Radiation-Induced Effects on DNA Synthesis in Developing Sea Urchin Eggs

1968 ◽  
Vol 34 (1) ◽  
pp. 200 ◽  
Author(s):  
L. Zeitz ◽  
R. Ferguson ◽  
E. Garfinkel
Keyword(s):  
Dna Synthesis ◽  
Sea Urchin ◽  
Sea Urchin Eggs ◽  
Radiation Induced

Differential replication capacities of G1 and S-phase extracts from sea urchin eggs

1993 ◽  
Vol 104 (2) ◽  
pp. 565-572
Author(s):  
H. Zhang ◽  
J.V. Ruderman
Keyword(s):  
Dna Synthesis ◽  
Sea Urchin ◽  
Nuclear Dna ◽  
Specific Pattern ◽  
S Phase ◽  
Sperm Chromatin ◽  
G1 Arrest ◽  
Sea Urchin Eggs ◽  
Egg Extracts ◽  
Fertilized Egg

Sea urchin eggs are arrested in G1 of the first mitotic cell cycle. Fertilization triggers release from G1 arrest and the onset of DNA synthesis about 20 minutes later, even when protein synthesis is blocked. Here we describe extracts from eggs and S-phase embryos that reproduce this stage-specific pattern of DNA synthesis. Fertilized egg extracts formed nuclear membranes around decondensed Xenopus sperm chromatin whereas unfertilized egg extracts did not. Aphidicolin-sensitive deoxynucleotide incorporation was high in extracts of fertilized S-phase eggs and low in those of unfertilized eggs. In contrast, single-stranded DNA templates directed high rates of incorporation in both unfertilized and fertilized egg extracts, suggesting that the stage-specific activities in nuclear DNA synthesis is restricted to initiation on double-stranded DNA. Mixing experiments showed that unfertilized eggs do not contain a dominant inhibitor of replication, nor does fertilization induce the appearance of a soluble, dominant activator.

scholarly journals Variations in the phosphate content and thiol/disulphide ratio of histones during the cell cycle. Studies with regenerating rat liver and sea urchins

1968 ◽  
Vol 107 (3) ◽  
pp. 403-410 ◽  
Author(s):  
Margery G. Ord ◽  
L A Stocken
Keyword(s):  
Dna Synthesis ◽  
Sea Urchin ◽  
Rat Liver ◽  
Sea Urchins ◽  
Phosphate Content ◽  
Γ Irradiation ◽  
Sea Urchin Eggs ◽  
Regenerating Rat Liver ◽  
S Period

1. In regenerating rat liver the phosphate content of the lysine-rich histone F1, but not that of the more arginine-rich histone F3-1, increases during the period of DNA synthesis. 2. The phosphorylation of histone F1 in this ‘S period’ is decreased by γ-irradiation, but, like phosphate uptake into DNA, is affected to an even greater extent if the irradiation is given in the presynthetic period. 3. Histones from three species of sea-urchin eggs show similarities to the F2 and F3 groups of histones from mammalian thymus gland. 4. The proportion of thiol to total thiol plus disulphide in acid extracts from sea-urchin eggs varies from less than 20% in mature unfertilized eggs to 59% just before cleavage. 5. The phosphorylated forms of histones F1 and F3 are less effective in decreasing DNA synthesis by DNA polymerase than the non-phosphorylated forms. 6. Oxidation of thiol groups on histone F3-1 does not affect its capacity to decrease DNA synthesis in vitro.

Analysis of DNA Synthesis and X-Ray-Induced Mitotic Delay in Sea Urchin Eggs

1965 ◽  
Vol 26 (4) ◽  
pp. 534 ◽  
Author(s):  
Bhashini Rao ◽  
R. T. Hinegardner
Keyword(s):  
Dna Synthesis ◽  
Sea Urchin ◽  
X Ray ◽  
Sea Urchin Eggs ◽  
Mitotic Delay
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