In vitro increases in plasmid DNA supercoiling by hydrostatic pressure

Self-nanoemulsifying drug delivery systems: formulation insights, applications and advances

There has been a resurgence of interest in nanoemulsions for various pharmaceutical applications since low-energy emulsification methods, such as spontaneous or self-nanoemulsification, have been described. Self-nanoemulsifying drug delivery systems (SNEDDS) are anhydrous homogenous liquid mixtures consisting of oil, surfactant, drug and coemulsifier or solubilizer, which spontaneously form oil-in-water nanoemulsion of approximately 200 nm or less in size upon dilution with water under gentle stirring. The physicochemical properties, drug solubilization capacity and physiological fate considerably govern the selection of the SNEDDS components. The composition of the SNEDDS can be optimized with the help of phase diagrams, whereas statistical experimental design can be used to further optimize SNEDDS. SNEDDS can improve oral bioavailability of hydrophobic drugs by several mechanisms. The conversion of liquid SNEDDS to solid oral dosage forms or solid SNEDDS has also been achieved by researchers. Solid SNEDDS can offer better patient compliance and minimize problems associated with capsules filled with liquid SNEDDS.

Prokaryotic lifestyles in deep sea habitats

Gradients of physicochemical factors influence the growth and survival of life in deep-sea environments. Insights into the characteristics of deep marine prokaryotes has greatly benefited from recent progress in whole genome and metagenome sequence analyses. Here we review the current state-of-the-art of deep-sea microbial genomics. Ongoing and future genome-enabled studies will allow for a better understanding of deep-sea evolution, physiology, biochemistry, community structure and nutrient cycling.

The unique 16S rRNA genes of piezophiles reflect both phylogeny and adaptation

In the ocean's most extreme depths, pressures of 70 to 110 megapascals prevent the growth of all but the most hyperpiezophilic (pressure-loving) organisms. The physiological adaptations required for growth under these conditions are considered to be substantial. Efforts to determine specific adaptations permitting growth at extreme pressures have thus far focused on relatively few gamma-proteobacteria, in part due to the technical difficulties of obtaining piezophilic bacteria in pure culture. Here, we present the molecular phylogenies of several new piezophiles of widely differing geographic origins. Included are results from an analysis of the first deep-trench bacterial isolates recovered from the southern hemisphere (9.9-km depth) and of the first gram-positive piezophilic strains. These new data allowed both phylogenetic and structural 16S rRNA comparisons among deep-ocean trench piezophiles and closely related strains not adapted to high pressure. Our results suggest that (i) the Circumpolar Deep Water acts as repository for hyperpiezophiles and drives their dissemination to deep trenches in the Pacific Ocean and (ii) the occurrence of elongated helices in the 16S rRNA genes increases with the extent of adaptation to growth at elevated pressure. These helix changes are believed to improve ribosome function under deep-sea conditions.

Pressure effects on in vivo microbial processes

Pressures between 10 and 100 MPa can exert powerful effects on the growth and viability of organisms. Here I describe the effects of elevated pressure in this range on mesophilic (atmospheric pressure adapted) and piezophilic (high-pressure adapted) microorganisms. Examination of pressure effects on mesophiles makes use of this unique physical parameter to aid in the characterization of fundamental cellular processes, while in the case of piezophiles it provides information on the essence of the adaptation of life to high-pressure environments, which comprise the bulk of our biosphere. Research is presented on the isolation of pressure-resistant mutants, high-pressure regulation of gene expression, the role of membrane lipids and proteins in determining growth ability at high pressure, pressure effects on DNA replication and topology as well as on cell division, and the role of extrinsic factors in modulating enzyme activity at high pressure.