Lethality and Developmental Delay in Drosophila melanogaster Larvae after Ingestion of Selected Pseudomonas fluorescens Strains

The fruit fly, Drosophila melanogaster, is a well-established model organism for probing the molecular and cellular basis of physiological and immune system responses of adults or late stage larvae to bacterial challenge. However, very little is known about the consequences of bacterial infections that occur in earlier stages of development. We have infected mid-second instar larvae with strains of Pseudomonas fluorescens to determine how infection alters the ability of larvae to survive and complete development.We mimicked natural routes of infection using a non-invasive feeding procedure to study the toxicity of the three sequenced P. fluorescens strains (Pf0-1, SBW25, and Pf-5) to Drosophila melanogaster. Larvae fed with the three strains of P. fluorescens showed distinct differences in developmental trajectory and survival. Treatment with SBW25 caused a subset of insects to die concomitant with a systemic melanization reaction at larval, pupal or adult stages. Larvae fed with Pf-5 died in a dose-dependent manner with adult survivors showing eye and wing morphological defects. In addition, larvae in the Pf-5 treatment groups showed a dose-dependent delay in the onset of metamorphosis relative to control-, Pf0-1-, and SBW25-treated larvae. A functional gacA gene is required for the toxic properties of wild-type Pf-5 bacteria.These experiments are the first to demonstrate that ingestion of P. fluorescens bacteria by D. melanogaster larvae causes both lethal and non-lethal phenotypes, including delay in the onset of metamorphosis and morphological defects in surviving adult flies, which can be decoupled

O NMR of terminal oxygen: application of the tool of increasing electron demand

The 17O shift values δ0 of over 100 benzoyl compounds of the type p-YC6H4COX are discussed, with X comprising 14 different elements directly bound to carbonyl. In terms of the "tool of increasing electron demand", the sensitivity ρ+ to variation of Y is a measure of the electrophilicity of -COX. It is used to approximate the bond order term of the Karplus-Pople equation; the electronic excitation energy term is taken, as usual, from the UV-Vis absorption. Depending upon the position of X in the Periodic Table, variation of one or the other of these terms prevails for determining changes of δ0; this demonstrates that the two terms are, to a certain degree, independent from one another

Total, Asymmetric-Synthesis of (1r)-1-C-(6'-Amino-7'h-Purin-8'-Yl)-1,4-Anhydro-3-Azido-2,3-Dideoxy-D-Er Ythro-Pentitol

The "naked sugar" (+)-(1R,2R,4R)-2-cyano-7-oxabicyclo[2.2.1]hept-5-en-2-exo-yl acetate ((+)-3) was converted in ten synthetic steps into the new C-nucleoside (1R)-1-C-(6'-amino-7'H-purin-8'-yl)-1,4-anhydro-3-azido-2,3-dideoxy-D-er ythro-pentitol ((+)-2) in 19% overall yield

Passivation of nanocrystalline TiO2 junctions by surface adsorbed phosphinate amphiphiles enhances the photovoltaic performance of dye sensitized solar cells

We report a new class of molecular insulators that electronically passivate the surface of nanocrystalline titania films for high performance dye sensitized solar cells (DSC). Using electrical impedance measurements we demonstrate that co-adsorption of dineohexyl bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP), along with the amphiphilic ruthenium sensitizer Z907Na increased substantially the power output of the cells mainly due to a retardation of interfacial recombination of photo-generated charge carriers. The use of phosphinates as anchoring groups opens up new avenues for modification of the surface by molecular insulators, sensitizers and other electro-active molecules to realize the desired optoelectronic performance of devices based on oxide junctions

High-efficiency (7.2%) flexible dye-sensitized solar cells with Ti-metal substrate for nanocrystalline-TiO2 photoanode

High-efficiency flexible dye-sensitized solar cells were fabricated with a Ti-metal foil substrate for photo anode and using a Pt-electrodeposited counter electrode on ITO/polyethylene naphthalate (ITO/PEN); these devices were characterized by incident photon-to-current efficiency (IPCE), optical transmittance and electrical impedance spectroscopy

Polymer wiring of insulating electrode materials: An approach to improve energy density of lithium-ion batteries

10.1016/j.elecom.2009.04.030Electrochemistry Communications1171350-1352ECCM