Use of Ion-Channel Modulating Agents to Study Cyanobacterial Na(+) - K(+) Fluxes

Here we describe an experimental design aimed to investigate changes in total cellular levels of Na(+) and K(+) ions in cultures of freshwater filamentous cyanobacteria. Ion concentrations were measured in whole cells by flame photometry. Cellular Na(+) levels increased exponentially with rising alkalinity, with K(+) levels being maximal for optimal growth pH (~8). At standardized pH conditions, the increase in cellular Na(+), as induced by NaCl at 10 mM, was coupled by the two sodium channel-modulating agents lidocaine hydrochloride at 1 μM and veratridine at 100 μM. Both the channel-blockers amiloride (1 mM) and saxitoxin (1 μM), decreased cell-bound Na(+) and K(+) levels. Results presented demonstrate the robustness of well-defined channel blockers and channel-activators in the study of cyanobacterial Na(+)- K(+) fluxes

Untapped Resources: Biotechnological Potential of Peptides and Secondary Metabolites in Archaea

Archaea are an understudied domain of life often found in “extreme” environments in terms of temperature, salinity, and a range of other factors. Archaeal proteins, such as a wide range of enzymes, have adapted to function under these extreme conditions, providing biotechnology with interesting activities to exploit. In addition to producing structural and enzymatic proteins, archaea also produce a range of small peptide molecules (such as archaeocins) and other novel secondary metabolites such as those putatively involved in cell communication (acyl homoserine lactones), which can be exploited for biotechnological purposes. Due to the wide array of metabolites produced there is a great deal of biotechnological potential from antimicrobials such as diketopiperazines and archaeocins, as well as roles in the cosmetics and food industry. In this review we will discuss the diversity of small molecules, both peptide and nonpeptide, produced by archaea and their potential biotechnological applications

Carotenoid analysis of Halophilic Archaea by Resonance Raman spectroscopy

This is the publisher's version, also available electronically from "http://online.liebertpub.com".Recently, halite and sulfate evaporate rocks have been discovered on Mars by the NASA rovers, Spirit and Opportunity. It is reasonable to propose that halophilic microorganisms could have potentially flourished in these settings. If so, biomolecules found in microorganisms adapted to high salinity and basic pH environments on Earth may be reliable biomarkers for detecting life on Mars. Therefore, we investigated the potential of Resonance Raman (RR) spectroscopy to detect biomarkers derived from microorganisms adapted to hypersaline environments. RR spectra were acquired using 488.0 and 514.5 nm excitation from a variety of halophilic archaea, including Halobacterium salinarum NRC-1, Halococcus morrhuae, and Natrinema pallidum. It was clearly demonstrated that RR spectra enhance the chromophore carotenoid molecules in the cell membrane with respect to the various protein and lipid cellular components. RR spectra acquired from all halophilic archaea investigated contained major features at approximately 1000, 1152, and 1505 cm−1. The bands at 1505 cm−1 and 1152 cm−1 are due to in-phase C=C (ν1 ) and C–C stretching ( ν2 ) vibrations of the polyene chain in carotenoids. Additionally, in-plane rocking modes of CH3 groups attached to the polyene chain coupled with C–C bonds occur in the 1000 cm−1 region. We also investigated the RR spectral differences between bacterioruberin and bacteriorhodopsin as another potential biomarker for hypersaline environments. By comparison, the RR spectrum acquired from bacteriorhodopsin is much more complex and contains modes that can be divided into four groups: the C=C stretches (1600–1500 cm−1), the CCH in-plane rocks (1400–1250 cm−1), the C–C stretches (1250–1100 cm−1), and the hydrogen out-of-plane wags (1000–700 cm−1). RR spectroscopy was shown to be a useful tool for the analysis and remote in situ detection of carotenoids from halophilic archaea without the need for large sample sizes and complicated extractions, which are required by analytical techniques such as high performance liquid chromatography and mass spectrometry

Identification and Characterization of Helicobacter pylori Genes Essential for Gastric Colonization

Helicobacter pylori causes one of the most common, chronic bacterial infections and is a primary cause of severe gastric disorders. To unravel the bacterial factors necessary for the process of gastric colonization and pathogenesis, signature tagged mutagenesis (STM) was adapted to H. pylori. The Mongolian gerbil (Meriones unguiculatus) was used as model system to screen a set of 960 STM mutants. This resulted in 47 H. pylori genes, assigned to 9 different functional categories, representing a set of biological functions absolutely essential for gastric colonization, as verified and quantified for many mutants by competition experiments. Identification of previously known colonization factors, such as the urease and motility functions validated this method, but also novel and several hypothetical genes were found. Interestingly, a secreted collagenase, encoded by hp0169, could be identified and functionally verified as a new essential virulence factor for H. pylori stomach colonization. Furthermore, comB4, encoding a putative ATPase being part of a DNA transformation-associated type IV transport system of H. pylori was found to be absolutely essential for colonization, but natural transformation competence was apparently not the essential function. Thus, this first systematic STM application identified a set of previously unknown H. pylori colonization factors and may help to potentiate the development of novel therapies against gastric Helicobacter infections

Genome-wide Analyses Identify KIF5A as a Novel ALS Gene

To identify novel genes associated with ALS, we undertook two lines of investigation. We carried out a genome-wide association study comparing 20,806 ALS cases and 59,804 controls. Independently, we performed a rare variant burden analysis comparing 1,138 index familial ALS cases and 19,494 controls. Through both approaches, we identified kinesin family member 5A (KIF5A) as a novel gene associated with ALS. Interestingly, mutations predominantly in the N-terminal motor domain of KIF5A are causative for two neurodegenerative diseases: hereditary spastic paraplegia (SPG10) and Charcot-Marie-Tooth type 2 (CMT2). In contrast, ALS-associated mutations are primarily located at the C-terminal cargo-binding tail domain and patients harboring loss-of-function mutations displayed an extended survival relative to typical ALS cases. Taken together, these results broaden the phenotype spectrum resulting from mutations in KIF5A and strengthen the role of cytoskeletal defects in the pathogenesis of ALS.Peer reviewe

Micromorphological and chemical investigation of late-Viking age grave fills at Hofstaðir, Iceland

Grave fills from seven human burials from a late-Viking age - early medieval cemetery at Hofstaðir, Mývatnssveit (Iceland) were examined by soil micromorphology and organic chemical analysis. Detailed analysis of the weathering of the mineral constituents of the grave fills demonstrates a relationship between the extent of weathering of volcanic silicates within the fills and the presence of buried human remains. Gas chromatography-mass spectrometry (GC–MS) of extracts from the fills and controls of two graves revealed organic signatures dominated by plant-derived organic matter, with no evidence of degradation products of the body tissues. Transformation of n-alkanes into n-alkan-2-ones provides evidence for microbial activity within the fills. GC–MS analysis of the organic extract from under one of the skulls and pyrolysis gas chromatography of wood fragments found in that grave provide compelling evidence for the former presence of a conifer wood coffin. The use of this non-native wood in the burial provides evidence for either the import of foreign lumber or the utilisation of driftwood, most likely originating from Russia/Siberia