Deoxyribonucleases of the organs of Drosophila hydei at the onset of metamorphosis

The tissue distribution of deoxyribonucleases has been studied in the organs of Drosophila hydei at the onset of metamorphosis. The enzymes were separated by disc electrophoresis and detected directly in the gel. An extensive shift in the wide spectrum of activities that has been observed at metamorphosis indicates that deoxyribonucleases play an important role at this time in development. On the basis of the tissue distribution of these enzymes, it has been possible to assign probable functions to several of the activities. An intense activity appears in the prepupal salivary gland which is not detected in this organ in the larval stage. This observation is of particular interest in view of the changes that have been observed in the chromosomal puffing patterns of the salivary glands just prior to metamorphosis. A class of activities, which is probably of lysosomal origin, is more prevalent in the prepupal tissues. The data suggest that an increased synthesis of lysosomes is a general reaction of most larval tissues at the onset of metamorphosis irrespective of whether a tissue undergoes total histolysis. The larval intestine contains a factor which strongly inhibits Drosophila nucleases that are active at low pH. The major nuclease activities of each tissue have been tentatively characterized. A knowledge of the enzyme properties is expected to facilitate the isolation of DNA from the individual tissues.This work was performed in the Max-Planck-Institut für Biologie, Abteilung Beermann, Tübingen, Germany. The senior author was supported by the Helen Hay Whitney Foundation.