1970-1979 Theses (MU)
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Item Characteristics of litter decomposition in the Grassland Biome of the United States(University of Missouri--Columbia, 1976) Schnauss, Janet; Kucera, Clair L.The Grassland Biome in the United States includes tail grass, annual, shortgrass, mixed prairie, and mountain grass lands. This extensive region ranges from Indiana and portions of Ohio westward to the Rocky Mountains and beyond. Widespread areas such as these are (subject to climatic variations.) Similarly, this wide range of environmental conditions plays a major role in ecosystem dynamics. Rates of decomposition and nutrient recycling are especially influenced by temperature and moisture conditions. Warm, moist climates enhance decom position rates, whereas, cooler and/or drier climates would have a retarding effect.Item Biosystematics of the Lupinus mexicanus complex(University of Missouri--Columbia, 1976) Rafaill, Barbara L; Dunn, David B."Lupinus mexicanus was the first taxon in the genus Lupinus named for Mexico; therefore, the establishment of its identity and description became of substantial importance to the taxonomy of the complex it represented, as well as to the systematics of the genus in Mexico. Work was formally initiated on the Lupinus mexicanus complex after Dunn (1972) probed into the perplexing question of the taxon, L. mexicanus, and proposed the illustration in Edward’s Botanical Register (#457; 1820) serve as the type. The present monograph represents an effort to reveal the limits of the complex beginning with the previously ignored taxon, L. mexicanus. It also attempts to resolve the systematic and nomenclatural problems which resulted from such an investigation. Pursuit of a complete understanding of the Lupinus mexicanus complex involved reviewing taxonomic literature and correlating and comparing it with as many herbarium specimens as could be obtained relating to the complex. Distribution, ecology, and plant associations of the populations under study were noted. Morphological studies were performed. In addition to these traditional approaches to taxonomy, alkaloid thin-layer chromatography and breeding studies, including pollen viability, were also incorporated. Thus, a biosystematic approach was utilized in evaluating the Lupinus mexicanus complex of Mexico."--Introduction.Item Isolation and characterization of photosystem I and II membrane particles from the blue-green alga, Synechococcus cedrorum(University of Missouri--Columbia, 1978) Newman, Peter Jay; Sherman, Louis A."Photosynthesis is the process of converting sunlight into chemical energy which can be utilized for the biosynthesis of useful organic molecules. This metabolic process has been termed the most important series of reactions to take place on earth, for it alone makes available the ultimate source of energy, sunlight, to nearly all heterotrophic organisms. Photosynthesis that leads to the evolution of oxygen is an event that occurs in all green plants, in the eucaryotic algae, and in the procaryotic blue-green algae. Although the process itself is several billion years old, its discovery and early study date back only as far as the late 18th century. Obviously, a process as fundamental as photosynthesis deserves considerable interest and examination. However, only in the last 25 years has any real progress been made in understanding the complex nature of the mechanism by which light is converted into useful chemical energy."--Introduction.Item Lethal effect of visible fluorescent light on human cells in culture(University of Missouri--Columbia, 1977) Nixon, Bryan Tracy; Wang, Richard J.Human D98/AH2 epithelial cells in serum-free Dulbecco’s modified Eagle's culture medium depleted of phenol red were not able to divide and form clones subsequent to illumination by "Daylight," "Special Blue" or "Bilirubin" broad-spectrum visible fluorescent lamps. The dose of light required to produce this inhibition of clonal growth increased with increasing cell density. Irradiation of serum-free medium alone was sufficient to effect trypan blue staining and cell fragmentation within a few hours after treatment with exposed medium. Cell killing was found to be caused by the formation of toxic photoproducts from medium components riboflavin, tryptophan and/or tyrosine. Hydrogen peroxide was determined to be one such photoproduct, responsible for approxiamately half of the medium toxicity. Adjusting riboflavin, tyrosine and phenol red concentrations altered the production rate of products toxic for D98 cells and 3T6-DF8 fibroblasts. When included in the medium during irradiation, the reducing agents cysteine, reduced glutathione and sodium pyruvate also inhibited the formation of toxic photoproducts. In an appendix are results indicating that cells are able to detoxify exposed medium, that irradiation of the serum component bilirubin also yields toxic photoproducts, that generated hydrogen peroxide may induce single strand breaks in cellular DNA, and that D98 cells may become more resistant to toxic photoproducts with the addition of trace amounts of selenium.Item Seasonal fluctuations in the benthic and planktonic communities of the Salt River, Missouri(University of Missouri--Columbia, 1977) Meierhoff, Murray Leo; Hazelwood, Donald H."Introduction: The Salt River has been intensively studied in the past ten years due to its pending impoundment. The purpose of this study is to determine the seasonal trends in the abundance and distribution of zooplankton and macrobenthos in the Salt River. When combined with previous works, this study will provide a baseline for comparison for future studies of the Salt River after its impoundment."--Page 1.