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Articles 1 - 11 of 11

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

Post-Orbital Color Pattern Variation And The Evolution Of A Radiation Of Turtles (Graptemys), Erin M. Myers Jan 2008

Post-Orbital Color Pattern Variation And The Evolution Of A Radiation Of Turtles (Graptemys), Erin M. Myers

Retrospective Theses and Dissertations

One of the most studied areas in the field of evolutionary biology is the formation and maintenance of new species, as well as variation in the rate and extent to which taxa radiate. A range of evolutionary processes, from ecological adaptation to sexual selection and reinforcement, can lead species formation. However, the generation of new species likely results from several isolating mechanisms acting in concert. The map turtle complex (genus: Graptemys) is an excellent model system for exploring the nature of speciation given its exceptional species richness and morphological diversity, particularly in facial coloration patterns. This research utilizes an integrative ...


Taxonomic Review, Phylogeny, And Geographical Population Structure Of The Sawfishes (Chondrichthyes, Pristiformes), Vicente Vieira Faria Jan 2007

Taxonomic Review, Phylogeny, And Geographical Population Structure Of The Sawfishes (Chondrichthyes, Pristiformes), Vicente Vieira Faria

Retrospective Theses and Dissertations

Sawfishes (Pristidae) are considered endangered species worldwide, but their conservation and management have been undermined due to poor understanding of the group's natural taxonomy. The main purpose of this work was to review the taxonomy of sawfishes based on historical taxonomic literature supplemented with empirical observations on morphology, genetics, and geographic distribution. A molecular phylogenetics study based on both mitochondrial and nuclear genes was carried out to estimate the evolutionary interrelationships among the different species of sawfishes. Seven distinct living species are recognized based on external morphology and DNA sequence comparisons. Four are distributed in the Indo-West Pacific, two ...


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 ...


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 ...


Pou Domain Genes And The Immunoglobulin Octamer Motif In Chickens , Lynn Marie Heltemes Jan 1997

Pou Domain Genes And The Immunoglobulin Octamer Motif In Chickens , Lynn Marie Heltemes

Retrospective Theses and Dissertations

This research was undertaken to test the hypothesis that multiple POU genes exist and that POU proteins are involved in transcriptional regulation in the chicken. The POU protein Oct-2 has been hypothesized to partially regulate immunoglobulin gene expression through its interaction with the octamer motif found in the promoter of immunoglobulin genes. Transcriptional regulation of immunoglobulin genes provides a model for tissue-specific gene expression in the immune system. In searching for a chicken Oct-2 homologue, two partial chicken POU domain genes were identified. A cDNA clone encoding the POU domain of Brn-3a was isolated and showed near identity to the ...


The Role Of Rat Brain Ptp-1 Surface Basic Residues In Substrate Reactivity , Deborah Sue Baedke Jan 1996

The Role Of Rat Brain Ptp-1 Surface Basic Residues In Substrate Reactivity , Deborah Sue Baedke

Retrospective Theses and Dissertations

Previous work by others has demonstrated that rat brain protein tyrosine phosphatase (rbPTP-1) exhibited increased reactivity toward substrates containing acidic residues N-terminal to phosphotyrosine. We show that substrates containing a single acidic residue C-terminal to the phosphotyrosine also enhanced reactivity with rbPTP-1. A substrate aspartate residue at the P+2 position exhibited the greatest enhancement of reactivity;Surface basic residues of rbPTP-1 were investigated for their role in the increased reactivity due to substrate acidic residues. Mutation of R47 or K120 to alanine decreased the enhancement of reactivity due to acidic residues N-terminal to phosphotyrosine by 78% and 73% respectively ...


Molecular Analysis Of Protein Kinase C In The Sea Urchin Lytechinus Pictus , Terese Louise Rakow Jan 1993

Molecular Analysis Of Protein Kinase C In The Sea Urchin Lytechinus Pictus , Terese Louise Rakow

Retrospective Theses and Dissertations

Protein kinase C (PKC) was originally described as a serine threonine kinase in brain tissue. This activity was found to be dependent upon Ca[superscript]2+ and phosphatidyl serine. Today protein kinase C consists of a family of kinases with nine known members. Some members are Ca[superscript]2+-independent isozymes, and all of them have subtle activation differences. The multiple isozymes with varying activities in addition to different tissue distributions lead to the idea that members of the family have different functions. PKC has been well studied in mammalian systems and it is concluded that PKC is activated in ...


Characterization Of Cis-Acting Replication Control Elements In Ribosomal Rna Genes Of Tetrahymena Thermophila , Wen-Ling Shaiu Jan 1993

Characterization Of Cis-Acting Replication Control Elements In Ribosomal Rna Genes Of Tetrahymena Thermophila , Wen-Ling Shaiu

Retrospective Theses and Dissertations

This dissertation describes the identification and characterization of specific cis-acting replication control elements in the replication origin of Tetrahymena rDNA. Earlier studies of a mutant rDNA allele, C3-rmm1, identified a cis-acting sequence (the Type I repeat) within the 5[superscript]' non-transcribed spacer of rDNA that affects rDNA replication (Larson et al. 1986). Characterization of two additional, independently-isolated mutants (C3-rmm3 and C3-rmm4) and a revertant of C3-rmm4 strongly argue that the Type I repeat is indeed a cis-acting replication control element. Mutations causing rDNA replication defects were identified in copies of the Type I repeat that are separated by >600 bp ...


Purification And Properties Of The Malic Enzyme And The Malate Dehydrogenases From The Gill Tissue Of The Ribbed Mussel (Modiolus Demissus) , Mary Michael Brodey Jan 1991

Purification And Properties Of The Malic Enzyme And The Malate Dehydrogenases From The Gill Tissue Of The Ribbed Mussel (Modiolus Demissus) , Mary Michael Brodey

Retrospective Theses and Dissertations

To assess the role of dicarboxylic acid metabolism in the synthesis of alanine and other compounds by the ribbed mussel under conditions of hyperosmotic and anaerobic stress, the cytosolic and mitochondrial malate dehydrogenases and the mitochondrial malic enzyme from this organism were purified and their kinetics studied. Both the cytosolic and mitochondrial malate dehydrogenases were found to be dimers with native M[subscript] r = 60,000. One cMDH allele (designated slow) was found to predominate in populations from Cape Cod, MA. Similar low K[subscript] m's were observed for purified preparations of the slow/slow homodimer (cMDH) and for ...


Identification Of The Immediate-Early Products Of Bovine Herpesvirus-1 , David A. Hulce Jan 1990

Identification Of The Immediate-Early Products Of Bovine Herpesvirus-1 , David A. Hulce

Retrospective Theses and Dissertations

Bovine herpesvirus-1 (BHV-1) is a member of the alphaherpesvirinae. Productive infections of the alphaherpesvirinae progress through three stages of viral transcription and translation. The first stage, immediate-early (IE), does not require prior viral gene expression and is required for the second, delayed-early (DE), and third, late (L), stages of the infectious cycle. Like other herpesviruses, BHV-1 frequently establishes latent infections. This study was undertaken to characterize the IE stage of the productive BHV-1 infection. The number and location of IE genes and the size of IE polypeptides and IE mRNAs were investigated;Probing genomic Southern blots of BHV-1 cloned in ...


A Novel Insulin From The Bullfrog: Its Structure And Function In Protein Secretion By Hepatocytes , Jocelyn Jean Hulsebus Jan 1987

A Novel Insulin From The Bullfrog: Its Structure And Function In Protein Secretion By Hepatocytes , Jocelyn Jean Hulsebus

Retrospective Theses and Dissertations

Bullfrog insulin was extracted and purified from the pancreas of Rana catesbeiana adults using gel filtration and reverse phase high performance liquid chromatography. Amino acid analysis of bullfrog insulin revealed 52 amino acids instead of the most common number of 51. Hagfish insulin is the only other known insulin with 52 amino acids. The most unique feature of bullfrog insulin is a two amino acid extension on the amino terminus (A1) of the A chain. This is the only insulin to date that has an extension at this position. In mammals, the deletion of A1 glycine or addition of a ...