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

Abstract

Mitochondria were prepared by differential centrifuging from tissues of Schistocerca gregaria (desert locust). The preparations, which were essentially free from nuclei and cell debris, were examined under the electron microscope. The QO2 values of oxoglutarate and succinate oxidation by homogenates and particle suspensions from whole thorax, legs, integument, thoracic muscle and fat body were compared with the respiration of the live insect and the intact tissues. The Q02 values obtained at 30[degree] for the whole tissues ranged from about 1 for the wings to about 7 for the fat body and thoracic muscle. Values for the homogenates were on the whole higher than those of the intact tissue and the increased respiration on the addition of substrate was four to six times as high as in the intact tissue. Mitochondria-like particles containing the pigment insectorubin, which is partially responsible for the external color of the locust, were isolated from the integument and characterized. Acetylcholine (about 60 [mu]g/g dry weight) was found in 0.25 M sucrose homogenates of head tissue. After centrifuging, acetylcholine (130 [mu]g/g dry weight) was found in the particulate fraction which sedimented between 1000 and 10,200 g for 10 minutes. A choline acetylase system was demonstrated in head homogenates and in the particles described above. Values for the sum of glutamic acid and glutamine ( [mu] moles/g wet weight) in tissues from S. gregaria are: fat body 4.8, integument 5.3, thoracic muscle 9.6 and head 17.8. The proportion of glutamine to total glutamic acid and glutamine ranged from 0.9 in the thoracic muscle to 0.1 in the head. On fractionation the particulate fraction of the head homogenate (containing 55 {mu] moles of glutamic acid and glutamine/g dry weight) sedimenting between 650 and 1000 g in 10 minutes contained 165 [mu] moles of glutamic acid and glutamine/g dry weight and that sedimenting between 650 and 10,200 g in 10 minutes contained 50 [mu] moles of glutamic acid and glutamine/g dry weight.