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Fletcher LS, Tedder ML, Olayiwola SO, Joyner NA, Mason MM, Oliver AG, Ensor DD, Dixon DA, Carrick JD. Next-Generation 3,3'-AlkoxyBTPs as Complexants for Minor Actinide Separation from Lanthanides: A Comprehensive Separations, Spectroscopic, and DFT Study. Inorg Chem 2024; 63:4819-4827. [PMID: 38437739 DOI: 10.1021/acs.inorgchem.3c02061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2024]
Abstract
Progress toward the closure of the nuclear fuel cycle can be achieved if satisfactory separation strategies for the chemoselective speciation of the trivalent actinides from the lanthanides are realized in a nonproliferative manner. Since Kolarik's initial report on the utility of bis-1,2,4-triazinyl-2,6-pyridines (BTPs) in 1999, a perfect complexant-based, liquid-liquid separation system has yet to be realized. In this report, a comprehensive performance assessment for the separation of 241Am3+ from 154Eu3+ as a model system for spent nuclear fuel using hydrocarbon-actuated alkoxy-BTP complexants is described. These newly discovered complexants realize gains that contemporary aryl-substituted BTPs have yet to achieve, specifically: long-term stability in highly concentrated nitric acid solutions relevant to the low pH of unprocessed spent nuclear fuel, high DAm over DEu in the economical, nonpolar diluent Exxal-8, and the demonstrated capacity to complete the separation cycle with high efficiency by depositing the chelated An3+ to the aqueous layer via decomplexation of the metal-ligand complex. These soft-N-donor BTPs are hypothesized to function as bipolar complexants, effectively traversing the organic/aqueous interface for effective chelation and bound metal/ligand complex solubility. Complexant design, separation assays, spectroscopic analysis, single-crystal X-ray crystallographic data, and DFT calculations are reported.
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Affiliation(s)
- Lesta S Fletcher
- Department of Chemistry, Tennessee Technological University, Cookeville, Tennessee 38505-0001, United States
| | - Mariah L Tedder
- Department of Chemistry, Tennessee Technological University, Cookeville, Tennessee 38505-0001, United States
| | - Samiat O Olayiwola
- Department of Chemistry, Tennessee Technological University, Cookeville, Tennessee 38505-0001, United States
| | - Nickolas A Joyner
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Marcos M Mason
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Allen G Oliver
- Department of Chemistry, The University of Notre Dame, Notre Dame, Indiana 46656, United States
| | - Dale D Ensor
- Department of Chemistry, Tennessee Technological University, Cookeville, Tennessee 38505-0001, United States
| | - David A Dixon
- Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Jesse D Carrick
- Department of Chemistry, Tennessee Technological University, Cookeville, Tennessee 38505-0001, United States
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2
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Lontchi E, Mason MM, Vasiliu M, Dixon DA. Prediction of the structures and heats of formation of MO 2, MO 3, and M 2O 5 for M = V, Nb, Ta, Pa. Phys Chem Chem Phys 2023; 25:8355-8368. [PMID: 36912479 DOI: 10.1039/d3cp00380a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Structures for the mono-, di-, and tri-bridge isomers of M2O5 as well as those for the MO2 and MO3 fragments for M = V, Nb, Ta, and Pa were optimized at the density functional theory (DFT) level. Single point CCSD(T) calculations extrapolated to the complete basis set (CBS) limit at the DFT geometries were used to predict the energetics. The lowest energy dimer isomer was the di-bridge for M = V and Nb and the tri-bridge for M = Ta and Pa. The di-bridge isomers were predicted to be composed of MO2+ and MO3- fragments, whereas the mono- and tri-bridge are two MO2+ fragments linked by an O2-. The heats of formation of M2O5 dimers, as well as MO2 and MO3 neutral and ionic species were predicted using the Feller-Peterson-Dixon (FPD) approach. The heats of formation of the MF5 species were calculated to provide additional benchmarks. Dimerization energies to form the M2O5 dimers are predicted to become more negative going down group 5 and range from -29 to -45 kcal mol-1. The ionization energies (IEs) for VO2 and TaO2 are essentially the same at 8.75 eV whereas the IEs for NbO2 and PaO2 are 8.10 and 6.25 eV, respectively. The predicted adiabatic electron affinities (AEAs) range from 3.75 eV to 4.45 eV for the MO3 species and vertical detachment energies from 4.21 to 4.59 eV for MO3-. The calculated MO bond dissociation energies increase from 143 kcal mol-1 for M = V to ∼170 kcal mol-1 for M = Nb and Ta to ∼200 kcal mol-1 for M = Pa. The M-O bond dissociation energies are all similar ranging from 97 to 107 kcal mol-1. Natural bond analysis provided insights into the types of chemical bonds in terms of their ionic character. Pa2O5 is predicted to behave like an actinyl species dominated by the interactions of approximately linear PaO2+ groups.
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Affiliation(s)
- Eddy Lontchi
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, AL 35487-0336, USA.
| | - Marcos M Mason
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, AL 35487-0336, USA.
| | - Monica Vasiliu
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, AL 35487-0336, USA.
| | - David A Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, AL 35487-0336, USA.
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Mason MM, Wachs IE, Dixon DA. Assignment of Vibrational Bands of Critical Surface Species Containing Nitrogen in the Selective Catalytic Reduction of NO by NH 3. J Phys Chem A 2023; 127:240-249. [PMID: 36563176 DOI: 10.1021/acs.jpca.2c08580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The selective catalytic reduction (SCR) of NO by NH3 on metal oxides plays a key role in minimizing NOx emissions. Electronic structure calculations at the density functional theory level have been performed to predict the vibrational modes of NH3/NH4+ bound to validated cluster models of vanadium oxide bound to a TiO2 surface. Excellent agreement of the scaled calculated values with the observed bands attributed to surface-bound species is found. The presence of NH3 bound to Lewis acid sites and NH4+ bound to Brønsted acid sites when VOH groups are present is supported by our predictions. NH4+ is expected to dominate the spectra even at low concentrations, with predicted intensities 5 to 30 times greater than those predicted for surface-bound NH3. This is particularly evident in the lowest-energy N-H stretches of surface NH4+ due to partial proton transfer interactions with the vanadium oxide surface model. The current work is consistent with experimental vibrational spectroscopy results and does not support the presence of a significant amount of NH2 on the catalyst surface for the SCR reaction on VOx/TiO2. The combined experimental and computational results support the presence of both NH3- and NH4+-type species bound to the surface.
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Affiliation(s)
- Marcos M Mason
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Israel E Wachs
- Operando Molecular Spectroscopy & Catalysis Laboratory, Department of Chemical and Biomolecular Engineering, Lehigh University, Iacocca Hall, Bethlehem, Pennsylvania 18015, United States
| | - David A Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
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Mason MM, Dixon DA. Electronic Structure Investigation of NO 2 and NO Binding on Vanadium Oxides. J Phys Chem A 2022; 126:8618-8632. [DOI: 10.1021/acs.jpca.2c05340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marcos M. Mason
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - David A. Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
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Gole JL, Chalek CL, Mason MM, de Melo GF, Vasiliu M, Dixon DA. Observation of Selectively Populated Monohalide Excited States from the Reactions of Group 3 Metal (Sc, Y, and La) Monomers and Dimers with Halogen-Containing Molecules. J Phys Chem A 2022; 126:3403-3426. [PMID: 35613075 DOI: 10.1021/acs.jpca.2c01779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The chemiluminescent reactions of the group 3 metals Sc and Y with F2, Cl2, Br2, ClF, ICl (Sc), IBr (Y), and SF6 and La with F2, SF6, Cl2, and ClF have been studied at low pressures (6 × 10-6 to 4 × 10-4 Torr) using a beam-gas arrangement and extended to the 10-3 Torr multiple collision pressure range. Contrary to previous reports, the observed chemiluminescent spectra are primarily attributed to emission from the metal monohalides. Extensive pressure and temperature dependence studies and high-level correlated molecular orbital theory calculations of the bond dissociation energies support this conclusion and the attribution of the chemiluminescence. Evidence for the "selective" production of a monohalide excited electronic state is obtained for several of the Sc and Y reactions. All reactions producing the metal monofluorides are first order with respect to the oxidant, while reactions producing the monochlorides and monobromides are found to be "faster than first order" with respect to the oxidant. This difference is associated with the metal halide bond dissociation energies and the metal halide product internal density of states. Analysis of the temperature dependence for six representative reactions indicates that the "selective" excited-state formation of the metal monohalides proceeds via a direct mechanism with negligible activation energy. We compare and contrast the present results with previous experiments and interpretations which have assigned the selective emission from these systems to the group 3 dihalides produced in a two-step reaction sequence analogous to an electron jump process. The current results suggest a distinctly different interpretation of the observed processes in these systems. The observed selectivity observed in these studies is remarkable given the significant number of known and potential excited states in the scandium and yttrium halides as well as their different electronic configurations.
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Affiliation(s)
- James L Gole
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Carl L Chalek
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Marcos M Mason
- Department of Chemistry and Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336, United States
| | - Gabriel F de Melo
- Department of Chemistry and Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336, United States
| | - Monica Vasiliu
- Department of Chemistry and Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336, United States
| | - David A Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Tuscaloosa, Alabama 35487-0336, United States
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Tedder ML, Dzeagu FO, Mason MM, Dixon DA, Carrick JD. Microwave-assisted C–H oxidation of methylpyridylheteroarenes via a Kornblum-Type reaction. Tetrahedron 2022. [DOI: 10.1016/j.tet.2022.132805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Mason MM, Smith C, Vasiliu M, Carrick JD, Dixon DA. Prediction of An(III)/Ln(III) Separation by 1,2,4-Triazinylpyridine Derivatives. J Phys Chem A 2021; 125:6529-6542. [PMID: 34286991 DOI: 10.1021/acs.jpca.1c01854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effect of frustrated Lewis donors on metal selectivity between actinides and lanthanides was studied using a series of novel organic ligands. Structures and thermodynamic energies were predicted in the gas phase, in water, and in butanol using 9-coordinate, explicitly solvated (H2O) Eu, Gd, Am, and Cm in the +III oxidation state as reactants in the formation of complexes with 2-(6-[1,2,4]-triazin-3-yl-pyridin-2-yl)-1H-indole (Core 1), 3-[6-(2H-pyrazol-3-yl)pyridin-2-yl]-1,2,4-triazine (Core 2), and several derivatives. These complexations were studied using density functional theory (DFT) incorporating scalar relativistic effects on the actinides and lanthanides using a small core pseudopotential and corresponding basis set. A self-consistent reaction field approach was used to model the effect of water and butanol as solvents. Coordination preferences and metal selectivity are predicted for each ligand. Several ligands are predicted to have a high degree of selectivity, particularly when a low ionization potential in the ligand permits charge transfer to Eu(III), reducing it to Eu(II) and creating a half-filled f7 shell. Reasonable separation is predicted between Cm(III) and Gd(III) with Core 1 ligands, possibly due to ligand donor frustration. This separation is largely absent from Core 2 ligands, which are predicted to lose their frustration due to proton transfer from the 2N to the 3N position of the pyrazole component of the ligands via tautomerization.
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Affiliation(s)
- Marcos M Mason
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Caris Smith
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Monica Vasiliu
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
| | - Jesse D Carrick
- Department of Chemistry, Tennessee Technological University, 803 Stadium Drive, Cookeville, Tennessee 38505-0001, United States
| | - David A Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa, Alabama 35487-0336, United States
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Mason MM, Lee ZR, Vasiliu M, Wachs IE, Dixon DA. Initial Steps in the Selective Catalytic Reduction of NO with NH3 by TiO2-Supported Vanadium Oxides. ACS Catal 2020. [DOI: 10.1021/acscatal.0c03693] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marcos M. Mason
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa Alabama 35487-0336, United States
| | - Zachary R. Lee
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa Alabama 35487-0336, United States
| | - Monica Vasiliu
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa Alabama 35487-0336, United States
| | - Israel E. Wachs
- Operando Molecular Spectroscopy & Catalysis Laboratory, Department of Chemical and Biomolecular Engineering, Lehigh University, Iacocca Hall, Bethlehem Pennsylvania 18015, United States
| | - David A. Dixon
- Department of Chemistry and Biochemistry, The University of Alabama, Shelby Hall, Tuscaloosa Alabama 35487-0336, United States
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Chao L, Marcus-Samuels B, Mason MM, Moitra J, Vinson C, Arioglu E, Gavrilova O, Reitman ML. Adipose tissue is required for the antidiabetic, but not for the hypolipidemic, effect of thiazolidinediones. J Clin Invest 2000; 106:1221-8. [PMID: 11086023 PMCID: PMC381440 DOI: 10.1172/jci11245] [Citation(s) in RCA: 281] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2000] [Accepted: 10/11/2000] [Indexed: 02/06/2023] Open
Abstract
There is uncertainty about the site(s) of action of the antidiabetic thiazolidinediones (TZDs). These drugs are agonist ligands of the transcription factor PPAR gamma, which is abundant in adipose tissue but is normally present at very low levels in liver and muscle. We have studied the effects of TZDs in A-ZIP/F-1 mice, which lack white adipose tissue. The A-ZIP/F-1 phenotype strikingly resembles that of humans with severe lipoatrophic diabetes, including the lack of fat, marked insulin resistance and hyperglycemia, hyperlipidemia, and fatty liver. Rosiglitazone or troglitazone treatment did not reduce glucose or insulin levels, suggesting that white adipose tissue is required for the antidiabetic effects of TZDs. However, TZD treatment was effective in lowering circulating triglycerides and increasing whole body fatty acid oxidation in the A-ZIP/F-1 mice, indicating that this effect occurs via targets other than white adipose tissue. A-ZIP/F-1 mice have markedly increased liver PPAR gamma mRNA levels, which may be a general property of fatty livers. Rosiglitazone treatment increased the triglyceride content of the steatotic livers of A-ZIP/F-1 and ob/ob mice, but not the "lean" livers of fat-transplanted A-ZIP/F-1 mice. In light of this evidence that rosiglitazone acts differently in steatotic livers, the effects of rosiglitazone, particularly on hepatic triglyceride levels, should be examined in humans with hepatic steatosis.
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Affiliation(s)
- L Chao
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892-1770, USA
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Gavrilova O, Leon LR, Marcus-Samuels B, Mason MM, Castle AL, Refetoff S, Vinson C, Reitman ML. Torpor in mice is induced by both leptin-dependent and -independent mechanisms. Proc Natl Acad Sci U S A 1999; 96:14623-8. [PMID: 10588755 PMCID: PMC24486 DOI: 10.1073/pnas.96.25.14623] [Citation(s) in RCA: 167] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We tested the effect of chronic leptin treatment on fasting-induced torpor in leptin-deficient A-ZIP/F-1 and ob/ob mice. A-ZIP/F-1 mice have virtually no white adipose tissue and low leptin levels, whereas ob/ob mice have an abundance of fat but no leptin. These two models allowed us to examine the roles of adipose tissue and leptin in the regulation of entry into torpor. Torpor is a short-term hibernation-like state that allows conservation of metabolic fuels. We first characterized the A-ZIP/F-1 animals, which have a 10-fold reduction in total body triglyceride stores. Upon fasting, A-ZIP/F-1 mice develop a lower metabolic rate and decreased plasma glucose, insulin, and triglyceride levels, with no increase in free fatty acids or beta-hydroxybutyrate. Unlike control mice, by 24 hr of fasting, they have nearly exhausted their triglycerides and are catabolizing protein. To conserve energy supplies during fasting, A-ZIP/F-1 (but not control) mice entered deep torpor, with a minimum core body temperature of 24 degrees C, 2 degrees C above ambient. In ob/ob mice, fasting-induced torpor was completely reversed by leptin treatment. In contrast, neither leptin nor thyroid hormone prevented torpor in A-ZIP/F-1 mice. These data suggest that there are at least two signals for entry into torpor in mice, a low leptin level and another signal that is independent of leptin and thyroid hormone levels. Studying rodent torpor provides insight into human torpor-like states such as near drowning in cold water and induced hypothermia for surgery.
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Affiliation(s)
- O Gavrilova
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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11
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Reitman ML, Mason MM, Moitra J, Gavrilova O, Marcus-Samuels B, Eckhaus M, Vinson C. Transgenic mice lacking white fat: models for understanding human lipoatrophic diabetes. Ann N Y Acad Sci 1999; 892:289-96. [PMID: 10842669 DOI: 10.1111/j.1749-6632.1999.tb07802.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The human disease lipoatrophic (or lipodystrophic) diabetes is a rare syndrome in which a deficiency of adipose tissue is associated with Type 2 diabetes. This disease is an interesting contrast to the usual situation in which diabetes is associated with obesity, an excess of fat. Aside from obesity, patients with lipodystrophic diabetes have the other features associated with Metabolic Syndrome X, including hypertension and dyslipidemia. The contrast between diabetes with a lack of fat and diabetes with an excess of fat provides an opportunity to study the mechanisms causing Type 2 diabetes and its complications. Recently, three laboratories have produced transgenic mice that are deficient in white adipose tissue. These mice have insulin resistance and other features of lipoatrophic diabetes, and are a faithful model for the human disease. Here we review the different murine models of fat ablation and compare the murine and human diseases, addressing the questions: Is the lack of fat causative of the diabetes, and if so by what mechanism? How could the other clinical features be explained mechanistically? And finally, what can be gleaned about insight into treatment options?
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Affiliation(s)
- M L Reitman
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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12
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Miettinen HM, Gripentrog JM, Mason MM, Jesaitis AJ. Identification of putative sites of interaction between the human formyl peptide receptor and G protein. J Biol Chem 1999; 274:27934-42. [PMID: 10488141 DOI: 10.1074/jbc.274.39.27934] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Wild-type and 35 mutant formyl peptide receptors (FPRs) were stably expressed in Chinese hamster ovary cells. All cell surface-expressed mutant receptors bound N-formyl peptide with similar affinities as wild-type FPR, suggesting that the mutations did not affect the ligand-binding site. G protein coupling was examined by quantitative analysis of N-formyl-methionyl-leucyl-phenylalanine-induced increase in binding of (35)S-labeled guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) to membranes. The most prominent uncoupled FPR mutants were located in the N-terminal part of the second transmembrane domain (S63W and D71A) and the C-terminal interface of the third transmembrane domain (R123A and C124S/C126S). In addition, less pronounced uncoupling was detected with deletion mutations in the third cytoplasmic loop and in the cytoplasmic tail. Further analysis of some of the mutants that were judged to be uncoupled based on the [(35)S]GTPgammaS membrane-binding assay were found to transduce a signal, as evidenced by intracellular calcium mobilization and activation of p42/44 MAPK. Thus, these single point mutations in FPR did not completely abolish the interaction with G protein, emphasizing that the coupling site is coordinated by several different regions of the receptor. Mutations located in the putative fifth and sixth transmembrane domains near the N- and C-terminal parts of the third cytoplasmic loop did not result in uncoupling. These regions have previously been shown to be critical for G protein coupling to many other G protein-coupled receptors. Thus, FPR appears to have a G protein-interacting site distinct from the adrenergic receptors, the muscarinic receptors, and the angiotensin receptors.
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MESH Headings
- Amino Acid Sequence
- Amino Acid Substitution
- Androstadienes/pharmacology
- Animals
- CHO Cells
- Cell Membrane/metabolism
- Cell Membrane/ultrastructure
- Cricetinae
- Cytoplasm/metabolism
- Enzyme Activation
- Enzyme Inhibitors/pharmacology
- GTP-Binding Proteins/chemistry
- GTP-Binding Proteins/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Humans
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinases/metabolism
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- N-Formylmethionine Leucyl-Phenylalanine/pharmacology
- Protein Structure, Secondary
- Receptors, Formyl Peptide
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Receptors, Peptide/chemistry
- Receptors, Peptide/genetics
- Receptors, Peptide/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Transfection
- Virulence Factors, Bordetella/pharmacology
- Wortmannin
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Affiliation(s)
- H M Miettinen
- Department of Microbiology, Montana State University, Bozeman, Montana 59717-3520, USA.
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Moitra J, Mason MM, Olive M, Krylov D, Gavrilova O, Marcus-Samuels B, Feigenbaum L, Lee E, Aoyama T, Eckhaus M, Reitman ML, Vinson C. Life without white fat: a transgenic mouse. Genes Dev 1998; 12:3168-81. [PMID: 9784492 PMCID: PMC317213 DOI: 10.1101/gad.12.20.3168] [Citation(s) in RCA: 562] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We have generated a transgenic mouse with no white fat tissue throughout life. These mice express a dominant-negative protein, termed A-ZIP/F, under the control of the adipose-specific aP2 enhancer/promoter. This protein prevents the DNA binding of B-ZIP transcription factors of both the C/EBP and Jun families. The transgenic mice (named A-ZIP/F-1) have no white adipose tissue and dramatically reduced amounts of brown adipose tissue, which is inactive. They are initially growth delayed, but by week 12, surpass their littermates in weight. The mice eat, drink, and urinate copiously, have decreased fecundity, premature death, and frequently die after anesthesia. The physiological consequences of having no white fat tissue are profound. The liver is engorged with lipid, and the internal organs are enlarged. The mice are diabetic, with reduced leptin (20-fold) and elevated serum glucose (3-fold), insulin (50- to 400-fold), free fatty acids (2-fold), and triglycerides (3- to 5-fold). The A-ZIP/F-1 phenotype suggests a mouse model for the human disease lipoatrophic diabetes (Seip-Berardinelli syndrome), indicating that the lack of fat can cause diabetes. The myriad of consequences of having no fat throughout development can be addressed with this model.
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Affiliation(s)
- J Moitra
- Laboratory of Biochemistry, National Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, Maryland 20892 USA
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14
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Abstract
Leptin is a hormone produced in adipose cells that regulates energy expenditure, food intake, and adiposity. To understand leptin's transcriptional regulation, we are studying its promoter. Four conserved and functional regions were identified. Mutations in the C/EBP and TATA motifs each caused an approximately 10-fold decrease in promoter activity. The C/EBP motif bound recombinant C/EBP alpha and mediated trans-activation by C/EBP alpha, -beta, and -delta. Mutation of a consensus Sp1 site reduced promoter activity 2.5-fold and abolished binding of Sp1. Mutation of a fourth factor-binding site, denoted LP1, abolished protein binding and reduced promoter activity 2-fold. Factor binding to the LP1 motif was observed with adipocyte, but not with nonadipocyte extracts. Adipocytes from fa/fa Zucker rats transcribed the reporter plasmids more efficiently than did control adipocytes. No effect on the transient expression of leptin was noted upon treatment with a thiazolidinedione, BRL49653, or upon cotransfection with peroxisome proliferator-activated receptor-gamma/retinoid X receptor-alpha or sterol response element-binding protein-1. Mutations of the Sp1, LP1, and C/EBP sites in pairwise combinations diminished promoter activity to the extent predicted assuming these motifs contribute independently to leptin promoter function. Our identification of motifs regulating leptin transcription is an important step in the elucidation of the mechanisms underlying hormonal and metabolic regulation of this gene.
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Affiliation(s)
- M M Mason
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-1770, USA
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15
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Abstract
Leptin is a hormone that regulates metabolic efficiency, energy expenditure, and food intake. Leptin is produced chiefly in adipose cells, but in humans, mRNA encoding leptin is also present in the placenta. Here we elucidate the basis for placental leptin production. The same promoter is used for adipose and placental transcription. An upstream enhancer functions in the JEG-3 and JAR choriocarcinoma cell lines but not in adipocytes or HeLa cells. The minimal positive acting region is 60 base pairs in length. This region is within a MER11 repetitive element, suggesting that human placental expression of leptin is the result of insertion of this element. Binding analyses demonstrated three protein binding sites, designated placental leptin enhancer elements (PLE)1, PLE2, and PLE3. PLE2 binds Sp1. Enhancer activity was reduced by mutation of the PLE1 or PLE3 sites but was unaffected by alteration of PLE2. Proteins binding to PLE3 were present in JEG-3 and human placental nuclear extracts but not in extracts from non-placental sources. Upon triplication, the PLE3 element was a strong enhancer in choriocarcinoma cells but not in HeLa cells. The protein binding to the PLE3 motif appears to be a novel, placenta-specific transcription factor.
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Affiliation(s)
- S Bi
- Diabetes Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-1770, USA.
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Mason MM, Grasso JA, Gavrilova O, Reitman M. Identification of functional elements of the chicken epsilon-globin promoter involved in stage-specific interaction with the beta/epsilon enhancer. J Biol Chem 1996; 271:25459-67. [PMID: 8810316 DOI: 10.1074/jbc.271.41.25459] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Expression of the chicken globin genes is regulated in part by competition between the betaA-globin and epsilon-globin promoters for the enhancer found between the genes. To understand the determinants of the enhancer-promoter interaction in stage-specific regulation, the functional elements of the embryonic chicken epsilon-globin promoter were characterized. In vitro assays demonstrated that: (a) the TATA motif at -30 bound GATA-1, (b) Sp1 bound to an element centered at -54, and (c) both Sp1 and another factor, designated CACCC (which appears related to erythroid Krüppel-like factor, EKLF) bound in the -120 to -128 region. The functions of these motifs were tested using transient expression in embryonic erythroid cells. In the absence of the enhancer, promoter point mutants showed that the TATA, Sp1, and CCAAT motifs (but not the CACCC motif) contributed to promoter activity. In contrast, in the presence of the enhancer, all four motifs (including the CACCC motif) contributed to transcription. Developmental regulation of the enhancer activity was observed, with enhancement decreasing sharply from 185-fold at 4 days (cells expressing epsilon-globin) to 16-fold at 10 days (when epsilon-globin is no longer expressed). Taken together, the data suggest that multiple transcription factors contribute to promoter-enhancer interaction and the developmental regulation of epsilon-globin expression, with EKLF-like factors having an especially important role. Regulation of stage specificity occurs at the level of enhancer/epsilon-promoter interaction, even in the absence of competition, and is not simply a property of the enhancer or promoter in isolation.
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Affiliation(s)
- M M Mason
- Diabetes Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA
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17
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Mason MM, Lee E, Westphal H, Reitman M. Expression of the chicken beta-globin gene cluster in mice: correct developmental expression and distributed control. Mol Cell Biol 1995; 15:407-14. [PMID: 7799949 PMCID: PMC231981 DOI: 10.1128/mcb.15.1.407] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
To investigate the regulation of gene clusters, we introduced the entire chicken beta-globin cluster into mice. This 35-kb region includes the four globin genes (rho-beta H-beta A-epsilon), the four upstream hypersensitive sites, and the intergenic beta A/epsilon enhancer. The chicken globins are not arranged in order of developmental expression, which is unlike the case for the human beta-globin cluster, in which gene order plays a role in the regulation of globin expression. Mice carrying the chicken cluster expressed the transgenes with the same developmental patterns as seen in the chicken. Therefore, stage-specific erythroid transcriptional milieus existed before the divergence of birds and mammals and have been conserved since then. Mice bearing the complete cluster except for a deletion removing the beta A/epsilon enhancer displayed markedly reduced expression of the beta H, beta A, and epsilon genes with efficient (but variable) rho expression. Mice carrying the four genes and beta A/epsilon enhancer but without the upstream hypersensitive sites showed reduced expression of rho, beta H, and beta A, with variable expression of epsilon. We conclude that (i) all of the genes (except possibly rho) are under the control of both the upstream hypersensitive sites and the enhancer, (ii) the influence of the control elements can extend beyond the nearest active gene, (iii) a single element (the enhancer) can influence more than one gene in a single developmental stage, (iv) the enhancer can work bidirectionally, and (v) neither the upstream sites (as a group) nor the enhancer showed developmental stage specificity. Thus, the regulation of this cluster is achieved by interaction of two distinct control regions with each of the globin genes.
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Affiliation(s)
- M M Mason
- Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892
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18
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Abstract
In searching for a nondepolarizing muscle relaxant with intermediate duration but more rapid onset of action than the presently available compounds, the neuromuscular and circulatory effects of ORG9426 were investigated in two studies in humans receiving fentanyl, droperidol, thiopental, and nitrous oxide-oxygen anesthesia. Eighty patients, randomly assigned to one of four groups of 20 each, received 0.12, 0.16, 0.20, or 0.24 mg/kg ORG9426. In the first study, the doses (in milligrams per kilogram) of ORG9426 that caused 50% (ED50), 90% (ED90), or 95% (ED95) neuromuscular block were determined by the individual dose-response method; they were 0.170, 0.268, and 0.305 mg/kg, respectively. In the second study, after induction of anesthesia, patients received 0.6 mg/kg (about 2 x ED95) of ORG9426, either in a single bolus (group 1) or in two unequal (0.1 and 0.5 mg/kg) increments 4 min apart (group 2). After the administration of 0.6 mg/kg ORG9426, maximal neuromuscular block developed in 1.5 +/- 0.12 min in group 1 and in 1.2 +/- 0.14 min in group 2. Patients tracheas were intubated after development of the maximal neuromuscular effect of the intubating dose and after the recording of heart rate and systolic and diastolic blood pressure. There was no difference in the clinical duration of the intubating doses, which were 40.0 +/- 3.2 (15-73) min in group 1 and 39.3 +/- 2.4 (19-57) min in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- F F Foldes
- Department of Anesthesiology, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York 10467
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19
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Abstract
The mitochondrial DNA (mtDNA) of Candida albicans contains a large inverted duplication. As is the case with most chloroplast DNAs and one other mtDNA, the nonduplicated regions of the molecule occur in two orientations with respect to each other, indicating that internal recombination occurs. Like some other mtDNAs, the C. albicans mtDNA contains a single SalI restriction site located near one end of the large rRNA gene. In contrast to other cases, however, the inverted duplication does not appear to contain any sequences coding for rRNA.
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Affiliation(s)
- J A Shaw
- Department of Microbiology, University of Tennessee, Knoxville 37996-0845
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20
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Abstract
A cloned DNA fragment from Candida albicans containing the gene for the protein actin was used to probe the molecular structure of the actin gene of several medically important yeasts (C. albicans, Candida stellatoidea, Candida tropicalis, Candida pseudotropicalis, Candida krusei, Candida parapsilosis, Candida guilliermondii, and Torulopsis glabrata). Whole-cell DNA from each species was digested with restriction endonucleases, electrophoresed on agarose gels, and transferred to nitrocellulose. Radioactively labeled C. albicans actin gene was hybridized to the DNA fragments on the nitrocellulose. The C. albicans probe produced a strong signal with all of the Candida DNAs tested, indicating considerable conservation of this gene. In addition, the actin genes of all of the species tested were found to have no internal EcoRI or SalI restriction sites. With the exception of C. guilliermondii, all of the species tested had a single internal HindIII recognition site. However, the location of flanking restriction sites was found to be species specific. For all of the enzymes tested, the locations of the flanking restriction sites in C. albicans and C. stellatoidea were identical; all of the other strains yielded fragments clearly distinct from one another. These differences provide a molecular tool for the differentiation of medically important Candida species.
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Sarkar SD, Beierwaltes H, Ice RD, Basmadjian GP, Hetzel KR, Kennedy WP, Mason MM. A new and superior adrenal scanning agent, NP-59. J Nucl Med 1975; 16:1038-42. [PMID: 1185265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The first synthesis of 131I-19-iodocholesterol had a 10-25% radiochemical impurity that was not iodide ion. This impurity has been identified as 6beta-131I-iodomethyl-19-nor cholest 5(10)-en-3beta-ol (NP-59) and has been synthesized. Tissue distribution studies with 131I-NP-59 in rats and dogs revealed a higher adrenal uptake and adrenal-to-tissue ratios compared to 131I-19-iodocholesterol, probably less in vivo deiodination, and superior adrenal images. A high uptake was seen in the adrenal medulla in addition to that in the cortex. Iodine-131-NP-59 is being evaluated for the early detection of adrenal-cortical disorders and as a potential scanning agent for detecting structural abnormalities of the adrenal medulla.
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Bogden AE, Taylor DJ, Kuo EY, Mason MM, Speropoulos A. The effect of perphenazine-induced serum prolactin response on estrogen-primed mammary tumor-host systems, 13762 and R-35 mammary adenocarcinomas. Cancer Res 1974; 34:3018-25. [PMID: 4419558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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25
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Baker JR, Mason MM, Yerganian G, Weisburger EK, Weisburger JH. Induction of tumors of the stomach and esophagus in inbred Chinese hamsters by oral diethylnitrosamine. Proc Soc Exp Biol Med 1974; 146:291-3. [PMID: 4363827 DOI: 10.3181/00379727-146-38090] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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26
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Esber HJ, Menninger FF, Bogden AE, Mason MM. Immunological deficiency associated with cigarette smoke inhalation by mice. Primary and secondary hemagglutinin response. Arch Environ Health 1973; 27:99-104. [PMID: 4721205 DOI: 10.1080/00039896.1973.10666328] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Mason MM, Bogden AE, Ilievski V, Esber HJ, Baker JR, Chopra HC. History of a rhesus monkey adenocarcinoma containing virus particles resembling oncogenic RNA viruses. J Natl Cancer Inst 1972; 48:1323-31. [PMID: 4624149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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29
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Chopra HC, Zelljadt I, Jensen EM, Mason MM, Woodside NJ. Infectivity of cell cultures by a virus isolated from a mammary carcinoma of a rhesus monkey. J Natl Cancer Inst 1971; 46:127-37. [PMID: 4100556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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30
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Jensen EM, Zelljadt I, Chopra HC, Mason MM. Isolation and propagation of a virus from a spontaneous mammary carcinoma of a rhesus monkey. Cancer Res 1970; 30:2388-93. [PMID: 4990901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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31
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Chopra HC, Mason MM. A new virus in a spontaneous mammary tumor of a rhesus monkey. Cancer Res 1970; 30:2081-6. [PMID: 4195910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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32
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Smith ER, Mason MM, Epstein E. The ocular effects of repeated dermal applications of dimethyl sulfoxide to dogs and monkeys. J Pharmacol Exp Ther 1969; 170:364-70. [PMID: 4982311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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33
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Mason MM, Whiting MG. Caudal motor weakness and ataxia in cattle in the Caribbean area following ingestion of cycads. Cornell Vet 1968; 48:541-54. [PMID: 5693644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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34
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Smith ER, Hadidian Z, Mason MM. The toxicity of single and repeated dermal applications of dimethyl sulfoxide. J Clin Pharmacol J New Drugs 1968; 8:315-21. [PMID: 4970689 DOI: 10.1002/j.1552-4604.1968.tb00281.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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35
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36
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37
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38
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Affiliation(s)
- O Rahn
- Laboratory of Bacteriology, New York State College of Agriculture, Cornell University, Ithaca, New York
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39
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Affiliation(s)
- M M Mason
- Laboratory of Bacteriology, New York State College of Agriculture, Cornell University, Ithaca, New York
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