Thesis--University of Florida. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 198-206).

No description available.

Calcium transporters regulate calcium fluxes within cells. Plants, like all organisms, contain channels, pumps and exchangers to carefully modulate intracellular calcium levels. Numerous Arabidopsis proteins have been characterized which can transport calcium. However, there are numerous genes whose products have not been fully characterized. One method I used to infer function was to analyze various promoter lengths of 17 putative cation transporters fused to reporter and to observe changes in the reporter expression in response to various stimuli. Using a more in depth approach I set out to characterize the function of AtCCX3. Here I show Arabidopsis AtCCX3 can suppress yeast mutants defective in vacuolar Na+ and K+ transport. AtCCX3-expressing yeast cells conferred Mn2+ sensitivity when highly expressed. Functional epitope tagged AtCCX3 fusion proteins were localized to endomembranes in plants and yeast. Expression of AtCCX3 increased in plants treated with NaCl, KCl and MnCl2 and caused increased Na+ accumulation and increased K+ transport. Ectopic expression of AtCCX3 in tobacco produced lesions in the leaves, stunted growth, resulted in the accumulation of higher levels of numerous cations and increased protein oxidation preceded alterations in leaf growth. These characteristics define AtCCX3 as an endomembrane localized transporter with biochemical properties distinct from previously characterized plant transporters. In the remaining studies I used the mouse model to determine how molecular changes to plants can improve the nutritional quality of the food. Previously, the cod5 M. truncatula mutant was identified which contains identical calcium concentrations to wild-type, but contains no oxalate crystals. Mice fed intrinsically labeled cod5 plants had 22.87% (p<0.001) calcium absorption compared to wild type plants. In a second study, using mice I examined if increased expression of a calcium transporter which increases calcium concentration 2-fold, alters bioavailable calcium. In mice feeding regimes (n = 120), I measured 45Ca-incorporation into bones, and determined that mice required twice the serving size of control carrots to obtain the calcium found in sCAX1-carrots. Together, these two studies demonstrate how the potential utility of removing calcium absorption inhibitors and fortifying vegetables can improve calcium bioavailability.

Calcium transporters regulate calcium fluxes within cells. Plants, like all organisms, contain channels, pumps and exchangers to carefully modulate intracellular calcium levels. Numerous Arabidopsis proteins have been characterized which can transport calcium. However, there are numerous genes whose products have not been fully characterized. One method I used to infer function was to analyze various promoter lengths of 17 putative cation transporters fused to reporter and to observe changes in the reporter expression in response to various stimuli. Using a more in depth approach I set out to characterize the function of AtCCX3. Here I show Arabidopsis AtCCX3 can suppress yeast mutants defective in vacuolar Na+ and K+ transport. AtCCX3-expressing yeast cells conferred Mn2+ sensitivity when highly expressed. Functional epitope tagged AtCCX3 fusion proteins were localized to endomembranes in plants and yeast. Expression of AtCCX3 increased in plants treated with NaCl, KCl and MnCl2 and caused increased Na+ accumulation and increased K+ transport. Ectopic expression of AtCCX3 in tobacco produced lesions in the leaves, stunted growth, resulted in the accumulation of higher levels of numerous cations and increased protein oxidation preceded alterations in leaf growth. These characteristics define AtCCX3 as an endomembrane localized transporter with biochemical properties distinct from previously characterized plant transporters. In the remaining studies I used the mouse model to determine how molecular changes to plants can improve the nutritional quality of the food. Previously, the cod5 M. truncatula mutant was identified which contains identical calcium concentrations to wild-type, but contains no oxalate crystals. Mice fed intrinsically labeled cod5 plants had 22.87% (p<0.001) calcium absorption compared to wild type plants. In a second study, using mice I examined if increased expression of a calcium transporter which increases calcium concentration 2-fold, alters bioavailable calcium. In mice feeding regimes (n = 120), I measured 45Ca-incorporation into bones, and determined that mice required twice the serving size of control carrots to obtain the calcium found in sCAX1-carrots. Together, these two studies demonstrate how the potential utility of removing calcium absorption inhibitors and fortifying vegetables can improve calcium bioavailability.

Alpha-1-microglobulin is co-synthesized with bikunin on the AMBP gene (

Thesis (Ph. D.)--University of Minnesota. / Manuscript copy. Vita.

M. Tech. (Department of Biotechnology, Faculty of Applied and Computer Sciences), Vaal University of Technology / Taro [Colocasia esculenta (L) Schott] belongs to the family Araceae. It is an important staple food crop grown mainly by small scale farmers in many parts of the world. Taro is also grown in South Africa from the costal parts of the northern Eastern Cape to the KwaZulu-Natal north coast. Although it is an important staple crop in South Africa, very little information exists on the genetic diversity of the crop. Knowledge of the genetic diversity of a crop is important for breeding programmes. The aim of this study is to assess the genetic diversity of taro using morphological and molecular techniques and to determine the calcium oxalate content of 25 South African taro accessions. This study showed that the aerial portions of taro are variable for most quantitative characters. Most of the morphological variation was due to lamina length, petiole length, lamina width and plant girth that explained 54% of the variance in principal component analysis. The number of raphides was able to divide the accessions into two groups, one with relatively low counts and the other with high counts. Ntumeni had the lowest raphide count of only 27 ±12 raphides and Modderfontein had the highest count with 1150 ±104 raphides. Twelve accessions having low raphide counts ranging from 27 ±12 to 147 ±28 raphides per cell have been identified. RAPD data separated the accessions into three main groups that were further divided into five subgroups. The accessions did not group according to geographical locations. The ITS2 sequence generated clustering patterns that were similar to that obtained from RAPDs. The variation in the ITS2 secondary structure of taro included one common motif that was present in all 25 accessions. Some motifs were only present in some accessions. The discovery of these motifs strengthens the potential of the ITS2 region as a taxonomic marker and a powerful barcode for taro. The ITS2 motifs provide the means of identifying each of the 25 accessions of taro. The high genetic diversity, morphological variation and accessions with low calcium oxalate content found in this study provide taro breeders a selection of parent crops for the improvement of taro.

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