Biology of archaea from a novel family Cuniculiplasmataceae (Thermoplasmata) ubiquitous in hyperacidic environments

The order Thermoplasmatales (Euryarchaeota) is represented by the most acidophilic organisms known so far that are poorly amenable to cultivation. Earlier culture-independent studies in Iron Mountain (California) pointed at an abundant archaeal group, dubbed 'G-plasma'. We examined the genomes and physiology of two cultured representatives of a Family Cuniculiplasmataceae, recently isolated from acidic (pH 1-1.5) sites in Spain and UK that are 16S rRNA gene sequence-identical with 'G-plasma'. Organisms had largest genomes among Thermoplasmatales (1.87-1.94 Mbp), that shared 98.7-98.8% average nucleotide identities between themselves and 'G-plasma' and exhibited a high genome conservation even within their genomic islands, despite their remote geographical localisations. Facultatively anaerobic heterotrophs, they possess an ancestral form of A-type terminal oxygen reductase from a distinct parental clade. The lack of complete pathways for biosynthesis of histidine, valine, leucine, isoleucine, lysine and proline pre-determines the reliance on external sources of amino acids and hence the lifestyle of these organisms as scavengers of proteinaceous compounds from surrounding microbial community members. In contrast to earlier metagenomics-based assumptions, isolates were S-layer-deficient, non-motile, non-methylotrophic and devoid of iron-oxidation despite the abundance of methylotrophy substrates and ferrous iron in situ, which underlines the essentiality of experimental validation of bioinformatic predictions

Preparation and Characterization of a Lovastatin-Loaded Protein-Free Nanostructured Lipid Carrier Resembling High-Density Lipoprotein and Evaluation of its Targeting to Foam Cells

This study was designed to investigate whether a non-protein nanostructured lipid carrier (NLC) resembling high-density lipoprotein (HDL) could deliver a hydrophobic anti-atherogenic drug, lovastatin, to foam cells. Lovastatin-loaded NLC (LT-NLC) was prepared by a nanoprecipitation/solvent diffusion method. The LT-NLC-apoprotein (LT-NLC-apo) was prepared by incubating LT-NLC with native HDL. The physicochemical parameters of LT-NLC were characterized in terms of particle size, zeta potential, morphology, entrapment efficiency, and crystallization behavior. Targeting behavior and mechanism were demonstrated by the incubation of LT-NLC-apo with a RAW 264.7 macrophage-derived foam cell model in the presence or absence of very-low-density lipoprotein (VLDL) and lipase. The results showed that LT-NLC was solid spherical or oval in shape with an average diameter of 13.8 ± 2.2 nm, zeta potential of −29.3 ± 0.2 mV and entrapment efficiency of 96.2 ± 1.3%. Phagocytosis studies showed that uptake of LT-NLC-apo by macrophages was significantly lower than LT-NLC (p < 0.01), suggesting that LT-NLC-apo could possibly escape recognition from macrophages in vivo. The uptake was increased twofold when LT-NLC-apo was incubated with transfected foam cells containing VLDL and lipase. These results indicated that non-protein NLC resembling HDL could be a useful tool to deliver lipophilic anti-atherogenic drugs to foam cells, and that uptake could be enhanced by the VLDL receptor pathway

Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to resistance; and strengthen the case for a role in survival of systems involved in manganese and iron homeostasis

Towards Computer-Supported Self-debriefing of a Serious Game Against Cyber Bullying

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