Heterostructures for Optical Devices

Contains research objectives and reports on eight research projects.Joint Services Electronics Program (Contract DAAL03-86-K-0002)Joint Services Electronics Program (Contract DAALO3-89-C-0001)National Science Foundation (Grant EET 87-03404)Charles Stark Draper Laboratory (Contract DL-H-315251)Xerox Corporation FellowshipMIT Fund

Heterostructures for High Performance Devices

Contains an introduction, reports on thirteen research projects and a list of publications.Charles S. Draper Laboratory Contract DL-H-418483DARPA/NCIPT Subcontract 542383Joint Services Electronics Program Contract DAAL03-89-C-0001IBM Corporation FellowshipNational Science Foundation FellowshipVitesse SemiconductorAT&T Bell LaboratoriesHertz Foundation FellowshipNational Science FoundationTRWBelgian American Education Foundation (BAEF) FellowshipNational Science Foundation Grant ECS 90-08485Harvard University. Division of Applied PhysicsAT&T Bell Laboratories FellowshipNational Science Foundation Grant ECS 90-0774

Heterostructures for High Performance Devices

Contains an introduction and reports on ten research projects.Charles S. Draper Laboratory, Contract DL-H-315251Joint Services Electronics Program, Contract DAAL03-89-C-0001National Science Foundation Grant, Grant EET 87-03404MIT FundsInternational Business Machines CorporationNational Science Foundation Grant ECS 84-1317

Heterostructures for High Performance Devices

Contains table of contents for Part I, table of contents for Section 1, an introduction, reports on eighteen research projects and a list of publications.Charles S. Draper Laboratories Contract DL-H-418483DARPA/NCIPTJoint Services Electronics Program Contract DAAL03-89-C-0001Joint Services Electronics Program Contract DAAL03-92-C-0001IBM Corporation FellowshipNational Science Foundation FellowshipVitesse SemiconductorGTE LaboratoriesCharles S. Draper LaboratoriesElectronics and Telecommunications Research Institute (ETRI) FellowshipNational Science Foundation/Northeastern UniversityTRW SystemsU.S. Army Research OfficeNational Science FoundationAT&T Bell Laboratories FellowshipNational Science Foundation Grant ECS 90-0774

Two Plant Viral Suppressors of Silencing Require the Ethylene-Inducible Host Transcription Factor RAV2 to Block RNA Silencing

RNA silencing is a highly conserved pathway in the network of interconnected defense responses that are activated during viral infection. As a counter-defense, many plant viruses encode proteins that block silencing, often also interfering with endogenous small RNA pathways. However, the mechanism of action of viral suppressors is not well understood and the role of host factors in the process is just beginning to emerge. Here we report that the ethylene-inducible transcription factor RAV2 is required for suppression of RNA silencing by two unrelated plant viral proteins, potyvirus HC-Pro and carmovirus P38. Using a hairpin transgene silencing system, we find that both viral suppressors require RAV2 to block the activity of primary siRNAs, whereas suppression of transitive silencing is RAV2-independent. RAV2 is also required for many HC-Pro-mediated morphological anomalies in transgenic plants, but not for the associated defects in the microRNA pathway. Whole genome tiling microarray experiments demonstrate that expression of genes known to be required for silencing is unchanged in HC-Pro plants, whereas a striking number of genes involved in other biotic and abiotic stress responses are induced, many in a RAV2-dependent manner. Among the genes that require RAV2 for induction by HC-Pro are FRY1 and CML38, genes implicated as endogenous suppressors of silencing. These findings raise the intriguing possibility that HC-Pro-suppression of silencing is not caused by decreased expression of genes that are required for silencing, but instead, by induction of stress and defense responses, some components of which interfere with antiviral silencing. Furthermore, the observation that two unrelated viral suppressors require the activity of the same factor to block silencing suggests that RAV2 represents a control point that can be readily subverted by viruses to block antiviral silencing

Defensin-Like ZmES4 Mediates Pollen Tube Burst in Maize via Opening of the Potassium Channel KZM1

Species-preferential osmotic pollen tube burst and sperm discharge in maize involve induced opening of the pollen tube-expressed potassium channel KZM1 by the egg apparatus-derived defensin-like protein ZmES4

Quantitative determination of tenuazonic acid in pig and broiler chicken plasma by LC-MS/MS and its comparative toxicokinetics

A liquid chromatography–tandem mass spectrometry (LC-MS/MS) method to quantitate tenuazonic acid (TeA) in pig and broiler chicken plasma was successfully developed and validated. Linear matrix-matched calibration curves ranged between 5 and 200 ng/mL. Correlation coefficients, goodness-of-fit coefficients, and within-day and between-day precision and accuracy fell well within the acceptance criteria. The limit of quantitation was 5.0 ng/mL in both pig and broiler chicken plasma. The LC-MS/MS method was applied in a comparative toxicokinetic study in both pigs and broiler chickens. TeA was completely bioavailable after oral administration in both animal species. However, absorption was deemed to be slower in broiler chickens (mean tmax 0.32 h in pigs vs 2.60 h in chickens). TeA was more slowly eliminated in broiler chickens (mean t1/2el 0.55 h in pigs vs 2.45 h in chickens after oral administration), mainly due to the significantly lower total body clearance (mean Cl 446.1 mL/h/kg in pigs vs 59.2 mL/h/kg in chickens after oral administration). Tissue residue studies and further research to elucidate the biotransformation and excretion processes of TeA in pigs, broiler chickens, and other animal species are imperative