Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xi, 88 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 84-85).

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xvi, 112 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 85-87).

Hybrids and polyploids are very common in plants and some animals. Although hybrid vigor or heterosis has been widely adopted in agricultural practices, the underlying mechanisms are poorly understood partly because of their multigenic nature and the lack of a good model system for the study. Allotetraploidy is an emerging model system for investigating molecular mechanisms of hybrid vigor. An allotetraploid is formed by interspecific hybridization followed by chromosome doubling or hybridization between two autotetraploid parents and is genetically stable. A previous study showed nonadditive expression (different from the mid-parent value) of over 5% of genes in the allotetraploids, suggesting altered transcriptional and post-transcriptional regulation. Here oligo-gene microarray analysis of mRNA stability in allotetraploids was carried out to investigate how nonadditive gene regulation upon allopolyploidization is achieved at the posttranscriptional level. Approximately 1% of annotated genes were identified as unstable transcripts, and their estimated half-life is less than 60 minutes. The unstable transcripts in Arabidopsis allotetraploids are associated with nonadditive gene expression and with stress and environmental responses. The nonadditively expressed genes identified in the previous study include those encoding proteins involved in energy and metabolic pathways, which are putative targets of circadian clock regulators. To test how circadian clock genes affect downstream genes and pathways, expression of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) was up- or down-regulated by overexpressing CCA1 or cca1(RNAi) driven by the promoter of TIMING OF CAB EXPRESSION 1 (TOC1). Upregulation of CCA1 was associated with repression of downstream genes in chlorophyll biosynthesis and starch metabolism, whereas down-regulation of CCA1 correlated with upregulation of these downstream genes. As a result, chlorophyll and starch content was ~10% higher in the TOC1::cca1(RNAi) transgenic plants than the controls, while the growth vigor is lower in the TOC1::CCA1 transgenic plants. To further test the effects of clock genes in growth vigor, CCA1 expression was examined in reciprocal hybrids of A. thaliana ecotypes. The maternal effect on starch content was observed in several combinations of hybrids, which was correlated with preferential expression of maternal CCA1 during early stages of seed development. Although the cause of parent-of-origin effects is still unclear, the data have clearly documented parent-of-origin effects on circadian clock gene expression and starch metabolism in hybrids. / text

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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An integrated circuit processing schedule is presented that enables fabrication of both high speed I²L gates and high voltage linear type transistors on the same silicon starting substrate material. This process design circumvents conflicting processing requirements normally encountered in considering an I²L/Linear compatible structure by providing two separate epitaxial thicknesses for the I²L and linear section of the chip. The electrical characteristics of the I²L cells and the linear transistors are presented to illustrate their dependence on the doping conditions and are shown to be in contrast to each other. As a consequence of the separate epitaxial thicknesses, independence of the processing constraints is achieved. Experimental results of linear transistors and I²L devices fabricated using this processing schedule are presented and compared to calculated and computer simulations. Modifications to the basic process design is shown possible and enhanced performance of I²L devices results.

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