The Fraser fir (Abies fraseri (Pursh) Poir.) on Mt. Rogers is an isolated relic population and part of the southern Appalachian spruce-fir ecosystem. The population has, so far, been able to withstand the impacts of insect infestation and the possible influence of atmospheric deposition factors which may be causing mortality in other regions of the southern Appalachians. It was hypothesized that population vigor may be due to a unique genetic structure. The objective of this study was to determine the amount of genetic diversity within this population and to relate observed diversity to environmental variables. To quantify the genetic structure 304 trees from 35 plots were genotyped for 13 isozyme loci. Four loci were polymorphic using the 95% criterion. At a fifth locus there were two rare alleles with a combined frequency of approximately 3%. Range wide studies of eastern fir species have shown that other populations are more diverse. There were no significant differences in gene frequencies among three arbitrarily defined subpopulations or among the 35 plots. There were no significant correlations between any environmental characters and isozyme frequencies. There was a significant difference among subpopulations for seed weight and germination value as well as a slight, yet significant, correlation between seed weight and elevation, germination value and elevation, and germination value and aspect. Spatial autocorrelation analysis, Wright's F-statistics, Nei's genetic distances, and Gregorius' "𝜹" index all indicated little or no substructuring of the population. It is suggested that a population bottleneck (a drastic reduction of population numbers), which may have occurred following the last glaciation, is the cause for the relatively low genetic diversity found in the population. The lack of substructure is likely due to extensive gene flow. / Ph. D.

Indiana University-Purdue University Indianapolis (IUPUI) / ALDH isoenzymes are known to impact the sensitivity of certain neoplastic cells toward cyclophosphamides and its analogs. Despite its bone marrow toxicity, cyclophos-phamide is still used to treat various recalcitrant forms of cancer. When activated, cyclo-phosphamide forms aldophosphamide that can spontaneously form the toxic phospho-ramide mustard, an alkylating agent unless detoxified by ALDH isozymes to the carbox-yphosphamide metabolite. Prior work has demonstrated that the ALDH1A1 and ALDH3A1 isoenzymes can convert aldophosphamide to carboxyphosphamide. This has also been verified by over expression and siRNA knockdown studies. Selective small molecule inhibitors for these ALDH isoenzymes are not currently available. We hypothe-sized that novel and selective small molecule inhibitors of ALDH3A1 would enhance cancer cells’ sensitivity toward cyclophosphamide. If successful, this approach can widen the therapeutic treatment window for cyclophosphamides; permitting lower effective dos-ing regimens with reduced toxicity. An esterase based absorbance assay was optimized in a high throughput setting and 101, 000 compounds were screened and two new selective inhibitors for ALDH3A1, which have IC50 values of 0.2 µM (CB7) and 16 µM (CB29) were discovered. These two compounds compete for aldehyde binding, which was vali-dated both by kinetic and crystallographic studies. Structure activity relationship dataset has helped us determine the basis of potency and selectivity of these compounds towards ALDH3A1 activity. Our data is further supported by mafosfamide (an analog of cyclo-phosphamide) chemosensitivity data, performed on lung adenocarcinoma (A549) and gli-oblastoma (SF767) cell lines. Overall, I have identified two compounds, which inhibit ALDH3A1’s dehydrogenase activity selectively and increases sensitization of ALDH3A1 positive cells to aldophosphamide and its analogs. This may have the potential in improving chemotherapeutic efficacy of cyclophosphamide as well as to help us understand better the role of ALDH3A1 in cells. Future work will focus on testing these compounds on other cancer cell lines that involve ALDH3A1 expression as a mode of chemoresistance.