Rate of synthesis of nucleic acids and their precursors in developing ovaries of Galleria mellonella

Three groups of ovarioles were selected for study: previtellogenetic (I), those in the course of vitellogenesis (II), and postvitellogenetic (III). Previtellogenetic ovarioles showed the highest content of DNA and acid-soluble nucleotide fraction. The mean rate of incorporation of [³H]-thymine into the mononucleotide fraction within 2·5 min mainly depends on the rate of transport of the pyrimidine base into the ovarioles, and was found to be highest (35 × 10⁴ dis/min per μmole of nucleotide per min) in vitellogenetic ovarioles. The rate for [³H]-uracil is highest in previtellogenetic ovarioles.Incorporation of pyrimidine bases into the polynucleotide fraction was corrected for the mononucleotide pool available for synthesis. [³H]-Thymine is incorporated into the polynucleotide fraction most actively in group III of the ovarioles, being probably restricted to numerous follicular cells, whereas [³H]-uracil is mainly incorporated during vitellogenesis.