantification of two independent <i>pNF-YA2</i>:<i>NF-YA2</i> plant lines (n≥24). C) The expression pattern of <i>pNF-YA2</i>:<i>GUS</i> in leaves of 10 day old plants. D) Relative transcript abundance of <i>CO</i>, <i>FT</i>, and <i>AP1</i>. Asterisks in 1A and 1B represent significant differences derived from one-way ANOVA (P < 0.05) followed by Dunnett’s multiple comparison post hoc tests against Col-0. Asterisks in 1D represent significant differences derived from Student’s T-tests (P < 0.05). All experiments were repeated with identical results.</p

<i>pNF-YA2</i>:<i>NF-YA2-EDLL</i> can induce flowering in the absence of CO.

<p>Flowering time quantification for 15–20 randomly selected T1 plants in A) Col-0, B) <i>co-2</i>, and C) <i>ft-10</i>. Asterisks represent significant differences derived from one-way ANOVA (P < 0.05) followed by Bonferroni’s multiple comparison tests.</p

NF-YB2^E65R loses interaction with NF-YA subunits.

<p>A) Alignment of the core domain of human and Arabidopsis NF-YB subunits. * marks the position of the conserved glutamic acid required for interaction with NF-YA in humans [<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1006496#pgen.1006496.ref027" target="_blank">27</a>]. B) NF-YB2 and NF-YB2^E65R interact with NF-YC3, NF-YC4, and NF-YC9 in Y2H assays. C) NF-YB2, but not NF-YB2^E65R, interacts with NF-YA2 when NF-YC9 is expressed using a bridge vector in yeast three-hybrid assays. DBD: DNA binding domain, AD: activation domain, EV: empty vector control.</p