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Abstract
Nuclear migration encompasses three areas: separation of daughter nuclei during mitosis, congress of parental nuclei before they fuse during fertilization, and positioning of nuclei in interphase cells. This review deals primarily with interphase nuclear migration, which is crucial for events as disparate as vertebrate embryonic development and growth of fungal mycelia. Mutants of Aspergillus nidulans, Neurospora crassa and Saccharomyces cerevisiae have been particularly informative, and a detailed molecular analysis of this process is now well under way.
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102
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Xiang X, Osmani AH, Osmani SA, Xin M, Morris NR. NudF, a nuclear migration gene in Aspergillus nidulans, is similar to the human LIS-1 gene required for neuronal migration. Mol Biol Cell 1995; 6:297-310. [PMID: 7612965 PMCID: PMC301189 DOI: 10.1091/mbc.6.3.297] [Citation(s) in RCA: 266] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
During a study of the genetics of nuclear migration in the filamentous fungus Aspergillus nidulans, we cloned a gene, nudF, which is required for nuclear migration during vegetative growth as well as development. The NUDF protein level is controlled by another protein NUDC, and extra copies of the nudF gene can suppress the nudC3 mutation. nudF encodes a protein with 42% sequence identity to the human LIS-1 (Miller-Dieker lissencephaly-1) gene, which is required for proper neuronal migration during brain development. This strong similarity suggests that the LIS-1 gene product may have a function similar to that of NUDF and supports previous findings to suggest that nuclear migration may play a role in neuronal migration.
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103
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Xiang X, Zhang Y, Liu L. [The three dimensional finite element analysis of fracture in mandibular body treated by rigid internal fixations]. ZHONGHUA KOU QIANG YI XUE ZA ZHI = ZHONGHUA KOUQIANG YIXUE ZAZHI = CHINESE JOURNAL OF STOMATOLOGY 1995; 30:95-8. [PMID: 7648927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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104
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Xiang X, Osmani AH, Osmani SA, Roghi CH, Willins DA, Beckwith S, Goldman G, Chiu Y, Xin M, Liu B. Analysis of nuclear migration in Aspergillus nidulans. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 1995; 60:813-9. [PMID: 8824456 DOI: 10.1101/sqb.1995.060.01.087] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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105
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Xiang X, Marshall AG. Simulated ion trajectory and induced signal in ion cyclotron resonance ion traps. Effect of ion initial axial position on ion coherence, induced signal, and radial or z ejection in a cubic trap. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1994; 5:807-813. [PMID: 24222028 DOI: 10.1016/1044-0305(94)87003-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/1993] [Revised: 04/22/1994] [Accepted: 04/25/1994] [Indexed: 06/02/2023]
Abstract
The effects of ion initial axial position on coherence of ion motion, induced ion cyclotron resonance (ICR) signal. and radial and z ejection have been evaluated by numerical simulation for a cubic Fourier transform-ion cyclotron resonance ion trap. For a given initial ion cyclotron phase and radius, ions of different initial z position are shown to be excited to significantly different ion cyclotron radii (and ultimately radially ejected at significantly different excitation amplitude-duration products). Ion initial z displacement from the trap midplane affects observed ICR signal magnitude in two ways: (1) for the same postexcitation cyclotron radius, an ion with larger initial z displacement induces a smaller ICR signal and (2) an ion with larger initial z displacement is excited to a smaller cyclotron radius. We also evaluate the induced ICR signal as a function of excitation amplitude-duration product for spatially uniform or Gaussian ion initial z distributions. In general, if the excitation waveform contains components at frequency, 2 ωz or (ω+ + 2 ωz, in which ωz is the axial C"trapping") oscillation frequency, then ejection occurs axially. However, the resulting excitation amplitude-duration product for such axial ejection is significantly higher (factor of, ∼ 4) than that required for radial ejection (at ω+) for ions of small initial radius. The present results offer the first explanation of how, even if the ion is initially at rest on the z axis (i.e., zero excitation electric field amplitude on the z axis), z ejection (axial ejection) may nevertheless occur if the excitation waveform contains frequency components at ω+ + 2ωz and/or 2w z Namely, our simulations reveal that off-resonant excitation pushes ions away from the z axis, after which the ions are exposed to z excitation and eventual z ejection.
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106
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Xiang X, Guan S, Marshal AG. Simulated ion trajectory and induced signal in ion cyclotron resonance ion traps. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1994; 5:238-249. [PMID: 24222561 DOI: 10.1016/1044-0305(94)85014-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/1993] [Revised: 12/07/1993] [Accepted: 12/07/1993] [Indexed: 06/02/2023]
Abstract
We present a numerical method for computation of electrostatic (trapping) and time-varying (excitation) electric fields and the resulting ion trajectory and detected time-domain-induced voltage signal in a rectangular (or cubic) ion cyclotron resonance (ICR) ion trap. The electric potential is calculated by use of the superposition principle and relaxation method with a large number of grid points (e.g., 100 × 100 × 100 for a cubic trap). Complex ICR experiments and spectra may now be simulated with high accuracy. Ion trajectories may be obtained for any combination of trapping and excitation modes, including quadrupolar or cubic trapping in static or dynamic mode; and dipolar, quadrupolar, or parametric excitation with single-frequency, frequency-sweep (chirp), or stored waveform inverse Fourier transform waveforms. The resulting ion trajectory may be represented either as its three dimensional spatial path or as two-dimensional plots of x-, y-, or z-position, velocity, or kinetic energy versus time in the absence or presence of excitation. Induced current is calculated by use of the reciprocity principle, and simulated ICR mass spectra are generated by Fourier transform of the corresponding time-domain voltage signal.
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107
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Xiang X, Beckwith SM, Morris NR. Cytoplasmic dynein is involved in nuclear migration in Aspergillus nidulans. Proc Natl Acad Sci U S A 1994; 91:2100-4. [PMID: 8134356 PMCID: PMC43317 DOI: 10.1073/pnas.91.6.2100] [Citation(s) in RCA: 270] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Nuclear migration plays an important role in the growth and development of many organisms including the multinuclear fungus Aspergillus nidulans. We have identified four genes, nudA, nudC, nudF, and nudG, in which temperature-sensitive mutations affect nuclear distribution. In this report, we describe the cloning of the nudA gene by complementation of the mutant phenotype by using a chromosome VIII-specific cosmid library. A genomic fragment of nudA hybridized to an mRNA of approximately 14 kb. Sequencing analysis of nudA revealed four ATP-binding sites that are characteristic of the cytoplasmic dynein heavy chain. The amino acid sequence of the nudA gene product shows 52% overall identity with the rat brain cytoplasmic dynein heavy chain. Our study provides in vivo evidence that dynein, a microtubule motor molecule, plays a role in the nuclear migration process.
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108
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Liang G, Sahiner A, Croft M, Xu W, Xiang X, Badresingh D, Li W, Chen J, Peng J, Zettl A, Lu F. X-ray-absorption near-edge structure study of IBi2Sr2CaCu2Oy. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:1029-1035. [PMID: 10005582 DOI: 10.1103/physrevb.47.1029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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109
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Hoen S, Chopra NG, Xiang X, Mostovoy R, Hou J, Vareka WA, Zettl A. Elastic properties of a van der Waals solid: C60. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:12737-12739. [PMID: 10003194 DOI: 10.1103/physrevb.46.12737] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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110
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Crespi VH, Hou JG, Xiang X, Cohen ML, Zettl A. Electron-scattering mechanisms in single-crystal K3C60. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 46:12064-12067. [PMID: 10003115 DOI: 10.1103/physrevb.46.12064] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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111
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Duncan M, DiCicco-Bloom EM, Xiang X, Benezra R, Chada K. The gene for the helix-loop-helix protein, Id, is specifically expressed in neural precursors. Dev Biol 1992; 154:1-10. [PMID: 1426618 DOI: 10.1016/0012-1606(92)90042-f] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
While mammalian neurogenesis has been characterized extensively, the molecules involved in regulating neural cell determination and differentiation remain ill-defined. There is accruing evidence that various members of the basic helix-loop-helix (bHLH) protein family critically regulate these biological processes in a number of tissues. Id, a negative regulator of bHLH proteins, was found to exhibit peak gene expression during mouse embryogenesis with a striking pattern in the central nervous system. Id transcripts were specifically localized to undifferentiated neural precursors of the ventricular zone and were not present in their differentiated derivatives. In addition, in the peripheral nervous system, dorsal root ganglia sensory precursors, known to be undifferentiated while dividing, also expressed Id mRNA. However, in the sympathetic nervous system and adrenal medulla, where differentiation and division occur simultaneously in precursors, Id was not expressed. Since Id transcript abundance inversely correlated with differentiation, this protein, similar to its Drosophila homolog, extramacrochaetae, may play a negative regulatory role in neural differentiation.
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112
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Chung M, Wang Y, Brill JW, Xiang X, Mostovoy R, Hou JG, Zettl A. ac calorimetry of C60 single crystals. PHYSICAL REVIEW. B, CONDENSED MATTER 1992; 45:13831-13833. [PMID: 10001497 DOI: 10.1103/physrevb.45.13831] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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113
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Xiang X, Vareka WA, Zettl A, Corkill JL, Cohen ML, Kijima N, Gronsky R. Metallization of the resistivity tensor in Bi2Sr2CaCu2Ox through epitaxial intercalation. PHYSICAL REVIEW LETTERS 1992; 68:530-533. [PMID: 10045920 DOI: 10.1103/physrevlett.68.530] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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114
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Newman KE, Xiang X. Demonstration of ordering in semiconducting (chalcopyrite)-(zinc blende) alloys. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 44:4677-4680. [PMID: 10000131 DOI: 10.1103/physrevb.44.4677] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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115
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Xiang X, Zettl A, Vareka WA, Corkill JL, Barbee TW, Cohen ML. Epitaxial intercalation of the Bi-Sr-Ca-Cu-O superconductor series. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 43:11496-11499. [PMID: 9996911 DOI: 10.1103/physrevb.43.11496] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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116
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Xiang X, Benson KF, Chada K. Mini-mouse: disruption of the pygmy locus in a transgenic insertional mutant. Science 1990; 247:967-9. [PMID: 2305264 DOI: 10.1126/science.2305264] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A founder transgenic mouse harbored two different integration patterns of a transgene at the same locus, each of which gave rise to a similar autosomal recessive mutation. Mice of the mutant phenotype were of small stature but had normal levels of growth hormone. The disrupted locus was cloned, and a genetic and molecular analysis showed that the insertional mutants were allelic to a spontaneous mutant, pygmy. The mice should be a useful model for the growth hormone-resistant human dwarf syndromes and could lead to a greater understanding of the pathways involved in growth and development.
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117
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Xiang X, Brill JW. Frequency dependence of elastic anomalies in charge-density-wave conductors. PHYSICAL REVIEW LETTERS 1989; 63:1853-1856. [PMID: 10040690 DOI: 10.1103/physrevlett.63.1853] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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118
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Xiang X, Brill JW. Effects of charge-density-wave depinning on the elastic properties of NbSe3. PHYSICAL REVIEW. B, CONDENSED MATTER 1989; 39:1290-1297. [PMID: 9948316 DOI: 10.1103/physrevb.39.1290] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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119
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Xiang X, Brill JW. Shear modulus of TaS3. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 36:2969-2971. [PMID: 9943202 DOI: 10.1103/physrevb.36.2969] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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120
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Huang T, Wang X, Xiang X. Quark mass and spin effects in meson wave functions. Int J Clin Exp Med 1987; 35:1013-1017. [PMID: 9957748 DOI: 10.1103/physrevd.35.1013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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