Fuels for flight in the fruit beetle,Pachnoda Sinuata, and control of flight metabolism

Auerswald, Lutz

Fuels for flight in the fruit beetle,Pachnoda Sinuata, and control of flight metabolism

Doctoral Thesis

1997

Publisher

University of Cape Town

Department

Department of Biological Sciences

Faculty

Faculty of Science

Abstract

Isolated flight muscle mitochondria of Pachnoda sinuata, Decapotoma lunata, Trichostetha fascicularis, Lepithrix sp. and Camenta innocua prefer the oxidation of proline, pyruvate and α- glycerophosphate, while those of Locusta migratoria prefer the oxidation of palmitoyl-carnitine,pyruvate and α-glycerophosphate. Palmitoyl-carnitine cannot be oxidised directly by P. sinuata flight muscle mitochondria, while proline is oxidised at low rates in locust mitochondria. At low concentrations of proline, the respiration rate during co-oxidation of proline and pyruvate is additive, while at high proline concentrations it is equal to the respiration rates of sole proline oxidation. Flight muscles of P. sinuata and D. lunata were found to have high activities of the enzymes alanine aminotransferase and NAD-dependent malic enzyme which are involved in proline metabolism, while the activities of these enzymes were lower in locust flight muscles. The activity of 3-hydroxyacyl-CoA dehydrogenase, an enzyme used in fatty acid oxidation, is low in the flight muscles of P. sinuata and D. lunata, but high in locust flight muscles. Enzymes involved In carbohydrate breakdown (glyceraldehyde-3-phosphatedehydrogenase, glycogen phosphorylase) were found to have high activities in flight muscles of P. sinuata, D. lunata and L. migratoria. Two methods of tethered flight were investigated. One of these allowed the animals to produce lift. During lift generating flight, proline concentrations in haemolymph and flight muscles of P. sinuata decrease sharply with concomitant increases in alanine concentrations. During recovery after flight, proline concentrations increase while concentrations of alanine decrease. Haemolymph carbohydrate concentrations increase during the first seconds off light but decline consistently thereafter. During a subsequent rest period concentrations again increase. Glycogen concentration in the flight muscles decrease sharply in the first few seconds of flight, gradually declining thereafter. During subsequent recovery, flight muscle glycogen concentrations increase. Lipid haemolymph concentration increase only slightly during flight and rest thereafter. Two distinct metabolic phases were observed during lift generating flight.

Description

Bibliography: p. 131-143.

Keywords

Zoology

Reference:

Collections

PhD / Doctoral

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