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Articles 1 - 17 of 17

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

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 ...


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 ...


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 ...


Expression Of Genes Encoding Acetyl-Coa Carboxylase, Biotin Synthase, And Acetyl-Coa Generating Enzymes In Arabidopsis Thaliana , Jinshan Ke Jan 1997

Expression Of Genes Encoding Acetyl-Coa Carboxylase, Biotin Synthase, And Acetyl-Coa Generating Enzymes In Arabidopsis Thaliana , Jinshan Ke

Retrospective Theses and Dissertations

Acetyl-CoA carboxylase catalyzes the formation of malonyl-CoA from acetyl-CoA. The four genes encoding heteromeric acetyl-CoA carboxylase are coordinately expressed in leaves, flowers, and developing siliques and embryos. The highest expression occurs in tissues undergoing rapid growth and high oil deposition. The gene encoding the E1 [beta] subunit of chloroplastidic pyruvate dehydrogenase has an identical pattern, indicating it may provide acetyl-CoA for seeds. In contrast, the gene encoding acetyl-CoA synthetase has a different expression pattern and is expressed at low levels in seeds;The ACC1 genes encoding homomeric acetyl-CoA shows transient expression in a variety of cell types. The homomeric acetyl-CoA ...


Characterization Of The Expression Of Two Maize Root-Preferential Genes At The Protein Level , Lathika Pinto Moragoda Jan 1997

Characterization Of The Expression Of Two Maize Root-Preferential Genes At The Protein Level , Lathika Pinto Moragoda

Retrospective Theses and Dissertations

The zrp2 gene encodes an mRNA that accumulates preferentially in roots of maize. To study zrp2 gene expression at the protein level, an antibody was raised against an E. coli-produced ZRP2 protein. Western analyses using this antibody revealed an approximately 100 kDa protein in seedling roots that was not detected in seedling leaves. This size is about 30 kDa larger than the predicted molecular weight. Within seedling roots, low levels of ZRP2 protein were detected in the root tip and high levels were detected throughout the rest of the root. In mature maize plants, the ZRP2 protein was present at ...


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 ...


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 ...


Molecular And Ultrastructural Aspects Of The Adaptation Of Chlamydomonas Reinhardtii To Limiting Co2 , Anne Margaret Geraghty Jan 1994

Molecular And Ultrastructural Aspects Of The Adaptation Of Chlamydomonas Reinhardtii To Limiting Co2 , Anne Margaret Geraghty

Retrospective Theses and Dissertations

Change occurring in Chlamydomonas reinhardtii as cells adapt to limiting CO2 conditions were examined at both a molecular level and an ultrastructural level. It was demonstrated using antibodies that the time course of the de novo synthesis of LIP-21, a 21 kD limiting-CO2 induced polypeptide, correlates with the appearance of CO2 concentrating activity and that expression of the nuclear gene for LIP-21 is regulated at the level of translatable message. These results are consistent with LIP-21 being a component of an adaptive response to limiting CO2, such as the induction of the CO2 concentrating mechanism. Phase separation of membrane proteins ...


Oat Phya Containing Transgenic Tobacco: An Examination Of Oat Phya Mrna Stability And The Role Of Oat Phya In Germination Of Tobacco Seed , Linda Joanne Barnes Jan 1994

Oat Phya Containing Transgenic Tobacco: An Examination Of Oat Phya Mrna Stability And The Role Of Oat Phya In Germination Of Tobacco Seed , Linda Joanne Barnes

Retrospective Theses and Dissertations

The regulation of oat phytochrome A (phyA) mRNA stability and the photoregulation of germination of tobacco seeds containing the oat phyA gene was examined using oat phyA containing transgenic tobacco. Oat phyA mRNA has been previously shown to be a relatively unstable mRNA. The intent of this research was to identify elements within the phyA mRNA responsible for rendering the message unstable. The approach taken was to use tobacco transformed with either the full-length or truncated versions of the oat phyA gene and examine the half-lives of the resulting oat phyA mRNAs in transgenic tobacco. RNA blot analysis of oat ...


Identification Of Potential Oat Phytochrome A Mrna Degradation Mechanisms , David Charles Higgs Jan 1994

Identification Of Potential Oat Phytochrome A Mrna Degradation Mechanisms , David Charles Higgs

Retrospective Theses and Dissertations

The phytochrome plant photoreceptor is important for perceiving the light environment and initiating plant developmental and environmental responses. When dark-grown oat seedlings are treated with light the phytochrome A (PHYA) mRNA abundance rapidly declines due, in part, to the inherent instability of the PHYA mRNA. Messenger RNA stability is an important process in regulating eukaryotic gene expression. My primary goal was to investigate both the mechanism of oat PHYA mRNA degradation and cis-acting sequences involved in regulating oat PHYA mRNA degradation. An oat protoplast system was established to investigate its use as a quick and reliable system to study plant ...


Expression Of Chlamydomonas Reinhardtii Periplasmic Carbonic Anhydrase In Escherichia Coli And Transgenic Tobacco Plants , Cyril Sebastian Roberts Jan 1994

Expression Of Chlamydomonas Reinhardtii Periplasmic Carbonic Anhydrase In Escherichia Coli And Transgenic Tobacco Plants , Cyril Sebastian Roberts

Retrospective Theses and Dissertations

Carbonic anhydrase (CA) catalyzes the reversible hydration of CO2. The periplasmic CA gene CAH1 of Chlamydomonas reinhardtii codes for a highly processed secreted glycoprotein. The primary translation product of the CAH1 gene is targeted to the algae's ER, where it is proteolytically processed to yield two different subunits, glycosylated, assembled into an active heterotetramer, and secreted. Expression of CAH1 in Escherichia coli and tobacco plants were effected in this study. For bacterial expression, two constructs, one with and another without, the algal target leader sequence were used. Similarly, after replacing the algal's target leader sequence with that from ...


Isolation And Characterization Of Maize (Zea Mays L.) Mitochondrial Polyribosomes , Virginia Cox Crane Jan 1993

Isolation And Characterization Of Maize (Zea Mays L.) Mitochondrial Polyribosomes , Virginia Cox Crane

Retrospective Theses and Dissertations

Maize mitochondrial polyribosomes were isolated and characterized in the first and so far most complete study of the polysomal component of the translational apparatus of higher plant mitochondrial. Higher plant mitochondria are unique in that more than one, and often many, transcripts for a mitochondrial particular gene are found in abunDance; This made the characterization of the mRNA content of maize mitochondrial polyribosomes crucial to the understanding of information storage and use in these organelles;The protein gene transcript content of mitochondrial polysomes was described and compared to whole mitochondrial transcript content for seven maize mitochondrial genes. It was found ...


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 ...


Changes In Gene Expression During Induction Of The Carbon Dioxide Concentrating Mechanism In Chlamydomonas Reinhardtii , Thomas Leslie Winder Jan 1991

Changes In Gene Expression During Induction Of The Carbon Dioxide Concentrating Mechanism In Chlamydomonas Reinhardtii , Thomas Leslie Winder

Retrospective Theses and Dissertations

The regulation of genes by CO[subscript]2 concentration in wild type and mutants of the unicellular green alga Chlamydomonas reinhardtii was studied. This and other algal species can photosynthesize efficiently under limiting concentrations of CO[subscript]2 due to the activities of a CO[subscript]2 concentrating mechanism and carbonic anhydrase. A cDNA copy of the gene that codes for a periplasmic carbonic anhydrase (perCA) was isolated and used to study regulation of perCA synthesis in a cell wall-deficient mutant (CW-15). Over-expression of perCA in CW-15, relative to wild type, was found at the levels of enzyme activity, protein ...


Avena Phytochrome Mrna: In Vivo Localization, Degradation Products, And Half-Life , Kevin Andrew Seeley Jan 1991

Avena Phytochrome Mrna: In Vivo Localization, Degradation Products, And Half-Life , Kevin Andrew Seeley

Retrospective Theses and Dissertations

The purpose of this research is to determine the role that post-transcriptional processes play in the regulation of phytochrome (phy) steady-state messenger RNA (mRNA) levels. The control of etiolated phytochrome (phyA) and chlorophyll a/b binding protein (cab) gene transcription and steady-state mRNA levels are known to be regulated by the phyA signal transduction pathway. I performed a number of control experiments that indicate the degradation products detected in northern analysis of phyA mRNA were produced in vivo and were not an artifact of RNA isolation techniques. I have also shown that infrared (IR) irradiation has no appreciable effect on ...