A DNA polymerase alpha partially resistant to aphidicolin in cells and embryos of Med-fly (Ceratitis capitata Wied.).

We have studied the DNA polymerase activities in cultured cells and embryos of Med-fly (Ceratitis capitata Wied.) and we observed that only DNA polymerases alpha and gamma were detectable in crude extracts. The level of DNA polymerase alpha, measured during the life cycle of the insect embryos, increased in parallel with the rate of embryonic cell proliferation, whereas DNA polymerase gamma increased at much later fertilization time, when cell differentiation is already taking place. DNA polymerase alpha, purified 100 folds from Med-fly embryos, was 10 times more resistant to aphidicolin, its specific inhibitor, than the mammalian DNA polymerase alpha. In situ visualization of the active peptides after NaDodSO4/PAGE, confirmed that only high Mr DNA polymerase fragments were present in embryo extracts and in purified preparations of DNA polymerase alpha. It appears that C. capitata cells represent a rather peculiar system in the phylogeny of DNA polymerases since they are devoid of DNA polymerase beta and present a DNA polymerase alpha partially resistant to aphidicolin.