DNA replication in the amphibia

Autoradiographic techniques were used to measure rate of replication and length of the replication unit in cultured cells of Scaphiopus couchi, Bufo cognatus, Rana clamitans, and Triturus viridescens, having nuclear DNA amounts in the ratio 1:4:7:39 respectively. The autoradiographic experiments wer...

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Bibliographic Details
Published in:Chromosoma 1975-07, Vol.51 (3), p.213-224
Main Author: Wilson, B G
Format: Article
Language:English
Subjects:
Amphibians
Animals
Anura
Autoradiography
Bufonidae
DNA Replication - drug effects
Floxuridine - metabolism
Floxuridine - pharmacology
Isotope Labeling - methods
Ranidae
Thymidine - metabolism
Tritium
Triturus
Uridine - metabolism
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Summary:Autoradiographic techniques were used to measure rate of replication and length of the replication unit in cultured cells of Scaphiopus couchi, Bufo cognatus, Rana clamitans, and Triturus viridescens, having nuclear DNA amounts in the ratio 1:4:7:39 respectively. The autoradiographic experiments were designed to show whether the larger amounts of nuclear DNA are correlated with more rapid rates of synthesis and/or with longer replication units. -- The DNA replication rate was 2.5 mu/minute (corrected for two growing points) with 10 minutes 3H-thymidine label at 22 degrees C, but decreased with longer labelling durations. The length of the replication unit (estimated by the distance from the center of one autoradiograph to the center of the next in sequence) was most commonly in the 10-25 mu range with a 30 minute label, in all four species. The average center-to-center distance was 8 mu at 10 minutes and increased with label duration, to over 45 mu with 24 hours label. Replication was predominantly but not exclusively bidirectional. Neither rate of replication nor length of the replication unit was proportional to the amount of DNA in these species.
ISSN:0009-5915
1432-0886
DOI:10.1007/BF00284816