Fat Body Triacylglycerol Lipase in Solitary and Gregarious Phases of Schistocerca gregaria (Forskal) (Orthoptera: Acrididae)

Abstract

The activities of the fat body triacylglycerol lipase were determined using 14C-trioleoylglycerol. Resting activities were estimated at 1.98 ± 0.24 and 1.95 ± 0.53 nmol free fatty acid (FFA)/hr/mg protein for gregarious and solitary locusts, respectively. Administration of adipokinetic hormone (AKH) I led to the activation of lipase with peak activities occurring after 30 min. In the solitary locusts, activities of 2.28 ± 0.16 and 2.30 ± 0.43 nmol FFA/hr/mg were obtained following administration of 10 and 2 pmol AKH I, respectively. In the gregarious locusts, enzyme activities of 3.17 ± 0.66 and 2.47 ± 0.39 nmol FFA/hr/mg were obtained after administration of 10 and 2 pmol AKH I, respectively. The Km values were estimated at 46.67 and 18.75 μM for gregarious and solitary locusts, respectively. Similarly, the Vmax values were estimated at 10.29 and 2.52 nmol/hr/mg for gregarious and solitary locusts, respectively. These results confirm phase-dependent differences in lipase properties with the gregarious form having a higher catalytic ability, but a lower affinity for the substrate than the solitary type.