A previously reported piggyBac minimal sequence cartridge, which is capable of efficient transposition in embryo interplasmid transposition assays, failed to produce transformants at a significant frequency in Drosophila melanogaster compared with full-length or less extensive internal deletion constructs. We have re-examined the importance of these internal domain (ID) sequences for germline transformation using a PCR strategy that effectively adds increasing lengths of ID sequences to each terminus. A series of these piggyBac ID synthetic deletion plasmids containing the 3xP3-ECFP marker gene are compared for germline transformation of D. melanogaster. Our analyses identify a minimal sequence configuration that is sufficient for movement of piggyBac vectored sequences from plasmids into the insect genome. Southern hybridizations confirm the presence of the piggyBac transposon sequences, and insertion site analyses confirm these integrations target TTAA sites. The results verify that ID sequences adjacent to the 5' and 3' terminal repeat domains are crucial for effective germline transformation with piggyBac even though they are not required for excision or interplasmid transposition. Using this information we reconstructed an inverted repeat cartridge, ITR1.1k, and a minimal piggyBac transposon vector, pXL-BacII-ECFP, each of which contains these identified ID sequences in addition to the terminal repeat configuration previously described as essential for mobility. We confirm in independent experiments that these new minimal constructs yield transformation frequencies similar to the control piggyBac vector. Sequencing analyses of our constructs verify the position and the source of a point mutation within the 3' internal repeat sequence of our vectors that has no apparent effect on transformation efficiency.

Mosquito-vectored diseases such as yellow fever and dengue fever continue to have a substantial impact on human populations world-wide. Novel strategies for control of these mosquito vectored diseases can arise through the development of reliable systems for genetic manipulation of the insect vector. A piggyBac vector marked with the Drosophila melanogaster cinnabar (cn) gene was used to transform the white-eyed khw strain of Aedes aegypti. Microinjection of preblastoderm embryos resulted in four families of cinnabar transformed insects. An overall transformation frequency of 4%, with a range of 0% to as high as 13% for individual experiments, was achieved when using a heat-shock induced transposase providing helper plasmid. Southern hybridizations indicated multiple insertion events in three of four transgenic lines, while the presence of duplicated target TTAA sites at either ends of individual insertions confirmed characteristic piggyBac transposition events in these three transgenic lines. The transgenic phenotype has remained stable for more than twenty generations. The transformations effected using the piggyBac element establish the potential of this element as a germ-line transformation vector for Aedine mosquitoes.

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Data are presented on the insulating properties and capacitance-voltage (CV) characteristics of metal-oxide-semiconductor (MOS) device-thickness (below ~100 nm) native oxides formed by wet thermal oxidation of thin InAlP epilayers lattice matched to GaAs. Low leakage current densities of J=1.4 x 10 -9 A/cm 2 and J=8.7 x 10 -11 A/cm 2 are observed at an applied field of 1 MV/cm for MOS capacitors fabricated with 17 nm and 48 nm oxides, respectively. TEM images show that the In-rich interfacial particles which exist in 110 nm oxides are absent in 17 nm oxide films. Quasi-static capacitance-voltage measurements of MOS capacitors fabricated on both n-type and p-type GaAs show that the InAlP oxide-GaAs interface is sufficiently free of traps to 1 support inversion, indicating an unpinned Fermi level. These data suggest that InAlP native oxides may be a viable insulator for GaAs MOS device applications. 2Due to the wide array of high electron mobility alloys of varying bandgaps that can be epitaxially grown on its surface, GaAs remains the most widely used semiconductor for high-speed electronic applications. While Schottky gates are commonly used in high-speed GaAs transistors, the restricted forward bias (a few tenths of a volt) that can be applied without excessive gate leakage currents limits their power handling capability.The electrical characteristics of native oxides of GaAs are far inferior to those of SiO 2 on Si, and an alternative insulator has long been pursued 1,2 to enable the preferred metal-insulator-semiconductor gate structure. Many deposited insulator/GaAs structures have been investigated, although only a few have yielded promising results. 3-6 Native oxide films on GaAs can offer advantages of processing convenience and low cost.Wet thermal oxides of AlGaAs 7 have been studied but found to suffer from midgap traps caused by residual interfacial As. 8 These traps lead to increased interface recombination velocity 9,10 and high leakage currents. 11 However, the wet thermal oxides of As-free As shown in the bright-field TEM images of Fig. 2, dark particles exist near the oxide/GaAs interface in the 110 nm oxide of Fig. 2 (a), while no dark interfacial particles appear in the 17 nm oxide of Fig. 2 (b). Fig. 2 (b) is representative of the entire observable area for this and a second wedge-polished cross section specimen, with the absence of particles also confirmed for plan-view specimens (not shown) in which possible loss of particles due to ion milling and electron beam interactions is suppressed by the fact that they are protected from the vacuum by the substrate and overlying oxide film. The interfacial particles in Fig. 2 (a) are believed to be indium rich based on Z-contrast TEM images 16 (not shown) and Auger depth profiling. 17 The size of the particles increases with the progressive consumption of the InAlP epilayer during oxidation. 16 We hypothesize that In, the heaviest element in the structure, outdiffuses more slowly than the other alloy constituents and hence accumulates near the inter...