Sequence of expression of paternal and maternal esterases in the ontogeny of Drosophila virilis

The order of appearance of the parental fractions of the enzyme in ontogeny was investigated in hybrids between laboratory strains of Drosophila virilis differing in the electrophoretic mobility of certain esterases. Activity of the esterases was shown to persist at a low level during most of embryogenesis and to increase toward its end, especially after emergence. At the 16th-20th hour of embryonic development the maternal fractions are accompanied by the manifestation of paternal fractions of the slowly migrating esterase-4. Paternal forms of fast-migrating esterases (esterases-2 and -6) are found only after emergence in age I larvae.