Biosynthesis of N-acyl glutamines in the insect gut: impact and characterisation of microbial enzymes

N-acyl glutamines are key signal molecules mediating the plant-insect interaction. A protein fraction has been isolated from a bacterium, Microbacterium arborescens SE14 living commensally in herbivore insect gut. The protein belongs to the bacterial Dps protein family (DNA-binding protein from starved cell), and catalyses reversible formation of N-acyl glutamines when free fatty acids and amino acids were supplied exogenously. The protein has some novel properties adapted well to the insect gut environment. The cloned gene increased the activity of strain M. arborescens DSM20754 when transformed into it

Vital Dye Reaction and Granule Localization in Periplasm of Escherichia coli

Background Tetrazolium salts are widely used in biology as indicators of metabolic activity – hence termed vital dyes – but their reduction site is still debated despite decades of intensive research. The prototype, 2,3,5- triphenyl tetrazolium chloride, which was first synthesized a century ago, often generates a single formazan granule at the old pole of Escherichia coli cells after reduction. So far, no explanation for their pole localization has been proposed. Method/Principal Findings Here we provide evidence that the granules form in the periplasm of bacterial cells. A source of reducing power is deduced to be thiol groups destined to become disulfides, since deletion of dsbA, coding for thiol-oxidase, enhances the formation of reduced formazan. However, pervasive reduction did not result in a random distribution of formazan aggregates. In filamentous cells, large granules appear at regular intervals of about four normal cell-lengths, consistent with a diffusion-to-capture model. Computer simulations of a minimal biophysical model showed that the pole localization of granules is a spontaneous process, i.e. small granules in a normal size bacterium have lower energy at the poles. This biased their diffusion to the poles. They kept growing there and eventually became fixed. Conclusions We observed that formazan granules formed in the periplasm after reduction of tetrazolium, which calls for re-evaluation of previous studies using cell-free systems that liberate inaccessible intracellular reductant and potentially generate artifacts. The localization of formazan granules in E. coli cells can now be understood. In living bacteria, the seeds formed at or migrated to the new pole would become visible only when that new pole already became an old pole, because of the relatively slow growth rate of granules relative to cell division

Tripotassium (bis­{[bis­(carboxyl­atometh­yl)amino]­meth­yl}phosphinato)cuprate(II) dihydrate

In the title compound, K3[Cu(C10H12N2O10P)]·2H2O, the CuII ion, one potassium cation and a P atom are situated on a twofold rotation axis. The CuII ion is coordinated by two N and four O atoms from one bis­{[bis­(carboxyl­atometh­yl)amino]­meth­yl}phosphinate ligand in a distorted octa­hedral coordination geometry. The two crystallographically independent potassium ions exhibit different coordination environments. The potassium ion in a general position is hepta­coordinated by five carboxyl­ate O atoms, one phosphinate O atom and one water mol­ecule [K—O = 2.718 (3)–3.040 (3) Å], and the potassium ion situated on the twofold rotation axis is hexa­coordinated by four carboxyl­ate O atoms and two water mol­ecules [K—O = 2.618 (3)–2.771 (3) Å]. The water mol­ecules are also involved in formation of inter­molecular O—H⋯O hydrogen bonds

Osmotic Pressure in a Bacterial Swarm

Using Escherichia coli as a model organism, we studied how water is recruited by a bacterial swarm. A previous analysis of trajectories of small air bubbles revealed a stream of fluid flowing in a clockwise direction ahead of the swarm. A companion study suggested that water moves out of the agar into the swarm in a narrow region centered ~30 mm from the leading edge of the swarm and then back into the agar (at a smaller rate) in a region centered ~120 mm back from the leading edge. Presumably, these flows are driven by changes in osmolarity. Here, we utilized green/red fluorescent liposomes as reporters of osmolarity to verify this hypothesis. The stream of fluid that flows in front of the swarm contains osmolytes. Two distinct regions are observed inside the swarm near its leading edge: an outer high-osmolarity band (~30 mOsm higher than the agar baseline) and an inner low-osmolarity band (isotonic or slightly hypotonic to the agar baseline). This profile supports the fluid-flow model derived from the drift of air bubbles and provides new (to our knowledge) insights into water maintenance in bacterial swarms. High osmotic pressure at the leading edge of the swarm extracts water from the underlying agar and promotes motility. The osmolyte is of high molecular weight and probably is lipopolysaccharide.Molecular and Cellular BiologyPhysic

Frequent alterations in cytoskeleton remodelling genes in primary and metastatic lung adenocarcinomas

The landscape of genetic alterations in lung adenocarcinoma derived from Asian patients is largely uncharacterized. Here we present an integrated genomic and transcriptomic analysis of 335 primary lung adenocarcinomas and 35 corresponding lymph node metastases from Chinese patients. Altogether 13 significantly mutated genes are identified, including the most commonly mutated gene TP53 and novel mutation targets such as RHPN2, GLI3 and MRC2. TP53 mutations are furthermore significantly enriched in tumours from patients harbouring metastases. Genes regulating cytoskeleton remodelling processes are also frequently altered, especially in metastatic samples, of which the high expression level of IQGAP3 is identified as a marker for poor prognosis. Our study represents the first large-scale sequencing effort on lung adenocarcinoma in Asian patients and provides a comprehensive mutational landscape for both primary and metastatic tumours. This may thus form a basis for personalized medical care and shed light on the molecular pathogenesis of metastatic lung adenocarcinoma

Signals from the underground: bacterial volatiles promote growth in Arabidopsis

Plant-growth-promoting rhizobacteria colonize the root systems of plants and can modulate plant growth by enhancing the availability of nutrients, inducing metabolic activities by phytohormones and analogs, by shifting the phytohormonal balance, by ind

Reward expectation regulates brain responses to task-relevant and task-irrelevant emotional words: ERP evidence

We investigated the effect of reward expectation on the processing of emotional words in two experiments using event-related potentials (ERPs). A cue indicating the reward condition of each trial (incentive vs non-incentive) was followed by the presentation of a negative or neutral word, the target. Participants were asked to discrim inate the emotional content of the target word in Experiment 1 and to discriminate the color of the target word in Experiment 2, rendering the emotionality of the target word task-relevant in Experiment 1, but task-irrelevant in Experiment 2. The negative bias effect, in terms of the amplitude difference between ERPs for negative and neutral targets, was modulated by the task-set. In Experiment 1, P3(1) and early posterior negativity revealed a larger negative bias effect in the incentive condition than that in the non-incentive condition. However, in Experiment 2, P3(1) revealed a diminished negative bias effect in the incentive condition compared with that in the non-incentive condition. These results indicate that reward expectation improves top-down attentional concentration to task-relevant information, with enhanced sensitivity to the emotional content of target words when emotionality is task-relevant, but with reduced differential brain responses to emotional words when their content is task-irrelevant