Nucleotides and nucleotide sugars in early development of Bufo arenarum. I. Mature oocytes

Ontogenic screening of aldosterone in the South American toad Bufo arenarum (Hensel)

The content of aldosterone in the South American toad Bufo arenarum embryos developed in Holtfreter's 10% solutions and in distilled water was measured. The screening was carried out on embryos from the following periods of their development: 15 min after fertilization; gray crescent-32 cells; mid cleavage-late gastrula; neural plate-neural tube; tail bud-heart beat; gill circulation-tail fin circulation and operculum fold-complete operculum. The aldosterone content of embryos incubated both in Holtfreter and in distilled water decreased gradually up to gill circulation-tail fin circulation stages. The steroid content of both groups of embryos rose sharply at the end of their development (operculum fold-complete operculum); the observed increase was significantly higher in distilled water animals.

Nucleotides in embryos in the stages of morula, gastrula, and neurula

Levels of nucleotides and sugar nucleotides in embryos of Bufo arenarum at the stages of morula, gastrula, and neurula have been measured. The total amounts of purine nucleoside diphosphates decreased from morula to gastrula, but increased sharply from gastrula to neurula. The levels of ADP followed this pattern, but those of GDP did not change significantly through the three stages. Purine nucleoside triphosphate levels, which had increased immediately after fertilization, remained almost constant through morula, gastrula, and neurula. As with the purine nucleoside diphosphates, the adenine nucleotide decreased from morula to gastrula, and increased from gastrula to neurula. In contrast, the level of GTP showed a sharp maximum at gastrula. The total pyrimidine nucleoside triphosphate did not change significantly from morula through neurula. As in previous stages of development, only uridine sugar nucleotides were detected. A sharp increase of the galactosyl ester of nucleotides was found at gastrula.