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Articles 1 - 16 of 16

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

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 ...


Posttranslational Processing And Functional Analysis Of Tractin, An L1 Family Member In Leech , Yingzhi Xu Jan 2003

Posttranslational Processing And Functional Analysis Of Tractin, An L1 Family Member In Leech , Yingzhi Xu

Retrospective Theses and Dissertations

During neurogenesis, glycosylated cell adhesion molecules (CAMs) mediate the growth cone navigation and synapse formation. The structure of neuronal CAMs of Ig superfamily is characterized by the variability and complexity of their extracellular region which contain multiple tandemly arranged domains. The diversity in the structure of the neuronal CAMs is generated by alternative splicing and posttranslational modification, such as differential glycosylation and proteolytic processing.;Tractin is a member of the L1-family of neuronal CAMs in leech. It contains six Ig domains, 4 FNIII-like domains, an acidic domain, 12 repeats of a novel proline- and glycine-rich motif (PG/YG) with sequence ...


The Role Of Rev-Sr Protein Interactions In The Regulation Of Equine Infectious Anemia Virus Replication , Gregory Saang Park Jan 2003

The Role Of Rev-Sr Protein Interactions In The Regulation Of Equine Infectious Anemia Virus Replication , Gregory Saang Park

Retrospective Theses and Dissertations

Equine infectious anemia virus (EIAV) is a member of the lentivirus subfamily of retroviruses that produces a variable clinical disease course characterized as acute, chronic, and inapparent. The clinical signs can vary according to the stage of disease, and generally correlate with levels of virus replication. As with other retroviruses, EIAV utilizes both RNA and proteins to produce alternatively spliced transcripts required for virus replication. EIAV encodes a protein called Rev, which functions by binding unspliced and singly spliced viral mRNAs in the nucleus at a sequence called the Rev responsive element (RRE) and exporting them into the cytoplasm. Rev ...


Protein Structure, Distribution Of Homoplasy And Phylogenetic Inference , Olivier Fedrigo Jan 2003

Protein Structure, Distribution Of Homoplasy And Phylogenetic Inference , Olivier Fedrigo

Retrospective Theses and Dissertations

All molecular phylogenetic methods are based on two assumptions: independence of characters and constant selective pressure. It is well known that these assumptions are often violated, but it is assumed that the methods are robust to such violations. However, the increase of unorthodox phylogenies makes us wonder about their reliability. None of the currently used phylogenetic methods and models account for a change of functional/structural constraint at the protein level. In order to understand the consequences on the phylogenetic inference, I studied the distribution of the structural/functional misleading phylogenetic signal in the tree and described the effect of ...


Identification And Functional Analysis Of Thylakoid Membrane Proteome , Yingchun Wang Jan 2003

Identification And Functional Analysis Of Thylakoid Membrane Proteome , Yingchun Wang

Retrospective Theses and Dissertations

Membrane proteins play crucial roles in many biological functions. Identities and functions of most membrane proteins remain to be revealed. New technological breakthroughs in proteomics together with the availability of genomic sequence information make it possible to study functions of membrane proteins on a genome-wide scale. We used a multidisciplinary approach combining biochemistry, genetics, proteomics and bioinformatics to study the functions of the thylakoid proteome of Synechocystis sp. PCC6803. The thylakoid membrane proteins were separated into peripheral and integral fractions and resolved into 2-D gels with different pH ranges. The protein spots in the 2-D gels were subjected to peptide ...


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 ...


Protein-Carbohydrate And Protein-Protein Interactions: Using Models To Better Understand And Predict Specific Molecular Recognition, Alain Teboho Laederach Jan 2003

Protein-Carbohydrate And Protein-Protein Interactions: Using Models To Better Understand And Predict Specific Molecular Recognition, Alain Teboho Laederach

Retrospective Theses and Dissertations

Any molecular recognition event results in a change in the free energy of the system. The extent of this change is related to the association constant, such that the more negative the free energy change is, the tighter the interaction between receptor and ligand. Protein-carbohydrate interactions play a critical role in signal transduction, innate immunity, and metabolism. Modeling these interactions is somewhat complicated by the inherent flexibility of carbohydrates as well as their relatively large number of functional groups. An empirical scoring function for docking carbohydrates to proteins, specifically tailored to predict both the correct binding orientation and free energy ...


Genetic And Phenotypic Variation Of The Equine Infectious Anemia Virus Surface Unit Envelope Glycoprotein During Disease Progression , Brett Alan Sponseller Jan 2003

Genetic And Phenotypic Variation Of The Equine Infectious Anemia Virus Surface Unit Envelope Glycoprotein During Disease Progression , Brett Alan Sponseller

Retrospective Theses and Dissertations

Lentiviruses are single-stranded RNA viruses generally associated with chronic diseases of the immune and central nervous systems. In contrast to the insidious, progressive nature of most lentiviral diseases, equine infectious anemia virus (EIAV) infection results in rapid onset of a variable disease course in equids. Acute disease is accompanied with high-titered viremia, thrombocytopenia, fever, depression, and inappetance. The chronic stage is usually characterized by recurrent episodes of disease. Equids that survive recurrent disease episodes progress to the inapparent stage of disease where no clinical signs are evident; however, there is persistent, ongoing virus replication. Lentiviruses exist within the host as ...


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 ...


Herpes Virus Icp47 And Us11 Suppression Of Ctl Activity Adapted For Use In Gene Therapy , Thomas Joseph Radosevich Jan 2003

Herpes Virus Icp47 And Us11 Suppression Of Ctl Activity Adapted For Use In Gene Therapy , Thomas Joseph Radosevich

Retrospective Theses and Dissertations

A major stumbling block encountered in gene therapy clinical trials has been the rapid destruction of the therapeutic product by the host's immune response. The goal of this work is to diminish the host Cytotoxic T Lymphocyte (CTL) response to gene therapy transgenes and transduced cells by incorporating immunosuppression genes into gene therapy vectors. The processing and presentation of antigens through the class I Major Histocompatibility Complex (class I MHC) pathway is known to be an early response to viral infection. Disruption of the class I MHC pathway results in a decrease of the CD8+ CTL response and prolongs ...


Navigating Heterochromatin , Peter Fuerst Jan 2003

Navigating Heterochromatin , Peter Fuerst

Retrospective Theses and Dissertations

The condensed structure of heterochromatin differs significantly from euchromatin and DNA bound in heterochromatin is generally not transcriptionally active. Transcriptional silencing allows the control of gene expression and affords a novel mechanism of defense against genomic parasites. In addition, the physical structure of heterochromatin plays a direct role by contributing to centromere function in many eukaryotes. Mechanisms by which heterochromatin is established and maintained are only partly understood at this time. By studying the interaction of Ty5, a retrotransposon that integrates preferentially into heterochromatin-bound DNA, some of the basic biology of heterochromatin and the proteins that compose it were elucidated ...


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 ...


Functional Divergence And Genome Evolution Of Vertebrate Protein Kinases (Kinome), Jianying Gu Jan 2003

Functional Divergence And Genome Evolution Of Vertebrate Protein Kinases (Kinome), Jianying Gu

Retrospective Theses and Dissertations

The emerging complete and nearly complete genome sequences have provided a significant amount of materials for large-scale comparative genomic analysis. Novel methods have been developed to elucidate the function of gene products and functional interacting networks. Many of these post-genomic attempts have focused on unveiling the evolutionary forces that have shaped the network organization. Among various evolutionary forces, duplication of functional domain, individual gene, chromosomal segment, or entire genome has long been thought as primary resource for the function novelties in a vast number of gene families. It is therefore intriguing to quantitatively trace the changes of evolutionary constraints after ...


The Mechanism Of Integration Preference To Heterochromatin Of Yeast Retrotransposon Ty5 , Weiwu Xie Jan 2003

The Mechanism Of Integration Preference To Heterochromatin Of Yeast Retrotransposon Ty5 , Weiwu Xie

Retrospective Theses and Dissertations

Ty5 is a retrotransposon in Saccharomyces cerevisiae. In wild type yeast strains, over 90% of Ty5 insertions occur at the telomeres or HM loci. These regions are bound in silent chromatin, which is analogous to heterochromatin of higher eukaryotes. Our laboratory previously described a targeting mutant of Ty5 that has an amino acid substitution near the C-terminus of integrase. Targeting to silent chromatin is reduced more than 20-fold in the mutant. We further defined the Ty5 targeting domain (TD) by saturation mutagenesis. All of the targeting mutations mapped to a stretch of six amino acids (LDSSPP). We tethered TD to ...


Characterization Of Two Novel Spindle Matrix Proteins In Drosophila, Chromator And Megator , Dong Wang Jan 2003

Characterization Of Two Novel Spindle Matrix Proteins In Drosophila, Chromator And Megator , Dong Wang

Retrospective Theses and Dissertations

A spindle matrix has been proposed to help organize and stabilize microtubules during mitosis. This concept has gained new interest due to the identification of Skeletor as a potential component of the spindle matrix. Skeletor is associated with chromosomes during interphase but reorganizes into a spindle-like structure during early prophase before the nuclear envelope breaks down and microtubules enter the nucleus. The Skeletor spindle extends from pole to pole during metaphase coaligning with the microtubule spindle and persists even after nocodazole treatment dissembles the microtubules. These features make Skeletor an ideal candidate as a spindle matrix protein.;In this study ...