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Articles 361 - 385 of 385

Full-Text Articles in Medicine and Health Sciences

Asbestos Induces Nuclear Factor Kappa B (Nf-Kappa B) Dna-Binding Activity And Nf-Kappa B-Dependent Gene Expression In Tracheal Epithelial Cells., Yvonne M. Janssen, Aaron Barchowsky, Melinda Treadwell, Kevin E. Driscoll, B T. Mossman Aug 1995

Asbestos Induces Nuclear Factor Kappa B (Nf-Kappa B) Dna-Binding Activity And Nf-Kappa B-Dependent Gene Expression In Tracheal Epithelial Cells., Yvonne M. Janssen, Aaron Barchowsky, Melinda Treadwell, Kevin E. Driscoll, B T. Mossman

Dartmouth Scholarship

Nuclear factor kappa B (NF-kappa B) is a transcription factor regulating expression of genes intrinsic to inflammation and cell proliferation--features of asbestos-associated diseases. In studies here, crocidolite asbestos caused protracted and dose-responsive increases in proteins binding to nuclear NF-kappa B-binding DNA elements in hamster tracheal epithelial (HTE) cells. This binding was modulated by cellular glutathione levels. Antibodies recognizing p65 and p50 protein members of the NF-kappa B family revealed these proteins in two of the DNA complexes. Transient transfection assays with a construct containing six NF-kappa B-binding DNA consensus sites linked to a luciferase reporter gene indicated that asbestos induced …

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Increased Alpha 1(I) Procollagen Gene Expression In Tight Skin (Tsk) Mice Myocardial Fibroblasts Is Due To A Reduced Interaction Of A Negative Regulatory Sequence With Ap-1 Transcription Factor., Neena Philips, Reza I. Bashey, Sergio A. Jimenez Apr 1995

Increased Alpha 1(I) Procollagen Gene Expression In Tight Skin (Tsk) Mice Myocardial Fibroblasts Is Due To A Reduced Interaction Of A Negative Regulatory Sequence With Ap-1 Transcription Factor., Neena Philips, Reza I. Bashey, Sergio A. Jimenez

Department of Medicine Faculty Papers

The TSK mouse, a model of fibrosis, displays exaggerated connective tissue accumulation in skin and visceral organs including the heart. To study the mechanisms of myocardial fibrosis in TSK mice, we established several strains of TSK mice myocardial fibroblasts in culture and examined the regulation of collagen gene expression in these cells. These strains displayed increased collagen gene expression in comparison with myocardial fibroblasts established from normal mice. On an average, the TSK myocardial fibroblast cultures showed a 4-fold increase in collagen synthesis and 4.4- and 3.6-fold increases, respectively, in alpha 1(I) and alpha 1(III) collagen mRNA steady state levels. …

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Regulation Of Collagenase Gene Expression By Il-1 Beta Requires Transcriptional And Post-Transcriptional Mechanisms, Matthew P. Vincenti, Charles I. Coon, Oneil Lee, Constance E. Brinckerhoff Sep 1994

Regulation Of Collagenase Gene Expression By Il-1 Beta Requires Transcriptional And Post-Transcriptional Mechanisms, Matthew P. Vincenti, Charles I. Coon, Oneil Lee, Constance E. Brinckerhoff

Dartmouth Scholarship

Interleukin-1 beta is believed to contribute to the pathophysiology of rheumatoid arthritis by activating collagenase gene expression. We have used a cell culture model of rabbit synovial fibroblasts to examine the molecular mechanisms of IL-1 beta-mediated collagenase gene expression. Stimulation of rabbit synovial fibroblasts with 10 ng/ml recombinant human IL-1 beta resulted in a 20-fold increase in collagenase mRNA by 12 h. Transient transfection studies using collagenase promoter-CAT constructs demonstrated that proximal sequences responded poorly to IL-1 beta, possibly due to insufficient activation of AP-1 by this cytokine. More distal sequences were required for IL-1 beta responsiveness, with a 4700 …

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Epidermal Growth Factor Coordinately Regulates The Expression Of Prostaglandin G/H Synthase And Cytosolic Phospholipase A2 Genes In Embryonic Mouse Cells., Kenneth P. Chepenik, Arturo Diaz, Sergio A. Jimenez Aug 1994

Epidermal Growth Factor Coordinately Regulates The Expression Of Prostaglandin G/H Synthase And Cytosolic Phospholipase A2 Genes In Embryonic Mouse Cells., Kenneth P. Chepenik, Arturo Diaz, Sergio A. Jimenez

Department of Medicine Faculty Papers

Confluent, primary cultures of mouse embryo palate mesenchyme (MEPM) cells are refractory to activation of phospholipase A2 (PLA2) by the calcium ionophore A23187. However, treatment of these cultures with epidermal growth factor (EGF) permits the cells to activate PLA2 in response to A23187. We have developed this finding by exploring molecular mechanisms by which growth factors modulate mobilization and metabolism of arachidonic acid. We found chronic treatment (> 6 h) of confluent MEPM cells with EGF (a) increases their ability to metabolize exogenous arachidonic acid to prostaglandin E2 (PGE2) and (b) stimulated constitutive expression of activities of PLA2 and cyclooxygenase …

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Functional Analysis Of Human Alpha 1(I) Procollagen Gene Promoter. Differential Activity In Collagen-Producing And -Nonproducing Cells And Response To Transforming Growth Factor Beta 1., Sergio A. Jimenez, John A. Varga, Anne Olsen, Liye Li, Arturo Diaz, Janet Herhal, Julie Koch Apr 1994

Functional Analysis Of Human Alpha 1(I) Procollagen Gene Promoter. Differential Activity In Collagen-Producing And -Nonproducing Cells And Response To Transforming Growth Factor Beta 1., Sergio A. Jimenez, John A. Varga, Anne Olsen, Liye Li, Arturo Diaz, Janet Herhal, Julie Koch

Department of Medicine Faculty Papers

To gain a further understanding of the regulation of human type I collagen gene expression under physiologic and pathologic conditions, we characterized 5.3 kilobase pairs (kb) of the human alpha 1(I) procollagen gene promoter. A series of deletion constructs containing portions of the alpha 1(I) procollagen 5'-flanking region (with end points from -5.3 kb to -84 base pairs (bp)) ligated to the chloramphenicol acetyltransferase (CAT) reporter gene were transiently transfected into NIH/3T3 cells. Maximal CAT activity was observed with constructs having 5' end points from -804 to -174 bp. A further 5' deletion to -84 bp caused a marked reduction …

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Estimation Of The Incidence Of A Rare Genetic Disease Through A Two-Tier Mutation Survey., R Chakraborty, M R Srinivasan, S Raskin Jun 1993

Estimation Of The Incidence Of A Rare Genetic Disease Through A Two-Tier Mutation Survey., R Chakraborty, M R Srinivasan, S Raskin

Journal Articles

Recent attempts to detect mutations involving single base changes or small deletions that are specific to genetic diseases provide an opportunity to develop a two-tier mutation-screening program through which incidence of rare genetic disorders and gene carriers may be precisely estimated. A two-tier survey consists of mutation screening in a sample of patients with specific genetic disorders and in a second sample of newborns from the same population in which mutation frequency is evaluated. We provide the statistical basis for evaluating the incidence of affected and gene carriers in such two-tier mutation-screening surveys, from which the precision of the estimates …

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Regulation Of Human Lung Fibroblast Alpha 1(I) Procollagen Gene Expression By Tumor Necrosis Factor Alpha, Interleukin-1 Beta, And Prostaglandin E2., Arturo Diaz, Elena Munoz, Rosemary Johnston, Joseph H. Korn, Sergio A. Jimenez May 1993

Regulation Of Human Lung Fibroblast Alpha 1(I) Procollagen Gene Expression By Tumor Necrosis Factor Alpha, Interleukin-1 Beta, And Prostaglandin E2., Arturo Diaz, Elena Munoz, Rosemary Johnston, Joseph H. Korn, Sergio A. Jimenez

Department of Medicine Faculty Papers

We investigated the participation of prostaglandin (PG) E2 in the regulation of the alpha 1(I) procollagen gene expression by tumor necrosis factor alpha (TNF alpha), and interleukin-1 beta (IL-1 beta) in normal adult human lung fibroblasts. TNF alpha (100 units/ml) and IL-1 beta (100 units/ml) stimulated the production of PGE2 and caused a dose-dependent inhibition of up to 54 and 66%, respectively, of the production of type I procollagen. Preincubation of cultures with indomethacin partially reversed the inhibition of procollagen production induced by the cytokines. Cytokine-stimulated endogenous fibroblast PG accounted for 35 and 68% of the inhibition induced by TNF …

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Indistinguishable Nuclear Factor Binding To Functional Core Sites Of The T-Cell Receptor Delta And Murine Leukemia Virus Enhancers., Juan M. Redondo, Jeffrey L. Pfohl, Cristina Hernandez-Munain, Shuwen Wang, Nancy A. Speck, Michael S. Krangel Nov 1992

Indistinguishable Nuclear Factor Binding To Functional Core Sites Of The T-Cell Receptor Delta And Murine Leukemia Virus Enhancers., Juan M. Redondo, Jeffrey L. Pfohl, Cristina Hernandez-Munain, Shuwen Wang, Nancy A. Speck, Michael S. Krangel

Dartmouth Scholarship

We have previously shown that the delta E3 site is an essential element for transcriptional activation by the human T-cell receptor (TCR) delta enhancer and identified two factors, NF-delta E3A and NF-delta E3C, that bound to overlapping core (TGTGGTTT) and E-box motifs within delta E3. In this study, we show that protein binding to the core motif is necessary but not sufficient for transcriptional activation by the delta E3 element. In contrast, protein binding to the E-box motif does not contribute significantly to enhancer activity. A similar core motif present within the enhancers of T-cell-tropic murine retroviruses has been shown …

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A Phorbol Ester Response Element Within The Human T-Cell Receptor Beta-Chain Enhancer., Haydn M. Prosser, David Wotton, Anne Gegonne, Jacques Ghysdael, Shuwen Wang, Nancy A. Speck, Michael J. Owen Oct 1992

A Phorbol Ester Response Element Within The Human T-Cell Receptor Beta-Chain Enhancer., Haydn M. Prosser, David Wotton, Anne Gegonne, Jacques Ghysdael, Shuwen Wang, Nancy A. Speck, Michael J. Owen

Dartmouth Scholarship

The activity of the T-cell receptor beta-chain gene enhancer is increased by activators of the protein kinase C pathway during T-cell activation. Analysis of mutant enhancer constructs identified two elements, beta E2 and beta E3, conferring phorbol ester inducibility. Multimerized beta E2 acted in isolation as a phorbol ester-responsive element. Both beta E2 and beta E3, which contain a consensus Ets-binding site, were shown to bind directly to the product of the c-ets-1 protooncogene. Both regions also bound a second factor, core-binding factor. Mutation of the beta E2 Ets site abolished the inducibility of the beta E2 multimer. beta E2 …

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Differential Regulation Of Collagenase Gene Expression By Retinoic Acid Receptors--Alpha, Beta And Gamma, Luying Pan, Stephen H. Chamberlain, David T. Auble, Constance E. Brinckerhoff Jun 1992

Differential Regulation Of Collagenase Gene Expression By Retinoic Acid Receptors--Alpha, Beta And Gamma, Luying Pan, Stephen H. Chamberlain, David T. Auble, Constance E. Brinckerhoff

Dartmouth Scholarship

The mechanisms involved in retinoic acid (RA)-mediated regulation of the collagenase gene in a rabbit synovial fibroblast cell line (HIG82) were investigated. When HIG82 cells are cotransfected with expression vectors containing cDNAs for retinoic acid receptor (RAR) α1, β2, or γ1 and collagenase promoter-driven CAT reporter constructs, only RAR-γ1 represses basal CAT expression upon RA treatment, while RAR-α1, β2, and γ1 all suppress phorbol-induced CAT expression. Thus, transcriptional regulation of collagenase by RA is mediated by RARs in an RAR-type specific manner. Using mutatlonal and deletional analysis, we find that interaction between elements within 182 bp collagenase promoter plays an …

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Alternative Splicing Of Human Prostaglandin G/H Synthase Mrna And Evidence Of Differential Regulation Of The Resulting Transcripts By Transforming Growth Factor Beta 1, Interleukin 1 Beta, And Tumor Necrosis Factor Alpha., Arturo Diaz, Anthony M. Reginato, Sergio A. Jimenez May 1992

Alternative Splicing Of Human Prostaglandin G/H Synthase Mrna And Evidence Of Differential Regulation Of The Resulting Transcripts By Transforming Growth Factor Beta 1, Interleukin 1 Beta, And Tumor Necrosis Factor Alpha., Arturo Diaz, Anthony M. Reginato, Sergio A. Jimenez

Department of Medicine Faculty Papers

Prostaglandin G/H synthase (PGG/HS) is the rate-limiting enzyme in the conversion of arachidonic acid to prostaglandins and thromboxanes. We screened a human lung fibroblast cDNA library with an ovine PGG/HS cDNA and isolated a 2.3-kilobase clone (HCO-T9). Sequence analysis of this clone showed that (a) it contained the entire translated region of PGG/HS and (b) it displayed an in-frame splicing of the last 111 base pairs encoded by exon 9, which resulted in the elimination of the N-glycosylation site at residue 409. Polymerase chain reaction amplification with specific oligonucleotides of reverse-transcribed mRNA from diverse human tissues and cultured cells yielded …

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Multiple Alleles And Estimation Of Genetic Parameters: Computational Equations Showing Involvement Of All Alleles., R Chakraborty Jan 1992

Multiple Alleles And Estimation Of Genetic Parameters: Computational Equations Showing Involvement Of All Alleles., R Chakraborty

Journal Articles

No abstract provided.

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A Genetic Classification Of Floodplains, G C. Nanson, J C. Croke Jan 1992

A Genetic Classification Of Floodplains, G C. Nanson, J C. Croke

Faculty of Science, Medicine and Health - Papers: part A

Floodplains are formed by a complex interaction of fluvial processes but their character and evolution is essentially the product of stream power and sediment character. The relation between a stream's ability to entrain and transport sediment and the erosional resistance of floodplain alluvium that forms the channel boundary provides the basis for a genetic classification of floodplains. Three classes are recognised: (1) high-energy non-cohesive; (2) medium-energy non-cohesive; and (3) low-energy cohesive floodplains. Thirteen derivative orders and suborders, ranging from confined, coarse-grained, non-cohesive floodplains in high-energy environments to unconfined fine-grained cohesive floodplains in low-energy environments, are defined on the basis of …

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Purification Of Core-Binding Factor, A Protein That Binds The Conserved Core Site In Murine Leukemia Virus Enhancers., Shuwen W. Wang, Nancy A. Speck Jan 1992

Purification Of Core-Binding Factor, A Protein That Binds The Conserved Core Site In Murine Leukemia Virus Enhancers., Shuwen W. Wang, Nancy A. Speck

Dartmouth Scholarship

The Moloney murine leukemia virus causes thymic leukemias when injected into newborn mice. A major genetic determinant of the thymic disease specificity of the Moloney virus genetically maps to two protein binding sites in the Moloney virus enhancer, the leukemia virus factor b site and the adjacent core site. Point mutations introduced into either of these sites significantly shifts the disease specificity of the Moloney virus from thymic leukemia to erythroleukemia (N. A. Speck, B. Renjifo, E. Golemis, T. Frederickson, J. Hartley, and N. Hopkins, Genes Dev. 4:233-242, 1990). We have purified several polypeptides that bind to the core site …

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Regulation Of Transforming Growth Factor-Beta 1 Gene Expression By Glucocorticoids In Normal Human T Lymphocytes., O. Ayanlarbatuman, A. P. Ferrero, Arturo Diaz, Sergio A. Jimenez Nov 1991

Regulation Of Transforming Growth Factor-Beta 1 Gene Expression By Glucocorticoids In Normal Human T Lymphocytes., O. Ayanlarbatuman, A. P. Ferrero, Arturo Diaz, Sergio A. Jimenez

Department of Medicine Faculty Papers

Glucocorticoids (GC) modulate immune function in a number of ways, including suppression of T cell proliferation and other IL-2-mediated T cell functions. These inhibitory effects are similar to those induced by transforming growth factor-beta 1 (TGF-beta 1), a cytokine with potent T cell inhibiting activities. We examined the hypothesis that GC effects may be at least partially achieved through modulation of the expression of the TGF-beta 1 gene in activated T cells. Normal T cells were cultured with or without purified phytohemagglutinin (PHA-p) and 4 beta-phorbol 12-myristate 13-acetate (PMA) in the presence or absence of the synthetic GC, dexamethasone (100-200 …

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Expression Of A Human Cartilage Procollagen Gene (Col2a1) In Mouse 3t3 Cells., Leena Ala-Kokko, James Hyland, Carol Smith, Kari I. Kivirikko, Sergio A. Jimenez, Darwin J. Prockop Aug 1991

Expression Of A Human Cartilage Procollagen Gene (Col2a1) In Mouse 3t3 Cells., Leena Ala-Kokko, James Hyland, Carol Smith, Kari I. Kivirikko, Sergio A. Jimenez, Darwin J. Prockop

Department of Medicine Faculty Papers

Expression in a recombinant system has been difficult to obtain for any of the major fibrillar collagens that require processing by eight or more post-translational enzymes. Here, two DNA constructs were designed so that the promoter region of the gene for the pro-alpha 1(I) chain of human type I procollagen drove expression of the human type II procollagen gene in mouse NIH 3T3 cells, a culture line that normally synthesizes type I procollagen but not any cartilage-specific protein such as type II procollagen. Both constructs were expressed as both mRNA and protein. In clones expressing the construct at high levels, …

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Population Amalgamation And Genetic Variation: Observations On Artificially Agglomerated Tribal Populations Of Central And South America., R Chakraborty, P E Smouse, J V Neel Nov 1988

Population Amalgamation And Genetic Variation: Observations On Artificially Agglomerated Tribal Populations Of Central And South America., R Chakraborty, P E Smouse, J V Neel

Journal Articles

The interpretation of data on genetic variation with regard to the relative roles of different evolutionary factors that produce and maintain genetic variation depends critically on our assumptions concerning effective population size and the level of migration between neighboring populations. In humans, recent population growth and movements of specific ethnic groups across wide geographic areas mean that any theory based on assumptions of constant population size and absence of substructure is generally untenable. We examine the effects of population subdivision on the pattern of protein genetic variation in a total sample drawn from an artificial agglomerate of 12 tribal populations …

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Patterns Of Polyadenylation Site Selection In Gene Constructs Containing Multiple Polyadenylation Signals., Roger Denome, Charles Cole Nov 1988

Patterns Of Polyadenylation Site Selection In Gene Constructs Containing Multiple Polyadenylation Signals., Roger Denome, Charles Cole

Dartmouth Scholarship

We have constructed a series of plasmids containing multiple polyadenylation signals downstream of the herpes simplex virus type 1 (HSV) thymidine kinase (tk)-coding region. The signals used were from the simian virus 40 (SV40) late gene, the HSV tk gene, and an AATAAA-containing segment of the SV40 early region. This last fragment signals polyadenylation poorly in our constructs and not at all during SV40 infection. All plasmids contained the SV40 origin of replication. Plasmids were transfected into Cos-1 cells; after 48 h, cytoplasmic RNA was isolated and the quantity and 3'-end structure of tk mRNAs was analyzed by using S1 …

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Parentage Analysis With Genetic Markers In Natural Populations. I. The Expected Proportion Of Offspring With Unambiguous Paternity., R Chakraborty, T R Meagher, P E Smouse Mar 1988

Parentage Analysis With Genetic Markers In Natural Populations. I. The Expected Proportion Of Offspring With Unambiguous Paternity., R Chakraborty, T R Meagher, P E Smouse

Journal Articles

Recent studies indicate that polymorphic genetic markers are potentially helpful in resolving genealogical relationships among individuals in a natural population. Genetic data provide opportunities for paternity exclusion when genotypic incompatibilities are observed among individuals, and the present investigation examines the resolving power of genetic markers in unambiguous positive determination of paternity. Under the assumption that the mother for each offspring in a population is unambiguously known, an analytical expression for the fraction of males excluded from paternity is derived for the case where males and females may be derived from two different gene pools. This theoretical formulation can also be …

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Fine-Structure Analysis Of The Processing And Polyadenylation Region Of The Herpes Simplex Virus Type 1 Thymidine Kinase Gene By Using Linker Scanning, Internal Deletion, And Insertion Mutations., Fang Zhang, Roger M. Denome, Charles N. Cole Dec 1986

Fine-Structure Analysis Of The Processing And Polyadenylation Region Of The Herpes Simplex Virus Type 1 Thymidine Kinase Gene By Using Linker Scanning, Internal Deletion, And Insertion Mutations., Fang Zhang, Roger M. Denome, Charles N. Cole

Dartmouth Scholarship

Most eucaryotic mRNAs are polyadenylated. In higher eucaryotes, the sequence AATAAA is located 7 to 30 base pairs (bp) upstream from the site of processing and polyadenylation and is a critical part of the signal for processing and polyadenylation. Efficient cleavage and polyadenylation also require sequences downstream of polyadenylation sites. The herpes simplex virus type 1 thymidine kinase (tk) gene contains two copies of the AATAAA hexanucleotide and a GT box (18 of 19 consecutive residues are G or T) previously shown to be required for efficient processing and polyadenylation of tk mRNA (C. N. Cole and T. P. Stacy, …

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Two Separable Functional Domains Of Simian Virus 40 Large T Antigen: Carboxyl-Terminal Region Of Simian Virus 40 Large T Antigen Is Required For Efficient Capsid Protein Synthesis., Joanne Tornow, Maryellen Polvino-Bodnar, George Santangelo, Charles N. Cole Feb 1985

Two Separable Functional Domains Of Simian Virus 40 Large T Antigen: Carboxyl-Terminal Region Of Simian Virus 40 Large T Antigen Is Required For Efficient Capsid Protein Synthesis., Joanne Tornow, Maryellen Polvino-Bodnar, George Santangelo, Charles N. Cole

Dartmouth Scholarship

The carboxyl-terminal portion of simian virus 40 large T antigen is essential for productive infection of CV-1 and CV-1p green monkey kidney cells. Mutant dlA2459, lacking 14 base pairs at 0.193 map units, was positive for viral DNA replication, but unable to form plaques in CV-1p cells (J. Tornow and C.N. Cole, J. Virol. 47:487-494, 1983). In this report, the defect of dlA2459 is further defined. Simian virus 40 late mRNAs were transcribed, polyadenylated, spliced, and transported in dlA2459-infected cells, but the level of capsid proteins produced in infected CV-1 green monkey kidney cells was extremely low. dlA2459 large T …

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Inhibition Of Growth Of Toxoplasma Gondii In Cultured Fibroblasts By Human Recombinant Gamma Interferon., E. R. Pfefferkorn, Paul M. Guyre May 1984

Inhibition Of Growth Of Toxoplasma Gondii In Cultured Fibroblasts By Human Recombinant Gamma Interferon., E. R. Pfefferkorn, Paul M. Guyre

Dartmouth Scholarship

The growth of Toxoplasma gondii in cultured human fibroblasts was inhibited by recombinant human gamma interferon at concentrations of 8 to 16 U/ml. The interferon was titrated by observing a total inhibition of parasite plaque formation 7 days after infection. Inhibition of the growth of T. gondii in the early days after infection was measured by marked reductions in the incorporation of radioactive uracil, a precursor that can only be used by the parasites. This assay showed that when cells were pretreated with gamma interferon for 1 day and then infected, inhibition of T. gondii growth could be readily detected …

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Genetically Controlled Variation Of "Acid" Beta-Galactosidase Detected In Rattus Norvegicus By Isoelectric Focusing., T C Douglas, K A Kimmel, P E Dawson Mar 1982

Genetically Controlled Variation Of "Acid" Beta-Galactosidase Detected In Rattus Norvegicus By Isoelectric Focusing., T C Douglas, K A Kimmel, P E Dawson

Journal Articles

Two genetically variant forms of rat "acid" beta-galactosidase were found to differ in isoelectric point and pH dependence, but not in thermostability or sensitivity to inhibition by p-mercuribenzoate (PMB). The results of two backcrosses and an intercross indicated that the isoelectric focusing phenotypes are controlled by two codominant alleles at a single autosomal locus, for which we propose the name Glb-1. No significant linkage between Glb-1 and albino (LG I), brown (LG II), or hooded (LG VI) was observed. Strain-specific differences in total levels of kidney beta-galactosidase were detected, but it is not yet known whether the variation is controlled …

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Polymorphisms, Linkage And Mapping Of Four Enzyme Loci In The Fish Genus Xiphophorus (Poeciliidae)., D C Morizot, M J Siciliano Dec 1979

Polymorphisms, Linkage And Mapping Of Four Enzyme Loci In The Fish Genus Xiphophorus (Poeciliidae)., D C Morizot, M J Siciliano

Journal Articles

Electrophoretic variants at four additional enzyme loci--two esterases (Est-2, Est-3), retinal lactate dehydrogenase (LDH-1) and mannose phosphate isomerase (MPI)--among three species and four subspecies of fish of the genus Xiphophorus were observed. Electrophoretic patterns in F1 hybrid heterozygotes confirmed the monomeric structures of MPI and the esterase and the tetrametric structure of LDH in these fishes. Variant alleles of all four loci displayed normal Mendelian segregation in backcross and F2 hybrids. Recombination data from backcross hybrids mapped with Haldane's mapping function indicate the four loci to be linked as Est-2--0.43--Est3--0.26--LDH-1--0.19--MPI. Significant interference was detected and apparently concentrated in the Est-3 …

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Three Linked Enzyme Loci In Fishes: Implications In The Evolution Of Vertebrate Chromosomes., D C Morizot, D A Wright, M J Siciliano Jul 1977

Three Linked Enzyme Loci In Fishes: Implications In The Evolution Of Vertebrate Chromosomes., D C Morizot, D A Wright, M J Siciliano

Journal Articles

A three-point linkage group comprised of loci coding for adenosine deaminase (ADA), glucose-6-phosphate dehydrogenase (G6PDH), and 6-phospho-gluconate dehydrogenase (6PGD) is described in fish of the genus Xiphophorus (Poeciliidae). The alleles at loci in this group were shown to assort independently from the alleles at three other loci--isocitrate dehydrogenase 1 and 2, and glyceraldehyde-3-phosphate dehydrogenase 1. Alleles at the latter three loci also assort independently from each other. Data were obtained by observing the segregation of electrophoretically variant alleles in reciprocal backcross hybrids derived from crosses between either X. helleri guentheri or X. h. strigatus and X. maculatus. The linkage component …

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