Open Access. Powered by Scholars. Published by Universities.®

Cell Biology Commons

Open Access. Powered by Scholars. Published by Universities.®

Retrospective Theses and Dissertations

Discipline
Keyword
Publication Year

Articles 1 - 30 of 113

Full-Text Articles in Cell Biology

Functional Analysis Of The C-Terminal Domain In The Drosophila Jil-1 Histone H3 Kinase, Xiaomin Bao Jan 2008

Functional Analysis Of The C-Terminal Domain In The Drosophila Jil-1 Histone H3 Kinase, Xiaomin Bao

Retrospective Theses and Dissertations

Epigenetic regulation is an important process utilized by biological systems to control gene expression and organize development, with histone modification enzymes among the most important components in this regulatory network. The predominant interphase H3 Serine10 kinase in Drosophila is JIL-1, which plays an important role in regulating chromosome structure and modulating gene expression. The full-length JIL-1 protein is composed of four domains including a N-terminal domain (NTD), two kinase domains (KDI and KDII), and a unique C-terminal domain (CTD). In order to study the biological importance of these individual domains, a domain analysis research approach was taken and different functions ...


Dissection Of The Mitotic And Nuclear Functions Of Chromator, A Nuclear-Derived Spindle Matrix Component In Drosophila, Yun Ding Jan 2008

Dissection Of The Mitotic And Nuclear Functions Of Chromator, A Nuclear-Derived Spindle Matrix Component In Drosophila, Yun Ding

Retrospective Theses and Dissertations

A spindle matrix has long been proposed to serve as a stationary or elastic molecular matrix substrate for the organization and activities of microtubules and motors, based on the consideration of a mechanical and functional support for the stabilization of microtubule spindle during force generation from mitotic motors. Recently, the identification of four Drosophila proteins, Skeletor, Megator, EAST and Chromator has provided molecular evidence for the existence of this macromolecular matrix structure during mitosis. All of these four proteins have been shown to interact with each other within a protein complex and redistribute from the nucleus at interphase to form ...


Functional Characterization Of Arabidopsis Sorting Nexin Atsnx2b, Nguyen Phan Jan 2008

Functional Characterization Of Arabidopsis Sorting Nexin Atsnx2b, Nguyen Phan

Retrospective Theses and Dissertations

Sorting nexins are conserved proteins that function in vesicular trafficking and are defined by the presence of a phox (PX) domain. Here we present the characterization of Arabidopsis thaliana sorting nexin AtSNX2b. The ubiquitously-expressed sorting nexin is a peripherally-associated membrane protein whose PX domain binds to phosphatidylinositol 3-phosphate in vitro. AtSNX2b localizes to the trans-Golgi network (TGN), prevacuolar compartment and endosomes. Overexpression of GFP-tagged AtSNX2b produces enlarged GFP-labeled compartments that can be also labeled by the endocytic tracer FM4-64, while untagged AtSNX2b overexpression generates compartments which are not as large. Endocytic trafficking of FM4-64 is arrested in cells overexpressing AtSNX2b ...


Hras Intracellular Trafficking And Signal Transduction, Jodi Ho-Jung Mckay Jan 2007

Hras Intracellular Trafficking And Signal Transduction, Jodi Ho-Jung Mckay

Retrospective Theses and Dissertations

Cancer, which is characterized by uncontrolled cell division and proliferation, is the second leading cause of death in the United States. Of these deaths, approximately 30% are the result of mutations in Ras protein. When activated, Ras propagates multiple signal transduction cascades and induces cell proliferation, differentiation, and apoptosis. Within the Ras subfamily, there are several isoforms of Ras which differ in their posttranslational modifications. The modifications include proteolytic cleavage of the CAAX box, farnesylation, and palmitoylation which act as plasma membrane anchors where most signal transduction takes place. This dissertation demonstrates that Ras endocytosis takes place through a novel ...


Deciphering Molecular Mechanisms That Regulate Programmed Cell Death Of Primordial Germ Cells In Drosophila Melanogaster, Yukiko Yamada Jan 2007

Deciphering Molecular Mechanisms That Regulate Programmed Cell Death Of Primordial Germ Cells In Drosophila Melanogaster, Yukiko Yamada

Retrospective Theses and Dissertations

Programmed cell death (PCD) is a genetically regulated process that is central to life of multicellular organisms. During development, PCD serves to sculpt tissues, remove temporary structures, regulate cell populations, and eliminate harmful cells. Deregulation of PCD can lead to medical conditions such as cancer and neurodegenerative disorders. Core components of PCD machineries are conserved across the animal phyla. Therefore, studies in model organisms provide valuable insights for further understanding of this very important process. The research presented here uses Drosophila primordial germ cells as a model system to investigate genes that are important for germ cell PCD. During embryogenesis ...


Osteoarthritis: Clinical Evaluation And Cartilage Tissue Engineering, Wanda June Gordon-Evans Jan 2007

Osteoarthritis: Clinical Evaluation And Cartilage Tissue Engineering, Wanda June Gordon-Evans

Retrospective Theses and Dissertations

Osteoarthritis (OA) is the 2nd leading cause of long term disability in North America affecting 40 million Americans. The work presented in this manuscript addresses clinical outcome measures used to determine treatment effect and 2 in vitro studies using tissue engineering techniques to grow cartilage suitable for in vivo use. In the first study, radiographs of the stifle joint in dogs were scored for the severity of OA, and limb function was measured by force platform gait analysis. The 2 outcome measures were analyzed using regression methods. There was no correlation of the severity of radiographic OA and limb function ...


Novel Amphiphilic Block Copolymers And Their Self-Assembled Injectable Hydrogels For Gene Delivery, Ankit Agarwal Jan 2007

Novel Amphiphilic Block Copolymers And Their Self-Assembled Injectable Hydrogels For Gene Delivery, Ankit Agarwal

Retrospective Theses and Dissertations

This work describes the development and investigation of a family of novel "smart" copolymers as non-viral gene delivery vectors. The copolymers have five blocks, and thus named pentablock, with a central block of a hydrophobic polymer, surrounded by two blocks of a hydrophilic polymer, and capped at each terminal end with cationic polymer blocks, arranged in an architecture to provide temperature and pH sensitivity to the copolymers. They are derived from commercially available triblock Pluronic copolymers. The cationic copolymers can efficiently condense negatively charged plasmid DNA in nanostructures with efficient cellular uptake. The amphiphilic nature of copolymers causes them to ...


Characterizing And Influencing Differentiation Of Retinal Progenitor Cells, Tyra Ellen Dunn-Thomas Jan 2007

Characterizing And Influencing Differentiation Of Retinal Progenitor Cells, Tyra Ellen Dunn-Thomas

Retrospective Theses and Dissertations

Blinding degenerative retinal diseases including retinitis pigmentosa, macular degeneration and glaucoma are characterized by loss of retinal neurons. At this time there is no way to replace retinal cell loss due to disease or injury since differentiated retinal cells are unable to regenerate. As a potential approach for treating retinal injury, neural progenitor cells have been proposed as a unique source of transplantable cells to replace lost cells in the damaged retina. Previous studies have transplanted a variety of neural stem cells to the eye in hopes of developing a therapy to replace retinal neurons lost to disease. Successful integration ...


The Role Of Peroxisome Proliferator Activated-Receptor Gamma In Ovarian Function, Lacey Jeanne Luense Jan 2007

The Role Of Peroxisome Proliferator Activated-Receptor Gamma In Ovarian Function, Lacey Jeanne Luense

Retrospective Theses and Dissertations

The transcription factor, peroxisome proliferator activated-receptor γ (PPARγ), regulates many processes critical for normal ovarian function. The role of PPARγ in the ovary was investigated by determining its expression throughout the bovine estrous cycle, and luteal tissue was cultured with agonists and an antagonist of PPARγ to determine its impact on progesterone production. Protein, but not mRNA for PPARγ, was lower in regressing compared to functional luteal tissue. Treatment with a PPARγ agonist decreased progesterone secretion from late phase luteal tissue. These findings indicate that PPARγ may play a role in luteal formation/function, and alter progesterone production during specific ...


Role Of Leu[Superscript B 10] In Cytoglobin And Comparison Of Direct And Indirect Measurements Of Hexacoordinate Hemoglobin Ligand Affinity, Jordan Richard Witmer Jan 2007

Role Of Leu[Superscript B 10] In Cytoglobin And Comparison Of Direct And Indirect Measurements Of Hexacoordinate Hemoglobin Ligand Affinity, Jordan Richard Witmer

Retrospective Theses and Dissertations

Hexacoordinate hemoglobins (HxHbs) have recently been discovered and have been found in nearly all living organisms. In humans, hxHbs are represented by neuroglobin (Ngb) and cytoglobin (Cgb). While Ngb is principally found in the brain, Cgb is ubiquitously expressed in all tissues. Ligand binding in hexacoordinate hemoglobins is complex due to the reversible coordination of the heme iron by the distal histidine. Hexacoordination regulates ligand binding and is regulated by specific residues in the heme pocket including the B10 position. Therefore, we investigated the influence of LeuB10 on hexacoordination and ligand binding in Cgb. Ligand binding was analyzed for recombinant ...


Characterization Of Three Spindle Matrix Proteins, Megator, East And Asator, In Drosophila, Hongying Qi Jan 2007

Characterization Of Three Spindle Matrix Proteins, Megator, East And Asator, In Drosophila, Hongying Qi

Retrospective Theses and Dissertations

Two previously identified proteins Skeletor and Chromator provide the molecular evidence for the existence of a spindle matrix complex in Drosophila. The spindle matrix has been proposed to be a macromolecular complex, which plays a role in organization and stabilization of the mitotic spindle as well as in providing structural support for counterbalancing force production.;In this dissertation, I present the identification and characterization of three more putative spindle matrix candidate proteins, Megator, EAST and Asator. Megator, an ortholog of the mammalian TPR protein, contains a large coiled-coil domain at its NH2-terminus and an acidic, non-structural COOH-terminus. Immunohistochemistry studies show ...


Map Based Candidate Gene Cloning And Functional Analysis Of Genes Involved In Vlcfas Synthesis, Li Fan Jan 2007

Map Based Candidate Gene Cloning And Functional Analysis Of Genes Involved In Vlcfas Synthesis, Li Fan

Retrospective Theses and Dissertations

VLCFAs are biosynthesized by an endoplasmic reticulum associated enzyme system, referred to as fatty acid elongase. Fatty acid elongase generates VLCFAs by elongating 18C fatty acids. The enzymatic machinery of fatty acid elongation is believed to be composed of 3-ketoacyl-CoA synthase, 3-ketoacyl-CoA reductase, 3-hydroxyacyl-CoA dehydratase, and enoyl-CoA reductase. However, the insoluble nature of the fatty acid elongase system has hampered efforts to purify the system and to identify the genes that encode the component proteins. In the current study a candidate gene cloning approach was used to demonstrate that the previously defined gl26 gene of maize encodes a predicted enoyl-CoA ...


Directed Growth And Selective Differentiation Of Neural Progenitor Cells Using A Synergistic Combination Of Topographical And Soluble Cues , Jennifer Behr Recknor Jan 2006

Directed Growth And Selective Differentiation Of Neural Progenitor Cells Using A Synergistic Combination Of Topographical And Soluble Cues , Jennifer Behr Recknor

Retrospective Theses and Dissertations

The purpose of this study is to develop strategies to facilitate nerve regeneration using a synergistic combination of guidance cues. We are investigating the cellular mechanisms of development using adult rat hippocampal progenitor cells (AHPCs) and have demonstrated that manipulating a combination of physical, chemical and biological cues can lead to oriented astrocyte and neural progenitor cell outgrowth and can influence progenitor cell differentiation. To provide physical guidance, micropatterned polystyrene (PS) substrates were fabricated and chemically modified with laminin. Astrocytes or AHPCs cultured on these substrates align along the grooves of the patterned surface extending highly elongated processes. To further ...


Understanding Il-12 Responsiveness During Leishmania Amazonensis Infection , Amanda Ellen Ramer Jan 2006

Understanding Il-12 Responsiveness During Leishmania Amazonensis Infection , Amanda Ellen Ramer

Retrospective Theses and Dissertations

Cutaneous leishmaniasis is a vector-borne disease caused by intracellular protozoan parasites of the genus Leishmania. C3H mice challenged with L. major develop a polarized Th1 response and subsequently heal, whereas L. amazonensis challenge leads to chronic lesions with high parasite loads. This work demonstrates that infection with L. amazonensis creates a population of antigen-responsive, CD44hi CD4+ T cells that proliferate and produce IL-2 but do not polarize to an effector phenotype and exhibit limited IFN-gamma production in response to IL-12. CD44 hi CD4+ T cells from L. amazonensis-infected mice fail to accumulate in culture as compared to cells from L ...


From Endomembrane To The Plasma Membrane: The Traffic, Signal Transduction And Micro-Localization Of H-Ras , Hui Zheng Jan 2006

From Endomembrane To The Plasma Membrane: The Traffic, Signal Transduction And Micro-Localization Of H-Ras , Hui Zheng

Retrospective Theses and Dissertations

Ras proteins are small G proteins that play key roles in many aspect of cell signal transduction. H-Ras is one of three isoforms of mammalian Ras protein that is best studied. The work presented in this dissertation describes how the carboxyl terminal lipid modifications affect the transportation, signal transduction and micro-localizations of H-Ras protein. The already known traffic pathway for H-Ras to the plasma membrane is Golgi mediated classical vesicular Transportation; However, we found the H-Ras transportation has many different features other than the classical pathway, and thereby discovered a new pathway for H-Ras targeting to the plasma membrane. This ...


Comparative Study Of Immunocytochemical Patterns Of Somatotrophs, Mammotrophs, And Mammosomatotrophs In The Porcine Anterior Pituitary , Jin-Sook Lee Jan 2006

Comparative Study Of Immunocytochemical Patterns Of Somatotrophs, Mammotrophs, And Mammosomatotrophs In The Porcine Anterior Pituitary , Jin-Sook Lee

Retrospective Theses and Dissertations

The anterior pituitary gland is a dynamic and complex endocrine gland that synthesizes and secretes trophic hormones from distinct endocrine cells including mammotrophs (prolactin cells or lactotrophs) and somatotrophs (growth hormone cells) to play essential roles in the maintenance of homeostasis, metabolism, reproduction, growth, and lactation. Recently, the existence of a novel anterior pituitary cell type, the mammosomatotroph which contained both growth hormone (GH) and prolactin (PRL) was proposed to function as a transitional cell or progenitor cell between somatotrophs and mammotrophs under various physiological conditions. The present study investigated the spatial distribution patterns of somatotrophs, mammotrophs, and mammosomatotrophs by ...


Analysis Of A Nuclear Complex Of Proteins That Form A Spindle Matrix During Mitosis In Drosophila , Uttama Rath Jan 2005

Analysis Of A Nuclear Complex Of Proteins That Form A Spindle Matrix During Mitosis In Drosophila , Uttama Rath

Retrospective Theses and Dissertations

A spindle matrix is a macromolecular structure hypothesized to provide a stationary support or strut for the anchorage of motor proteins during force generation, microtubule sliding, and chromosome segregation in mitosis. Previous work in Drosophila has shown Skeletor, as the first putative molecular candidate of spindle matrix structure since it possesses many features consistent with the proposed spindle matrix structure.;We have identified two more putative spindle matrix candidate proteins, Chromator and Megator, using yeast two-hybrid interaction assay, cross-immunoprecipitation and immunocytochemistry. Chromator is a novel and essential chromodomain containing protein that interacts directly with Skeletor and extensively colocalizes with it ...


Investigation Of The Function Of Branching Enzymes I, Iia, And Iib In The Determination Of Amylopectin Structure And Regulation Of Starch Biosynthesis , Rebekah Suzanne Marsh Jan 2005

Investigation Of The Function Of Branching Enzymes I, Iia, And Iib In The Determination Of Amylopectin Structure And Regulation Of Starch Biosynthesis , Rebekah Suzanne Marsh

Retrospective Theses and Dissertations

Starch is one of the most abundant carbohydrates on earth serving vital roles as the primary energy reserve of plants, a significant source of calories in the human diet, and a renewable resource for other industrial applications. The multiplicity of starch biosynthetic enzymes is evolutionarily conserved in plants suggesting their functions are essential in starch biosynthesis. The overall goal of this research is to determine the specific molecular functions of the multiple starch branching enzyme (BE) isoforms in maize.;This dissertation first addresses what, if any, are the differences in enzymatic properties of BEIIa and BEIIb. Two polyclonal antisera were ...


Characterization Of The Sireviruses: A Unique Group Of Ty1/Copia Ltr Retrotransposons In Plants, Ericka Ruth Havecker Jan 2005

Characterization Of The Sireviruses: A Unique Group Of Ty1/Copia Ltr Retrotransposons In Plants, Ericka Ruth Havecker

Retrospective Theses and Dissertations

Plant genomes have allowed the expansion of many types of mobile genetic elements. LTR retrotransposons are a subclass of mobile genetic elements that replicate using an RNA intermediate. The Sireviruses are one of three genera in the Ty1/copia class of LTR retrotransposons. The name 'Sireviruses' comes from the founding member (soybean SIRE1) and the fact that retrotransposons, although not known to be infectious, have many traits in common with viruses.;Besides being phylogenetically distinct, the Sireviruses have features that set them apart from other LTR retrotransposons. Different Sirevirus members show great variability in their genomic structures and the translational ...


Identification Of A Role For Janus Kinase2 (Jak2) In Skeletal Muscle Mitogenesis, Myogenesis, And Hypertrophy , Symantha Ann Anderson Jan 2005

Identification Of A Role For Janus Kinase2 (Jak2) In Skeletal Muscle Mitogenesis, Myogenesis, And Hypertrophy , Symantha Ann Anderson

Retrospective Theses and Dissertations

Skeletal muscle is a dynamic tissue with tight developmental control and the ability to significantly remodel in the postnatal animal. Understanding the molecular mechanisms underlying skeletal muscle development and postnatal growth is critical to potential therapeutic manipulation. Janus kinase2 (JAK2) is a tyrosine kinase critical for growth of numerous cell types and is causative in many cancers, including leukemia. In this study we sought to understand the role of the JAK/STAT signaling cascade in skeletal muscle. In particular, this research focused on the role of JAK2 in skeletal muscle mitogenesis, myogenesis, and hypertrophy. Little work has been done regarding ...


A Cell Culture System And Production Of An Infectious Clone Of Rhopalosiphum Padi Virus (Dicistroviridae) , Sandhya Boyapalle Jan 2005

A Cell Culture System And Production Of An Infectious Clone Of Rhopalosiphum Padi Virus (Dicistroviridae) , Sandhya Boyapalle

Retrospective Theses and Dissertations

Rhopalosiphum padi virus (RhPV) was first isolated from the bird cherry-oat aphid, Rhopalosiphum padi. RhPV, an icosahedral virus, belongs to the family Dicistroviridae. It has a 10 kb positive-sense RNA genome, with two viral open reading frames (ORFs). We have identified two cell lines, Z10-2 and DMII derived from the homopterans, Homalodisca coagulata and Dalbulus maidis that are permissive for RhPV. Infection, viral replication and production of virions was confirmed by northern blot hybridization, RT-PCR, western blot analysis and immunoelectron microscopy. A cell culture system that allows replication of the virus is crucial for further study of the biology of ...


The Identification, Cloning, And Characterization Of A Phospholipase C-Beta Isoform From The Sea Urchin Egg , Andre Peter Joseph Kulisz Jan 2004

The Identification, Cloning, And Characterization Of A Phospholipase C-Beta Isoform From The Sea Urchin Egg , Andre Peter Joseph Kulisz

Retrospective Theses and Dissertations

This work was the first to provide direct evidence for the presence of a PLCbeta isoform within the sea urchin egg, named suPLCbeta. The coding sequence was identified and cloned from the eggs of Lytechinus pictus and when translated, determined to have the greatest degree of homology and identity with the mammalian PLCbeta4 isoforms. This alone is a unique finding in that the presence of PLCbeta4 has only been found in the retina and specific neuronal tissues. The presence of the protein within the egg was verified using antibodies that were generated specifically against suPLCbeta, which indicate that the majority ...


Structural And Molecular Analysis Of Leech Neuronal Proteins, Calsensin And Filamin , Deepa V. Venkitaramani Jan 2004

Structural And Molecular Analysis Of Leech Neuronal Proteins, Calsensin And Filamin , Deepa V. Venkitaramani

Retrospective Theses and Dissertations

This thesis describes the structural and molecular analysis of two leech neuronal proteins, Calsensin and Filamin. Calsensin is an EF-hand calcium-binding protein expressed by a subset of peripheral sensory neurons which fasciculate into a single tract in the leech central nervous system. Calsensin is a 9 kD protein with two EF-hand calcium-binding motifs. Calsensin can multimerize via disulfide bridge formation involving the two cysteine residues in vitro. Furthermore, Calsensin shows differential gel migration depending on the presence or absence of calcium suggesting a conformational change upon calcium binding. Using multidimensional NMR spectroscopy we have determined the solution structure and backbone ...


The Essential Jil-1 Kinase Regulates Histone H3 Phosphorylation And Maintains Chromatin Structure In Drosophila , Weiguo Zhang Jan 2004

The Essential Jil-1 Kinase Regulates Histone H3 Phosphorylation And Maintains Chromatin Structure In Drosophila , Weiguo Zhang

Retrospective Theses and Dissertations

JIL-1 encodes a chromatin-associated tandem serine/threonine kinase in Drosophila melanogaster. JIL-1 predominantly associates with interbands on polytene chromosomes. It appears at higher levels on the X chromosome than on autosomes in males, and distributes about equally on all chromosomes in females. In addition, in males JIL-1 overlaps with the MSL (for male specific lethal) complex that specifically associates with the male X chromosome on which expression of most genes are upregulated.;We isolated JIL-1 mutants by inducing imprecise excision of an EP element inserted in JIL-1. We found that JIL-1 is required for viability of both females and males ...


The Role Of Integrin Mediated Adhesion And Signaling During Xenopus Retinal Development , Ming Li Jan 2003

The Role Of Integrin Mediated Adhesion And Signaling During Xenopus Retinal Development , Ming Li

Retrospective Theses and Dissertations

Integrins are the major family of cell adhesion receptors for extracellular matrix (ECM) components and are involved in cell-cell and cell-ECM adhesion. Integrins also participate in cytoskeletal rearrangements, activation of signal transductions, and co-regulation of growth factor activities.;In this dissertation, I have investigated the role of beta1 integrin-mediated adhesion and signaling during early Xenopus retinal development. First, I characterized the expression patterns of focal adhesion associated proteins, beta1 integrin, talin, vinculin, paxillin and phosphotyrosine in retinal glial cell line XR1 and in the developing Xenopus retina. These proteins are colocalized at focal adhesions located at the termini of F-actin ...


The Potential Of Neural Progenitor Cells: An Investigation Into Their Fate In Vitro And After Transplantation , Samantha J. Van Hoffelen Jan 2003

The Potential Of Neural Progenitor Cells: An Investigation Into Their Fate In Vitro And After Transplantation , Samantha J. Van Hoffelen

Retrospective Theses and Dissertations

Neuronal loss within the central nervous system (CNS) has been considered an irreversible process, as cells within the mammalian CNS fail to regenerate after degeneration and trauma. Neural stem (and progenitor) cells have been proposed as a potential source of new neurons. This investigation describes the fate of neural progenitor cells both in vitro and after transplantation. Progenitor cells were isolated from the brains of neonatal green fluorescent protein (GFP) expressing mice thereby allowing cells to be easily visualized both in culture and after transplantation. We have shown brain-derived progenitor cells (BPCs) can be maintained in defined conditions and are ...


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 ...


Molecular Interactions Of Talin And Actin: A Study On The Specific Domains Of Talin Involved In The Interactions , Ho-Sup Lee Jan 2002

Molecular Interactions Of Talin And Actin: A Study On The Specific Domains Of Talin Involved In The Interactions , Ho-Sup Lee

Retrospective Theses and Dissertations

Talin is an essential cytoskeletal protein present in cell-matrix type adherens junctions where it helps in attachment of the actin cytoskeleton to the plasma membrane. The nature of the interaction between talin and actin was examined in this dissertation by investigating three actin binding sites (ABS1--3), with ABS1 located in the 47 kDa N-terminal head and ABS2 and ABS3 present in the 190 kDa C-terminal tail of the talin molecule. Cosedimentation of expressed GST-fusion deletion constructs from the talin head with F-actin showed that actin binding activity of the talin head is contained within residues 271--320. Talin constructs containing the ...


Nitric Oxide In Astrocyte-Neuron Signaling , Nianzhen Li Jan 2002

Nitric Oxide In Astrocyte-Neuron Signaling , Nianzhen Li

Retrospective Theses and Dissertations

Astrocytes, a subtype of glial cell, have recently been shown to exhibit Ca2+ elevations in response to neurotransmitters. A Ca 2+ elevation can propagate to adjacent astrocytes as a Ca2+ wave, which allows an astrocyte to communicate with its neighbors. Additionally, glutamate can be released from astrocytes via a Ca2+ -dependent mechanism, thus modulating neuronal activity and synaptic transmission.;In this dissertation, I investigated the roles of another endogenous signal, nitric oxide (NO), in astrocyte-neuron signaling. First I tested if NO is generated during astrocytic Ca2+ signaling by imaging NO in purified murine cortical astrocyte cultures. Physiological concentrations of a ...


Mechanisms Of Somatostatin-Induced Paradoxical Increase In Insulin Secretion In The Presence Of Arginine Vasopressin In Clonal [Beta]-Cell Hit-T15 , Henrique Cheng Jan 2002

Mechanisms Of Somatostatin-Induced Paradoxical Increase In Insulin Secretion In The Presence Of Arginine Vasopressin In Clonal [Beta]-Cell Hit-T15 , Henrique Cheng

Retrospective Theses and Dissertations

We investigated the mechanism underlying somatostatin-induced increase in [Ca2+]i leading to insulin release in the presence of arginine vasopressin (AVP) in clonal beta-cell HIT-T15. Somatostatin increased [Ca2+]i and insulin release in a biphasic pattern, characterized by a sharp and transient increase followed by a rapid decline to the sub-basal level. Pretreatment with pertussis toxin, which inactivates Gi/Go, abolished the effects of somatostatin. U-73122, an inhibitor of phospholipase C, antagonized somatostatin-induced increase in [Ca2+] i. In Ca2+-free environment, somatostatin still increased [Ca2+]i, whereas depletion of intracellular Ca 2+ stores with thapsigargin, a microsomal Ca2+ ATPase inhibitor ...