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. 1994 Oct 2;127(2):287–302. doi: 10.1083/jcb.127.2.287

Visualization of G1 chromosomes: a folded, twisted, supercoiled chromonema model of interphase chromatid structure

PMCID: PMC2120203  PMID: 7929576

Abstract

We have used light microscopy and serial thin-section electron microscopy to visualize intermediates of chromosome decondensation during G1 progression in synchronized CHO cells. In early G1, tightly coiled 100-130-nm "chromonema" fibers are visualized within partially decondensed chromatin masses. Progression from early to middle G1 is accompanied by a progressive uncoiling and straightening of these chromonema fibers. Further decondensation in later G1 and early S phase results in predominantly 60-80-nm chromonema fibers that can be traced up to 2-3 microns in length as discrete fibers. Abrupt transitions in diameter from 100-130 to 60-80 nm along individual fibers are suggestive of coiling of the 60-80-nm chromonema fibers to form the thicker 100-130-nm chromonema fiber. Local unfolding of these chromonema fibers, corresponding to DNA regions tens to hundreds of kilobases in length, reveal more loosely folded and extended 30-nm chromatin fibers. Kinks and supercoils appear as prominent features at all observed levels of folding. These results are inconsistent with prevailing models of chromosome structure and, instead, suggest a folded chromonema model of chromosome structure.

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Selected References

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  1. Adolph K. W. Organization of chromosomes in mitotic HeLa cells. Exp Cell Res. 1980 Jan;125(1):95–103. doi: 10.1016/0014-4827(80)90193-7. [DOI] [PubMed] [Google Scholar]
  2. Agard D. A., Hiraoka Y., Shaw P., Sedat J. W. Fluorescence microscopy in three dimensions. Methods Cell Biol. 1989;30:353–377. doi: 10.1016/s0091-679x(08)60986-3. [DOI] [PubMed] [Google Scholar]
  3. Belmont A. S., Braunfeld M. B., Sedat J. W., Agard D. A. Large-scale chromatin structural domains within mitotic and interphase chromosomes in vivo and in vitro. Chromosoma. 1989 Aug;98(2):129–143. doi: 10.1007/BF00291049. [DOI] [PubMed] [Google Scholar]
  4. Belmont A. S., Sedat J. W., Agard D. A. A three-dimensional approach to mitotic chromosome structure: evidence for a complex hierarchical organization. J Cell Biol. 1987 Jul;105(1):77–92. doi: 10.1083/jcb.105.1.77. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Belmont A. S., Zhai Y., Thilenius A. Lamin B distribution and association with peripheral chromatin revealed by optical sectioning and electron microscopy tomography. J Cell Biol. 1993 Dec;123(6 Pt 2):1671–1685. doi: 10.1083/jcb.123.6.1671. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Benavente R., Dabauvalle M. C., Scheer U., Chaly N. Functional role of newly formed pore complexes in postmitotic nuclear reorganization. Chromosoma. 1989 Oct;98(4):233–241. doi: 10.1007/BF00327308. [DOI] [PubMed] [Google Scholar]
  7. Bohrmann B., Kellenberger E. Immunostaining of DNA in electron microscopy: an amplification and staining procedure for thin sections as alternative to gold labeling. J Histochem Cytochem. 1994 May;42(5):635–643. doi: 10.1177/42.5.7512586. [DOI] [PubMed] [Google Scholar]
  8. Boy de la Tour E., Laemmli U. K. The metaphase scaffold is helically folded: sister chromatids have predominantly opposite helical handedness. Cell. 1988 Dec 23;55(6):937–944. doi: 10.1016/0092-8674(88)90239-5. [DOI] [PubMed] [Google Scholar]
  9. Burke B., Gerace L. A cell free system to study reassembly of the nuclear envelope at the end of mitosis. Cell. 1986 Feb 28;44(4):639–652. doi: 10.1016/0092-8674(86)90273-4. [DOI] [PubMed] [Google Scholar]
  10. Eissenberg J. C., Cartwright I. L., Thomas G. H., Elgin S. C. Selected topics in chromatin structure. Annu Rev Genet. 1985;19:485–536. doi: 10.1146/annurev.ge.19.120185.002413. [DOI] [PubMed] [Google Scholar]
  11. Enger M. D., Tobey R. A., Saponara A. G. RNA synthesis in Chinese hamster cells. I. Differential synthetic rate for ribosomal RNA in early and late interphase. J Cell Biol. 1968 Mar;36(3):583–593. doi: 10.1083/jcb.36.3.583. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Ericsson C., Mehlin H., Björkroth B., Lamb M. M., Daneholt B. The ultrastructure of upstream and downstream regions of an active Balbiani ring gene. Cell. 1989 Feb 24;56(4):631–639. doi: 10.1016/0092-8674(89)90585-0. [DOI] [PubMed] [Google Scholar]
  13. Garcia-Segura L. M., Lafarga M., Berciano M. T., Hernandez P., Andres M. A. Distribution of nuclear pores and chromatin organization in neurons and glial cells of the rat cerebellar cortex. J Comp Neurol. 1989 Dec 15;290(3):440–450. doi: 10.1002/cne.902900311. [DOI] [PubMed] [Google Scholar]
  14. Harauz G., Borland L., Bahr G. F., Zeitler E., van Heel M. Three-dimensional reconstruction of a human metaphase chromosome from electron micrographs. Chromosoma. 1987;95(5):366–374. doi: 10.1007/BF00293184. [DOI] [PubMed] [Google Scholar]
  15. Heck M. M., Earnshaw W. C. Topoisomerase II: A specific marker for cell proliferation. J Cell Biol. 1986 Dec;103(6 Pt 2):2569–2581. doi: 10.1083/jcb.103.6.2569. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Hiraoka Y., Swedlow J. R., Paddy M. R., Agard D. A., Sedat J. W. Three-dimensional multiple-wavelength fluorescence microscopy for the structural analysis of biological phenomena. Semin Cell Biol. 1991 Jun;2(3):153–165. [PubMed] [Google Scholar]
  17. Hodge L. D., Martinez J. E., Allsbrook W. C., Pantazis C. G., Welter D. A. Intermediate structures in nuclear morphogenesis following metaphase from HeLaS3 cells can be isolated and temporally grouped. Chromosoma. 1990 Jul;99(3):169–182. doi: 10.1007/BF01731127. [DOI] [PubMed] [Google Scholar]
  18. Horowitz R. A., Giannasca P. J., Woodcock C. L. Ultrastructural preservation of nuclei and chromatin: improvement with low-temperature methods. J Microsc. 1990 Feb;157(Pt 2):205–224. doi: 10.1111/j.1365-2818.1990.tb02959.x. [DOI] [PubMed] [Google Scholar]
  19. Hozák P., Hassan A. B., Jackson D. A., Cook P. R. Visualization of replication factories attached to nucleoskeleton. Cell. 1993 Apr 23;73(2):361–373. doi: 10.1016/0092-8674(93)90235-i. [DOI] [PubMed] [Google Scholar]
  20. Lafond R. E., Woodcock C. L. Status of the nuclear matrix in mature and embryonic chick erythrocyte nuclei. Exp Cell Res. 1983 Aug;147(1):31–39. doi: 10.1016/0014-4827(83)90268-9. [DOI] [PubMed] [Google Scholar]
  21. Lawrence J. B., Singer R. H., McNeil J. A. Interphase and metaphase resolution of different distances within the human dystrophin gene. Science. 1990 Aug 24;249(4971):928–932. doi: 10.1126/science.2203143. [DOI] [PubMed] [Google Scholar]
  22. Marsden M. P., Laemmli U. K. Metaphase chromosome structure: evidence for a radial loop model. Cell. 1979 Aug;17(4):849–858. doi: 10.1016/0092-8674(79)90325-8. [DOI] [PubMed] [Google Scholar]
  23. Paulson J. R., Laemmli U. K. The structure of histone-depleted metaphase chromosomes. Cell. 1977 Nov;12(3):817–828. doi: 10.1016/0092-8674(77)90280-x. [DOI] [PubMed] [Google Scholar]
  24. Rattner J. B., Lin C. C. Radial loops and helical coils coexist in metaphase chromosomes. Cell. 1985 Aug;42(1):291–296. doi: 10.1016/s0092-8674(85)80124-0. [DOI] [PubMed] [Google Scholar]
  25. Sedat J., Manuelidis L. A direct approach to the structure of eukaryotic chromosomes. Cold Spring Harb Symp Quant Biol. 1978;42(Pt 1):331–350. doi: 10.1101/sqb.1978.042.01.035. [DOI] [PubMed] [Google Scholar]
  26. Setterfield G., Sheinin R., Dardick I., Kiss G., Dubsky M. Structure of interphase nuclei in relation to the cell cycle. Chromatin organization in mouse L cells temperature-sensitive for DNA replication. J Cell Biol. 1978 Apr;77(1):246–263. doi: 10.1083/jcb.77.1.246. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Spector D. L. Macromolecular domains within the cell nucleus. Annu Rev Cell Biol. 1993;9:265–315. doi: 10.1146/annurev.cb.09.110193.001405. [DOI] [PubMed] [Google Scholar]
  28. Tobey R. A., Crissman H. A. Preparation of large quantities of synchronized mammalian cells in late G1 in the pre-DNA replicative phase of the cell cycle. Exp Cell Res. 1972 Dec;75(2):460–464. doi: 10.1016/0014-4827(72)90453-3. [DOI] [PubMed] [Google Scholar]
  29. Tobey R. A., Ley K. D. Regulation of initiation of DNA synthesis in Chinese hamster cells. I. Production of stable, reversible G1-arrested populations in suspension culture. J Cell Biol. 1970 Jul;46(1):151–157. doi: 10.1083/jcb.46.1.151. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Woodcock C. L. Chromatin fibers observed in situ in frozen hydrated sections. Native fiber diameter is not correlated with nucleosome repeat length. J Cell Biol. 1994 Apr;125(1):11–19. doi: 10.1083/jcb.125.1.11. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Xing Y., Johnson C. V., Dobner P. R., Lawrence J. B. Higher level organization of individual gene transcription and RNA splicing. Science. 1993 Feb 26;259(5099):1326–1330. doi: 10.1126/science.8446901. [DOI] [PubMed] [Google Scholar]

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