Chromosoma

, Volume 71, Issue 3, pp 249–262 | Cite as

A quantitative electron microscopic analysis of transcription in sea urchin embryos

  • Sharon Busby
  • Aimée Bakken
Article
Received:
Accepted:

Abstract

In an effort to define stage-specific embryonic patterns of sea urchin transcription, we have examined by electron microscopy the distribution of nascent RNP fibrils in dispersed chromatin from nuclei of Strongylocentrotus purpuratus gastrulae. Detailed analysis of individual embryonic nuclei has revealed several new features of nuclear RNA production. Most (82%) of the active chromatin regions observed were represented by only a single fibril. 11% of the active regions contained multiple RNP fibril arrays with an average RNA polymerase density of 1.7±1.0 polymerases/μm of chromatin and an average contour length of 4.7±2.8 μm chromatin. An analysis of the lengths of RNP fibrils in single vs. multiple fibril arrays indicates that the differential distribution of RNA polymerases is due to different rates of initiation rather than to different lengths of transcription units (assuming the rate of RNA chain elongation to be constant). We discuss these data in relation to various transcriptional parameters measured by other workers and to EM analyses of other embryonic nuclei. Elucidation of transcriptional patterns in gastrula embryos can provide the basis for further comparative studies of transcription at other stages of sea urchin development in which rates of total genomic transcription vary but the rate at individual loci is as yet unknown.

Keywords

Fibril Embryonic Pattern Disperse Chromatin Average Contour Genomic Transcription 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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References

  1. Aronson, A.I., Chen, K.: Rates of RNA chain growth in developing sea urchin embryos. Develop. Biol. 59, 39–48 (1977)Google Scholar
  2. Bakken, A.H., Hamkalo, B.A.: Techniques for visualizing genetic material. In: Principles and techniques of electron microscopy (M.A. Hayat, ed.), pp. 84–106. New York: Van Nostrand Reinhold Co. 1978Google Scholar
  3. Bloom, F.E., Aghajanian, G.K.: Cytochemistry of synapsis: Selective staining for electron microscopy. Science 154, 1575–1577 (1966)Google Scholar
  4. Davidson, E.H.: Gene activity in early development, 2nd ed., chapters 5–6. New York: Academic Press 1976Google Scholar
  5. Dubroff, L.M., Nemer, M.: Molecular classes of heterogenous nuclear RNA in sea urchin embryos. J. molec. Biol. 95, 455–476 (1975)Google Scholar
  6. Foe, V.E., Wilkinson, L.E., Laird, C.D.: Comparative organization of active transcription units in Oncopeltus fasciatus. Cell 9, 131–146 (1976)Google Scholar
  7. Freund, J.E.: Mathematical statistics, pp. 319–320. Englewood Cliffs, N.J.: Prentice-Hall 1971Google Scholar
  8. Grainger, R.M., Wilt, F.H.: The incorporation of 13C-15N nucleosides and measurements of RNA synthesis and turnover in sea urchin embryos. J. molec. Biol. 104, 589–601 (1976)Google Scholar
  9. Guidice, G.: Developmental Biology of the Sea Urchin Embryo, chapter 10. New York and London: Academic Press 1973Google Scholar
  10. Hough, B.R., Smith, M.J., Britten, R.J., Davidson, E.H.: Sequence complexity of heterogeneous nuclear RNA in sea urchin embryos. Cell 5, 291–299 (1975)Google Scholar
  11. Kleene, K.C., Humphreys, T.: Similarity of hnRNA sequences in blastula and pluteus stage sea urchin embryos. Cell 12, 143–155 (1977)Google Scholar
  12. Kung, C.S.: On the size relationship between nuclear and cytoplasmic RNA in sea urchin embryos. Develop. Biol. 36, 343–356 (1974)Google Scholar
  13. Laird, C.D., Wilkinson, L.E., Foe, V.E., Chooi, W.Y.: Analysis of chromatin-associated fiber arrays. Chromosoma (Berl.) 58, 169–192 (1976)Google Scholar
  14. Laird, C.D., Chooi, W.Y.: Morphology of transcription units in Drosophila melanogaster. Chromosoma (Berl.) 58, 193–218 (1976)Google Scholar
  15. McKnight, S.L., Miller, O.L., Jr.: Ultrastructural patterns of RNA synthesis during early embryogenesis of Drosophila melanogaster. Cell 8, 305–319 (1976)Google Scholar
  16. Miller, O.L., Jr., Bakken, A.H.: Morphological studies of transcription. Acta Endocrinol. 168, 155–177 (1972)Google Scholar
  17. Miller, O.L., Jr., Beatty, B.R.: Visualization of nucleolar genes. Science 164, 955–957 (1969)Google Scholar
  18. Olins, A.L., Olins, D.E.: Spheroid chromatin units (γ bodies). Science 183, 330–332 (1974)Google Scholar
  19. Roeder, R.G., Rutter, W.J.: Multiple RNA polymerases and RNA synthesis during sea urchin development. Biochemistry 9, 2543–2553 (1970)Google Scholar
  20. Silverman, L., Glick, D.: The reactivity and staining of tissue proteins with phosphotungstic acid. J. Cell Biol. 40, 761–767 (1969)Google Scholar
  21. Smith, M.J., Hough, B.R., Chamberlin, M.E., Davidson, E.H.: Repetitive and non-repetitive sequence in sea urchin heterogeneous nuclear RNA. J. molec. Biol. 85, 103–126 (1974)Google Scholar
  22. Spadofora, C., Bellard, M., Compton, J.L., Chambon, P.: The DNA repeat lengths in chromatins from sea urchin sperm and gastrula cells are markedly different. F.E.B.S. Letters 69, 281–285 (1976)Google Scholar

Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • Sharon Busby
    • 1
  • Aimée Bakken
    • 1
  1. 1.Department of ZoologyUniversity of WashingtonSeattleUSA

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