Fig. 3. Cyclic-GMP dependent kinase (cGK) activity in for^s tissue. cGK activity was assayed in head, body and tubule preparations from for^R and for^s 7-day-old adults, as described, in the absence and presence of cGMP. Data was corrected for specific cGMP-dependent activity, and for^s data expressed as a % of for^R. Values are means ± S.E.M., N=8-12. Mean cGMP-dependent activities (pmol ATP min^-1 mg^-1 protein) for for^R flies were: 15.4±1.3 (heads), 1.1±0.1 (bodies), 12.9±1.5 (tubules); and for^s flies: 12.84±1.1 (heads), 1.2±0.1 (bodies), 13.57±2.6 (tubules). In all experiments, cGK activity (pmol ATP min^-1 mg^-1 protein) was consistently lower in bodies than in either head or tubules.