Changes of RNA precursor pools (ATP, UTP) during embryogenesis ofDrosophila melanogaster (Diptera) andBruchidius obtectus (coleoptera).

The total amount of ATP and UTP was measured in embryos ofDrosophila melanogaster andBruchidius obtectus at different development stages. The pool-sizes were measured by their ability to enhance poly(AU) synthesis in an in vitro test, using RNA polymerase ofE. coli, poly-d(AT), ATP, and3H-UTP. In embryos ofD. melanogaster, the amount of UTP decreased from 4.5 pmoles/ embryo during cleavage and early blastoderm to 2 pmoles at later stages. The ATP pool decreased from 14 pmoles/ embryo to 6 pmoles at the same developmental stages. In embryos ofB. obtectus, the UTP pool expanded from about 1 pmole/embryo during cleavage and early blastoderm to about 3 pmoles during gastrulation and organogenesis. Much more ATP was found inB. obtectus embryos: during fertilization 23 pmoles/embryo were found. At late syncytial blastoderm stages the amount of ATP rose to about 50 pmoles/embryo. At cellular blastoderm stages and during gastrulation only 26 pmoles/embryo of ATP were found. During organogenesis the ATP pool decreased to about 14 pmoles/embryo.