The structure and metabolic properties of tissue preparations from Schistocerca gregaria (desert locust)

This work is part of a survey of the sedimentation characteristics and metabolic properties of mito- chondria isolated from a wide variety of animal species.The desert locust (Schitocerca gregaria) was chosen as a representative of the class Insecta because of its large size, and also because many individuals could be obtained at one time from standard populations.The only comparable work on the metabolic processes of isolated locust tissues is that of Rees (1954), who used homogenates and a particulate preparation from the combined thorax and appendages of Locusta migratoria (the Moroccan locust).These preparations oxidized tricarboxylic acid-cycle intermediates and carried out oxidative phosphorylation under suitable conditions.In the present work three tissues were selected for study: the nervous tissue of the head, the muscle from the thorax and legs, and the fat body.The latter organ was used because it is in some respects similar to the liver of vertebrates (Wigglesworth, 1950; Kilby & Neville, 1957).This paper records methods of preparing mito- chondrial suspensions and gives a comparison of the rates of oxidation of a-oxoglutarate and succinate by different tissue preparations in a simple standard medium without the addition of cofactors.The concentrations of glutamic acid and acetylcholine were measured in particles from the head, and some observations were made on the choline acetylase activity of these particles.Some properties of isolated pigment granules from the integument have also been investigated. MATERIALS AND METHODSCare of insects.Immature adult male and female insects were obtained from the Anti-Locust Research Centre, London, about 10 days after the final moult, and were either used at once or fed on fresh grass and kept 1 or 2 days at 280.Occasionally insects were obtained from the Department of Entomology, Oxford.Preparation of homogenates.All dissections were carried out on cracked ice and subsequent operations were per- formed as close to 00 as possible.Homogenizing media.These were 0-25M-sucrose, 0-25M- sucrose containing 2-5 % of dried human serum as supplied for transfusion purposes and 0-15M-KCI.The media were adjusted to pH 7-6 with 0-1 M-2-amino-2-hydroxymethylpropane-1:3-diol before use.