Phytoplankton blooms characterize temperate ocean margin zones in spring. We investigated the bacterioplankton response to a diatom bloom in the North Sea and observed a dynamic succession of populations at genus-level resolution. Taxonomically distinct expressions of carbohydrate-active enzymes (transporters; in particular, TonB-dependent transporters) and phosphate acquisition strategies were found, indicating that distinct populations of Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria are specialized for successive decomposition of algal-derived organic matter. Our results suggest that algal substrate availability provided a series of ecological niches in which specialized populations could bloom. This reveals how planktonic species, despite their seemingly homogeneous habitat, can evade extinction by direct competition.

The functional annotation of transcriptomes and identification of noncoding RNA (ncRNA) classes has been greatly facilitated by the advent of next-generation RNA sequencing which, by reading the nucleotide order of transcripts, theoretically allows the rapid profiling of all transcripts in a cell. However, primary sequence per se is a poor predictor of function, as ncRNAs dramatically vary in length and structure and often lack identifiable motifs. Therefore, to visualize an informative RNA landscape of organisms with potentially new RNA biology that are emerging from microbiome and environmental studies requires the use of more functionally relevant criteria. One such criterion is the association of RNAs with functionally important cognate RNA-binding proteins. Here we analyze the full ensemble of cellular RNAs using gradient profiling by sequencing (Grad-seq) in the bacterial pathogen Salmonella enterica, partitioning its coding and noncoding transcripts based on their network of RNA-protein interactions. In addition to capturing established RNA classes based on their biochemical profiles, the Grad-seq approach enabled the discovery of an overlooked large collective of structured small RNAs that form stable complexes with the conserved protein ProQ. We show that ProQ is an abundant RNA-binding protein with a wide range of ligands and a global influence on Salmonella gene expression. Given its generic ability to chart a functional RNA landscape irrespective of transcript length and sequence diversity, Grad-seq promises to define functional RNA classes and major RNA-binding proteins in both model species and genetically intractable organisms.small RNA | noncoding RNA | RNA-protein interaction | ProQ | Hfq

Short antimicrobial peptides rich in arginine (R) and tryptophan (W) interact with membranes. To learn how this interaction leads to bacterial death, we characterized the effects of the minimal pharmacophore RWRWRW-NH 2 . A ruthenium-substituted derivative of this peptide localized to the membrane in vivo, and the peptide also integrated readily into mixed phospholipid bilayers that resemble Gram-positive membranes. Proteome and Western blot analyses showed that integration of the peptide caused delocalization of peripheral membrane proteins essential for respiration and cell-wall biosynthesis, limiting cellular energy and undermining cell-wall integrity. This delocalization phenomenon also was observed with the cyclic peptide gramicidin S, indicating the generality of the mechanism. Exogenous glutamate increases tolerance to the peptide, indicating that osmotic destabilization also contributes to antibacterial efficacy. Bacillus subtilis responds to peptide stress by releasing osmoprotective amino acids, in part via mechanosensitive channels. This response is triggered by membrane-targeting bacteriolytic peptides of different structural classes as well as by hypoosmotic conditions. mechanism of action | respiratory chain | hypoosmotic stress response | metallocenes

The research and development of c-TiAl based alloys for aero-engine and automotive components have been the target of several R & D projects since more than 20 years. [1][2][3] Titanium aluminides are considered for future advanced aero-engines due to their potential of significant component weight savings. Although, remarkable progress has been made, today, titanium aluminides have not been applied for aeroengine parts. Both fundamental materials research and design as well as production technologies have achieved an advanced state of maturity. But overall, the limited tensile ductility, poor crack propagation resistance and detrimental effects of defects, damage and long term cycling loads as well as exposure to hot oxidizing atmospheres on the fatigue life are the mayor concerns in the area of aero-engine components reliability and lifetime issues. There are further needs of understanding the source and effect of the different relevant damages and defects on the life-prediction for a particular titanium aluminide alloy and aero engine component. The attempts of scaling up the production of ingot materials, castings and forgings, have not yet met the required targets of reproducibility and affordability. Large-scale production of titanium aluminides ingots and parts requires further alloy and process development to become a reliable technology. Current titanium and nickel alloys exhibit balanced properties and achieve all requirements of the current design practices.Intermetallic c-TiAl based alloys are certainly among the most promising candidates to fulfill the required thermal and mechanical specifications. Especially, TiAl alloys with high Nb-contents showing a baseline composition of Ti-(42-45)Al-(5-10)Nb-(0-0.5)B (all compositions are stated in at%), termed TNB alloys, have attracted much attention because of their high creep strength, good ductility at room temperature, good fatigue properties, and excellent oxidation resistance. [1][2][3][4][5][6][7] Nb reduces the stacking fault energy in c-TiAl, retards diffusion processes and modifies the structure of the oxidation layer. [4,6,8] Cast alloys based on Ti-(42-45)Al, which solidify via the body-centered cubic b-phase, exhibit an isotropic, equiaxed and texture-free microstructure with modest micro-segregation, whereas peritectic alloys (solidification via the hexagonal a-phase) show anisotropic microstructures as well as significant texture and segregation. [9] Alloy design concepts for c-TiAl based alloys showing refined cast microstructures were recently reported by Imayev et al. [10] An alloy design strategy to improve the hot-workability of TiAl alloys is to exploit a combination of thermo-mechanical processing and additional alloying elements to induce the disordered b-phase at elevated temperatures as ductile phase. [11][12][13][14][15][16][17] The disordered b-phase with bcc lattice provides a sufficient number of independent slip systems. Thus, it may improve the deformability at elevated temperature, where, for example, processes such as rollin...

SummaryThe opportunistic pathogen Legionella pneumophila employs the Icm/Dot type IV secretion system and ∼300 different effector proteins to replicate in macrophages and amoebae in a distinct 'Legionella-containing vacuole' (LCV). LCVs from infected RAW 264.7 macrophages were enriched by immuno-affinity separation and density gradient centrifugation, using an antibody against the L. pneumophila effector SidC, which specifically binds to the phosphoinositide PtdIns(4)P on the pathogen vacuole membrane. The proteome of purified LCVs was determined by mass spectrometry (data are available via ProteomeXchange with identifier PXD000647). The proteomics analysis revealed more than 1150 host proteins, including 13 small GTPases of the Rab family. Using fluorescence microscopy, 6 novel Rab proteins were confirmed to localize on pathogen vacuoles harbouring wild-type but not ΔicmT mutant L. pneumophila. Individual depletion of 20 GTPases by RNA interference indicated that endocytic GTPases (Rab5a, Rab14 and Rab21) restrict intracellular growth of L. pneumophila, whereas secretory GTPases (Rab8a, Rab10 and Rab32) implicated in Golgi-endosome trafficking promote bacterial replication. Upon silencing of Rab21 or Rab32, fewer LCVs stained positive for Rab4 or Rab9, implicated in secretory or retrograde trafficking respectively. Moreover, depletion of Rab8a, Rab14 or Rab21 significantly decreased the number of SidC-positive LCVs, suggesting that PtdIns(4)P is reduced under these conditions. L. pneumophila proteins identified in purified LCVs included proteins putatively implicated in phosphorus metabolism and as many as 60 Icm/Dottranslocated effectors, which are likely required early during infection. Taken together, the phagocyte and Legionella proteomes of purified LCVs lay the foundation for further hypothesis-driven investigations of the complex process of pathogen vacuole formation.