Dataset Information

Some properties of mitochondria isolated from the flight muscle of the periodical cicada, Magicicada septendecim.

ABSTRACT: Mitochondria from the flight muscle of the periodical cicada oxidize pyruvate and d-glycerol 1-phosphate at rates comparable with those obtained with flight-muscle mitochondria from other insects. The oxidation of d-glycerol 1-phosphate is greatly stimulated by low concentrations of Ca(2+). However, oxidative phosphorylation with this substrate is optimum over only a narrow range of Ca(2+) concentration, because of the ability of these mitochondria actively to accumulate Ca(2+) present at micromolar concentrations. The oxidation of pyruvate via the complete tricarboxylic acid cycle is enhanced by high concentrations of phosphate. When both pyruvate and d-glycerol 1-phosphate are present simultaneously, there is no simple summation of the rates obtained with the substrates singly. Acetyl-l-carnitine, palmitoyl-l-carnitine, glutamate and 2-oxoglutarate are oxidized at rates similar to those obtained with mammalian mitochondria, though lower than those obtained with the two prime substrates. However, no other tricarboxylic acid-cycle intermediates added to the medium were oxidized. From these and other observations it has been concluded that these mitochondria possess a previously undescribed combination of substrate-anion permeases.

SUBMITTER: Hansford RG

PROVIDER: S-EPMC1176665 | biostudies-other | 1971 Mar

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:1. A study is presented of the mitochondrial NADH content during controlled (state 4) and active (state 3) pyruvate oxidation by blowfly flight-muscle mitochondria. The results confirm and extend those of an earlier study (Hansford, 1972), which indicated an increased reduction in state 3. Nicotinamide nucleotide is normally highly oxidized during state 4; however, there can be substantial reduction in the presence of carnitine or high concentrations of proline, or on lengthy incubation in the presence of either of the systems used to generate intramitochondrial tricarboxylate-cycle intermediate. 2. Omission of phosphate leads to substantial reduction and this can be reversed by adding phosphate or acetate. 3. Estimations of NAD-+ and NADH in fly thoraces show a marked increase in NADH on flight, tending to corroborate the results of mitochondrial experiments and testifying to the importance of dehydrogenase activation in this tissue. 4. Determination of intramitochondrial adenine nucleotides reveals a total of 4-5 nmol/mg of protein, and an ADP content of less than 0.1 nmol/mg during state 4 oxidation of pyruvate and proline. ATP content is found to increase slowly during state 4 and this is attributed to the net phosphorylation of AMP. 5. The uncoupling agent carbonyl cyanide p=trifluoromethoxyphenylhydrazone leads to hydrolysis of some, but not all, of the mitochondrial ATP. Studies of mitochondrial ATPase (adenosine triphosphatase), measured by external pH change, show that it is inactive unless the mitochondria are allowed to respire for several minutes in state 4 in the presence of phosphate before the addition of carbonyl cyanide p-trifluoromethoxyphenylhydrazone. It is suggested that phosphate uptake is essential for maximal ATPase activity. 6. Studies of the fluorescence of the fluorochrome 8-anilino-1-naphthalensulphonic acid suggest that the energy status of the mitochondrion is high during state 4-pyruvate oxidattion, and decrease slightly in state 3. The implications of these findings are discussed.

Dataset Information

Some properties of mitochondria isolated from the flight muscle of the periodical cicada, Magicicada septendecim.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets