The possible role of the superoxide ion in the induction of heat-shock and specific proteins in aerobic Drosophila cells during return to normoxia after a period of anaerobiosis.

In vitro cultured Drosophila melanogaster cells were shown to be aerobic and several kinetic parameters of their respiration were measured. This allowed us to define experimental conditions for a transient period of anaerobiosis followed by a reexposure to normal oxygenation. This treatment, applied without any change of temperature, induced not only the heat-shock proteins, but also a new specific peptide of 27 000 daltons and a twofold increase of the maximal rate of O2 uptake. This evokes a common molecular mechanism activated either by heat or by O2, which could involve the increase of the products of oxygen reduction such as the superoxide ion.