-transparent.png){kind=logo}
Uniformly labeled [3H] uridine is incorporated into DNA by dissociated Pleurodeles blastulae; the label is found in cytosine and to a much lesser extent in thymine. Ribonucleotide reductase activity cannot be detected in full grown oocytes of Xenopus and Pleurodeles, but is present in unfertilized egg. The enzyme is synthesized (or activated) when maturation is induced in Xenopus oocytes by in vitro hormonal treatment. The enzymatic activity increases after fertilization and reaches a peak at the 2--4 cell stage; it decreases at the blastula, gastrula and neurula stages to the low level initially present in unfertilized eggs. The enzyme is no longer detectable in swimming tadpoles. Addition of hydroxyurea (1 mg/ml) to fertilized eggs leads to complete loss of ribonucleotide reductase activity: cycloheximide (20 mug/ml) inhibits the rise in activity characteristic of early cleavage, while actinomycin D (20 mug/ml) has no effect. The significance of these results in discussed.
N Tondeur-Six, and
R Tencer, and
J Brachet
June 1970,
Enzymologia,
N Tondeur-Six, and
R Tencer, and
J Brachet
September 1973,
Archives of biochemistry and biophysics,
N Tondeur-Six, and
R Tencer, and
J Brachet
October 1971,
The Journal of experimental zoology,
N Tondeur-Six, and
R Tencer, and
J Brachet
November 2013,
Mini reviews in medicinal chemistry,
N Tondeur-Six, and
R Tencer, and
J Brachet
June 1976,
Biochemical and biophysical research communications,
N Tondeur-Six, and
R Tencer, and
J Brachet
September 2012,
Cell cycle (Georgetown, Tex.),
N Tondeur-Six, and
R Tencer, and
J Brachet
January 1986,
Leprosy review,
N Tondeur-Six, and
R Tencer, and
J Brachet
January 1983,
Advances in inorganic biochemistry,
N Tondeur-Six, and
R Tencer, and
J Brachet
August 2001,
The Journal of antibiotics,
N Tondeur-Six, and
R Tencer, and
J Brachet
March 1979,
Cancer research,
