Characterization of microsatellite loci in the eastern oyster, Crassostrea virginica.
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Journal Article↗
Biomedical subjects
M Hong
Publications and source records attributed to M Hong.
Characterization of microsatellite loci in the eastern oyster, Crassostrea virginica.
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Animals↗
[An etiological and pathologic study of Rhinoscleroma].
OBJECTIVE: To investigate the clinicopathologic characteristics and mechanism of tissue injury caused by Klebsiella rhinoscleromatis (KR) infection. METHODS: Thirty-three cases of rhinoscleromas in the nasal and pharyngeal region seen in this hospital from Jan. 1980 to Mar. 2000 were studied retrospectively. Warthin-Starry (W-S) stain was used to study all cases. Five cases were studied further with transmission electron microscope. RESULTS: W-S stain revealed a great number of KR in Mikulicz cells within the granuloma. Electron microscopy demonstrated a number of phagosomes in the cytoplasm of Mikulicz cells where many KR were found. A small number of other organelles such as endoplasmic reticulums and lysozymes were squeezed to the side of cells. There were many granular substances on the surface of intracellular bacteria, which were not found on the extracellular KR. CONCLUSION: KR is a facultative intracellular bacteria that is able to resist the digestion of macrophages and to proliferate in them. Formation of granulomas and fibrosis in KR infiltrated regions is the major cause of tissue injury.
Adolescent↗
[Study on improvement of liver cirrhosis and liver function in hepatolenticular degeneration patients treated with integrated Traditional and Western medicine].
OBJECTIVE: To observe the effects of sodium dimercaptosulphonate (DMPS) plus Gandou tablet, DMPS and calcium disodium ethylene diaminotetraacetate (EDTA) on improving liver cirrhosis and liver function of hepatolenticular degeneration (HLD) patients. METHODS: One hundred and forty-six HLD patients were divided into A, B, C three groups, and treated with DMPS plus Gandou tablet, DMPS and EDTA respectively, the therapeutic course was 8 weeks for three groups. The ultrasonography of liver, electrophoresis of serum protein and excretion of urinary copper were observed. RESULTS: The ultrasonography of liver was improved in all groups, the rate of improvement of group A was 54.0%, B was 44.0% and C was 39.1%. The amounts of serum albumin in A and B groups increased (P < 0.01, P < 0.05), and gamma-globulin decreased in all groups (P < 0.05). The excretion of urinary copper increased obviously in all groups (P < 0.01), and A, B groups increased more than that of C group (P < 0.05). CONCLUSIONS: The de-copper therapy could improve liver cirrhosis and liver function. The effect of DMPS plus Gandou tablet was better than that of DMPS and EDTA.
Adolescent↗
[High level expression of foreign gene via multiple joined operons and a new concept on the restricted constant of total amount of plasmid DNA per cell of Escherichia coli].
OBJECTIVE: To examine the feasibility of linking operons in tandem to enhance expression of heterologous genes in Escherichia coli and to clarify the potential control mechanism of the total plasmid DNA amount in each host cell. METHODS: Two series of expression plasmids, CW11 and CW12, containing 1 to 4 and 1 to 3 heterologous gene operon(s), respectively, were constructed. The molecular size of the CW11 series varied from 5.47 kb to 12.26 kb in 2.25 kb increments. The CW12 series varied from 5.40 kb to 9.72 kb in 2.16 kb increments. Protein expression was analyzed via SDS-PAGE and laser scanning. Plasmid copy number was determined by incorporation with 3H-TdR([3H]-thymidine). RESULTS: No influence of the tandem-joined operons on host growth and plasmid stability was observed. Upon induction, the desired protein accumulated in the CW11 series were 46.0%, 54.8%, 56.1%, and 60.1% of total cell protein. In the CW12 series, the yields were 33.5%, 44.0%, and 47.1% of total cell protein. With increasing size, however, plasmid copy number decreased. Further calculation showed that the total amount of plasmid DNA per cell is restricted to some extent. There seems exists a mechanism to control the maximum level of total plasmid DNA amount in each host cell. CONCLUSIONS: Increasing the target gene dosage by tandem linking of operons enhanced the expression level of a desired protein. Although the size (kb) and the copy number of each plasmid are negatively interrelated, it seems that as for certain plasmids, their total DNA amount per cell is a restricted constant for a specific E. coli strain under identical incubation condition.
Cloning, Molecular↗
[Syntheses, reactions and spectroscopic properties of cluster compounds containing ME4 (M = Mo, W; E = S, Se) units].
The synthetic reactions and spectroscopic studied of molybdenum (tungsten) -copper (silver, iron) -sulphur (selenium) cluster compounds, which can be prepared by the stepwise or unit construction reactions through the successive addition ML (L = Cl, Br, Sr, R2 etc) across six edges or four faces of ME4 (M = Mo, W; E = S, Se) tetrahedra, are described. A series of Mo (W)-Cu-S cluster compounds, (Et4N)2 [MCu2E4 (S2CNR2)2], (Et4N)2 [MCu2E3O (S2CNR2)2], [MCu2E4 (dppe)2] (dppe = bis (diphenylphosphine) ethane), (Et4N)2 [MCu3E4 (S2CNR2)4] (M = Mo, E = Se, R = Et (1a), R2 = C4H8 (1b), R = PhCH2 (lc)), (Et4N)2 [MCu4E4 (S2CNR2)4] (M = Mo, E = Se, R = Me (2)) (Et4N)2 [M2Cu4S8 (S2CNEt2)2], (Et4N)2 [M2Cu4S6O2- (S2CNC4H8)2], [Mo2Cu4S8 (dppm)2], [Mo2Cu4S6O2 (dppm)2], (dppm = bis (diphenylphosphine) -methane), (Et4N)4 (ME4Cu10L12) (M = Mo, E = Se, L = PhCH2S (3)), MoFe3Se4 (mu-R2NCS2)2 (R2NCS2)4 have been prepared and characterized by UV, IR and X-ray diffraction analyses.
Copper↗
Efficient aminoacylation of tRNA(Lys,3) by human lysyl-tRNA synthetase is dependent on covalent continuity between the acceptor stem and the anticodon domain.
In this work, we probe the role of the anticodon in tRNA recognition by human lysyl-tRNA synthetase (hLysRS). Large decreases in aminoacylation efficiency are observed upon mutagenesis of anticodon positions U35 and U36 of human tRNA(Lys,3). A minihelix derived from the acceptor-TPsiC stem-loop domain of human tRNA(Lys,3)was not specifically aminoacylated by the human enzyme. The presence of an anticodon-derived stem-loop failed to stimulate aminoacylation of the minihelix. Thus, covalent continuity between the acceptor stem and anticodon domains appears to be an important requirement for efficient charging by hLysRS. To further examine the mechanism of communication between the critical anticodon recognition elements and the catalytic site, a two piece semi-synthetic tRNA(Lys, 3)construct was used. The wild-type semi-synthetic tRNA contained a break in the phosphodiester backbone in the D loop and was an efficient substrate for hLysRS. In contrast, a truncated variant that lacked nucleotides 8-17 in the D stem-loop displayedseverely reduced catalytic efficiency. The elimination of key tRNA tertiary structural elements has little effect on anticodon-dependent substrate binding but severely impacts formation of the proper transition state for catalysis. Taken together, our studies provide new insights into human tRNA structural requirements for effective transmission of the anticodon recognition signal to the distal acceptor stem domain.
Anticodon↗
Antagonism of p53-dependent apoptosis by mitogen signals.
p53-mediated apoptosis is antagonized by growth factor stimulation. Here, we show that p53-dependent cell death induced by DNA damage was effectively prevented by mitogen activation. The levels of Bcl-2, Bcl-xL, and Bax were not altered by cisplatin treatment and mitogen rescue. Instead, the protection against p53-regulated apoptosis was mediated by at least three distinct signaling pathways. Either phosphatidylinositol (PI) 3-kinase or mitogen-activated protein kinase kinase (MEK) antagonized p53-induced apoptosis, and an additive preventive effect was observed when both kinases were activated. However, the combination of PI 3-kinase and MEK was not sufficient to completely prevent apoptosis induced by DNA damage. Mitogen activation further suppressed cisplatin-induced p53 expression, and the inhibition was mainly dependent on the Ca2+ pathway. Our results demonstrate that effective antagonism of p53-dependent apoptosis by mitogenic activation requires the presence of multiple signal pathways, including PI 3-kinase, MEK, and Ca2+.
Animals↗
Missense and silent tau gene mutations cause frontotemporal dementia with parkinsonism-chromosome 17 type, by affecting multiple alternative RNA splicing regulatory elements.
Frontotemporal dementia with parkinsonism, chromosome 17 type (FTDP-17) is caused by mutations in the tau gene, and the signature lesions of FTDP-17 are filamentous tau inclusions. Tau mutations may be pathogenic either by altering protein function or gene regulation. Here we show that missense, silent, and intronic tau mutations can increase or decrease splicing of tau exon 10 (E10) by acting on 3 different cis-acting regulatory elements. These elements include an exon splicing enhancer that can either be strengthened (mutation N279(K)) or destroyed (mutation Delta280(K)), resulting in either constitutive E10 inclusion or the exclusion of E10 from tau transcripts. E10 contains a second regulatory element that is an exon splicing silencer, the function of which is abolished by a silent FTDP-17 mutation (L284(L)), resulting in excess E10 inclusion. A third element inhibiting E10 splicing is contained in the intronic sequences directly flanking the 5' splice site of E10 and intronic FTDP-17 mutations in this element enhance E10 inclusion. Thus, tau mutations cause FTDP-17 by multiple pathological mechanisms, which may explain the phenotypic heterogeneity observed in FTDP-17, as exemplified by an unusual family described here with tau pathology as well as amyloid and neuritic plaques.
Aged↗
Epitaxial cubic gadolinium oxide as a dielectric for gallium arsenide passivation
Epitaxial growth of single-crystal gadolinium oxide dielectric thin films on gallium arsenide is reported. The gadolinium oxide film has a cubic structure isomorphic to manganese oxide and is (110)-oriented in single domain on the (100) gallium arsenide surface. The gadolinium oxide film has a dielectric constant of approximately 10, with low leakage current densities of about 10(-9) to 10(-10) amperes per square centimeter at zero bias. Typical breakdown field is 4 megavolts per centimeter for an oxide film 185 angstroms thick and 10 megavolts per centimeter for an oxide 45 angstroms thick. Both accumulation and inversion layers were observed in the gadolinium oxide-gallium arsenide metal oxide semiconductor diodes, using capacitance-voltage measurements. The ability to grow thin single-crystal oxide films on gallium arsenide with a low interfacial density of states has great potential impact on the electronic industry of compound semiconductors.
Journal Article↗
Solid-state dipolar INADEQUATE NMR spectroscopy with a large double-quantum spectral width.
A technique for obtaining dipolar-mediated INADEQUATE NMR spectra with a large spectral window in the double-quantum dimension is presented. Using the dipolar recoupling sequence C7 to excite the double-quantum coherence under magic-angle spinning, the technique involves incrementing the evolution period in synchrony with the phase of the radiofrequency pulses in the C7 sequence. The technique is demonstrated on a uniformly 13C-labeled amino acid and an extensively 13C-labeled protein to identify 13C connectivity patterns for spectral assignment.
Amino Acids↗
g-matrix based on configuration interaction and Stone's perturbation theory
Stone's formula, which has usually been applied to the calculation of the g-matrix, is based on a single-configuration treatment. Here a limited configuration interaction is included to obtain the expressions of the principal g values for an orbitally nondegenerate molecule with spin S = 12. Copyright 1999 Academic Press.
Journal Article↗
The g values of some halomolybdenyl, -vanadyl, and -chromyl complexes.
The principal g values of a series of [MOXn]m- (M = VIV, CrV, MoV; X = F-, Cl-, Br-; n = 4, 5; m = 1, 2, 3) complexes are calculated by the INDO-CI-Stone method. The results agree well with the experimental data and reveal that the traditional models have some limitations in calculating g values for some complexes of this type.
Chromates↗
Determination of multiple ***φ***-torsion angles in proteins by selective and extensive (13)C labeling and two-dimensional solid-state NMR.
We describe an approach to efficiently determine the backbone conformation of solid proteins that utilizes selective and extensive (13)C labeling in conjunction with two-dimensional magic-angle-spinning NMR. The selective (13)C labeling approach aims to reduce line broadening and other multispin complications encountered in solid-state NMR of uniformly labeled proteins while still enhancing the sensitivity of NMR spectra. It is achieved by using specifically labeled glucose or glycerol as the sole carbon source in the protein expression medium. For amino acids synthesized in the linear part of the biosynthetic pathways, [1-(13)C]glucose preferentially labels the ends of the side chains, while [2-(13)C]glycerol labels the C(alpha) of these residues. Amino acids produced from the citric-acid cycle are labeled in a more complex manner. Information on the secondary structure of such a labeled protein was obtained by measuring multiple backbone torsion angles phi; simultaneously, using an isotropic-anisotropic 2D correlation technique, the HNCH experiment. Initial experiments for resonance assignment of a selectively (13)C labeled protein were performed using (15)N-(13)C 2D correlation spectroscopy. From the time dependence of the (15)N-(13)C dipolar coherence transfer, both intraresidue and interresidue connectivities can be observed, thus yielding partial sequential assignment. We demonstrate the selective (13)C labeling and these 2D NMR experiments on a 8.5-kDa model protein, ubiquitin. This isotope-edited NMR approach is expected to facilitate the structure determination of proteins in the solid state.
Carbon Isotopes↗
Age-dependent emergence and progression of a tauopathy in transgenic mice overexpressing the shortest human tau isoform.
Filamentous tau aggregates are hallmarks of tauopathies, e.g., frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17) and amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC). Since FTDP-17 tau gene mutations alter levels/functions of tau, we overexpressed the smallest human tau isoform in the CNS of transgenic (Tg) mice to model tauopathies. These mice acquired age-dependent CNS pathology similarto FTDP-17 and ALS/PDC, including insoluble, hyperphosphorylated tau and argyrophilic intraneuronal inclusions formed by tau-immunoreactive filaments. Inclusions were present in cortical and brainstem neurons but were most abundant in spinal cord neurons, where they were associated with axon degeneration, diminished microtubules (MTs), and reduced axonal transport in ventral roots, as well as spinal cord gliosis and motor weakness. These Tg mice recapitulate key features of tauopathies and provide models for elucidating mechanisms underlying diverse tauopathies, including Alzheimer's disease (AD).
Aging↗
Resonance assignment of 13C/15N labeled solid proteins by two- and three-dimensional magic-angle-spinning NMR.
The comprehensive structure determination of isotopically labeled proteins by solid-state NMR requires sequence-specific assignment of 13C and 15N spectra. We describe several 2D and 3D MAS correlation techniques for resonance assignment and apply them, at 7.0 Tesla, to 13C and 15N labeled ubiquitin to examine the extent of resonance assignments in the solid state. Both interresidue and intraresidue assignments of the 13C and 15N resonances are addressed. The interresidue assignment was carried out by an N(CO)CA technique, which yields Ni-C alpha i-1 connectivities in protein backbones via two steps of dipolar-mediated coherence transfer. The intraresidue connectivities were obtained from a new 3D NCACB technique, which utilizes the well resolved C beta chemical shift to distinguish the different amino acids. Additional amino acid type assignment was provided by a 13C spin diffusion experiment, which exhibits 13C spin pairs as off-diagonal intensities in the 2D spectrum. To better resolve carbons with similar chemical shifts, we also performed a dipolar-mediated INADEQUATE experiment. By cross-referencing these spectra and exploiting the selective and extensive 13C labeling approach, we assigned 25% of the amino acids in ubiquitin sequence-specifically and 47% of the residues to the amino acid types. The sensitivity and resolution of these experiments are evaluated, especially in the context of the selective and extensive 13C labeling approach.
Amino Acid Sequence↗
Selective and extensive 13C labeling of a membrane protein for solid-state NMR investigations.
The selective and extensive 13C labeling of mostly hydrophobic amino acid residues in a 25 kDa membrane protein, the colicin Ia channel domain, is reported. The novel 13C labeling approach takes advantage of the amino acid biosynthetic pathways in bacteria and suppresses the synthesis of the amino acid products of the citric acid cycle. The selectivity and extensiveness of labeling significantly simplify the solid-state NMR spectra, reduce line broadening, and should permit the simultaneous measurement of multiple structural constraints. We show the assignment of most 13C resonances to specific amino acid types based on the characteristic chemical shifts, the 13C labeling pattern, and the amino acid composition of the protein. The assignment is partly confirmed by a 2D homonuclear double-quantum-filter experiment under magic-angle spinning. The high sensitivity and spectral resolution attained with this 13C-labeling protocol, which is termed TEASE for ten-amino acid selective and extensive labeling, are demonstrated.
Amino Acid Sequence↗
Cloning of the genomic sequence encoding a processed adenylate kinase 2 pseudogene.
A chromosomal DNA sequence harboring a processed AK2B pseudogene was isolated from a human genomic library. It was a variant of the AK2B gene sequence including several point mutations, deletions, and insertions. The nucleotide sequence of the ORF of the AK2B pseudogene predicted a truncated form of the AK2B mutant suggesting that the processed pseudogene is nonfunctional. A repetitive sequence, AAAAGAGAG, found in the 5' and 3' flanking regions of the pseudogene and the poly(A) tract in the 3' end junction suggest that a mRNA of AK2B may have been converted to the processed pseudogene by retrotransposition events. Previously, it was suggested that an adenylate kinase (AK) 2 related gene on chromosome 2, confirmed by Southern analysis using somatic cell hybrid cell lines, may be a processed pseudogene. It is proposed that the processed pseudogene isolated in this study may be the AK2 related nonfunctional gene localized on human chromosomes 2.
Adenylate Kinase↗