In the course of our efforts to resolve Pi transport mechanisms in the model fungus Neurospora crassa we identified a null mutant, par-1, that displays enhanced Pi transport activity specifically under alkaline growth conditions. The PAR-1 protein is related to PalF of Aspergillus nidulans, which is one component of an ambient pH signaling pathway that is conserved among fungi. A deletion mutant for the PacC homolog, another component of the same pathway, phenocopies par-1, demonstrating that a defect in pH signaling is responsible for the altered Pi transport activity. Our results indicate that pH signaling in N. crassa plays an important role in coordinating high and low affinity Pi transport in response to ambient pH, but through different mechanisms. Sulfate acquisition also is influenced by pH signaling, suggesting that this regulatory system has a broad role in nutrient uptake and homeostasis.

Thesis (M.A.)--Ohio State University, 1954. / Available online via OhioLINK's ETD Center

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 112-114).

Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 79-81.

Thesis--University of Hawaii. / "Prepared for International Decade of Ocean Exploration ... and Office of Naval Research under contract no. N00014-70-0016-0001." Bibliography: p. 155-164.

The western phosphate field produced about 15 percent, in 1970, of the nation's domestically consumed phosphate rock and contains an estimated 58 percent of the nation's indicated phosphate reserves. The central portion of the western phosphate field, which contains the Dry Valley area of southeastern Idaho, encompasses the greatest amount of mineable phosphate reserves in the smallest geographic area within the western field. Exploration of properties in the area should follow an orderly sequence of literature search, area reconnaissance, detailed target appraisal, and detailed three-dimensional sampling to effectively evaluate each property. Present exploration techniques include topographic analysis, vegetative investigation, profile drilling patterns using a portable rotary-table drilling rig, geophysical logging of the drill holes including gamma-radiation logs, neutron logs, temperature gradient and differential temperature logs, and bulk density logs, trenching, tunneling, and test mining. The economic analysis of exploration programs embodies bookkeeping, project cost forecasting and an economic analysis of alternate methods of exploration. The evaluation of individual phosphate properties includes such variables as geology, mining characteristics, alternate concepts in reserve calculation, transportation and governmental policies. The structural geology of the Dry Valley area is less complex than the structural geology of other phosphate deposits in the western phosphate field. Yet most structural features outlined by drilling in Dry Valley occur elsewhere in the western phosphate field. The stratigraphy of the Phosphoria Formation and its Meade Peak Phosphatic Shale Member is simple and correlatable throughout southeastern Idaho through the use of gamma-radiation logs. The history of land acquisition and property evaluation by FMC in Dry Valley covers a relatively short eight-year period. Future plans for companies operating in the western phosphate field include trading and selling of properties to build mineable units covering large volumes of the estimated 300,000,000 tons of economically surface extractable ore in the Dry Valley vicinity.

Phosphorus is an essential element for plant growth and development. Due to its low availability, solubility and mobility, phosphate is often the limiting macronutrient for crops and other plants. Plants have evolved several responses to phosphate deficiency. However, very little is known about the molecular basis of these responses. Here, I study the expression of PAP12, its role in the phosphate starvation response and the interaction of its promoter with nuclear factors. Analysis of a PAP12 T-DNA insertion line (pap12-1) revealed PAP12 is responsible for the majority of the acid phosphatase activity detected by the standard in-gel assay. RNA gel blots showed that PAP12 was induced only by Pi deficiency, and not by general nutrient stress. PAP12 expression, at the RNA and protein level, reflected endogenous phosphate levels in two mutants with altered phosphate accumulation. In the pho1 mutant, PAP12 expression and activity were up-regulated with respect to wild-type plants, and in the pho2 mutant, PAP12 expression and activity were reduced. Analysis of the PAP12 promoter using promoter-GUS fusions revealed expression in leaves, roots, flowers, hydathodes, root tips, and pollen grains. This broad pattern of expression suggests that PAP12 functions throughout the plant in response to low phosphate concentrations. The results showed PAP12 does not play a major role in phosphate remobilization, acquisition or in helping plants cope with low phosphate environments. Instead, the major phenotype associated with PAP12 deficiency was a significant delay in flowering in the low-phosphate pho1 background and a slight acceleration of flowering in the high-phosphate pho2 background over-expressing PAP12. These results suggest that PAP12 may have a role in linking phosphate status with the transition to flowering. Finally, I used promoter deletion and DNA-protein interaction assay to understand PAP12 expression upon phosphate starvation. A 35-bp region of the PAP12 promoter was identified as an important phosphate regulatory cis-element required for induction during phosphate starvation. We isolated a 23.5 kDa nuclear factor, which binds to this 35-bp region of the PAP12 promoter in a phosphate-dependent manner. The work presented here will add to our knowledge about the molecular processes that regulate phosphate nutrition.

Phosphorus is an essential element for plant growth and development. Due to its low availability, solubility and mobility, phosphate is often the limiting macronutrient for crops and other plants. Plants have evolved several responses to phosphate deficiency. However, very little is known about the molecular basis of these responses. Here, I study the expression of PAP12, its role in the phosphate starvation response and the interaction of its promoter with nuclear factors. Analysis of a PAP12 T-DNA insertion line (pap12-1) revealed PAP12 is responsible for the majority of the acid phosphatase activity detected by the standard in-gel assay. RNA gel blots showed that PAP12 was induced only by Pi deficiency, and not by general nutrient stress. PAP12 expression, at the RNA and protein level, reflected endogenous phosphate levels in two mutants with altered phosphate accumulation. In the pho1 mutant, PAP12 expression and activity were up-regulated with respect to wild-type plants, and in the pho2 mutant, PAP12 expression and activity were reduced. Analysis of the PAP12 promoter using promoter-GUS fusions revealed expression in leaves, roots, flowers, hydathodes, root tips, and pollen grains. This broad pattern of expression suggests that PAP12 functions throughout the plant in response to low phosphate concentrations. The results showed PAP12 does not play a major role in phosphate remobilization, acquisition or in helping plants cope with low phosphate environments. Instead, the major phenotype associated with PAP12 deficiency was a significant delay in flowering in the low-phosphate pho1 background and a slight acceleration of flowering in the high-phosphate pho2 background over-expressing PAP12. These results suggest that PAP12 may have a role in linking phosphate status with the transition to flowering. Finally, I used promoter deletion and DNA-protein interaction assay to understand PAP12 expression upon phosphate starvation. A 35-bp region of the PAP12 promoter was identified as an important phosphate regulatory cis-element required for induction during phosphate starvation. We isolated a 23.5 kDa nuclear factor, which binds to this 35-bp region of the PAP12 promoter in a phosphate-dependent manner. The work presented here will add to our knowledge about the molecular processes that regulate phosphate nutrition.

Chez les plantes, alors qu'il est clair que l'homéostasie des différents nutriments est fortement dépendante les uns des autres, ils sont généralement étudiés indépendamment les uns des autres. Étant donné la rareté des études antérieures évaluant la signification biologique de l'interaction de l'homéostasie des nutriments minéraux, on en sait très peu sur la base génétique et moléculaire de ces interactions. Au cours de ma thèse, nous avons progressé de manière significative vers une compréhension plus intégrative du problème et identifié les bases moléculaires et génétiques d'une interaction nutritive très importante et conservée: l'interaction du zinc et du phosphate, dans laquelle les gènes PHO1;H3 et Lyso PhosphatidylCholine (PC) AcylTransferase 1 (LPCAT1) jouent des rôles centraux. En combinant des approches de biologie systémique et de biologie fonctionnelle, nous avons identifié le module fonctionnel (quatre facteurs transcriptions) qui régule l'expression de PHO1; H3 en condition de carence en Zn. Suite à une étude de génétique d’association (GWAS) nous avons découvert un nouveau rôle du gène LPCAT1 dans l’accumulation du phosphate en conditions de carence en Zn, Ensuite, nous avons déterminé une voie moléculaire complète contrôlant l'expression de ce gène. Ce travail nous permis de révéler un lien fondamental entre le métabolisme des phospholipides et l'interaction homéostasie Pi-Zn, et de proposer un nouveau rôle pour Lyso-PC et PC dans le contrôle de l'interaction homéostasie macro- et micronutriments chez les plantes. Les résultats obtenus offrent une nouvelle perspective pour élabore des nouvelles stratégies pour améliorer l’accumulation de Pi dans les plantes via la modulation de la voie de signalisation de la carence en Zn. / In plants, while it is clear the homeostasis of different nutrients is highly dependent on each other, they are usually studied independent of each other. Given the paucity of past studies assessing the biological significance of mineral nutrient homeostasis interaction, very little is known about the genetic and molecular basis of such interactions. During my thesis, we made significant progress in going towards a more integrative comprehension of the problem and identify the molecular and genetic bases for a highly important and conserved nutrients interaction: the interaction of zinc and phosphate. First, using the phosphate transporter PHO1;H3 as entry molecular point, and by combining system biology and functional genomics approaches we have identified the functional module (four transcription factors) that regulates the expression and activity of PHO1;H3 under Zn deficiency leading to control Pi accumulation in shoots. Second, following our discovery of Lyso PhosphatidylCholine (PC) AcylTransferase 1 (LPCAT1) using genome-wide association studies (GWAS), we determined complete molecular pathway controlling the expression of this gene. We further uncovered a fundamental link between phospholipid metabolism and Pi-Zn homeostasis interaction via LPCAT1, which lays the foundations to explore a new role for Lyso-PC and PC in control of macro- and micronutrients homeostasis interaction. Taken together, our discoveries offer a new perspective on how to improve Pi content in plants, as our findings suggests that modulating the Zn-deficiency signalling pathway might be a good and simple approach for that.

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