Figure 1: IPCs are required for the effect of low temperature on pupal size.

(a) Pupariation time of w¹¹¹⁸ at 18 °C was later than at 25 °C (n=5). (b) w¹¹¹⁸ pupal size was greater at 18 °C than at 25 °C (n=28 for females; n=22 for males). (c) Absorbance of iodo–starch reactions at 580 nm using residue food from w¹¹¹⁸ fly cultures at 25 or 18 °C. Food starch remaining after 25 °C culture was less than after 18 °C culture (n=3). See Methods section for further details. (d) Pupariation time of larvae expressing NaChBac with dilp2-Gal4 was later than that of controls both at 25 °C (n=7) and at 18 °C (n=8). (e,f) Pupal size of flies expressing NaChBac with dilp2-Gal4 was larger than that of controls at 18 °C (n=24 for both females and males) as shown in e, but not at 25 °C (n=24 for females; n=33 for males) as shown in f. (g) Absorbance of iodo–starch reaction at 580 nm using residue food after culturing flies expressing NaChBac with dilp2-Gal4. Food starch remaining for flies with IPCs hyperactivated was not different from that of controls (n=3). (h) Pupariation time of larvae expressing Kir2.1 by dilp2-Gal4 and control similarly increased at 18 °C as compared with at 25 °C (n=9). (i) Pupal sizes of flies with blocked IPCs cultured at 18 °C were not different from those cultured at 25 °C (P>0.05, n=13 for both females and males); pupal sizes of controls were significantly larger at 18 °C than at 25 °C (n=13). F, females; M, males; AEH, after egg hatching; error bars are s.e.m.; ***P<0.001, Student’s t-test.