Mild Chemotriggered Generation of a Fluorophore-Tethered Diazoalkane Species via Smiles Rearrangement

In situ generation of diazoalkanes under mild conditions is desired. A mechanism based on a Smiles rearrangement has been devised that releases a fluorophore-labeled unstabilized diazoalkane in the presence of various chemical triggers. Notably, the release of this diazoalkane is accompanied by an intense fluorescence turn-on, which calibrates the release of the diazoalkane. Carboxylic acids can trap this short-lived diazoalkane intermediate and yield the corresponding esters. This transformation has potential for broad applications

Simultaneous Quantification of Hg²⁺ and MeHg⁺ in Aqueous Media with a Single Fluorescent Probe by Multiplexing in the Time Domain

Development of a molecular probe for selective detection of MeHg⁺ in the presence of Hg²⁺ is a mission impossible to accomplish. Speciation analysis of two substrates with a single kinetic trace exploiting their differential reactivity toward a single probe, i.e., multiplexing in the time domain, is a cost-effective and powerful alternative. We have developed such a probe (<b>Hg410</b>) for simultaneously quantification of Hg²⁺ and MeHg⁺ in aqueous media. <b>Hg410</b> is designed via the “covalent-assembly” approach, displays a zero background, and bears a very concise molecular construct. It has harnessed proximity-based catalysis to achieve high reactivity toward Hg²⁺ and MeHg⁺. An unprecedentedly low detection limit of ca. 4.6 pM and 160 pM was measured for Hg²⁺ and MeHg⁺, respectively

Salinity Regulation of the Interaction of Halovirus SNJ1 with Its Host and Alteration of the Halovirus Replication Strategy to Adapt to the Variable Ecosystem

<div><p>Halovirus is a major force that affects the evolution of extreme halophiles and the biogeochemistry of hypersaline environments. However, until now, the systematic studies on the halovirus ecology and the effects of salt concentration on virus-host systems are lacking. To provide more valuable information for understanding ecological strategies of a virus-host system in the hypersaline ecosystem, we studied the interaction between halovirus SNJ1 and its host <i>Natrinema</i> sp.J7-2 under various NaCl concentrations. We found that the adsorption rate and lytic rate increased with salt concentration, demonstrating that a higher salt concentration promoted viral adsorption and proliferation. Contrary to the lytic rate, the lysogenic rate decreased as the salt concentration increased. Our results also demonstrated that cells incubated at a high salt concentration prior to infection increased the ability of the virus to adsorb and lyse its host cells; therefore, the physiological status of host cells also affected the virus-host interaction. In conclusion, SNJ1 acted as a predator, lysing host cells and releasing progeny viruses in hypersaline environments; in low salt environments, viruses lysogenized host cells to escape the damage from low salinity.</p></div

Single-step growth curves of halovirus SNJ1 incubated in media with differing salinity.

<p>(A) cells incubated in 18% medium; (B) cells incubated in 25% medium; (C) cells incubated in 30% medium. ●, extracellular and mature intracellular phage; ○, extracellular phage and infective centers.</p

Thin section electron micrographs of <i>Natrinema</i> sp. J7-2 for cells incubated in media with different salinity.

<p>(A) cells incubated in 18% medium; (B) cells incubated in 25% medium; (C) cells incubated in 30% medium. The scale bars represent 500 nm.</p

The effect of salinity on the infective activity of halovirus SNJ1 and the growth of its host cells.

<p>(A) the remaining infective activity of halovirus SNJ1 under different NaCl concentrations at indicative time; ■,●,▲,▼, and ○ represent the remaining infective activity in 12%, 15%, 18%, 25%, and 30% NaCl, respectively. (B) the growth curves of <i>Natrinema</i> sp. J7-2 under different NaCl concentrations at indicative time; the symbols △, ■, ●, ▲, and ▼ denote the growth of the host cells in 12%, 15%, 18%, 25%, and 30% NaCl, respectively.</p

Regulation of the replication cycles of halovirus SNJ1by salinity (w/v, %).

<p>Regulation of the replication cycles of halovirus SNJ1by salinity (w/v, %).</p

Adsorption efficiency of SNJ1 under different salt concentrations.

<p>Adsorption efficiency of SNJ1 under different salt concentrations.</p

Photocalibrated NO Release from N‑Nitrosated Napthalimides upon One-Photon or Two-Photon Irradiation

NO donors are routinely used as the exogenous source in in vitro studies. However, the kinetics or the dose of NO release from the existing donors is not readily monitored. This complicates the elucidation of the involvement of NO in a biological response. We report herein a series of NO donors (<b>NOD545a–g</b>), whose NO release is triggered by UV light at 365 nm or a two-photon laser at 740 nm, and importantly, their NO release is accompanied by a drastic fluorescence turn-on, which has been harnessed to follow the kinetics and dose of NO release in a real-time fashion with spectroscopic methods or microscopic methods in in vitro studies. These merits have rendered <b>NOD545a–g</b> useful molecular tools in NO biology

The Complete Genome Sequence of <em>Natrinema</em> sp. J7-2, a Haloarchaeon Capable of Growth on Synthetic Media without Amino Acid Supplements

<div><p><em>Natrinema</em> sp. J7-2 is an extreme haloarchaeon capable of growing on synthetic media without amino acid supplements. Here we report the complete genome sequence of <em>Natrinema</em> sp. J7-2 which is composed of a 3,697,626-bp chromosome and a 95,989-bp plasmid pJ7-I. This is the first complete genome sequence of a member of the genus <em>Natrinema</em>. We demonstrate that <em>Natrinema</em> sp. J7-2 can use gluconate, glycerol, or acetate as the sole carbon source and that its genome encodes complete metabolic pathways for assimilating these substrates. The biosynthetic pathways for all 20 amino acids have been reconstructed, and we discuss a possible evolutionary relationship between the haloarchaeal arginine synthetic pathway and the bacterial lysine synthetic pathway. The genome harbors the genes for assimilation of ammonium and nitrite, but not nitrate, and has a denitrification pathway to reduce nitrite to N₂O. Comparative genomic analysis suggests that most sequenced haloarchaea employ the TrkAH system, rather than the Kdp system, to actively uptake potassium. The genomic analysis also reveals that one of the three CRISPR loci in the <em>Natrinema</em> sp. J7-2 chromosome is located in an integrative genetic element and is probably propagated via horizontal gene transfer (HGT). Finally, our phylogenetic analysis of haloarchaeal genomes provides clues about evolutionary relationships of haloarchaea.</p> </div