The objective of this dissertation is to introduce low-cost processing methods for the fabrication of ZnO transparent thin-film transistors (TTFTs). A novel method for depositing ZnO body layers via spin-coating of a zinc nitrate-based spin solution is presented. The processing conditions of spin-coated ZnO are optimized to produce continuous and...
RNA silencing is an evolutionarily conserved system that
functions as an antiviral mechanism in higher plants and
insects. To counteract RNA silencing, viruses express
silencing suppressors that interfere with both siRNA- and
microRNA-guided silencing pathways. We used comparative
in vitro and in vivo approaches to analyse the molecular
mechanism of...
Forest health issues are on the rise in the United States, resulting from introduction of alien pests and diseases, coupled with abiotic stresses related to climate change. Increasingly, forest scientists are finding genetic/genomic resources valuable in addressing forest health issues. For a set of ten ecologically and economically important native...
A study was made of the subgenus Genuini of the genus Juncus in the Pacific States, California, Oregon and Washington. Extensive morphological comparisons, geographical distributions, habitat differences and observations of apparent presence or absence of natural hybrids provided the major data sources. Cytological studies were made, but were inconclusive. Eleven...
Invasive plants have the capacity to transform landscapes and alter ecosystem function, causing significant economic and ecological damage. These effects include displacement and reduction of native flora and fauna, altered fire regimes, modification of biotic and abiotic soil properties, as well as local, regional, and global economic impacts. With such...
A cytogeographical study was made of populations of tetraploid
(n=18) and hexaploid (n=27) Achillea millefolium (Compositae-
Anthemideae) from the Pacific Coast states. There is a complex
distributional pattern, involving overlapping ranges, mixed populations,
migration of one form into areas occuplied by the other,
pentaploid hybrids, and septaploid and octoploid plants....
A fossil seed cone with characters that have been hypothesized as transitional to the origin of crown group gnetophytes has been discovered in Lower Cretaceous deposits on Vancouver Island, British Columbia, Canada. This cone, described as Protoephedrites eamesii gen. et sp. nov., provides the first anatomically preserved fossil evidence for...
Cyanobacterial harmful algae blooms (cyanoHABs) are a growing concern worldwide due to damage of ecosystems and threats to human health. Previous research indicates that plant humics from aquatic and wetland vascular plants are effective inhibitors of cyanobacterial metabolism and growth and may be useful as control agents for mitigating cyanoHABs....
Premise of research. A third genus of anatomically preserved conifer seed cones has been recognized from
a Late Jurassic deposit in northeastern Scotland. This cone is described as Bancroftiastrobus digitata Rothwell,
Mapes, Stockey et Hilton.
Methodology. The cone was sectioned with the classic coal ball peel technique and studied and...
Transcriptome analysis of Pseudomonas fluorescensSBW25 showed that 702 genes were differentially regulated in a gacS::Tn5 mutant, with 300 and 402 genes up- and downregulated respectively. Similar to the Gac regulon of other Pseudomonas species, genes involved in motility, biofilm formation, siderophore biosynthesis and oxidative stress were differentially regulated in the...
A multi-year field study was conducted in Oregon and Washington to evaluate the influence of nitrogen fertilization rate and timing on cone quality, nitrate accumulation in cones, severity of powdery mildew (caused by Podosphaera macularis), arthropod pests, and the stability of conservation biological control of the twospotted spider mite (Tetranychus...
A cylindrical permineralized conifer seed cone has been identified from the Officer Member of the Trowbridge Formation, near Izee, in east-central Oregon. The cone is preserved in a Middle Jurassic (Callovian) marine calcium carbonate concretion, associated with araucarian seed cones, conifer twigs and wood, cycad seeds, fern rachides, and lycopodialean...
• Premise of the study: Colonists of even the most inhospitable environments, lichens are present in all terrestrial ecosystems.
Because of their ecological versatility and ubiquity, they have been considered excellent candidates for early colonizers of terrestrial
environments. Despite such predictions, good preservation potential, and the extant diversity of lichenized...
Rhizopogon is a large genus of ectomycorrhizal (EM) fungi that grows in association with host trees of the family Pinaceae. We have conducted a series of studies investigating the ecology and evolutionary biology of the EM symbiosis shared between R. subgenus Villosuli and trees of the genus Pseudotsuga. Two members...
Mosses (Phylum Bryophyta) are widely considered to be among the most ancient groups of land plants (embryophytes) and they are the second most speciose embryophyte phylum with ~13,000 extant species. Despite their diversity and antiquity, mosses have a limited fossil record, which primarily consists of gametophytes entombed in Cenozoic amber....
The binary power law (BPL) has been successfully used to characterize heterogeneity (overdispersion or small-scale aggregation) of disease incidence for many plant pathosystems. With the BPL, the log of the observed variance is a linear function of the log of the theoretical variance for a binomial distribution over the range...
Premise of study: Sequence analyses for Pinaceae have suggested that extant genera diverged in the late Mesozoic. While the fossil record indicates that Pinaceae was highly diverse during the Cretaceous, there are few records of living genera. This description of an anatomically preserved seed cone extends the fossil record for...
Accurate taxonomy is essential to preservation and management of native
grasses. Four problems in fescue taxonomy were investigated: the identity of the
native fescue that dominates western Oregon and Washington prairies, the relationship
of native Festuca roemeri to closely related grasses, the status of F. howellii and F.
washingtonica, and...
Data from nuclear ribosomal internal transcribed spacer regions (nrITS) and chloroplast DNA (cpDNA) have failed to resolve phylogenetic relationships in Pinus. To provide greater interspecific resolution, five low-copy nuclear genes were developed from mapped conifer anchor loci. Four genes were sequenced from species representing all Pinus subsections. Individual loci do...
The leaf surface is a stark environment for bacterial colonists with limited
availability of nutrients, water and protected niches. Despite these limitations, a
plethora of bacteria appear to have adapted ways to survive and flourish on leaf
surfaces. One mechanism of survival is the formation of biofilms. Biofilms are a...