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

Biochemical And Genetic Analyses Of Physical Associations Among Zea Mays Starch Biosynthetic Enzymes, Tracie Ann Hennen-Bierwagen Jan 2008

Biochemical And Genetic Analyses Of Physical Associations Among Zea Mays Starch Biosynthetic Enzymes, Tracie Ann Hennen-Bierwagen

Retrospective Theses and Dissertations

Mutations affecting specific starch biosynthetic enzymes commonly have pleiotropic effects on other enzymes in the same metabolic pathway. Such genetic evidence indicates functional relationships between components of the starch biosynthetic system including starch synthases (SS), starch branching enzymes (BE), and starch debranching enzymes (DBE), however, the molecular explanation for these functional interactions is not known. One possibility is that specific SSs, BEs, and/or DBEs associate physically with each other in multisubunit complexes. To test this hypothesis, this study sought to identify stable associations between SSI, SSIIa, SSIII, SBEI, SBEIIa, and SBEIIb from maize amyloplasts. Three separate detection methods, yeast ...


Understanding The Biological Activity Of Hypericum Species Through Metabolomics Studies, Matthew Lee Hillwig Jan 2008

Understanding The Biological Activity Of Hypericum Species Through Metabolomics Studies, Matthew Lee Hillwig

Retrospective Theses and Dissertations

The Hypericum genus contains plants which biosynthesize various polyketides with various known and unknown biological and medicinal activities. However, many Hypericum species have not been chemically or biochemically characterized. These species represent an opportunity for understanding chemical ecology and for new drug discovery research. Acyl-phloroglucinols are of particular interest since they are the most diverse class of specialized metabolites in Hypericum. We used analytical methods such as HPLC, LC-MS and 2-D NMR to screen Hypericum species for metabolite diversity. One species, H. gentianoides, was investigated further based on its historical use by Native Americans and its unique metabolite fingerprint. This ...


A Negative Regulator Of Ribosomal Rna Processing Specifies R-Gene-Independent Cell Death In Barley - Powdery Mildew Interactions, Liu Xi Jan 2008

A Negative Regulator Of Ribosomal Rna Processing Specifies R-Gene-Independent Cell Death In Barley - Powdery Mildew Interactions, Liu Xi

Retrospective Theses and Dissertations

Programmed Cell Death (PCD) plays a pivotal role in plant development and defense. Pathogen dependent cell-death mutants were used to investigate the complex regulatory pathways between PCD and R-gene mediated resistance. Time-course expression profiles of Blumeria graminis f. sp. hordei (Bgh) challenged C.I. 16151 (harboring the Mla6 powdery mildew resistance allele) and its fast-neutron-derived "Bgh-induced tip cell death1" mutant, bcd1, were compared using the 22K Barley1 GeneChip. Contrasts were made to identify genes associated with the cell death phenotype as opposed to R-gene mediated resistance. One hundred eighty-two genes were found in the intersection of these contrasts at a ...


Analysis Of Globulin-1 Promoter Activity And The Expression Of Gfp In Transgenic Maize Seed Tissues And Processing Of Gfp-Containing Grain, Colin Shepherd Jan 2007

Analysis Of Globulin-1 Promoter Activity And The Expression Of Gfp In Transgenic Maize Seed Tissues And Processing Of Gfp-Containing Grain, Colin Shepherd

Retrospective Theses and Dissertations

The maize (Zea mays L) kernel is perfectly configured to store proteins and nutrients. The major proteins of the maize kernel are known as seed storage proteins because they have no enzymatic function and they accumulate to a high level for use during germination of the seed as an immediate nutrient source. These seed storage proteins are responsible for much of the nutrient quality of maize when used as a food or feed source. Understanding the regulation of seed storage protein deposition may allow researchers to improve the use of maize grain in a variety of food and feed products ...


Mechanism Of Cap-Independent Translation By Long Distance Kissing Stem-Loop Interactions In Plant Viral Rnas, Aurélie Mamisoa Rakotondrafara Jan 2007

Mechanism Of Cap-Independent Translation By Long Distance Kissing Stem-Loop Interactions In Plant Viral Rnas, Aurélie Mamisoa Rakotondrafara

Retrospective Theses and Dissertations

While the presence of a 5' cap and a 3' poly(A) tail are key elements for efficient translation of eukaryotic mRNAs, many viral mRNAs lack one or both of such structures and yet translate efficiently. Owing to the absence of a 5' cap, Barley yellow dwarf virus (BYDV, Luteoviridae family) genomic and subgenomic RNA1 rely on a cap-independent translation element (BTE), which is an RNA domain capable of promoting translation. In contrast to an internal ribosome entry site (IRES), the BTE is located at the 3' end of the viral mRNA, while translation initiation occurs at the 5' end ...


Enhancement Of Plant Performance And Biochemical Constituents In Field And Hairy Root Production Of Echinacea , Fredy Rolando Romero Orellana Jan 2006

Enhancement Of Plant Performance And Biochemical Constituents In Field And Hairy Root Production Of Echinacea , Fredy Rolando Romero Orellana

Retrospective Theses and Dissertations

Echinacea is a commercially important source of natural products and phytopharmaceuticals. Echinacea products currently constitute a significant portion of the rapidly growing, multi-billion dollar natural products market. This popularity has led to the expansion of commercial cultivation of Echinacea and the need to find alternative methods to meet the increasing demands of the phytopharmaceutical market. Two methods of producing biochemical constituents in commercial use include extraction from field-grown plants and in vitro hairy root production;Echinacea seeds in the wild typically show a high degree of dormancy. In order to enhance Echinacea seed germination for field production, alternative methods to ...


The Mechanism Of Arabidopsis Immutans Variegation , Aigen Fu Jan 2006

The Mechanism Of Arabidopsis Immutans Variegation , Aigen Fu

Retrospective Theses and Dissertations

The Arabidopsis immutans (im) is variegated with green sectors and white sectors containing defective plastids due to a nuclear gene mutation. IM is a plastid terminal oxidase (PTOX) sharing similarity with mitochondrial alternative oxidase (AOX). In order to better understand IM's biological roles and variegation mechanism of im, I characterized im plants at different levels;A structural model of IM, in which the diiron reaction center is composed of two conserved histidine and four glutamate residues, was tested by mutagenesis in vitro and in planta. It that these six conserved residues were found essential for IM activity and do ...


Recognition And Signal Transduction In The Expression Of Phytophthora Resistance In Soybean [Glycine Max (L) Merr] , Hongyu Gao Jan 2006

Recognition And Signal Transduction In The Expression Of Phytophthora Resistance In Soybean [Glycine Max (L) Merr] , Hongyu Gao

Retrospective Theses and Dissertations

Phytophthora sojae, a hemibiotrophic oomycete, is the causal pathogen of stem and root rot disease of soybean (Glycine max [L.] Merr). The annual soybean yield loss suffered from this disease is valued at about 300 million dollars. A series of single Rps genes protect soybean from the root and stem rot disease. In the last two decades Rps1-k has been the most stable and widely used Phytophthora resistance gene in the major soybean-producing regions of the United States;Two classes of CC-NB-LRR-type Rps1-k genes were isolated from the Rps1-k locus. Representative members from each gene class were expressed in transgenic ...


Phenotypic, Biochemical, And Molecular Diversity In Coriander (Coriandrum Sativum L) Germplasm, Pedro Antonio López Jan 2006

Phenotypic, Biochemical, And Molecular Diversity In Coriander (Coriandrum Sativum L) Germplasm, Pedro Antonio López

Retrospective Theses and Dissertations

A study was conducted to assess phenotypic, biochemical, and molecular diversity in coriander accessions from the North Central Regional Plant Introduction Station, in Ames, IA; initially, 139 accessions were characterized for phenological and morphological traits and for fatty-acid composition. A second year of data was collected on those traits from 60 accessions. Fruit essential-oil content and composition were determined, along with a headspace analysis from leaves and an analysis of amplified fragment length polymorphisms (AFLPs). Basic statistics and Pearson correlations were estimated. Matrices of geographical distances (GD), modified Rogers' (MD) distances for molecular data, and Euclidean distances for phenotypic (PD ...


Molecular Genetic Analyses Of Oilseed Brassica Germplasm: Determination Of Life Forms And Germplasm Management Strategies By Using Microsatellite Markers And Flowering Locus-C (Flc1 And Flc3) Gene Sequences , Von Mark V. Cruz Jan 2006

Molecular Genetic Analyses Of Oilseed Brassica Germplasm: Determination Of Life Forms And Germplasm Management Strategies By Using Microsatellite Markers And Flowering Locus-C (Flc1 And Flc3) Gene Sequences , Von Mark V. Cruz

Retrospective Theses and Dissertations

Molecular markers were utilized in conjunction with phenological and morphological information, and statistical methods for diversity analyses to address plant genetic resource conservation issues. The objectives of this study have been categorized into two sets. The first set pertains to exploratory surveys of genetic variation using molecular markers and DNA sequences to determine if microsatellite markers or variation in two copies of the FLOWERING LOCUS C gene (FLC1 and FLC3) can be used in determining life forms of fifty representative accessions of Brassica napus. The second set of objectives addresses good genebank practices and includes: characterization of flowering time of ...


Qtl Mapping And Gene Discovery In Perennial Ryegrass (Lolium Perenne L.) , Yanwen Xiong Jan 2005

Qtl Mapping And Gene Discovery In Perennial Ryegrass (Lolium Perenne L.) , Yanwen Xiong

Retrospective Theses and Dissertations

Perennial ryegrass (Lolium perenne L.) has been used extensively for both forage and turf in temperate regions. To understand the genetic basis of winter hardiness and forage quality and molecular basis of cold acclimation of ryegrass, we mapped quantitative trait loci (QTL) that control winter hardiness and forage quality by using an interspecific ryegrass population and identified a C&barbelow;-repeat (CRT)/dehydration-responsive element (DRE) b&barbelow;inding f&barbelow;actors (CBF)-like gene in perennial ryegrass. Winter hardiness related traits including fall growth (FG), freezing tolerance (FT), and winter survival (WS) were measured over two years. A total of twenty-six QTLs were ...


Sooty Blotch And Flyspeck On Apple: Expansion Of The Fungal Complex, Post-Harvest Removal And Heterogeneity Of Apple Canopy Wetness And Its Impact On The Outcome Of A Disease-Warning System , Jean Carlson Batzer Jan 2005

Sooty Blotch And Flyspeck On Apple: Expansion Of The Fungal Complex, Post-Harvest Removal And Heterogeneity Of Apple Canopy Wetness And Its Impact On The Outcome Of A Disease-Warning System , Jean Carlson Batzer

Retrospective Theses and Dissertations

Sooty blotch and flyspeck (SBFS) fungi blemish the cuticle of apples. Previous studies reported that the SBFS complex is comprised of four species. This is study surveyed the SBFS complex from nine orchards in four Midwestern states (USA). The LSU analyses of the rDNA inferred that 30 species were Dothideomycetes; one species was within the Pleosporales, 27 were within Dothideales, and two species could not be placed at the ordinal level. The LSU sequences of 17 Dothideales species clustered with LSU sequences of known species of Mycosphaerella. Post-harvest dips in commercial disinfestants were used to remove SBFS signs. Apples were ...


Co2 Concentrating Mechanism And Signal Transduction Pathway Associated With Limiting Co2 Acclimation In Chlamydomonas Reinhardtii , Yingjun Wang Jan 2005

Co2 Concentrating Mechanism And Signal Transduction Pathway Associated With Limiting Co2 Acclimation In Chlamydomonas Reinhardtii , Yingjun Wang

Retrospective Theses and Dissertations

Many aquatic photosynthetic organisms exhibit a variety of acclimation responses to limiting CO2 availability, including induction of CO2 concentrating mechanisms (CCMs), which represent adaptations to environments with changing and, at times, limiting CO2 availability. Although the characteristics and regulation of limiting CO2 acclimation, including the CCM, in the green alga Chlamydomonas reinhardtii have been well demonstrated by physiological and biochemical studies, much less information is available at the molecular level with regard to the components involved in the CCM and other parts of the limiting CO2 acclimation response. We have applied insertional mutagenesis and genetic approaches in an effort to ...


The Mechanism Of Var2 Leaf Variegation , Fei Yu Jan 2005

The Mechanism Of Var2 Leaf Variegation , Fei Yu

Retrospective Theses and Dissertations

The Arabidopsis f&barbelow;ilamentation t&barbelow;emperature s&barbelow;ensitive (FtsH) metalloprotease gene family comprises 12 members (AtFtH1-AtFtsH12 ), including three pairs of closely related genes that are targeted to chloroplasts (AtFtsH2 and AtFtsH8; AtFtsH1 and AtFtsH5; and AtFtsH7 and AtFtsH9). Mutations in AtFtsH5 ( var1) and AtFtsH2 (var2) give rise to variegated plants with green- and white-sectored leaves. Cells in the green sectors contain morphologically normal chloroplasts, whereas cells in the white sectors are blocked in chloroplast biogenesis. A major question is how chloroplasts arise in cells that have a mutant genotype. We have found by two-dimensional (2-D) green gel and gel filtration ...


Translational Control Of Gene Expression Mediated By The 3' Untranslated Region Of Barley Yellow Dwarf Virus , Elizabeth Lynn Pettit Jan 2005

Translational Control Of Gene Expression Mediated By The 3' Untranslated Region Of Barley Yellow Dwarf Virus , Elizabeth Lynn Pettit

Retrospective Theses and Dissertations

The 869 nt 3' untranslated region (3' UTR) of Barley yellow dwarf luteovirus (BYDV) RNA facilitates cap-independent and poly(A) tail-independent translation. A 105 nt cap-independent translation element (BTE, or BYDV TE) within the 3' UTR was previously defined using wheat germ translation extracts (Guo et al., 2000), but additional 3' UTR sequence is required for translation in plant cells. One domain, nt 4918--5008, confers cap-independent translation in vivo in a discrete and strong manner. Some of this extra sequence places the BTE on a phylogenetically conserved, long double-stranded "stalk", making it more accessible to cellular translational machinery. Another sequence ...


The Central Role Of Acetyl-Coa In Plant Metabolism, As Examined Through Studies Of Atp Citrate Lyase And The Bio1 Mutant Of Arabidopsis , Elizabeth K. Winters Jan 2004

The Central Role Of Acetyl-Coa In Plant Metabolism, As Examined Through Studies Of Atp Citrate Lyase And The Bio1 Mutant Of Arabidopsis , Elizabeth K. Winters

Retrospective Theses and Dissertations

The acetyl-CoA/biotin network encompasses acetyl-CoA generation and utilization, biotin synthesis, recovery, and transport, and myriad metabolic processes requiring biotin-containing enzymes. To expand understanding of this network and its control, plants with altered levels of ACL (ATP citrate lyase) and BIO1 (adenosylmethionine-8-amino-7-oxononanoate synthase) were examined.;An inducible promoter provides a powerful method to test the effects of altered expression of specific genes. The synthetic GVG promoter, reported to be sterol-inducible in Arabidopsis thaliana, was inducible in Glycine max (soybean) when used to control the GUS reporter gene, or the ACLA or ACLB genes. It showed the same unique pattern in ...


Genetic Basis Of Autumn Growth And Winter Hardiness In Alfalfa , Baldomero Alarcón Zúñiga Jan 2003

Genetic Basis Of Autumn Growth And Winter Hardiness In Alfalfa , Baldomero Alarcón Zúñiga

Retrospective Theses and Dissertations

Alfalfa (Medicago sativa L.) has a broad geographic distribution, with populations adapted to both cold and warm climates. Despite considerable research on winter hardiness, the mechanisms and genetic control of winter survival are poorly understood. We conducted two experiments designed to identify and quantify morphological, physiological, and biochemical traits associated with winter hardiness and to estimate the genetic relationship of these traits with winter hardiness. In Experiment 1, ten alfalfa genotypes were planted in June 2000 and in May 2001 at Ames, IA, and traits were measured in August, November, and the following April in each year. Concentrations of palmitate ...


Genetic And Molecular Characterization Of Maize Starch Debranching Enzymes , Jason Robert Dinges Jan 2003

Genetic And Molecular Characterization Of Maize Starch Debranching Enzymes , Jason Robert Dinges

Retrospective Theses and Dissertations

Starch is the primary carbohydrate reserve of plants, a significant source of food in the human diet, and an important industrial raw material. The arrangement of linear chains and branch linkages within amylopectin is responsible for the highly conserved architecture of the starch granule. This structure allows for efficient packaging of glucose and results in the unique functional properties of starch. It is known that starch synthases and branching enzymes catalyze alpha(1→4) chain elongation and introduction of alpha(1→6) branch linkages, respectively, but studies in several species suggests that starch debranching enzymes (DBE) are also involved in ...


Molecular Marker Analysis Of Population Genetic Structure And Progress From Reciprocal Recurrent Selection In Two Iowa Maize (Zea Mays L) Populations , Lori Lynn Hinze Jan 2003

Molecular Marker Analysis Of Population Genetic Structure And Progress From Reciprocal Recurrent Selection In Two Iowa Maize (Zea Mays L) Populations , Lori Lynn Hinze

Retrospective Theses and Dissertations

Studies of the genetic structure of the Iowa Corn Borer Synthetic #1 (CB) and Iowa Stiff Stalk Synthetic (SS) maize populations are of particular significance because they serve as the model on which development of modern commercial hybrids are based. These populations are part of a reciprocal recurrent selection breeding strategy. With this strategy, plants from one population are crossed to plants from the opposite population (i.e. forming hybrids). These hybrids are tested, and the best ones are chosen. The plants crossed to form the chosen hybrids are identified and used to form the next generation in each population ...


Investigation Of Iron-Deficiency Chlorosis In Soybean , Dirk Victor Charlson Jan 2003

Investigation Of Iron-Deficiency Chlorosis In Soybean , Dirk Victor Charlson

Retrospective Theses and Dissertations

Iron-Deficiency Chlorosis (IDC) causes yield losses in soybean and other crop species as a result of the plant's inability to efficiently acquire iron from calcareous soils. Although plants differ in their response to iron deficiency and IDC resistance has been improved in soybean, the biology of IDC is not well understood. We undertook an interdisciplinary approach towards increasing our knowledge of IDC resistance and iron acquisition strategies in higher plants. Firstly, we examined the usefulness of molecular markers to improve breeding efficiency for IDC resistance in soybean. After examining Simple Sequence Repeats (SSR) markers genetically linked to previously identified ...


Molecular And Genetic Characterization Of The Inheritance And Expression Of The Synthetic Porcine Alpha-Lactalbumin Transgene In Maize (Zea Mays L) , Earl H. Bicar Jan 2003

Molecular And Genetic Characterization Of The Inheritance And Expression Of The Synthetic Porcine Alpha-Lactalbumin Transgene In Maize (Zea Mays L) , Earl H. Bicar

Retrospective Theses and Dissertations

A codon-adjusted version of a gene encoding the porcine milk protein alpha-lactalbumin was synthesized to create maize with improved nutritional quality. Three expression vectors (P64, P45, P57) containing the synthetic gene were constructed and transformed into maize callus by particle bombardment. The constructs differed in their promoters and subcellular targeting domains. PCR analysis showed that the alpha-La transgene was integrated into the maize genome and transmitted to the F1 generation. Western blot analysis indicated that the transgenes were functional and the alpha-La protein accumulated in the target endosperm. Genomic Southern blot analysis detected no new rearrangements demonstrating stable transgene integration ...


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 ...


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 ...


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 ...


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 ...


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 ...


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 ...


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 ...


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 ...