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1993

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Articles 1 - 26 of 26

Full-Text Articles in Cell Biology

Unusual Structure Of A Human Middle Repetitive Dna, Duminda D. Ratnasinghe Dec 1993

Unusual Structure Of A Human Middle Repetitive Dna, Duminda D. Ratnasinghe

Electronic Theses and Dissertations

The L2Hs sequences are a polymorphic, interspersed, middle repetitive DNA family unique to human genomes. Genomic fingerprinting indicates that these DNAs vary from one individual to another and between tissues of the same individual. Sequence analysis reveals that they are AT-rich (76%) and contain many unusual sequence arrangements (palindromes, inverted and direct repeats). These sequence properties confer on the L2Hs elements the potential to fold into non-B-form structures, a characteristic of recombination hot spots. To test this hypothesis carbodiimide, osmium tetroxide and S$\sb1$ nuclease were used as single-strand specific probes to study a recombinant plasmid, pN6.4.39, containing ...


Gtp Hydrolysis By Complexes Of The Signal Recognition Particle And The Signal Recognition Particle Receptor, Timothy Connolly, Reid Gilmore Nov 1993

Gtp Hydrolysis By Complexes Of The Signal Recognition Particle And The Signal Recognition Particle Receptor, Timothy Connolly, Reid Gilmore

Open Access Articles

Translocation of proteins across the endoplasmic reticulum membrane is a GTP-dependent process. The signal recognition particle (SRP) and the SRP receptor both contain subunits with GTP binding domains. One GTP-dependent reaction during protein translocation is the SRP receptor-mediated dissociation of SRP from the signal sequence of a nascent polypeptide. Here, we have assayed the SRP and the SRP receptor for GTP binding and hydrolysis activities. GTP hydrolysis by SRP was not detected, so the maximal GTP hydrolysis rate for SRP was estimated to be < 0.002 mol GTP hydrolyzed x mol of SRP-1 x min-1. The intrinsic GTP hydrolysis activity of the SRP receptor ranged between 0.02 and 0.04 mol GTP hydrolyzed x mol of SRP receptor-1 x min-1. A 40-fold enhancement of GTP hydrolysis activity relative to that observed for the SRP receptor alone was obtained when complexes were formed between SRP and the SRP receptor. GTP hydrolysis activity was inhibited by GDP, but not by ATP. Extended incubation of the SRP or the SRP receptor with GTP resulted in substoichiometric quantities of protein-bound ribonucleotide. SRP-SRP receptor complexes engaged in GTP hydrolysis were found to contain a minimum of one bound guanine ribonucleotide per SRP-SRP receptor complex. We conclude that the GTP hydrolysis activity described here is indicative of one of the GTPase cycles that occur during protein translocation across the endoplasmic reticulum.


Redistribution Of Clathrin-Coated Vesicle Adaptor Complexes During Adipocytic Differentiation Of 3t3-L1 Cells, Ranjan Chakrabarti, Marguerite Joly, Silvia Corvera Oct 1993

Redistribution Of Clathrin-Coated Vesicle Adaptor Complexes During Adipocytic Differentiation Of 3t3-L1 Cells, Ranjan Chakrabarti, Marguerite Joly, Silvia Corvera

Open Access Articles

Mechanisms for intracellular retention of proteins are induced during adipocytic differentiation of 3T3-L1 cells. To investigate the potential role of clathrin lattices in these retention processes, we performed a morphological and biochemical analysis of coated vesicle components in 3T3-L1 cells. Optical sectioning and image restoration revealed a marked increase in the staining of clathrin and beta adaptins in the perinuclear region of cells with differentiation. In addition, predominance of beta (subunit of the AP-2, plasma membrane adaptor) over beta' (subunit of the AP-1, Golgi adaptor) adaptin was observed in immunoblots of clathrin-coated vesicles purified from nondifferentiated fibroblasts, and this ratio ...


Isoform-Specific 3'-Untranslated Sequences Sort Alpha-Cardiac And Beta-Cytoplasmic Actin Messenger Rnas To Different Cytoplasmic Compartments, Edward H. Kislauskis, Zhifang Li, Robert H. Singer, Krishan L. Taneja Oct 1993

Isoform-Specific 3'-Untranslated Sequences Sort Alpha-Cardiac And Beta-Cytoplasmic Actin Messenger Rnas To Different Cytoplasmic Compartments, Edward H. Kislauskis, Zhifang Li, Robert H. Singer, Krishan L. Taneja

Open Access Articles

We demonstrate that in differentiating myoblasts, the mRNAs encoding two actin isoforms, beta-cytoplasmic, and alpha-cardiac, can occupy different cytoplasmic compartments within the same cytoplasm. beta-actin mRNA is localized to the leading lamellae and alpha-actin mRNA is associated with a perinuclear compartment. This was revealed by co-hybridizing, in situ, fluorochrome-conjugated oligonucleotide probes specific for each isoform. To address the mechanism of isoform-specific mRNA localization, molecular chimeras were constructed by insertion of actin sequences between the Lac Z coding region and SV-40 3'UTR in a reporter plasmid. These constructs were transiently expressed in a mixed culture of embryonic fibroblasts, myoblasts and ...


Exofacial Epitope-Tagged Glucose Transporter Chimeras Reveal Cooh-Terminal Sequences Governing Cellular Localization, Michael P. Czech, Anil Chawla, Chee-Wai Woon, Joanne M. Buxton, Michal Armoni, Wei Tang, Marguerite Joly, Silvia Corvera Oct 1993

Exofacial Epitope-Tagged Glucose Transporter Chimeras Reveal Cooh-Terminal Sequences Governing Cellular Localization, Michael P. Czech, Anil Chawla, Chee-Wai Woon, Joanne M. Buxton, Michal Armoni, Wei Tang, Marguerite Joly, Silvia Corvera

Open Access Articles

The insulin-regulated adipocyte/skeletal muscle glucose transporter (GLUT4) displays a characteristic steady-state intracellular localization under basal conditions, whereas the erythrocyte/brain transporter isoform (GLUT1) distributes mostly to the cell surface. To identify possible structural elements in these transporter proteins that determine their cellular localization, GLUT1/GLUT4 chimera cDNA constructs that contain the hemagglutinin epitope YPYDVPDYA (HA) in their major exofacial loops were engineered. Binding of monoclonal anti-HA antibody to non-permeabilized COS-7 cells expressing HA-tagged transporter chimeras revealed that expression of transporters on the cell surface was strongly influenced by their cytoplasmic COOH-terminal domain. This method also revealed a less marked ...


Inhibition Of Cytochrome P-450 But Not Neutrophil Depletion Prevents The Pulmonary Toxicity Associated With 1-Nitronaphthalene, Steven Michael Green Aug 1993

Inhibition Of Cytochrome P-450 But Not Neutrophil Depletion Prevents The Pulmonary Toxicity Associated With 1-Nitronaphthalene, Steven Michael Green

Master's Theses

1-Nitronaphthalene (1-NN) is an environmental contaminant that has been shown to cause pulmonary toxicity in rodents. To examine the contribution of cytochrome P-450 to the metabolism and subsequent toxicity of 1-NN, rats were pretreated with chloramphenicol, a suicide substrate of P-450. To determine if inflammation plays a role in 1-NN toxicity, rats were pretreated with cyclophosphamide to deplete neutrophils. In both experiments, morphological analysis of the lower airways was performed with light and electron microscopy. A second group of animals was examined for biochemical indicators of inflammation and cell damage. The parameters examined were cell content, protein content and lactate ...


Guanosine Diphosphatase Is Required For Protein And Sphingolipid Glycosylation In The Golgi Lumen Of Saccharomyces Cerevisiae, Claudia Abeijon, Ken Yanagisawa, Elisabet C. Mandon, Alex Hausler, Kelley W. Moremen, Carlos B. Hirschberg, Phillips W. Robbins Jul 1993

Guanosine Diphosphatase Is Required For Protein And Sphingolipid Glycosylation In The Golgi Lumen Of Saccharomyces Cerevisiae, Claudia Abeijon, Ken Yanagisawa, Elisabet C. Mandon, Alex Hausler, Kelley W. Moremen, Carlos B. Hirschberg, Phillips W. Robbins

Open Access Articles

Current models for nucleotide sugar use in the Golgi apparatus predict a critical role for the lumenal nucleoside diphosphatase. After transfer of sugars to endogenous macromolecular acceptors, the enzyme converts nucleoside diphosphates to nucleoside monophosphates which in turn exit the Golgi lumen in a coupled antiporter reaction, allowing entry of additional nucleotide sugar from the cytosol. To test this model, we cloned the gene for the S. cerevisiae guanosine diphosphatase and constructed a null mutation. This mutation should reduce the concentrations of GDP-mannose and GMP and increase the concentration of GDP in the Golgi lumen. The alterations should in turn ...


Concerted Control Of Multiple Histone Promoter Factors During Cell Density Inhibition Of Proliferation In Osteosarcoma Cells: Reciprocal Regulation Of Cell Cycle-Controlled And Bone-Related Genes, Fusinita M. I. Van Den Ent, Andre J. Van Wijnen, Thomas J. Last, Rita Bortell, Janet L. Stein, Jane B. Lian, Gary S. Stein May 1993

Concerted Control Of Multiple Histone Promoter Factors During Cell Density Inhibition Of Proliferation In Osteosarcoma Cells: Reciprocal Regulation Of Cell Cycle-Controlled And Bone-Related Genes, Fusinita M. I. Van Den Ent, Andre J. Van Wijnen, Thomas J. Last, Rita Bortell, Janet L. Stein, Jane B. Lian, Gary S. Stein

Open Access Articles

Cell density-induced growth inhibition of osteosarcoma cells (ROS 17/2.8) results in the shutdown of proliferation-specific histone H4 and H2B genes and the concomitant up-regulation of several osteoblast-related genes. In several respects, this reciprocal regulatory relationship is analogous to the proliferation/differentiation transition stage during development of the bone cell phenotype in normal diploid osteoblasts. Here, we comprehensively analyzed the promoter binding activities interfacing with key regulatory elements in the cell cycle-dependent histone and bone-specific osteocalcin genes. Similarly, we examined factors interacting with a series of general transcription regulatory elements that are present in a broad spectrum of promoters ...


Immunomagnetic Selection Of Acrosome-Reacted Bovine Spermatozoa, Thomas Mccormick Apr 1993

Immunomagnetic Selection Of Acrosome-Reacted Bovine Spermatozoa, Thomas Mccormick

Life and Environmental Sciences Undergraduate Theses

The anterior end of the mammalian sperm nucleus is covered by a thin, double-layered membranous sac that contains hydrolytic enzymes including acrosin, hyaluronidase, esterases and acid hydrolases. These enzymes, which are involved in the initial phase of fertilization, are activated and released during the acrosome reaction. This exposure of the acrosomal contents occurs not only during fertilization, but also during sperm death.

Acrosome-reacted sperm cells were selected from thawed, cryopreserved samples of bovine spermatozoa using rabbit antibodies to bovine acrosine and goat anti-rabbit immunoglobulin-coated magnetic beads. The selection process was monitored by staining with fluorescence isothiocynate- beads coupled to anti-rabbit ...


Analysis Of The Proteoglycan Content In Fresh And Cryopreserved Porcine Cardiovascular Tissues, Yun Hee Shon Apr 1993

Analysis Of The Proteoglycan Content In Fresh And Cryopreserved Porcine Cardiovascular Tissues, Yun Hee Shon

Theses and Dissertations in Biomedical Sciences

The purpose of this research was to study the effects of cryopreservation on the proteoglycan (PG) and mineral content of aorta conduit tissue. Proteoglycans from fresh and cryopreserved porcine aorta conduit tissues were isolated by extraction with 4 M guanidine (Gdn) - hydrochloride (HCl) for 48 hours. Quantitative analysis of extracted proteoglycans revealed that the content of proteoglycan material from cryopreserved tissue, measured as uronate and protein per unit weight of wet tissue, was similar to that from fresh tissue. Gel permeation column chromatography studies suggested that proteoglycans present in three CsCl fractions from cryopreserved tissues had molecular weights similar to ...


The Integral Membrane Protein, Ponticulin, Acts As A Monomer In Nucleating Actin Assembly, C. P. Chia, A. Shariff, S. A. Savage, Elizabeth J. Luna Feb 1993

The Integral Membrane Protein, Ponticulin, Acts As A Monomer In Nucleating Actin Assembly, C. P. Chia, A. Shariff, S. A. Savage, Elizabeth J. Luna

Women’s Health Research Faculty Publications

Ponticulin, an F-actin binding transmembrane glycoprotein in Dictyostelium plasma membranes, was isolated by detergent extraction from cytoskeletons and purified to homogeneity. Ponticulin is an abundant membrane protein, averaging approximately 10(6) copies/cell, with an estimated surface density of approximately 300 per microns2. Ponticulin solubilized in octylglucoside exhibited hydrodynamic properties consistent with a ponticulin monomer in a spherical or slightly ellipsoidal detergent micelle with a total molecular mass of 56 +/- 6 kD. Purified ponticulin nucleated actin polymerization when reconstituted into Dictyostelium lipid vesicles, but not when a number of commercially available lipids and lipid mixtures were substituted for the endogenous ...


Atomic Force Microscopy And Manipulation Of Living Glial Cells, V. Parpura, P. G. Haydon, D. S. Sakaguchi, E. Henderson Jan 1993

Atomic Force Microscopy And Manipulation Of Living Glial Cells, V. Parpura, P. G. Haydon, D. S. Sakaguchi, E. Henderson

Zoology and Genetics Publications

The atomic force microscope (AFM) is capable of imaging surfaces at very high resolution. The AFM has been used to image living glial cells in culture. Typical images reveal the three‐dimensional shape of the cell and often internal cellular structures are visible. In this report, it is shown that by increasing the imaging force, cells can be removed from the surface on which they are grown. Although the forces involved in this process are complex, it is possible to compare relative adhesion of different types of living cells to a particular substrate.


Three-Dimensional Imaging Of Living Neurons And Glia With The Atomic Force Microscope, Vladimir Parpura, Philip G. Haydon, Eric Henderson Jan 1993

Three-Dimensional Imaging Of Living Neurons And Glia With The Atomic Force Microscope, Vladimir Parpura, Philip G. Haydon, Eric Henderson

Zoology and Genetics Publications

The atomic force microscope (AFM) was used to directly image hippocampal neurons and glia. Using chemically fixed and living cells it was possible to reconstruct three-dimensional cell structure and detect sub-cellular features such as the nucleus, mitochondria and filaments. By repeatedly scanning a single living cell we observed the movement of filaments beneath the cell membrane. Furthermore, by controlling the force applied to the scanning tip, nanosurgery was performed to selectively remove cells from the culture substratum. Thus, the atomic force microscope offers the opportunity to gain three-dimensional information about living cells and to observe the behavior of cellular components ...


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 ...


Atomic Force Microscopy Of Oriented Linear Dna Molecules Labeled With 5nm Gold Spheres, Wen-Ling Shaiu, Drena D. Larson, James Vesenka, Eric Henderson Jan 1993

Atomic Force Microscopy Of Oriented Linear Dna Molecules Labeled With 5nm Gold Spheres, Wen-Ling Shaiu, Drena D. Larson, James Vesenka, Eric Henderson

Zoology and Genetics Publications

The atomic force microscope (AFM;1) can image DNA and RNA in air and under solutions at resolution comparable to that obtained by electron microscopy (EM) (2–7). We have developed a method for depositing and imaging linear DNA molecules to which 5nm gold spheres have been attached. The gold spheres facilitate orientation of the DNA molecules on the mica surface to which they are adsorbed and are potentially useful as internal height standards and as high resolution gene or sequence specific tags. We show that by modulating their adhesion to the mica surface, the gold spheres can be moved ...


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 ...


In Vivo And In Vitro Evaluations Of A Bioactive Ceramic Tooth Root Implant , Gabriele Gruss Niederauer Jan 1993

In Vivo And In Vitro Evaluations Of A Bioactive Ceramic Tooth Root Implant , Gabriele Gruss Niederauer

Retrospective Theses and Dissertations

The objective of this research was to test both the in vitro and in vivo effects of implant surface properties on soft tissue attachment to a bioactive ceramic tooth root implant. The ceramic material used for the tooth root was a composite of tricalcium phosphate and magnesium aluminate spinel, which is called "osteoceramic." For the in vitro cell attachment assays, pure tricalcium phosphate and spinel materials were used in addition to the osteoceramic. The osteoceramic was treated to produce three different surface structures: smooth, irregular and rough. Characterization of the materials included scanning electron microscopy, elemental dispersive analysis, wetting angle ...


An Anatomical, Ultrastructural, Autoradiographic, And Cytophotometric Study Of Early Embryo, Endosperm, And Ovule Development In Soybean (Glycine Max L Merr) , Mark Alan Chamberlin Jan 1993

An Anatomical, Ultrastructural, Autoradiographic, And Cytophotometric Study Of Early Embryo, Endosperm, And Ovule Development In Soybean (Glycine Max L Merr) , Mark Alan Chamberlin

Retrospective Theses and Dissertations

Various aspects of early embryo, endosperm, and ovule development are described in soybean utilizing techniques in autoradiography, cytophotometry, image analysis, and light and electron microscopy. Pollen tube passage to the egg is facilitated by the break down of nucellar cells subtending the abfunicular synergid and degeneration of the latter prior to fertilization. Autoradiographic evidence indicates that the accumulation of [superscript]14C label assimilates within the ovular tissues is spatially and temporally regulated. At the zygote through proembryo stages, labeled assimilates enter the embryo sac micropylarly via the wandlabrinthe and chalazally via the hypostase. Nutrient movement into the lateral regions of ...


Identification Of The Substrate Specificity Of Three Intracellular Ptp's (Ptp-1, Ptp-5, And Yop-51) And Two Transmembrane Ptp's (Cd45 And Lar) And Evidence For An Active Site Arginine Residue , Keli Lee Hippen Jan 1993

Identification Of The Substrate Specificity Of Three Intracellular Ptp's (Ptp-1, Ptp-5, And Yop-51) And Two Transmembrane Ptp's (Cd45 And Lar) And Evidence For An Active Site Arginine Residue , Keli Lee Hippen

Retrospective Theses and Dissertations

This study has investigated the interaction of protein tyrosine phosphatases (PTP's) with their substrates both at the level of recognition and catalysis using three approaches. First, the one mechanism for substrate recognition by three intracellular PTP's (PTP-1, PTP-5, and YOP-51) and two transmembrane PTP's (CD45 and LAR). Acidic residues in several positions were found to affect peptide reactivity with all the PTP's tested. The intracellular PTP's that were tested all had similar responses to N-terminal acidic residues, but were quite distinct from the transmembrane PTP's (CD45 and LAR), which were also found to differ ...


Age, Gender And Diet Effects On Gene Expression Regulated By 1,25-Dihydroxyvitamin D3 , Julie Ann Johnson Jan 1993

Age, Gender And Diet Effects On Gene Expression Regulated By 1,25-Dihydroxyvitamin D3 , Julie Ann Johnson

Retrospective Theses and Dissertations

Age-related changes often occur in factors involved in regulation of bone mineral metabolism, including 1,25-dihydroxyvitamin D[subscript]3 (1,25(OH)[subscript]2D[subscript]3) and parathyroid hormone (PTH) in plasma, 1,25(OH)[subscript]2D[subscript]3 receptors (VDR) and vitamin D[subscript]3-dependent calcium (Ca) binding proteins (CaBP-28K and CaBP-9K) in target tissues, and the 1[alpha],25-dihydroxyvitamin D-24-hydroxylase (24-hydroxylase);Response to exogenous 1,25(OH)[subscript]2D[subscript]3 was studied in 2.5- and 18-mo-old male and female rats. Additionally, response to dietary Ca deficiency was examined in one- and 18-mo-old male rats;Plasma 1 ...


Cloning And Molecular Characterization Of Two Nuclear Genes For Zea Mays Mitochondrial Chaperonin 60 , Pamela Sue Close Jan 1993

Cloning And Molecular Characterization Of Two Nuclear Genes For Zea Mays Mitochondrial Chaperonin 60 , Pamela Sue Close

Retrospective Theses and Dissertations

Hsp60 is a mitochondrial protein first identified in Tetrahymena thermophila and Saccharomyces cerevisiae. It belongs to a class of proteins called "molecular chaperones" which prevent aggregation and precipitation of partially or completely unfolded polypeptides;Two cDNAs for maize cpn60 were identified and sequenced. Southern blots of maize DNA showed two bands hybridizing with mt-cpn60 in maize inbreds. One copy was present in Arabidopsis. Both maize genes are contained within the nuclear genome. The chromosomal location of the cpn60 genes have been mapped by RFLPs. A maize B73 genomic library has been constructed and screened for cpn60 clones and two major ...


Glia-Neuron Signaling , Vladimir Parpura Jan 1993

Glia-Neuron Signaling , Vladimir Parpura

Retrospective Theses and Dissertations

This dissertation deals with release of neurotransmitter from glia. It has been demonstrated that bradykinin causes a receptor-mediated release of excitatory amino acids (EAAs), glutamate and aspartate, from glial cultures obtained from dorsal root ganglia (DRG) together with an increase in the cytoplasmic level of glial free calcium. Perturbations which inhibited bradykinin-induced calcium mobilization prevented the release of EAAs from glia. The addition of ionomycin caused a calcium-dependent release of EAAs. Taken together, these data demonstrate that calcium is both necessary and sufficient for stimulating the release of EAAs from DRG glia;Bradykinin was applied to mixed neuron-glial cultures derived ...


The Effects Of Teratogens On Serotonin Expression In Drosophila Embryonic Cell Cultures, Keri Joel Hopkins Jan 1993

The Effects Of Teratogens On Serotonin Expression In Drosophila Embryonic Cell Cultures, Keri Joel Hopkins

Theses Digitization Project

No abstract provided.


Characterization Of Early B Lymphocyte Activation During Trichinella Spiralis Infection In Rats, Elizabeth Margaret Richards Jan 1993

Characterization Of Early B Lymphocyte Activation During Trichinella Spiralis Infection In Rats, Elizabeth Margaret Richards

Theses Digitization Project

No abstract provided.


Ultrastructure And Mitosis Of Glaucosphaera Vacuolata, Steven Philip Allan Goss Jan 1993

Ultrastructure And Mitosis Of Glaucosphaera Vacuolata, Steven Philip Allan Goss

Dissertations, Theses, and Masters Projects

No abstract provided.


Chronic Estrogen-Induced Alterations In Adrenocorticotropin And Corticosterone Secretion: Relationship To Mineralocorticoid And Glucocorticoid Receptor Regulation In The Female Rat Anterior Pituitary Gland And Brain, Loyd H. Burgess Jan 1993

Chronic Estrogen-Induced Alterations In Adrenocorticotropin And Corticosterone Secretion: Relationship To Mineralocorticoid And Glucocorticoid Receptor Regulation In The Female Rat Anterior Pituitary Gland And Brain, Loyd H. Burgess

Dissertations

No abstract provided.