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Studies on the repetitive sequence transcripts of Xenopus oocytes

Hough, Barbara R. and Davidson, Eric H. (1972) Studies on the repetitive sequence transcripts of Xenopus oocytes. Journal of Molecular Biology, 70 (3). pp. 491-509. ISSN 0022-2836. doi:10.1016/0022-2836(72)90555-4.

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RNA of the mature Xenopus oocyte was hybridized with an isolated repetitive DNA fraction of the Xenopus genome representing about 40% of the DNA and containing a major component with an average sequence-repetition frequency of about 1600. Ribonuelease-resistant hybrids which bind to hydroxyapatite represent the most stable fraction of the repetitive RNA-DNA duplexes. These hybrids were studied with CsCl equilibrium sedimentation, gel electrophoresis, and thermal chromatography from hydroxyapatite. It was concluded that after ribonuclease treatment the hybrids which bind to hydroxyapatite retain relatively long regions of duplex structure (over 10^2 nucleotides) but that, even so, they include significantly more nucleotide mismatch than do non-repetitive DNA-RNA hybrids formed with the same RNA. Hybrids were also detected by Cs_2SO_4 buoyant-density sedimentation in the material failing to bind to hydroxyapatite after ribonuclease treatment. These hybrids apparently retain only short duplex regions. RNA-driven hybridization reactions were carried out to obtain an estimate of the amount of repetitive DNA related in sequence to the RNA stored in the mature oocyte. In this procedure, the hybrids are not exposed to ribonuclease before binding to hydroxyapatite, and hybrids representing about 3.5% of the repetitive DNA were obtained. It was concluded that 2 to 5% of the total oocyte RNA is repetitive sequence transcript and that these transcripts are present in the oocyte at a much higher concentration than non-repetitive sequence transcripts.

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Additional Information:© 1972 Elsevier Ltd. Received 4 November 1971, Revised 1 May 1972. We wish to acknowledge the invaluable assistance which we have been fortunate to receive from many quarters, in carrying out this research. We acknowledge the gift of labeled Xenopus laevis DNA from Dr Donald Brown of the Department of Embryology, Carnegie Institution of Washington. Dr James Bonner of this Institute kindly made available to us the services of Mr Cameron Schlehuber, who carried out most of the computer data processing referred to herein. We acknowledge the expert and intelligent technical assistance of Miss Maggie Chamberlin. The oocytes from which RNA was extracted wore manually collected by Mr William Viets and several of the gradients were run by Mrs Margaret Mac)forris Swanson. Drs Roy J. Britten, Norman Davidson, James Bonner and Jerome Vinograd, all of this Institute, have each contributed greatly to the presentation of these experiments with their detailed and careful criticisms of earlier drafts of the manuscript. Their constructive assistance has indeed been invaluable. The research was supported by American Cancer Society grant E334E and by a grant from the National Institute of Child Health and Development, HD05753.
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American Cancer SocietyE334E
Issue or Number:3
Record Number:CaltechAUTHORS:20160803-110256541
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Official Citation:Barbara R. Hough, Eric H. Davidson, Studies on the repetitive sequence transcripts of Xenopus oocytes, Journal of Molecular Biology, Volume 70, Issue 3, 14 October 1972, Pages 491-509, ISSN 0022-2836, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69408
Deposited By: Ruth Sustaita
Deposited On:03 Aug 2016 18:48
Last Modified:11 Nov 2021 04:13

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