Fig. 1.

Proteolysis is largely dependent upon the proteasome (A–D) Male and female progeny of the Or-R strain were either not pretreated or were pretreated with (A,B) 10 µM hydrogen peroxide or (C,D) 0.5 µM paraquat as per Section 2 above. Afterwards, lysates were incubated in the absence (white) or presence (black) of the proteasome selective inhibitor, lactacystin. Subsequently, inhibition of proteolytic capacity was assessed in whole fly lysates by degradation of the fluorogenic peptide, Suc-LLVY-AMC. In the absence of lactacystin, female flies exhibited an adaptive increase in proteolytic capacity following H₂O₂ pretreatment (Panel A), whereas males exhibited increased proteolytic capacity following paraquat pretreatment (Panel D). In contrast, males did not adapt to H₂O₂ (Panel B), and females did not adapt to paraquat (Panel C). Importantly, both the adaptive increases in proteolytic capacity induced by H₂O₂ in females, and by paraquat in males, were blocked in lysates treated with lactacystin (Panels A and D), indicating that the adaptive increases in proteolytic capacity were largely conferred by increased expression of the proteasome. Error bars in all panels denote the standard error of the mean (S.E.M) values. * P<0.05, ** P<0.01, and *** P<0.001, relative to the samples not treated with inhibitor, using one-way ANOVA.