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Abstract
Chromosomes are units of the genom in eukaryotes containing a specific fraction of the DNA characteristic for the species. This DNA forms the backbone of the chromosome and usually is represented by a single DNA double helix stretching from one end of the chromosome to the other. Relative to the size of most nuclei the length of the DNA is considerable. In humans for instance the haploid set of DNA is about 1 m long and in certain amphibia can measure many meters. The analysis of chromosome structure is mainly concerned with the various levels of folding or coiling by which this DNA is compacted in a regular way into chromosomes of interphase and mitotic stages.The electron microscope has played an important role in the discovery of chromosome organization. The 20 nm fiber was first described in 1956 as a unit of interphase chromatin (Ris, 1956). Later the 10 nm fiber was recognized as the component of chromatin dispersed in the presence of chelating agents for biochemical studies (Ris, 1961).
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Vollenweider HJ. Visual biochemistry: new insight into structure and function of the genome. METHODS OF BIOCHEMICAL ANALYSIS 2006; 28:201-65. [PMID: 6178943 DOI: 10.1002/9780470110485.ch5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Horowitz-Scherer RA, Woodcock CL. Organization of interphase chromatin. Chromosoma 2005; 115:1-14. [PMID: 16362820 DOI: 10.1007/s00412-005-0035-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Revised: 11/01/2005] [Accepted: 11/03/2005] [Indexed: 11/25/2022]
Abstract
The organization of interphase chromatin spans many topics, ranging in scale from the molecular level to the whole nucleus, and its study requires a concomitant range of experimental approaches. In this review, we examine these approaches, the results they have generated, and the interfaces between them. The greatest challenge appears to be the integration of information on whole nuclei obtained by light microscopy with data on nucleosome-nucleosome interactions and chromatin higher-order structures, obtained in vitro using biophysical characterization, atomic force microscopy, and electron microscopy. We consider strategies that may assist in the integration process, and we review emerging technologies that promise to reduce the "resolution gap."
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Affiliation(s)
- Rachel A Horowitz-Scherer
- Biology Department and Molecular and Cellular Biology Program, University of Massachusetts at Amherst, 01003, USA
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Hoshi O, Ushiki T. Three-dimensional structure of G-banded human metaphase chromosomes observed by atomic force microscopy. ARCHIVES OF HISTOLOGY AND CYTOLOGY 2001; 64:475-82. [PMID: 11838707 DOI: 10.1679/aohc.64.475] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The structure of G-bands in human metaphase chromosomes was analyzed by comparison between light microscopic and atomic force microscopic (AFM) images of the same chromosomes. G-bands of the chromosomes were made by trypsin treatment followed by staining with a Giemsa solution. The banded chromosomes examined by light microscopy were dried either in air or in a critical point-drier, and observed by non-contact mode AFM. Air-dried chromosomes after G-band staining showed alternating ridges and grooves on their surface, which corresponded to light-microscopically determined G-positive and G-negative bands, respectively. At high magnification, the G-positive ridges were composed of densely packed chromatin fibers, while the fibers were loose in the G-negative grooves. Fibers bridging the gap between sister chromatids of a mitotic pair were often found, especially in the G-positive portions. These findings suggest that the G-banding pattern reflects the high-order structure of human metaphase chromosomes.
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Affiliation(s)
- O Hoshi
- Department of Cellular Function, Niigata University Graduate School of Medical and Dental Sciences, Japan
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Abstract
The nuclear changes accompanying spermatid elongation have been studied in two species of grasshopper, Dissosteira carolina and Melanoplus femur-rubrum. Testes were fixed in 1 per cent buffered OsO4, imbedded in butyl methacrylate, and examined as thin sections in the electron microscope. In both species nuclear changes during spermatid development involve (1) an early period, during which the nuclear contents are predominately fibrous; (2) a middle period, characterized by the lateral association of the nuclear fibers to form plates or lamellae which are oriented longitudinally in the major axis of the elongated nucleus; and (3) a late period, involving coalescence of the lamellae into a crystalline body which eventually becomes so dense that all resolvable detail is lost. The fibers seen in the early spermatid nucleus are about 150 A in diameter and so are similar to fibers described from other types of nuclei. The thickness of the lamellae varies from about 150 A when first formed to 70 A during the later stages. The lack of evident chromosomal boundaries in the spermatid nucleus makes it difficult to relate either the fibers or lamellae to more familiar aspects of chromosome structure. We see no apparent reason to consider that the fiber alignment described here is related to conventional chromosome pairing.
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CERVOS-NAVARRO J. [Electron microscopic findings in normal and pathological nerve cell nuclei]. ACTA ACUST UNITED AC 1998; 203:575-98. [PMID: 14019757 DOI: 10.1007/bf00343236] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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HOPWOOD DA, GLAUERT AM. The fine structure of Streptomyces coelicolor. II. The nuclear material. J Biophys Biochem Cytol 1998; 8:267-78. [PMID: 13715794 PMCID: PMC2224923 DOI: 10.1083/jcb.8.1.267] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Colonies and spore suspensions of Streptomyces coelicolor were fixed for electron microscopy by the method of Kellenberger, Ryter, and Séchaud (1958). In thin sections the nuclear regions have a lower average density than the cytoplasm and the outlines of these regions correspond well with the profiles of the chromatinic bodies observed with the light microscope. The nuclear regions contain fibrils, about 5 mmicro in diameter. In contrast, after fixation by the method of Palade (1952) the nuclear material is coagulated into irregular dense masses and tubular structures about 20 mmicro in diameter, lying in a nuclear "vacuole." The significance of these observations is discussed in relation to the observations of other workers on the fine structure of the nuclear material of other bacteria and the chromosomes of higher cells.
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Bahr GF, Engler WF. Artifacts observed in critical-point-dried preparations of human chromosomes by electron microscopy. JOURNAL OF ULTRASTRUCTURE RESEARCH 1980; 73:27-33. [PMID: 7007660 DOI: 10.1016/0022-5320(80)90113-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Heumann HG. Electron microscope observations of the organisation of chromatin fibers in isolated nuclei of of rat liver. Chromosoma 1974; 47:131-46. [PMID: 4140777 DOI: 10.1007/bf00331801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Tanaka K, Iino A. Demonstration of fibrous components in hepatic interphase nuclei by high resolution scanning electron microscopy. Exp Cell Res 1973. [DOI: 10.1016/0014-4827(73)90108-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Miyai K, Steiner JW. Fine structure of interphase liver cell nuclei in subacute ethionine intoxication. Exp Mol Pathol 1965; 4:525-66. [PMID: 5892049 DOI: 10.1016/0014-4800(65)90016-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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DuPraw EJ. Macromolecular organization of nuclei and chromosomes: a folded fibre model based on whole-mount electron microscopy. Nature 1965; 206:338-43. [PMID: 5835699 DOI: 10.1038/206338a0] [Citation(s) in RCA: 161] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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17
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Elektronenmikroskopische Untersuchungen �ber Strukturver�nderungen in den Kernen von Spinalganglienzellen der Ratte nach Bestrahlung mit 185 Mev-Protonen. Cell Tissue Res 1963. [DOI: 10.1007/bf00331184] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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COLE A. A Molecular Model for Biological Contractility: Implications in Chromosome Structure and Function. Nature 1962; 196:211-4. [PMID: 14022193 DOI: 10.1038/196211a0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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STEFFENSEN DM. Chromosome Structure with Special Reference to the Role of Metal Ions. INTERNATIONAL REVIEW OF CYTOLOGY 1962; 12:163-97. [PMID: 13916552 DOI: 10.1016/s0074-7696(08)60540-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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SCHLOTE FW. [On the fine structure of chromosomes. I. On the cytology of Escherichia coli. B. Cell growth, importance of electronoptic findings]. ARCHIV FUR MIKROBIOLOGIE 1961; 40:306-35. [PMID: 14498603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
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ODOR DL, RENNINGER DF. Polar body formation in the rat oocyte as observed with the electron microscope. Anat Rec (Hoboken) 1960; 137:13-23. [PMID: 14428300 DOI: 10.1002/ar.1091370103] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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OBERLING C. Ausblicke der Cellularpathologie. Virchows Arch 1959; 332:6-16. [PMID: 13648009 DOI: 10.1007/bf00968565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
Lampbrush chromosomes were isolated from germinal vesicles of oocytes from Necturus maculatus, Triturus viridescens, Pseudotriton montanus and Rana pipiens. After treatment of isolated nuclei with 10 per cent sucrose, chromosomes free of nuclear sap are obtained for examination in either the light microscope or in the electron microscope. For electron microscopy the chromosomes were prepared either by Anderson's critical-point procedure or were embedded in methacrylate and sectioned. The evidence presented in favor of the view that the loops, axis, and the chromomeres of lampbrush chromosomes are formed by two chromonemata is based on the following observations: 1. Treatment of isolated chromosomes with 0.002 M KCN loosens the structure of the loops, and a more or less coiled organization is then observed in most of them with the light microscope. At the electron microscope level, each loop consists of a bundle of microfibrils. The latter are 500 A in diameter, and their complex arrangement within the loops is best studied in stereoscopic preparations. 2. Treatment of chromosomes with 0.002 M KCN also unravels the "chromomeric" regions of the axis. A fibrillar organization then becomes visible in the light microscope. In the electron microscope, wide strands are seen within some chromomeres; their diameter corresponds closely to that of the chromonemata forming the loops associated with the same chromomeres. In thin transverse sections of isolated chromosomes, no special structure is visible in the axial region except random profiles of fibrils similar to those seen in the loops of the same preparations. 3. Two strands sometimes connect adjacent chromomeres. Where gaps exist along the axis, after stretching of the chromosomes, a loop occasionally straddles the break and returns to a chromomere on each side.
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Preusser HJ. Elektronenmikroskopische Untersuchungen �ber die Cytologie von Proteus vulgaris. Arch Microbiol 1958. [DOI: 10.1007/bf00418734] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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PREUSSER HJ. [Electron microscopy on the cytology of Proteus vulgaris]. ARCHIV FUR MIKROBIOLOGIE 1958; 29:17-37. [PMID: 13534421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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LEHMANN F. FUNCTIONAL ASPECTS OF SUBMICROSCOPIC NUCLEAR STRUCTURES IN AMOEBA PROTEUS, AND OF THE MITOTIC APPARATUS OF TUBIFEX EMBRYOS. Exp Cell Res 1958. [DOI: 10.1016/s0014-4827(21)00270-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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32
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Licht- und elektronenmikroskopische Untersuchungen an dem Dinoflagellaten Amphidinium elegans n. sp. Cell Tissue Res 1957. [DOI: 10.1007/bf00340000] [Citation(s) in RCA: 46] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
Electron micrographs of staminate hair cells of Tradescantia reflexa indicate that early prophase chromosomes are composed of a number of helically arranged chromonemata. Favorable preparations reveal as many as 64 identifiable subsidiary strands, assumedly arranged as intertwined pairs to form a hierarchy of pairs of pairs. The helices of the smallest discernible units have a diameter of about 125 A, with highly electron-scattering material disposed peripherally around a less dense "core." The wall of this peripheral ring has a thickness of about 40 A, and apparently represents another pair of coiled threads surrounding a 40 A central axis. The implications of the findings are discussed briefly.
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