Monocistronic transcription is the physiological mechanism of sea urchin embryonic histone gene expression

A. Mauron, S. Levy, G. Childs, L. Kedes

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

We have examined histone gene expression during the early stages of sea urchin embryogenesis. The five histone genes expressed at that time are contained in tandem repetitive segments. It has been suggested that adjacent coding regions and their intervening spacer sequences are transcribed into large polycistronic messenger ribonucleic acid (RNA) precursors. We have subcloned into pBR322 deoxyribonucleic acid (DNA) sequences mapping either in the coding region, the 5' spacer, or the 3' spacer of the H2B histone gene. These clones were used to produce radioiodinated hybridization probes. We measured the steady-state quantity of H2B messenger RNA as well as spacer-specific RNA in the total RNA from embryos taken at various stages of development from fertilization to hatching of blastulae (0 to 22 h post-fertilization). Small amounts of RNA hybridizing to both spacer probes could be found. However, we show that these RNAs form mismatched hybrids with the spacer DNA and therefore cannot originate from the spacers present in the histone genes. We conclude that there is no detectable transcription of the spacer regions on either side of the H2B histone gene. The detection limit for RNA complementary to the 5' spacer sequence corresponds to a maximum of about three RNA molecules per cell, an amount shown to be far less than the projected steady-state pool size of a putative polycistronic transcript, if such a precursor were to be obligatory transcript of the histone genes. (This conclusion was reached by using the known rates of production of H2B mRNA throughout early development). The physiologically relevant transcript of the histone genes in early development is therefore monocistronic and probably identical to the messenger RNA itself.

Original languageEnglish (US)
Pages (from-to)661-671
Number of pages11
JournalMolecular and cellular biology
Volume1
Issue number7
DOIs
StatePublished - 1981
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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