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Articles 1 - 25 of 25
Full-Text Articles in Life Sciences
A Mathematical Model For Transport And Growth Of Microbes In Unsaturated Porous Soil, Harihar Khanal, Andrei Ludu, Ramesh Chandra Timsina, Kedar Nath Uprety
A Mathematical Model For Transport And Growth Of Microbes In Unsaturated Porous Soil, Harihar Khanal, Andrei Ludu, Ramesh Chandra Timsina, Kedar Nath Uprety
Publications
In this work, we develop a mathematical model for transport and growth of microbes by natural (rain) water infiltration and flow through unsaturated porous soil along the vertical direction under gravity and capillarity by coupling a system of advection diffusion equations (for concentration of microbes and their growth-limiting substrate) with the Richards equation. (e model takes into consideration several major physical, chemical, and biological mechanisms. (e resulting coupled system of PDEs together with their boundary conditions is highly nonlinear and complicated to solve analytically. We present both a partial analytic approach towards solving the nonlinear system and finding the main …
Congenital Zika Virus Infection In Immunocompetent Mice Causes Postnatal Growth Impediment And Neurobehavioral Deficits, Amber M. Paul, Dhiraj Acharya, Biswas Neupane, E. Ashley Thompson, Gabriel Gonzalez-Fernandez, Katherine M. Copeland
Congenital Zika Virus Infection In Immunocompetent Mice Causes Postnatal Growth Impediment And Neurobehavioral Deficits, Amber M. Paul, Dhiraj Acharya, Biswas Neupane, E. Ashley Thompson, Gabriel Gonzalez-Fernandez, Katherine M. Copeland
Publications
A small percentage of babies born to Zika virus (ZIKV)-infected mothers' manifest severe defects at birth, including microcephaly. Among those who appeared healthy at birth, there are increasing reports of postnatal growth or developmental defects. However, the impact of congenital ZIKV infection in postnatal development is poorly understood. Here, we report that a mild congenital ZIKV-infection in pups born to immunocompetent pregnant mice did not display apparent defects at birth, but manifested postnatal growth impediments and neurobehavioral deficits, which include reduced locomotor and cognitive deficits that persisted into adulthood. We found that the brains of these pups were smaller, had …
Osteopontin Facilitates West Nile Virus Neuroinvasion Via Neutrophil “Trojan Horse” Transport, Amber M. Paul, Dhiraj Acharya, Laurel Duty, E. Ashley Thompson, Linda Le, Dobrivoje S. Stokic, A. Arturo Leis, Fengwei Bai
Osteopontin Facilitates West Nile Virus Neuroinvasion Via Neutrophil “Trojan Horse” Transport, Amber M. Paul, Dhiraj Acharya, Laurel Duty, E. Ashley Thompson, Linda Le, Dobrivoje S. Stokic, A. Arturo Leis, Fengwei Bai
Publications
West Nile virus (WNV) can cause severe human neurological diseases including encephalitis and meningitis. The mechanisms by which WNV enters the central nervous system (CNS) and host factors that are involved in WNV neuroinvasion are not completely understood. The proinflammatory chemokine osteopontin (OPN) is induced in multiple neuroinflammatory diseases and is responsible for leukocyte recruitment to sites of its expression. In this study, we found that WNV infection induced OPN expression in both human and mouse cells. Interestingly, WNV-infected OPN deficient (Opn−/−) mice exhibited a higher survival rate (70%) than wild type (WT) control mice (30%), suggesting OPN plays a …
Interleukin-17a Promotes Cd8 T Cell Cytotoxicity To Facilitate West Nile Virus Clearance, Amber M. Paul, Dhiraj Acharya, Penghua Wang, Jianfeng Dai, David Gate
Interleukin-17a Promotes Cd8 T Cell Cytotoxicity To Facilitate West Nile Virus Clearance, Amber M. Paul, Dhiraj Acharya, Penghua Wang, Jianfeng Dai, David Gate
Publications
CD8 T cells are crucial components of immunity and play a vital role in recovery from West Nile virus (WNV) infection. Here, we identify a previously unrecognized function of interleukin-17A (IL-17A) in inducing cytotoxic-mediator gene expression and promoting CD8 T cell cytotoxicity against WNV infection in mice. We find that IL-17A-deficient (Il17a/) mice are more susceptible to WNV infection and develop a higher viral burden than wild-type (WT) mice. Interestingly, the CD8 T cells isolated from Il17a/ mice are less cytotoxic and express lower levels of cytotoxic-mediator genes, which can be restored by supplying recombinant IL-17A in vitro and in …
An Ultrasensitive Electrogenerated Chemiluminescence-Based Immunoassay For Specific Detection Of Zika Virus, Amber M. Paul, Dhiraj Acharya, Pradip Bastola, Linda Le, Estenfani Fernandez, Michael S. Diamond, Wujian Miao, Fengwei Bai
An Ultrasensitive Electrogenerated Chemiluminescence-Based Immunoassay For Specific Detection Of Zika Virus, Amber M. Paul, Dhiraj Acharya, Pradip Bastola, Linda Le, Estenfani Fernandez, Michael S. Diamond, Wujian Miao, Fengwei Bai
Publications
Zika virus (ZIKV) is a globally emerging mosquito-transmitted flavivirus that can cause severe fetal abnormalities, including microcephaly. As such, highly sensitive, specific, and cost-effective diagnostic methods are urgently needed. Here, we report a novel electrogenerated chemiluminescence (ECL)-based immunoassay for ultrasensitive and specific detection of ZIKV in human biological fluids. We loaded polystyrene beads (PSB) with a large number of ECL labels and conjugated them with anti-ZIKV monoclonal antibodies to generate anti-ZIKV-PSBs. These anti-ZIKV-PSBs efficiently captured ZIKV in solution forming ZIKV-anti-ZIKV-PSB complexes, which were subjected to measurement of ECL intensity after further magnetic beads separation. Our results show that the anti-ZIKV-PSBs …
Loss Of Glycosaminoglycan Receptor Binding After Mosquito Cell Passage Reduces Chikungunya Virus Infectivity, Amber M. Paul, Dhiraj Acharya, John F. Anderson, Faqing Huang, Fengwei Bai
Loss Of Glycosaminoglycan Receptor Binding After Mosquito Cell Passage Reduces Chikungunya Virus Infectivity, Amber M. Paul, Dhiraj Acharya, John F. Anderson, Faqing Huang, Fengwei Bai
Publications
Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that can cause fever and chronic arthritis in humans. CHIKV that is generated in mosquito or mammalian cells differs in glycosylation patterns of viral proteins, which may affect its replication and virulence. Herein, we compare replication, pathogenicity, and receptor binding of CHIKV generated in Vero cells (mammal) or C6/36 cells (mosquito) through a single passage. We demonstrate that mosquito cell derived CHIKV (CHIKVmos) has slower replication than mammalian cell derived CHIKV (CHIKVvero), when tested in both human and murine cell lines. Consistent with this, CHIKVmos infection in both cell lines produce less cytopathic …
Urbanization Changes The Composition And Bioavailability Of Dissolved Organic Matter In Headwater Streams, Thomas B. Parr, Christopher Cronan, Tsutomu Ohno, Stuart Findlay, Sean Smith, Kevin Simon
Urbanization Changes The Composition And Bioavailability Of Dissolved Organic Matter In Headwater Streams, Thomas B. Parr, Christopher Cronan, Tsutomu Ohno, Stuart Findlay, Sean Smith, Kevin Simon
Publications
Population growth in cities has resulted in the rapid expansion of urbanized land. Most research and management of stream ecosystems affected by urban expansion has focused on the maintenance and restoration of biotic communities rather than their basal resources. We examined the potential for urbanization to induce bottom-up ecosystem effects by looking at its influence on dissolved organic matter (DOM) composition and bioavailability and microbial enzyme activity. We selected 113 headwater streams across a gradient of urbanization in central and southern Maine and used elemental and optical analyses, including parallel factor analysis of excitation-emission matrices, to characterize DOM composition. Results …
Comparafac: A Library And Tools For Rapid And Quantitative Comparison Of Dissolved Organic Matter Components Resolved By Parallel Factor Analysis., Thomas B. Parr, Tsutomu Ohno, Kevin Simon
Comparafac: A Library And Tools For Rapid And Quantitative Comparison Of Dissolved Organic Matter Components Resolved By Parallel Factor Analysis., Thomas B. Parr, Tsutomu Ohno, Kevin Simon
Publications
Parallel Factor Analysis (PARAFAC) is a well-established method for characterizing dissolved organic matter (DOM). While methods for sample processing and PARAFAC analysis are well defined and robust, subsequent classification of DOM fluorescence components and comparisons of components among studies remain highly qualitative. Because these comparisons often guide the interpretation of subsequent data, it is important that quantitatively accurate comparisons be made. We developed a statistical tool, comPARAFAC, using a modified Tucker’s Congruence Coefficient (mTCC), an established method of factor comparison, to provide a quantitative basis for comparing models. To develop and test this tool we used mTCC to compare factors …
A Genomewide Overexpression Screen Identifies Genes Involved In The Phosphatidylinositol 3-Kinase Pathway In The Human Protozoan Parasite Entamoeba Histolytica, Amrita B. Koushik, Brenda H. Welter, Michelle L. Rock, Lesly A. Temesvari
A Genomewide Overexpression Screen Identifies Genes Involved In The Phosphatidylinositol 3-Kinase Pathway In The Human Protozoan Parasite Entamoeba Histolytica, Amrita B. Koushik, Brenda H. Welter, Michelle L. Rock, Lesly A. Temesvari
Publications
Entamoeba histolytica is a protozoan parasite that causes amoebic dysentery and liver abscess. E. histolytica relies on motility, phagocytosis, host cell adhesion, and proteolysis of extracellular matrix for virulence. In eukaryotic cells, these processes are mediated in part by phosphatidylinositol 3-kinase (PI3K) signaling. Thus, PI3K may be critical for virulence. We utilized a functional genomics approach to identify genes whose products may operate in the PI3K pathway in E. histolytica. We treated a population of trophozoites that were overexpressing genes from a cDNA library with a near-lethal dose of the PI3K inhibitor wortmannin. This screen was based on the rationale …
Localization Of Phosphatidylinositol 4,5-Bisphosphate To Lipid Rafts And Uroids In The Human Protozoan Parasite Entamoeba Histolytica, Amrita B. Koushik, Rhonda R. Powell, Lesly A. Temesvari
Localization Of Phosphatidylinositol 4,5-Bisphosphate To Lipid Rafts And Uroids In The Human Protozoan Parasite Entamoeba Histolytica, Amrita B. Koushik, Rhonda R. Powell, Lesly A. Temesvari
Publications
Entamoeba histolytica is an intestinal protozoan parasite and is the causative agent of amoebiasis. During invasive infection, highly motile amoebae destroy the colonic epithelium, enter the blood circulation, and disseminate to other organs such as liver, causing liver abscess. Motility is a key factor in E. histolytica pathogenesis, and this process relies on a dynamic actomyosin cytoskeleton. In other systems, phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is known to regulate a wide variety of cellular functions, including signal transduction, actin remodeling, and cell motility. Little is known about the role of PI(4,5)P2 in E. histolytica pathogenicity. In this study, we …
Neurosteroid-Mediated Regulation Of Brain Innate Immunity In Hiv/Aids: Dhea-S Suppresses Neurovirulence, Amber Paul, Ferdinand G. Maingat, Maria J. Polyak, Pornpun Vivithanaporn, Farshid Noorbakhsh, Samir Ahboucha, Glen B. Baker, Keir Pearson, Christopher Power
Neurosteroid-Mediated Regulation Of Brain Innate Immunity In Hiv/Aids: Dhea-S Suppresses Neurovirulence, Amber Paul, Ferdinand G. Maingat, Maria J. Polyak, Pornpun Vivithanaporn, Farshid Noorbakhsh, Samir Ahboucha, Glen B. Baker, Keir Pearson, Christopher Power
Publications
Neurosteroids are cholesterol-derived molecules synthesized within the brain, which exert trophic and protective actions. Infection by human and feline immunodeficiency viruses (HIV and FIV, respectively) causes neuroinflammation and neurodegeneration, leading to neurological deficits. Secretion of neuroinflammatory host and viral factors by glia and infiltrating leukocytes mediates the principal neuropathogenic mechanisms during, although the effect of neurosteroids on these processes is unknown. We investigated the interactions between neurosteroid mediated effects and lentivirus infection outcomes. Analyses of HIV-infected uninfected human brains disclosed a reduction in neurosteroid synthesis enzyme expression. Human neurons exposed to supernatants from HIV macrophages exhibited suppressed enzyme expression without …
A Genome-Wide Over-Expression Screen Identifies Genes Involved In Phagocytosis In The Human Protozoan Parasite, Entamoeba Histolytica, Ada V. King, Brenda H. Welter, Amrita B. Koushik, Lindsay N. Gordon, Lesly A. Temesvari
A Genome-Wide Over-Expression Screen Identifies Genes Involved In Phagocytosis In The Human Protozoan Parasite, Entamoeba Histolytica, Ada V. King, Brenda H. Welter, Amrita B. Koushik, Lindsay N. Gordon, Lesly A. Temesvari
Publications
Functional genomics and forward genetics seek to assign function to all known genes in a genome. Entamoeba histolytica is a protozoan parasite for which forward genetics approaches have not been extensively applied. It is the causative agent of amoebic dysentery and liver abscess, and infection is prevalent in developing countries that cannot prevent its fecal-oral spread. It is responsible for considerable global morbidity and mortality. Given that the E. histolytica genome has been sequenced, it should be possible to apply genomic approaches to discover gene function. We used a genome-wide over-expression screen to uncover genes regulating an important virulence function …
Exposure To Host Ligands Correlates With Colocalization Of Gal/Galnac Lectin Subunits In Lipid Rafts And Phosphatidylinositol (4,5)-Bisphosphate Signaling In Entamoeba Histolytica, Amanda M. Goldston, Rhonda R. Powell, Amrita B. Koushik, Lesly A. Temesvari
Exposure To Host Ligands Correlates With Colocalization Of Gal/Galnac Lectin Subunits In Lipid Rafts And Phosphatidylinositol (4,5)-Bisphosphate Signaling In Entamoeba Histolytica, Amanda M. Goldston, Rhonda R. Powell, Amrita B. Koushik, Lesly A. Temesvari
Publications
Entamoeba histolytica is an intestinal parasite that causes dysentery and liver abscess. Parasite cell surface receptors, such as the Gal/GalNAc lectin, facilitate attachment to host cells and extracellular matrix. The Gal/GalNAc lectin binds to galactose or N-acetylgalactosamine residues on host components and is composed of heavy (Hgl), intermediate (Igl), and light (Lgl) subunits. Although Igl is constitutively localized to lipid rafts (cholesterol-rich membrane domains), Hgl and Lgl transiently associate with this compartment in a cholesterol-dependent fashion. In this study, trophozoites were exposed to biologically relevant ligands to determine if ligand binding influences the submembrane distribution of the subunits. Exposure …
Localisation To Lipid Rafts Correlates With Increased Function Of The Gal/Galnac Lectin In The Human Protozoan Parasite, Entamoeba Histolytica, Brenda H. Welter
Localisation To Lipid Rafts Correlates With Increased Function Of The Gal/Galnac Lectin In The Human Protozoan Parasite, Entamoeba Histolytica, Brenda H. Welter
Publications
Entamoeba histolytica is the causative agent of dysentery and liver abscess and is prevalent in developing countries. Adhesion to the host is critical to infection and is mediated by amoebic surface receptors. One such receptor, the Gal/GalNAc lectin, binds to galactose or N-acetylgalactosamine residues on host components and consists of heavy (Hgl), light (Lgl) and intermediate (Igl) subunits. The mechanism by which the lectin assembles into a functional complex is not known. The parasite also relies on cholesterol-rich domains (lipid rafts) for adhesion. Therefore, it is conceivable that rafts regulate the assembly or function of the lectin. To test …
Localization Of Phosphatidylinositol (3,4,5)-Trisphosphate To Phagosomes In Entamoeba Histolytica Achieved Using Glutathione S-Transferase- And Green Fluorescent Protein-Tagged Lipid Biosensors, Yevgeniya A. Byekova, Rhonda R. Powell, Brenda H. Welter, Lesly A. Temesvari
Localization Of Phosphatidylinositol (3,4,5)-Trisphosphate To Phagosomes In Entamoeba Histolytica Achieved Using Glutathione S-Transferase- And Green Fluorescent Protein-Tagged Lipid Biosensors, Yevgeniya A. Byekova, Rhonda R. Powell, Brenda H. Welter, Lesly A. Temesvari
Publications
Entamoeba histolytica is an intestinal protozoan parasite that causes amoebic dysentery and liver abscess. Phagocytosis by the parasite is a critical virulence process, since it is a prerequisite for tissue invasion and establishment of chronic infection. While the roles of many of the proteins that regulate phagocytosis-related signaling events in E. histolytica have been characterized, the functions of lipids in this cellular process remain largely unknown in this parasite. In other systems, phosphatidylinositol (3,4,5)-trisphosphate (PIP3), a major product of phosphoinositide 3 kinase (PI3-kinase) activity, is essential for phagocytosis. Pleckstrin homology (PH) domains are protein domains that specifically bind …
Overexpression Of A Mutant Form Of Ehraba, A Unique Rab Gtpase Of Entamoeba Histolytica, Alters Endoplasmic Reticulum Morphology And Localization Of The Gal/Galnac Adherence Lectin, B. H. Welter, Lesly A. Temesvari
Overexpression Of A Mutant Form Of Ehraba, A Unique Rab Gtpase Of Entamoeba Histolytica, Alters Endoplasmic Reticulum Morphology And Localization Of The Gal/Galnac Adherence Lectin, B. H. Welter, Lesly A. Temesvari
Publications
Entamoeba histolytica is a protozoan parasite that causes amoebic dysentery and liver abscess. Vesicle trafficking events, such as phagocytosis and delivery of plasma membrane proteins, have been implicated in pathogenicity. Rab GTPases are proteins whose primary function is to regulate vesicle trafficking; therefore, understanding the function of Rabs in this organism may provide insight into virulence. E. histolytica possesses a number of unique Rabs that exhibit limited homology to host Rabs. In this study we examined the function of one such Rab, EhRabA, by characterizing a mutant overexpressing a constitutively GTP-bound version of the protein. Overexpression of mutant EhRabA resulted …
Entamoeba Histolytica: Lipid Rafts Are Involved In Adhesion Of Trophozoites To Host Extracellular Matrix Components, K. Mittal, B. H. Welter, Lesly A. Temesvari
Entamoeba Histolytica: Lipid Rafts Are Involved In Adhesion Of Trophozoites To Host Extracellular Matrix Components, K. Mittal, B. H. Welter, Lesly A. Temesvari
Publications
Adhesion is an important virulence function for Entamoeba histolytica, the causative agent of amoebic dysentery. Lipid rafts, cholesterol-rich domains, function in compartmentalization of cellular processes. In E. histolytica, rafts participate in parasite–host cell interactions; however, their role in parasite–host extracellular matrix (ECM) interactions has not been explored. Disruption of rafts with a cholesterol extracting agent, methyl-β-cyclodextrin (MβCD), resulted in inhibition of adhesion to collagen, and to a lesser extent, to fibronectin. Replenishment of cholesterol in MβCD-treated cells, using a lipoprotein–cholesterol concentrate, restored adhesion to collagen. Confocal microscopy revealed enrichment of rafts at parasite–ECM interfaces. A raft-resident adhesin, the …
Involvement Of Raft-Like Plasma Membrane Domains Of Entamoeba Histolytica In Pinocytosis And Adhesion, Richard C. Laughlin, Glen C. Mcgugan, Rhonda R. Powell, Brenda H. Welter, Lesly A. Temesvari
Involvement Of Raft-Like Plasma Membrane Domains Of Entamoeba Histolytica In Pinocytosis And Adhesion, Richard C. Laughlin, Glen C. Mcgugan, Rhonda R. Powell, Brenda H. Welter, Lesly A. Temesvari
Publications
Lipid rafts are highly ordered, cholesterol-rich, and detergent-resistant microdomains found in the plasma membrane of many eukaryotic cells. These domains play important roles in endocytosis, secretion, and adhesion in a variety of cell types. The parasitic protozoan Entamoeba histolytica, the causative agent of amoebic dysentery, was determined to have raft-like plasma membrane domains by use of fluorescent lipid analogs that specifically partition into raft and nonraft regions of the membrane. Disruption of raft-like membrane domains in Entamoeba with the cholesterol-binding agents filipin and methyl-β-cyclodextrin resulted in the inhibition of several important virulence functions, fluid-phase pinocytosis, and adhesion to host …
The Wasp-Like Protein Scar Regulates Macropinocytosis, Phagocytosis And Endosomal Membrane Flow In Dictyostelium, David J. Seastone, Ed Harris, Lesly A. Temesvari, James E. Bear, Charles L. Saxe, James Cardelli
The Wasp-Like Protein Scar Regulates Macropinocytosis, Phagocytosis And Endosomal Membrane Flow In Dictyostelium, David J. Seastone, Ed Harris, Lesly A. Temesvari, James E. Bear, Charles L. Saxe, James Cardelli
Publications
Scar, a member of the WASp protein family, was discovered in Dictyostelium discoideum during a genetic screen for second-site mutations that suppressed a developmental defect. Disruption of the scar gene reduced the levels of cellular F-actin by 50%. To investigate the role of Scar in endocytosis, phagocytosis and endocytic membrane trafficking, processes that depend on actin polymerization, we have analyzed a Dictyostelium cell line that is genetically null for Scar. Rates of fluid phase macropinocytosis and phagocytosis are significantly reduced in the scar- cell-line. In addition, exocytosis of fluid phase is delayed in these cells and movement of fluid phase …
Inactivation Of Lmpa, Encoding A Limpii-Related Endosomal Protein, Suppresses The Internalization And Endosomal Trafficking Defects In Profilin-Null Mutants, Lesly A. Temesvari, Linyi Zhang, Brent Fodera, Klaus-Peter Janssen, Michael Schleicher, James A. Caradelli
Inactivation Of Lmpa, Encoding A Limpii-Related Endosomal Protein, Suppresses The Internalization And Endosomal Trafficking Defects In Profilin-Null Mutants, Lesly A. Temesvari, Linyi Zhang, Brent Fodera, Klaus-Peter Janssen, Michael Schleicher, James A. Caradelli
Publications
Profilin is a key phosphoinositide and actin-binding protein connecting and coordinating changes in signal transduction pathways with alterations in the actin cytoskeleton. Using biochemical assays and microscopic approaches, we demonstrate that profilin-null cells are defective in macropinocytosis, fluid phase efflux, and secretion of lysosomal enzymes but are unexpectedly more efficient in phagocytosis than wild-type cells. Disruption of the lmpA gene encoding a protein (DdLIMP) belonging to the CD36/LIMPII family suppressed, to different degrees, most of the profilin-minus defects, including the increase in F-actin, but did not rescue the secretion defect. Immunofluorescence microscopy indicated that DdLIMP, which is also capable of …
A Role For A Rab4-Like Gtpase In Endocytosis And In Regulation Of Contractile Vacuole Structure And Function In Dictyostelium Discoideum, John Bush, Lesly A. Temesvari, Juan Rodriguez-Paris, Greg Buczynski, James Cardelli
A Role For A Rab4-Like Gtpase In Endocytosis And In Regulation Of Contractile Vacuole Structure And Function In Dictyostelium Discoideum, John Bush, Lesly A. Temesvari, Juan Rodriguez-Paris, Greg Buczynski, James Cardelli
Publications
The small Mr Rab4-like GTPase, RabD, localizes to the endosomal pathway and the contractile vacuole membrane system in Dictyostelium discoideum. Stably transformed cell lines overexpressing a dominant negative functioning RabD internalized fluid phase marker at 50% of the rate of wild-type cells. Mutant cells were also slower at recycling internalized fluid. Microscopic and biochemical approaches indicated that the transport of fluid to large postlysosome vacuoles was delayed in mutant cells, resulting in an accumulation in acidic smaller vesicles, probably lysosomes. Also, RabD N121I-expressing cell lines missorted a small but significant percentage of newly synthesized lysosomal alpha-mannosidase precursor polypeptides. However, the …
Involvement Of The Vacuolar Proton-Translocating Atpase In Multiple Steps Of The Endo-Lysosomal System And In The Contractile Vacuole System Of Dictyostelium Discoideum, Lesly A. Temesvari, Juan M. Rodriguez-Paris, John M. Bush, Linyi Zhang, James A. Cardelli
Involvement Of The Vacuolar Proton-Translocating Atpase In Multiple Steps Of The Endo-Lysosomal System And In The Contractile Vacuole System Of Dictyostelium Discoideum, Lesly A. Temesvari, Juan M. Rodriguez-Paris, John M. Bush, Linyi Zhang, James A. Cardelli
Publications
We have investigated the effects of Concanamycin A (CMA), a specific inhibitor of vacuolar type H(+)-ATPases, on acidification and function of the endo-lysosomal and contractile vacuole (CV) systems of D. discoideum. This drug inhibited acidification and increased the pH of endo-lysosomal vesicles both in vivo and in vitro in a dose dependent manner. Treatment also inhibited endocytosis and exocytosis of fluid phase, and phagocytosis of latex beads. This report also confirms our previous conclusions (Cardelli et al. (1989) J. Biol. Chem. 264, 3454–3463) that maintenance of acidic pH in lumenal compartments is required for efficient processing and targeting of a …
Examination Of The Endosomal And Lysosomal Pathways In Dictyostelium Discoideum Myosin I Mutants, Lesly A. Temesvari, John M. Bush, Michelle D. Peterson, Kristine D. Novak, Margaret A. Titus, James A. Cardelli
Examination Of The Endosomal And Lysosomal Pathways In Dictyostelium Discoideum Myosin I Mutants, Lesly A. Temesvari, John M. Bush, Michelle D. Peterson, Kristine D. Novak, Margaret A. Titus, James A. Cardelli
Publications
The role of myosin Is in endosomal trafficking and the lysosomal system was investigated in a Dictyostelium discoideum myosin I double mutant myoB-/C-, that has been previously shown to exhibit defects in fluid-phase endocytosis during growth in suspension culture (Novak et al., 1995). Various properties of the endosomal pathway in the myoB-/C- double mutant as well as in the myoB- and myoC- single mutants, including intravesicular pH, and intracellular retention time and exocytosis of a fluid phase marker, were found to be indistinguishable from wild-type parental cells. The intimate connection between the contractile vacuole complex and the endocytic pathway in …
Characterization Of Lysosomal Membrane Proteins Of Dictyostelium Discoideum, Lesly A. Temesvari, Juan Rodriguez-Paris, John Bush, Theodore L. Steck, James Caradelli
Characterization Of Lysosomal Membrane Proteins Of Dictyostelium Discoideum, Lesly A. Temesvari, Juan Rodriguez-Paris, John Bush, Theodore L. Steck, James Caradelli
Publications
Highly purified lysosomes, prepared by magnetic fractionation of homogenates from Dictyostelium discoideum cells fed colloidal iron, were lysed under hypoosmotic conditions, and the membrane-associated proteins were subjected to gel electrophoresis. Thirteen major membrane polypeptides, ranging in molecular weight from 25,000 to 100,000 were identified. The isoelectric points of these proteins ranged from below 3.8 to greater than 7.0. Most of these proteins were stripped from membranes exposed to a chaotropic agent, 3,5-diodo-2-hydroxybenzoic acid lithium salt, and were therefore classified as peripheral membrane proteins. Twenty five glycoprotein species were detected by lectin blot analysis; 19 were classified as integral membrane proteins, …
A Rab4-Like Gtpase In Dictyostelium Discoideum Colocalizes With V-H(+)-Atpases In Reticular Membranes Of The Contractile Vacuole Complex And In Lysosomes, John Bush, Kathleen Nolta, Juan Rodriguez-Paris, Nancy Kaufmann, Theresa O'Halloran, Tracy Ruscetti, Lesly A. Temesvari, Theodore Steck, James Cardelli
A Rab4-Like Gtpase In Dictyostelium Discoideum Colocalizes With V-H(+)-Atpases In Reticular Membranes Of The Contractile Vacuole Complex And In Lysosomes, John Bush, Kathleen Nolta, Juan Rodriguez-Paris, Nancy Kaufmann, Theresa O'Halloran, Tracy Ruscetti, Lesly A. Temesvari, Theodore Steck, James Cardelli
Publications
In the course of screening a cDNA library for ras-related Dictyostelium discoideum genes, we cloned a 0.7 kb cDNA (rabD) encoding a putative protein that was 70% identical at the amino acid level to human Rab4. Rab4 is a small M(r) GTPase, which belongs to the Ras superfamily and functions to regulate endocytosis in mammalian cells. Southern blot analysis indicated that the rabD cDNA was encoded by a single copy gene while Northern blot analysis revealed that the rabD gene was expressed at relatively constant levels during growth and differentiation. Affinity-purified antibodies were prepared against a RabD fusion protein expressed …