Structural genes adjacent to interspersed repetitive DNA sequences
Abstract
The observation that repetitive and single copy sequences are interspersed in animal DNAs has suggested that repetitive sequences are adjacent to single copy structural gene sequences. To test this concept, single copy DNA sequences contiguous to interspersed repetitive sequences were prepared from sea urchin DNA by hydroxyapatite fractionation (repeat-contiguous DNA fraction). These single copy sequences included about one third of the total nonrepetitive sequence in the genome as determined by the amounts recovered during the hydroxyapatite fractionation and by reassociation kinetics. 3H-labeled mRNA from sea urchin gastrula was prepared by puromycin release from polysomes and used in DNA-driven hybridization reactions. The kinetics of mRNA hybridization reactions with excess whole DNA were carefully measured, and the rate of hybridization was found to be 3–5 times slower than the corresponding single copy DNA driver reassociation rate. The mRNA hybridized with excess repeat-contiguous DNA with similar kinetics relative to the driver DNA. At completion 80% of that mRNA hybridizable with whole DNA (approximately 65%) had reacted with the repeat-contiguous DNA fraction (50%). This result shows that 80–100% of the mRNA molecules present in sea urchin embryos are transcribed from single copy DNA sequences adjacent to interspersed repetitive sequences in the genome.
Additional Information
© 1975 Elsevier. Received October 17, 1974; revised December 9, 1974. We are pleased to acknowledge the expert technical assistance of Ms. Margaret Chamberlin. This research was supported by a US Public Health Service grant and a National Science Foundation grant. One of us (W.H.K.) was supported by a Damon Runyon Walter Winchell Cancer Fund Fellowship Grant. We would particularly like to express our appreciation for the detailed and helpful critical comments of Professors Norman Davidson, Leroy Hood, and Giuseppe Attardi of this Institute. We wish to draw attention to the finding of Bishop and Freeman (1974), who have shown that repetitive sequences occur preferentially in the vicinity of the duck hemoglobin structural chain. The import of this finding is basically the same as that reported in the present paper.Additional details
- Eprint ID
- 69551
- DOI
- 10.1016/0092-8674(75)90170-1
- Resolver ID
- CaltechAUTHORS:20160810-150351368
- U.S. Public Health Service (USPHS)
- NSF
- Damon Runyon Walter Winchell Cancer Fund
- Created
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2016-08-10Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field