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Articles 1 - 22 of 22

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

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 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 ...


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 ...


Molecular And Chemical Characterization Of Genes Involved In Maize Cuticular Wax Biosynthesis , M. Ann D. N. Perera Jan 2005

Molecular And Chemical Characterization Of Genes Involved In Maize Cuticular Wax Biosynthesis , M. Ann D. N. Perera

Retrospective Theses and Dissertations

The primary surfaces of the arial parts of plants, and the surfaces of reproductive organs are covered by an extra cellular layer called the cuticle. The cuticle provides the foremost protection to the plant in order to adapt to the terrestrial environment. The cuticle composed of a biopolymer (cutin), which is embedded in a coating of cuticular waxes. Understanding the biochemical, genetic and physiological mechanisms for the biosynthesis of these cuticular waxes is relatively poor. This body of work has established methods for the chemical analysis of the cuticular waxes of maize plants. I have used these methods to chemically ...


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 ...


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 ...


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 ...


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 ...


Carbohydrate Regulation Of Leaf Development: Investigating The Role Of Source Strength, Carbon Partitioning And Hexokinase Signaling In Regulating Leaf Senescence , Adam Christopher Miller Jan 2000

Carbohydrate Regulation Of Leaf Development: Investigating The Role Of Source Strength, Carbon Partitioning And Hexokinase Signaling In Regulating Leaf Senescence , Adam Christopher Miller

Retrospective Theses and Dissertations

For many plants, growth in elevated CO2 leads to reduced rates of photosynthesis. To examine the role leaf ontogeny plays in acclimation; we monitored photosynthesis and some related parameters throughout the development of tobacco leaves under ambient and high CO2 conditions. The pattern of photosynthetic rate over time was consistent with the expected pattern for a typical dicot leaf for both. However, the photosynthesis pattern in high-CO2-grown tobacco was shifted temporally to an earlier maximum and subsequent senescent decline. Rubisco activity appeared to be the main factor regulating photosynthetic rates in both treatments. Therefore, we propose a new model for ...


Biochemical Characterization And Positional Cloning Of The Var2 Variegation Mutant Of Arabidopsis Thaliana , Meng Chen Jan 1999

Biochemical Characterization And Positional Cloning Of The Var2 Variegation Mutant Of Arabidopsis Thaliana , Meng Chen

Retrospective Theses and Dissertations

Chloroplasts differentiation and development are highly coordinated with their host cells. To better elucidate the mechanisms involved in nuclear-chloroplast interactions, we characterized a nuclear encoded leaf variegation mutation called var2. While cotyledons appear normal, true leaves of var2 emerge as yellow, then turn into green-white sectors. The green sectors contain cells with normal chloroplasts, whereas the white sectors contain cells with abnormal plastid lacking of internal membrane structures. The phenotypes suggested that VAR2 might be involved in thylakoid biogenesis in early chloroplast differentiation. We cloned the VAR2 gene by a map-based method. Five original and two potential alleles were sequenced ...


Analyses Of A Genic Male-Sterile Mutant In Soybean , Wei Jin Jan 1997

Analyses Of A Genic Male-Sterile Mutant In Soybean , Wei Jin

Retrospective Theses and Dissertations

A new genic male-sterile mutant in soybean was characterized genetically, developmentally, and molecularly. This mutant is controlled by a single recessive gene, which is not allelic to six previously identified soybean genic male-sterile mutants: ms1, ms2, ms3, ms4, ms5, or ms6. No linkage was detected between the male-sterile gene and flower color (W1 locus), or between the male-sterile gene and pubescence color (T1 locus). Developmental and enzymatic studies showed that sterility was caused by retention of the callose walls, which normally are degraded by callase ([beta]-1,3-glucanase) at the late tetrad stage. Molecular markers linked with the male-sterile gene ...


Molecular And Biochemical Investigation Of The Mechanisms Of Acclimation To Chilling Stress In Maize Seedlings , Marc David Anderson Jan 1995

Molecular And Biochemical Investigation Of The Mechanisms Of Acclimation To Chilling Stress In Maize Seedlings , Marc David Anderson

Retrospective Theses and Dissertations

Seedlings of chilling-sensitive maize inbred G50 (Pioneer) survived poorly when exposed to a chilling stress. Acclimation or ABA treatment caused a dramatic improvement of chilling tolerance. Differences in gene expression between acclimated and unacclimated seedlings were investigated and three cDNA clones (designated car333, car30, and car757) were isolated, representing transcripts that were up-regulated during acclimation. Car30 and car757 were not homologous to any known sequence but car333 was 97.8% homologous to cat3, maize mitochondrial catalase. The up-regulation of CAT3 during acclimation suggested that chilling stress caused the generation of H[subscript]2O[subscript]2 in the mitochondria and increased ...


Cloning And Characterization Of Two Chlorophyll Synthesis Genes Expressed During Tomato Fruit Development , Gary Francis Polking Jan 1995

Cloning And Characterization Of Two Chlorophyll Synthesis Genes Expressed During Tomato Fruit Development , Gary Francis Polking

Retrospective Theses and Dissertations

Full-length clones that encode tomato (Lycopersicon esculentum Mill.) glutamate-1-semialdehyde-2,1-aminomutase (GSAAM) and 5-aminolevulinic acid dehydratase (ALAD) were isolated and characterized. Sequence analysis showed that tomato GSAAM and ALAD clones exhibited a high level of homology to corresponding clones found in other plant species. The primary structure of GSAAM predicted a 481-amino acid precursor that comprised a 46.7 kDa, 437-amino acid mature protein and a transit peptide of 44 amino acids. The primary structure of ALAD predicted a 430-amino acid precursor that comprised a 41.7 kDa, 383-amino acid mature protein and a 47-amino acid transit sequence. Southern analysis showed ...


Protein-Binding Sequences That May Regulate Organ-Preferential Transcription Of Zrp2, A Zea Mays Root-Preferential Gene, Therese Shamala Tirimanne Jan 1995

Protein-Binding Sequences That May Regulate Organ-Preferential Transcription Of Zrp2, A Zea Mays Root-Preferential Gene, Therese Shamala Tirimanne

Retrospective Theses and Dissertations

In this study, DNA-protein interactions of the first kilobase region proximal to the transcription start site of the zrp2 (Zea mays root-preferential 2) gene promoter was analyzed. The intent of this research was to identify regions of the promoter and DNA-protein interactions, that are responsible for root-preferential transcription. In vitro run-on transcription assays had revealed dramatically higher levels of transcription in 3-d-old roots than in 5-d-old leaves (Held, 1993). Interactions between regions of the zrp2 promoter and nuclear protein extracts from 3-d-old roots and 5-d-old leaves of maize were analyzed by gel mobility-shift assays. Two DNA-protein complexes with each protein ...


Characterization Of Genes Expressed During Vegetative Organ Development In Potato (Solanum Tuberosum L.) , Sang-Gu Kang Jan 1995

Characterization Of Genes Expressed During Vegetative Organ Development In Potato (Solanum Tuberosum L.) , Sang-Gu Kang

Retrospective Theses and Dissertations

The cp rps16 cDNA encoding the chloroplast ribosomal protein S16 and a MADS-box gene cDNA, POTM1-1, were isolated and characterized in potato (Solanum tuberosum L.) to understand molecular mechanisms of plant vegetative organ development;The rps16 gene is located between the trnK gene for tRNA Lys(UUU) and trnQ gene for tRNA Gln (UUG) on the same strand in the chloroplast genome. The ribosomal binding site, 5'-AGGA-3', is located at nucleotide position -6 to -9 from the initiation codon ATG. The coding sequence contains an 88 amino acid open reading frame (ORF) that is interrupted by an 855 bp ...


Root-Preferential Mrna Accumulation In Zea Mays , Bruce Marvin Held Jan 1993

Root-Preferential Mrna Accumulation In Zea Mays , Bruce Marvin Held

Retrospective Theses and Dissertations

To investigate the molecular basis of root development and function, I helped isolate several cDNA clones that corresponded to mRNAs that accumulated preferentially in the root of Zea mays L. (John, 1991; John et al., 1992). The purposes of the research described in this dissertation were: (1) to characterize one of these cDNA clones, pZRP4; and (2) to analyze the transcriptional regulation of root-preferential mRNA accumulation for another cDNA clone, pZRP2;Genomic Southern analysis indicated that the zrp4 gene was represented once in the corn genome. The ZRP4 mRNA accumulated preferentially in young roots, and was detected only at low ...


Cell-Wall Components And Lignin Biosynthesis In Forages , James Enderby Bidlack Jan 1990

Cell-Wall Components And Lignin Biosynthesis In Forages , James Enderby Bidlack

Retrospective Theses and Dissertations

Lignin is the major cell-wall (CW) component that lowers forage digestibility. Negative relationships between lignin and forage quality are caused by interactions and variability of lignin with other CW components. This study was conducted to better understand how lignin content, concentration, deposition, and change in concentration vary with other CW components in maturing stems and to provide preliminary information about phenylpropanoid metabolism in relation to lignification;Regrowth from basal stem tissue was sampled weekly or biweekly from greenhouse-grown forage grass and legume species. Samples were collected for a period of about 8 weeks and analyzed for fiber concentration and content ...


Chemistry Of Boron In Plants , Harold Jackson Perkins Jan 1957

Chemistry Of Boron In Plants , Harold Jackson Perkins

Retrospective Theses and Dissertations

No abstract provided.


Kinetics Of Herbicidal Action , Robert Earl Frans Jan 1955

Kinetics Of Herbicidal Action , Robert Earl Frans

Retrospective Theses and Dissertations

Several herbicides and growth substances were applied singly and in combinations at varying concentrations to soybean seedlings and yeast cultures in an attempt to characterize accurately the growth inhibition responses obtained. The growth measurements were subjected to a kinetic analysis in analogy with that proposed for enzyme systems and later modified to include auxin-induced growth;Growth inhibition of soybean seedlings induced by single applications of 2, 4-D, DCPA, 2,4,5-T, TCA, AT, IAA, and MH, satisfactorily supported the hypothesis inherent in the kinetic analysis. It is suggested that calculated Km values may be of value in determining relative affinities ...


Some Effects Of Plant Growth Regulants , Otto Louis Hoffmann Jan 1952

Some Effects Of Plant Growth Regulants , Otto Louis Hoffmann

Retrospective Theses and Dissertations

No abstract provided.


The Effect Of Genetic Constitution And Processing Methods On The Ability Of Maize Seed To Germinate In Cold Soil , Loyd Allen Tatum Jan 1942

The Effect Of Genetic Constitution And Processing Methods On The Ability Of Maize Seed To Germinate In Cold Soil , Loyd Allen Tatum

Retrospective Theses and Dissertations

In samples of commercial hybrid seed a highly significant negative correlation (r = -.81) was found between cold-test germination percentages and percentages of the kernels with pericarp injuries over the germ. Highly significant correlations of field stands with cold-test germination percentages were found, indicating that pericarp injuries over the germ are an important cause of poor stands;Pericarp injury was found to occur in shelling and in other steps in processing which involve an impact between the kernels and a hard surface. The moisture content of the seed during shelling and handling was a very important factor in determining the amount ...