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2002

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Articles 1 - 30 of 33

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Analysis Of Protistan Grazing On Bioremediative Bacteria Using In Wvo Fluorescent Protein Expression And Flow Cytometry, Yutao Fu Dec 2002

Analysis Of Protistan Grazing On Bioremediative Bacteria Using In Wvo Fluorescent Protein Expression And Flow Cytometry, Yutao Fu

Electronic Theses and Dissertations

Protistan bacterivory can influence the size distribution, cell structure and composition of natural bacterial communities and is of significant concern for design of bioremediation efforts, yet adequate methods for observation and modeling are lacking. In this investigation, fluorescent protein expression and flow cytometry were used to study protistan grazing on genetically modified strains of several bacterial species that have been considered for use in bioremediation. Broad-host-range plasmids were constructed and used to introduce genes encoding GFP (green fluorescent protein) or RFP (red fluorescent protein) to prey species. A heterotrophic flagellate Paraphysomonas imperforata (Hflag) served as a model predator. Predator-prey interactions ...


Critical Amino Acids Of The Gα2 Subunit Helical Domain In Dictyostelium Discoideum, Steven Martin Rauch Dec 2002

Critical Amino Acids Of The Gα2 Subunit Helical Domain In Dictyostelium Discoideum, Steven Martin Rauch

Electronic Theses and Dissertations

In Dictyostelium discoideum organism, the Gα2 subunit of the heterotrimeric G-protein signaling complex plays a pivotal role during the aggregation stage in the Dictyostelium life cycle. The biochemical functions of the G-protein complex include separation of the G-protein coupled receptor from the G-protein subunits, GDP displacement by GTP in the Gα subunit, separation of the Gα monomer from the βγ complex, GTP hydrolysis to GDP, activation of adenylyl cyclase as a downstream effector, and activation of guanylyl cyclase as a separate downstream effector. Upon release from the heterotrimer, the βγ subunits lead to downstream activation of the membrane bound adenylyl ...


Investigation Of Biochemical Mechanisms Associated With Insulin Resistance In The Non-Insulin-Dependent Diabetes Mellitus, To-Yu Huang Aug 2002

Investigation Of Biochemical Mechanisms Associated With Insulin Resistance In The Non-Insulin-Dependent Diabetes Mellitus, To-Yu Huang

Doctoral Dissertations

Non-insulin dependent diabetes mellitus (NIDDM) is a heterogeneous disease arising from metabolic defects in insulin secretion and insulin action. The inability of insulin to trigger full metabolic responses results in impaired glucose transport, which elicits compensatory hyperinsulinemia with increased lipogenesis. In order to identify the molecular defects responsible for insulin resistance, we have investigated three different model systems: the ability of sulfonylurea receptor (SUR) ligands to modify insulin regulated events in cultured rodent adipocytes; the ability of agouti and/or agouti related polypeptide (AGRP) to modify insulin regulated events; and the regulation of the activity and amount of the HNF-1a ...


Involvement Of Platelet-Derived Growth Factor, Pdgf Receptor Signaling, Focal Adhesion Kinase And Src In Pressure-Induced Vascular Smooth Muscle Hypertrophy, Darian Clark Rice Jul 2002

Involvement Of Platelet-Derived Growth Factor, Pdgf Receptor Signaling, Focal Adhesion Kinase And Src In Pressure-Induced Vascular Smooth Muscle Hypertrophy, Darian Clark Rice

Theses and Dissertations in Biomedical Sciences

Elevated blood pressure is associated with varying degrees of arterial remodeling. The mechanisms by which extracellular mechanical stress is converted into intracellular alterations in signal transduction and gene expression have yet to be fully elucidated. Our goal was to investigate the early events in the vascular smooth muscle response to acute hypertension and to identify mediators involved in long-term hypertensive remodeling.

In the acute phase of hypertension we targeted cell surface integrin and growth factor receptors thought to be mechanically sensitive. The signaling molecules FAK, Src and ERK-MAPK are known to be triggered by integrin engagement and growth factor receptor ...


Analysis Of Candidate Proteins Interacting With Eyal, Ryan Schwanke Apr 2002

Analysis Of Candidate Proteins Interacting With Eyal, Ryan Schwanke

Life and Environmental Sciences Undergraduate Theses

The Eyal gene is important for mammalian organogenesis, and mutations in the human EYA1 results in Branchio-Oto-Renal (BOR) syndrome. This syndrome is autosomal dominant and causes combinations of branchial, otic, and renal anomalies. All Eya gene products contain an extremely conserved 271 amino acid C-terminus that is essential in protein-protein interaction. Recently, it was found that during mouse development, the expression of certain Six genes relied on the function of Eyal, and that Eyal interacts with relevant Six proteins through its C-terminal domain. These results provided insight into the molecular and developmental basis for organ defects occurring in BOR syndrome ...


Prostate Specific Membrane Antigen (Psma): Immunoassay Development And Characterization Of Transcriptional Regulation, Zhen Xiao Apr 2002

Prostate Specific Membrane Antigen (Psma): Immunoassay Development And Characterization Of Transcriptional Regulation, Zhen Xiao

Theses and Dissertations in Biomedical Sciences

Prostate cancer (PCA) is the most common cancer and the second leading cause of death among American men. The high mortality is greatly attributed to the lack of early detection tools and effective treatment for metastasis and relapses. Biomarkers that can discriminate benign from malignant tumor and signal the development of androgen independent and metastatic tumor are needed. A biomarker designated prostate specific membrane antigen (PSMA) has the potential to fulfill this need. The objective of this study is to develop a clinically useful immunoassay for quantitation of serum PSMA and to study the molecular mechanism underlying the upregulation of ...


Molecular Genetic Studies Of Acetyl-Coa Carboxylase And 3-Methylcrotonyl-Coa Carboxylase In Plants , Hui-Rong Qian Jan 2002

Molecular Genetic Studies Of Acetyl-Coa Carboxylase And 3-Methylcrotonyl-Coa Carboxylase In Plants , Hui-Rong Qian

Retrospective Theses and Dissertations

Similar reverse-genetics approach is applied to investigate the function of two biotin-containing enzymes at the interface between catabolism and anabolism: acetyl-CoA carboxylase (ACCase) and 3-methylcrotonyl-CoA carboxylase (MCCase).;Plastidic ACCase catalyzes the first committed step of de novo fatty acid biosynthesis. Antisense Arabidopsis expressing antisense RNA of CAC1-A, which encodes the biotin carboxyl carrier protein (BCCP) of plastidic ACCase under the direction of CaMV 35S promoter, have been obtained. CAC1-A antisense plants with reduced BCCP possess different degrees of similar morphological changes. These include slow growth, smaller plant size, and crinkly and variegated-yellow vegetative and cauline leaves eventually leading to premature ...


A Dynamical Perspective On Enzymatic Catalysis, Shiying Shang Jan 2002

A Dynamical Perspective On Enzymatic Catalysis, Shiying Shang

Dissertations, Theses, and Masters Projects

No abstract provided.


Conformational Variability In Adenylosuccinate Synthetase As Revealed By Crystal Structures Of Mouse-Muscle And Escherichia Coli Enzymes , Cristina Valeria Iancu Jan 2002

Conformational Variability In Adenylosuccinate Synthetase As Revealed By Crystal Structures Of Mouse-Muscle And Escherichia Coli Enzymes , Cristina Valeria Iancu

Retrospective Theses and Dissertations

Adenylosuccinate synthetase governs the committed step of AMP biosynthesis from IMP: the generation of 6-phosphoryl-IMP from GTP and IMP, followed by the formation of adenylosuccinate from 6-phosphoryl-IMP and L-aspartate. Prokaryotes such as Escherichia coli (E. coli) have a single form of adenylosuccinate synthetase but vertebrates have two isozymes of the synthetase. The basic isozyme, which predominates in muscle, participates putatively in the purine nucleotide cycle, has a higher Km for IMP and exhibits substrate inhibition by this nucleotide. Compared to E. coli structures, there are conformational variations in the IMP pocket both in the ligand-free and IMP-ligated structures of the ...


Recovery Of Recombinant Proteins From Transgenic Plants: Strategies In Implementation And Optimization , Todd J. Menkhaus Jan 2002

Recovery Of Recombinant Proteins From Transgenic Plants: Strategies In Implementation And Optimization , Todd J. Menkhaus

Retrospective Theses and Dissertations

Strategies to optimize the recovery of recombinant proteins from plant hosts have been investigated. The use of different crops, different product molecules, and different separation techniques was studied to suggest modes of operation that reduce the overall processing cost for obtaining purified recombinant proteins from plants.;Polyelectrolyte precipitation of beta-glucuronidase (GUS), an acidic model protein, with polyethyleneimine (PEI), a polycatonic polymer, from the extracts of canola, corn germ, soybean, and pea met with varying degrees of success. Precipitation from canola required the least amount of PEI and was capable of providing the highest enrichment. In contrast, soy and pea allowed ...


Allosteric Regulation Of Fructose-1,6,-Bisphosphatase , Scott William Nelson Jan 2002

Allosteric Regulation Of Fructose-1,6,-Bisphosphatase , Scott William Nelson

Retrospective Theses and Dissertations

Fructose-1,6-bisphosphatase (FBPase) catalyzes the reaction of fructose-1,6-bisphosphate to fructose-6-phosphate and inorganic phosphate. The investigations described here concern the structure and function of FBPase, with special focus on those properties relating to the allosteric regulation of catalysis. It is our hypothesis that a loop spanning residues 52 through 72 plays a crucial role in the mechanism of allosteric regulation. Testing this hypothesis, a fluorescent reporter group was incorporated into loop 52-72, confirming the existence of three states of the loop dependent on the state of ligation: disordered, disengaged, and engaged. Furthermore, restriction of backbone flexibility by replacement of two ...


Nonphotochemical Hole-Burning Imaging Studies Of In Vitro Carcinoma And Normal Cells Utilizing A Mitochondrial Specific Dye , Richard Joseph Walsh Jan 2002

Nonphotochemical Hole-Burning Imaging Studies Of In Vitro Carcinoma And Normal Cells Utilizing A Mitochondrial Specific Dye , Richard Joseph Walsh

Retrospective Theses and Dissertations

Low temperature Nonphotochemical Hole Burning (NPHB) Spectroscopy of the dye rhodamine 800 (MF680) was applied for the purpose of discerning differences between cultured normal and carcinoma ovarian surface epithelial (OSE) cells. Both the cell lines were developed and characterized at the Mayo Clinic (Rochester, MN), with the normal cell line having been transfected with a strain of temperature sensitive Simian Virus 40 Large T Antigen (SV40) for the purpose of extending the life of the cell culture without inducing permanent changes in the characteristics of the cell line. The cationic lipophilic fluorophore rhodamine 800 preferentially locates in in situ mitochondria ...


Irreversible Oxidation Of Protein Cysteine Residues , Michael James Hamann Jan 2002

Irreversible Oxidation Of Protein Cysteine Residues , Michael James Hamann

Retrospective Theses and Dissertations

Cysteine residues have a reduced thiol group that frequently exerts an influence on the function of proteins. Oxidation of the cysteine through S-thiolation, S-nitrosylation, or irreversible oxidation perturbs these functions. Sulfinic and sulfonic acids produced by irreversible oxidation are exceptionally damaging since these modifications are permanent in cells. In order to detect and quantitate both protein sulfinic and sulfonic acids, it was necessary to develop an assay using a novel amino acid analysis procedure. Purified creatine kinase and carbonic anhydrase III were used to establish the method, and the assay produced results that agreed with total cysteine irreversible oxidation determined ...


Functional Characterization Of Mitochondrial And Cytosolic Aldehyde Dehydrogenases In Maize (Zea Mays L) , Feng Liu Jan 2002

Functional Characterization Of Mitochondrial And Cytosolic Aldehyde Dehydrogenases In Maize (Zea Mays L) , Feng Liu

Retrospective Theses and Dissertations

Aldehyde dehydrogenases (ALDHs) are a group of enzymes that catalyze oxidation of aldehydes in the presence of coenzyme NAD+ or NADP+. Few plant ALDHs have been studied at protein level, although many ALDH genes have been cloned. To date no functional characterization of plant ALDHs has been reported. This dissertation is focused on functional characterization of four ALDHs from maize, RF2A, RF2B, RF2C and RF2D. RF2A and RF2B are targeted to mitochondria, while RF2C and RF2D are located in cytosol. RF2A is required for normal pollen development: the anthers in lower florets from spikelets of homozygous mutant rf2a plants in ...


Characterization Of The De Novo Pyrimidine Biosynthetic Pathway In Arabidopsis Thaliana , Christopher W. Kafer Jan 2002

Characterization Of The De Novo Pyrimidine Biosynthetic Pathway In Arabidopsis Thaliana , Christopher W. Kafer

Retrospective Theses and Dissertations

We have characterized the enzyme cytidine deaminase. The full length cDNA was expressed in E. coli and purified to apparent homogeneity using a Ni-NTA agarose column. The Km and Vmax for cytidine were determined to be 226uM and 39.7 umoles/min respectively. The enzyme was also able to use 2'-deoxycytidine as substrate with an apparent Km of 49 uM and Vmax of 24 umoles/min.;We have also developed a single tube semi-quantitative relative reverse transcription polymerase chain reaction (RT-PCR) assay. We have used this assay to quantitate the relative transcript levels of the UMP synthase gene and ...


Molecular Interactions Of Talin And Actin: A Study On The Specific Domains Of Talin Involved In The Interactions , Ho-Sup Lee Jan 2002

Molecular Interactions Of Talin And Actin: A Study On The Specific Domains Of Talin Involved In The Interactions , Ho-Sup Lee

Retrospective Theses and Dissertations

Talin is an essential cytoskeletal protein present in cell-matrix type adherens junctions where it helps in attachment of the actin cytoskeleton to the plasma membrane. The nature of the interaction between talin and actin was examined in this dissertation by investigating three actin binding sites (ABS1--3), with ABS1 located in the 47 kDa N-terminal head and ABS2 and ABS3 present in the 190 kDa C-terminal tail of the talin molecule. Cosedimentation of expressed GST-fusion deletion constructs from the talin head with F-actin showed that actin binding activity of the talin head is contained within residues 271--320. Talin constructs containing the ...


Mechanisms Of Somatostatin-Induced Paradoxical Increase In Insulin Secretion In The Presence Of Arginine Vasopressin In Clonal [Beta]-Cell Hit-T15 , Henrique Cheng Jan 2002

Mechanisms Of Somatostatin-Induced Paradoxical Increase In Insulin Secretion In The Presence Of Arginine Vasopressin In Clonal [Beta]-Cell Hit-T15 , Henrique Cheng

Retrospective Theses and Dissertations

We investigated the mechanism underlying somatostatin-induced increase in [Ca2+]i leading to insulin release in the presence of arginine vasopressin (AVP) in clonal beta-cell HIT-T15. Somatostatin increased [Ca2+]i and insulin release in a biphasic pattern, characterized by a sharp and transient increase followed by a rapid decline to the sub-basal level. Pretreatment with pertussis toxin, which inactivates Gi/Go, abolished the effects of somatostatin. U-73122, an inhibitor of phospholipase C, antagonized somatostatin-induced increase in [Ca2+] i. In Ca2+-free environment, somatostatin still increased [Ca2+]i, whereas depletion of intracellular Ca 2+ stores with thapsigargin, a microsomal Ca2+ ATPase inhibitor ...


Characterization Of The Ftsyex Operon Of Escherichia Coli , Becky Graham Jan 2002

Characterization Of The Ftsyex Operon Of Escherichia Coli , Becky Graham

Retrospective Theses and Dissertations

The ftsYEX operon of Escherichia coli historically has been described as a cluster of essential cell division genes. Filamentation temperature-sensitive (fts) designates a class of mutants that displays normal cell morphology at the permissive temperature of 30°C, but filaments and dies at the restrictive temperature of 42°C. The first gene, ftsY, is known to encode an essential component of a protein localization system first described in eukaryotes, the signal recognition particle (SRP) pathway. The function of the following genes, ftsE and ftsX, are much less understood. It has been shown that FtsE and FtsX comprise a two-component ATP-binding ...


Roles Of The Mitogen-Induced Proteins, Mitogen Regulated Protein/Proliferin And 24p3/Uterocalin, During Mouse Development , Pierig Jean-Marie Lepont Jan 2002

Roles Of The Mitogen-Induced Proteins, Mitogen Regulated Protein/Proliferin And 24p3/Uterocalin, During Mouse Development , Pierig Jean-Marie Lepont

Retrospective Theses and Dissertations

Mitogens, serum and growth factors, induce the secretion of several proteins in cell cultures. Mitogen regulated protein/proliferin (MRP/PLF) is one such protein secreted from 3T3 cells 20 hours after the addition of fibroblast growth factor (FGF). 24p3/uterocalin is another protein induced 10 hours after FGF addition. When combined with cycloheximide, 24p3/uterocalin secretion is increased by 5 fold.;MRP/PLFs are glycoproteins, belonging to the prolactin-growth hormone family, expressed at high concentration during mid-gestation in the mouse placenta. MRP/PLFs are thought to stimulate angiogenesis in the placenta and the uterus, and stimulate uterine cell growth during ...


Transcription Factors Involved In The Development Of Potato (Solanum Tuberosum L) , Faye Michelle Rosin Jan 2002

Transcription Factors Involved In The Development Of Potato (Solanum Tuberosum L) , Faye Michelle Rosin

Retrospective Theses and Dissertations

The objective of this study was to gain insight into how classes of regulatory genes affect the growth and development of potato, particularly, the molecular processes of tuberization. This was accomplished by generating transgenic potato plants that overexpress the homeobox gene, POTH1 , and by using an antisense approach to suppress levels of the MADS box gene, POTM1.;POTH1 was shown to be involved in vegetative pattern formation via mediation of hormone levels. Overexpression of POTH1 resulted in dwarf plants with a 'mouse-ear' leaf phenotype. Leaves were heart-shaped with a decreased midvein and palmate venation. POTH1 overexpression lines exhibited an increase ...


Complexes Of Palladium(Ii) And Platinum(Ii) As Synthetic Proteases , Nebojša M. Milović Jan 2002

Complexes Of Palladium(Ii) And Platinum(Ii) As Synthetic Proteases , Nebojša M. Milović

Retrospective Theses and Dissertations

Selective cleavage of proteins is a common procedure in many biochemical applications ranging from standard protein sequencing to novel methods in proteomics and bioengineering. Few enzymes and synthetic reagents are available for this important task, but new chemical reagents with improved efficiency and adjustable selectivity are highly desired. Complexes of palladium(II) and platinum(II), two chemically similar transition-metal ions, are new reagents for selective cleavage of peptides and proteins. The cleavage by Pd(II) complexes, such as [Pd(H2O)4]2+ or cis-[Pd(en)(H 2O)2]2+, consistently occurs in weakly acidic aqueous solutions at the amide ...


Atp-Citrate Lyase Has An Essential Role In Cytosolic Acetyl-Coa Production In Arabidopsis , Beth Leann Fatland Jan 2002

Atp-Citrate Lyase Has An Essential Role In Cytosolic Acetyl-Coa Production In Arabidopsis , Beth Leann Fatland

Retrospective Theses and Dissertations

Acetyl-CoA is both an essential primary and secondary metabolite, however, the source of cytosolic acetyl-CoA has been unclear. We identified two non-overlapping groups of plant cDNAs that encode proteins similar to the amino and carboxy portions of human ATP-citrate lyase. In Arabidopsis, three genes encode the 45 kD ACLA subunit (ACLA-1, At1g10670; ACLA-2, At1g60810; ACLA-3, At1g09430) and two genes encode the 65 kD ACLB subunit (ACLB-1, At3g06650; ACLB-2, At5g49460). Co-expression of ACLA-1 and ACLB-2 cDNAs in Saccharomyces cerevisiae yields ATP-citrate lyase activity, indicating both polypeptides are required for activity. The Arabidopsis holoprotein has a molecular weight of 500 kDa, which ...


Proline Cis/Trans Isomerization Regulates A T Cell Specific Tyrosine Kinase , Kristine Nicole Brazin Jan 2002

Proline Cis/Trans Isomerization Regulates A T Cell Specific Tyrosine Kinase , Kristine Nicole Brazin

Retrospective Theses and Dissertations

This dissertation examines the role of protein-protein interactions that regulate the conformation and function of the Tec family kinase, interleukin-2 tyrosine kinase (Itk). Tec family kinases are expressed in hematopoetic cells and modulate intracellular signaling cascades in response to external stimuli. The domain structure of Tec family members contains the conserved SH3, SH2, and catalytic domains common to many kinase families, yet they are distinguishable by the presence of a unique N-terminal sequence. The mechanism by which Itk is regulated is not well understood. Both nuclear magnetic resonance spectroscopy and functional assays were used to elucidate a novel regulatory mechanism ...


A Candidate Gene Analysis For Response To Salmonella Enteritidis Challenge Or Vaccination In Young Chicks , Wei Liu Jan 2002

A Candidate Gene Analysis For Response To Salmonella Enteritidis Challenge Or Vaccination In Young Chicks , Wei Liu

Retrospective Theses and Dissertations

Salmonella enteritidis (SE) contamination of poultry products is a major cause of food-borne disease worldwide. The candidate gene approach for identification of quantitative trait loci (QTL) for chicken response to Salmonella enteritidis (SE) was applied in the current study. The Iowa Salmonella Response Resource Population (ISRRP), formed by crossing outbred broiler sires with three diverse, highly inbred dam lines (two major histocompatibility complex-congenic Leghorn lines G-B1 and G-B2 and one Fayoumi line) was studied. The F1 generation was evaluated as young chicks for either bacterial load in spleen and cecum after pathogenic SE inoculation, or antibody level after SE vaccination ...


Identification And Characterization Of Proteins Expressed In The Nectar Of Ornamental Tobacco , Clay Jeremy Carter Jan 2002

Identification And Characterization Of Proteins Expressed In The Nectar Of Ornamental Tobacco , Clay Jeremy Carter

Retrospective Theses and Dissertations

A small set of proteins, termed Nectarins, are secreted into the nectar of ornamental tobacco (Nicotiana langsdorffii x Nicotiana sanderae). The most highly expressed protein, Nectarin I (29 kD monomer), was originally identified as a germin-like protein (GLP) of unknown function. This remarkably stable protein was later shown to possess manganese dependent superoxide dismutase activity. Hydrogen peroxide, the product of SOD activity, was found to accumulate in nectar at levels up to 4 mM. The promoter (1.2 kb) of the Nectarin I gene was fused to the reporter gene chloramphenicol acetyl transferase (CAT) and shown to be expressed in ...


Actin And Myosin Remodeling In The A7r5 Smooth Muscle Cell, Michael E. Fultz Jan 2002

Actin And Myosin Remodeling In The A7r5 Smooth Muscle Cell, Michael E. Fultz

Theses, Dissertations and Capstones

Active remodeling of the cytoskeleton has been proposed to contribute to the low energy cost and maintenance of the sustained contraction in smooth muscle. Using confocal microscopy and standard immunohistochemical techniques, direct observation of actin remodeling was studied in the contracting A7r5 cell in response to the diacylglycerol (DAG) analog phorbol 12, 13 dibutyrate (PDBu). -actin was shown to exist in the resting cell as parallel stress cables that extend across the cell. Stimulation by PDBu resulted in a sustained contraction that occurred in approximately eighty-five percent of the A7r5 cells. The initial contraction was not uniform, but primarily occurred ...


Development Of A Chromatographic Method For The Analysis Of Carbohydrates In Posidonia Coriacea In Artificial Cultures, Olivia J. Oldfield Jan 2002

Development Of A Chromatographic Method For The Analysis Of Carbohydrates In Posidonia Coriacea In Artificial Cultures, Olivia J. Oldfield

Theses : Honours

Carbohydrates in P. coriacea leaves were analysed to determine if, when in artificial culture, they were unable to replenish their carbohydrate stores once the seed starch reserve was consumed. While no evidence was found to suggest that this was happening, other findings were made. Soluble carbohydrates determined in P. coriacea were sucrose, fructose, glucose, trehalose, myo-inositol and mannitol. However, mannitol was only found in in situ plants sampled in June. This may be due to high epiphyte coverage elevating plant stress and therefore mannitol levels. P. coriacea grown in tissue culture has soluble carbohydrate levels up to 20-fold higher than ...


Enzyme Activities In Soils As Affected By Management Practices , Mine Ekenler Jan 2002

Enzyme Activities In Soils As Affected By Management Practices , Mine Ekenler

Retrospective Theses and Dissertations

Studies were undertaken to investigate the long-term effects of lime application and tillage systems (no-till, ridge-till, and chisel plow) on soil microbial biomass C (Cmic) and N (Nmic) and the activities of glycosidases (alpha- and beta-glucosidases, alpha- and beta-galactosidases and beta-glucosaminidase); phosphatases (acid and alkaline phosphatases and phosphodiesterase); amidohydrolases (L-asparaginase, L-glutaminase, amidase, urease, and L-aspartase); and arylamidase at their optimal pH values. With the exception of acid phosphatase, which was significantly but negatively correlated, all other enzyme activities were significantly and positively correlated with soil pH values at four sites in Iowa. Delta activity/Delta pH values showed that among ...


Backcross Introgression And Two-Stage Testing For Conversion Of Improved Tropical Germplasm To Temperate Environments , Freeman Callaway Whitehead Jan 2002

Backcross Introgression And Two-Stage Testing For Conversion Of Improved Tropical Germplasm To Temperate Environments , Freeman Callaway Whitehead

Retrospective Theses and Dissertations

The use of exotic maize (Zea mays L.) germplasm, particularly of tropical and subtropical adaptation, has been suggested to increase genetic variability and grain yield of maize breeding material in temperate environments. Lack of adaptation to temperate areas and photoperiod sensitivity may mask desirable traits and reduce breeding progress. The objectives of this study included two-stage evaluation and selection of segregating families in the central U.S. Corn Belt derived from the backcross introgression of previously improved tropical CIMMYT germplasm into adapted, elite U.S. Corn Belt germplasm. The U.S. Corn Belt heterotic patterns of Stiff Stalk and non-Stiff ...


Molecular Marker Analysis Of Seed Size In Soybean , Joseph Andrew Hoeck Jan 2002

Molecular Marker Analysis Of Seed Size In Soybean , Joseph Andrew Hoeck

Retrospective Theses and Dissertations

Seed size is an important attribute of soybean [Glycine max (L.) Merr.] for some food uses. The objectives of this study were to identify markers associated with quantitative trait loci for seed size (SSQTL), determine the influence of the environment on expression of the marker-SSQTL associations, and compare the efficiency of phenotypic selection and marker-assisted selection for the trait. Three small-seeded lines were crossed to a line or cultivar with normal seed size to form three two-parent populations. The parents of the populations were screened with 178 simple sequence repeat (SSR) markers to identify polymorphism. Population 1 (Pop 1) had ...