Combined transgenic expression of Punica granatum conjugase (FADX) and FAD2 desaturase in high linoleic acid Arabidopsis thaliana mutant leads to increased accumulation of punicic acid.

MAIN CONCLUSION: Arabidopsis was engineered to produce 21.2 % punicic acid in the seed oil. Possible molecular factors limiting further accumulation of the conjugated fatty acid were investigated. Punicic acid (18:3Δ(9cis,11trans,13cis) ) is a conjugated linolenic acid isomer and is a main component of Punica granatum (pomegranate) seed oil. Medical studies have shown that punicic acid is a nutraceutical with anti-cancer and anti-obesity properties. It has been previously demonstrated that the conjugated double bonds in punicic acid are produced via the catalytic action of fatty acid conjugase (FADX), which is a homolog of the oleate desaturase. This enzyme catalyzes the conversion of the Δ(12)-double bond of linoleic acid (18:2Δ(9cis,12cis) ) into conjugated Δ(11trans) and Δ(13cis) -double bonds. Previous attempts to produce punicic acid in transgenic Arabidopsis thaliana seeds overexpressing P. granatum FADX resulted in a limited accumulation of punicic acid of up to 4.4 %, accompanied by increased accumulation of oleic acid (18:1∆(9cis) ), suggesting that production of punicic acid in some way inhibits the activity of oleate desaturase (Iwabuchi et al. 2003). In the current study, we applied a new strategy to enhance the production of punicic acid in a high linoleic acid A. thaliana fad3/fae1 mutant background using the combined expression of P. granatum FADX and FAD2. This approach led to the accumulation of punicic acid at the level of 21 % of total fatty acids and restored the natural proportion of oleic acid observed in the A. thaliana fad3/fae1 mutant. In addition, we provide new insights into the high oleate phenotype and describe factors limiting the production of punicic acid in genetically engineered plants.

Possible allostery and oligomerization of recombinant plastidial sn-glycerol-3-phosphate acyltransferase.

Plastidial acyl-acyl carrier protein:sn-glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15) catalyzes the acyl-acyl carrier protein-dependent sn-1 acylation of sn-glycerol 3-phosphate (G3P) to produce lysophosphatic acid. Functional recombinant Erysimum asperum GPAT (EaGPAT), devoid of transit peptide, was produced in yeast. Analysis of the dependence of EaGPAT activity on increasing G3P concentration resulted in a hyperbolic response. EaGPAT exhibited a preference for 18-carbon unsaturated acyl-CoAs. Assays with concentrations of oleoyl-CoA up to 90µM revealed an exponential response to increasing concentrations of acyl donor, and the introduction of increasing concentrations of unlabeled linoleoyl-CoA into the standard reaction mixture resulted in increased incorporation of radiolabeled oleoyl moieties into lysophosphatidic acid. Collectively, the kinetic results suggest that acyl-CoA may act as both substrate and allosteric effector. EaGPAT was also shown to oligomerize to form higher molecular mass multimers, with the monomer and trimer being the predominant forms of the enzyme. Since most allosteric enzyme exhibit quaternary structure, the self-associating properties of EaGPAT are consistent with those of an allosteric enzyme. These results could have important regulatory implications when plastidial GPAT is introduced into a cytoplasmic environment where acyl-CoA is the acyl donor supporting cytoplasmic glycerolipid assembly.

Rapid Growth of Nanostructured Diamond Film on Silicon and Ti-6Al-4V Alloy Substrates.

Nanostructured diamond (NSD) films were grown on silicon and Ti-6Al-4V alloy substrates by microwave plasma chemical vapor deposition (MPCVD). NSD Growth rates of 5 µm/h on silicon, and 4 µm/h on Ti-6Al-4V were achieved. In a chemistry of H2/CH4/N2, varying ratios of CH4/H2 and N2/CH4 were employed in this research and their effect on the resulting diamond films were studied by X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. As a result of modifying the stock cooling stage of CVD system, we were able to utilize plasma with high power densities in our NSD growth experiments, enabling us to achieve high growth rates. Substrate temperature and N2/CH4 ratio have been found to be key factors in determining the diamond film quality. NSD films grown as part of this study were shown to contain 85% to 90% sp³ bonded carbon.

LIFE: a sustainable solution for developing safe, clean fusion power.

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in California is currently in operation with the goal to demonstrate fusion energy gain for the first time in the laboratory-also referred to as "ignition." Based on these demonstration experiments, the Laser Inertial Fusion Energy (LIFE) power plant is being designed at LLNL in partnership with other institutions with the goal to deliver baseload electricity from safe, secure, sustainable fusion power in a time scale that is consistent with the energy market needs. For this purpose, the LIFE design takes advantage of recent advances in diode-pumped, solid-state laser technology and adopts the paradigm of Line Replaceable Units used on the NIF to provide high levels of availability and maintainability and mitigate the need for advanced materials development. The LIFE market entry plant will demonstrate the feasibility of a closed fusion fuel cycle, including tritium breeding, extraction, processing, refueling, accountability, and safety, in a steady-state power-producing device. While many fusion plant designs require large quantities of tritium for startup and operations, a range of design choices made for the LIFE fuel cycle act to reduce the in-process tritium inventory. This paper presents an overview of the delivery plan and the preconceptual design of the LIFE facility with emphasis on the key safety design principles being adopted. In order to illustrate the favorable safety characteristics of the LIFE design, some initial accident analysis results are presented that indicate potential for a more attractive licensing regime than that of current fission reactors.

Decontamination after a release of B. anthracis spores.

Decontaminating civilian facilities or large urban areas following an attack with Bacillus anthracis poses daunting challenges because of the lack of resources and proven technologies. Nevertheless, lessons learned from the 2001 cleanups together with advances derived from recent research have improved our understanding of what is required for effective decontamination. This article reviews current decontamination technologies appropriate for use in outdoor environments, on material surfaces, within large enclosed spaces, in water, and on waste contaminated with aerosolized B. anthracis spores.

Rigorous surface enhanced Raman spectral characterization of large-area high-uniformity silver-coated tapered silica nanopillar arrays.

Surface enhanced Raman spectroscopy (SERS) has been increasingly utilized as an analytical technique with significant chemical and biological applications (Qian et al 2008 Nat. Biotechnol. 26 83; Fujita et al 2009 J. Biomed. Opt. 14 024038; Chou et al 2008 Nano Lett.8 1729; Culha et al 2003 Anal. Chem. 75 6196; Willets K A 2009 Anal. Bioanal. Chem. 394 85; Han et al 2009 Anal. Bioanal. Chem. 394 1719; Sha et al 2008 J. Am. Chem. Soc. 130 17214). However, production of a robust, homogeneous and large-area SERS substrate with the same ultrahigh sensitivity and reproducibility still remains an important issue. Here, we describe a large-area ultrahigh-uniformity tapered silver nanopillar array made by laser interference lithography on the entire surface of a 6 inch wafer. Also presented is the rigorous optical characterization method of the tapered nanopillar substrate to accurately quantify the Raman enhancement factor, uniformity and repeatability. An average homogeneous enhancement factor of close to 10(8) was obtained for benzenethiol adsorbed on a silver-coated nanopillar substrate.

Plasmon resonant cavities in vertical nanowire arrays.

We investigate tunable plasmon resonant cavity arrays in paired parallel nanowire waveguides. Resonances are observed when the waveguide length is an odd multiple of quarter plasmon wavelengths, consistent with boundary conditions of node and antinode at the ends. Two nanowire waveguides satisfy the dispersion relation of a planar metal-dielectric-metal waveguide of equivalent width equal to the square field average weighted gap. Confinement factors over 10(3) are possible due to plasmon focusing in the interwire space.

Real-time chemical imaging of bacterial activity in biofilms using open-channel microfluidics and synchrotron FTIR spectromicroscopy.

Real-time chemical imaging of bacterial activities can facilitate a comprehensive understanding of the dynamics of biofilm structures and functions. Synchrotron-radiation-based Fourier transform infrared (SR-FTIR) spectromicroscopy can yield high spatial resolution and label-free vibrational signatures of chemical bonds in biomolecules, but the abundance of water in biofilms has hindered SR-FTIR's sensitivity in investigating bacterial activity. We developed a simple open-channel microfluidic system that can circumvent the water-absorption barrier for chemical imaging of the developmental dynamics of bacterial biofilms with a spatial resolution of several micrometers. This system maintains a 10 microm thick laminar-flow-through biofilm system that minimizes both the imaging volume in liquid and the signal interference from geometry-induced fringing. Here we demonstrate the ability of the open-channel microfluidic platform to maintain the functionality of living cells while enabling high-quality SR-FTIR measurements. We include several applications that show how microbes in biofilms adapt to their immediate environments. The ability to directly monitor and map bacterial changes in biofilms can yield significant insight into a wide range of microbial systems, especially when coupled to more sophisticated microfluidic platforms.

Modeling the acoustic radiation force in microfluidic chambers.

A procedure is demonstrated to quantitatively evaluate the acoustic radiation forces in microfluidic particle manipulation chambers. Typical estimates of the acoustic pressure and the acoustic radiation force are based on an analytical solution for a simple one-dimensional standing wave pattern. The complexities of a typical microfluidic channel limit the usefulness of this approach. By leveraging finite elements, and a generalized equation for the acoustic radiation force, channel designs can be investigated in two and three dimensions. Calculations and experimental observations in this report and the literature, confirm these claims.