Effects of oxygen concentration on the intermediary metabolism of Leishmania major promastigotes

Keegan, Frank P.; Blum, J. J.

doi:10.1016/0166-6851(90)90062-q

Cited by 27 publications

(18 citation statements)

References 22 publications

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“…RPMI 1640 medium supplemented with 10 to 20% fetal bovine serum has been shown to support amastigote-to-promastigote conversion, though with lower sensitivity than other traditional methods (1,2,17), possibly due to the high content of dissolved oxygen in this type of culture system. Microaerophilic conditions and high CO 2 levels are permissive to amastigote-to-promastigote transformation (20,21,39), hence the success of the microculture system (2). Traditional cultures of lesion aspirates, scrapings, and biopsy samples using NNN medium, Tobie's medium, Schneider's Drosophila medium, or M199 Leishmania culture medium typically have sensitivities that range from 40 to 75%, though this is somewhat species dependent, with L. (V.) braziliensis constituting one of the more difficult species to culture (32,37).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of a Microculture Method for Isolation of Leishmania Parasites from Cutaneous Lesions of Patients in Peru

et al. 2007

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Section: Discussionmentioning

confidence: 99%

Evaluation of a Microculture Method for Isolation of Leishmania Parasites from Cutaneous Lesions of Patients in Peru

et al. 2007

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“…Although it was shown that proline oxidation by mitochondria isolated from L. braziliensis was inhibited by rotenone and by antimycin A and that succinate oxidation was inhibited by antimycin A, KCN, and NaN,, the effects of metabolites such as malate or fumarate on succinate oxidation were not examined.In the present study we have measured the rates of I4CO, formation from I4C-labeled succinate, alanine, glutamate, and acetate by L. major promastigotes under a variety of conditions chosen to provide further insight into some factors that may be involved in the regulation of intermediary metabolism in these cells. Succinate was of interest because it is oxidized at a very low rate by intact cells and is an important end product of metabolism at low PO, values [15]. Alanine was of interest because it is the major osmolyte of these cells and its rate of metabolism is inhibited by hyperosmolality [3, 51.…”

mentioning

confidence: 99%

Oxidation of Alanine, Acetate, Glutamate, and Succinate by Digitonin‐Permeabilized Leishmania major Promastigotes

Blum

1996

J Eukaryotic Microbiology

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Leishmania major promastigotes were treated with digitonin and the rates at which [1-14C]acetate, [1,4-14C]succinate, [1-14C]glutamate, and [U-14C]alanine are oxidized were measured in the presence of suitable cofactors. Acetate was oxidized at the lowest rate of the four substrates examined, even in the presence of added NAD, CoA, ADP and acetyl-CoA synthase. Its rate of oxidation was negligible if the permeabilized cells were washed before the cofactors were added, indicating the requirement for an as yet unknown factor. Succinate was oxidized at a rate much higher than the very slow rate at which it is oxidized by intact cells. Its rate of oxidation was strongly inhibited by antimycin A, but that of glutamate was scarcely affected. Fumarate inhibited the rate of oxidation of acetate, glutamate, and succinate, but increased that of alanine. Ca++ inhibited the rates of oxidation of alanine and succinate, but not of acetate or glutamate. Increasing the osmolality by addition of mannitol partially inhibited the rate of oxidation of alanine but had little effect on that of glutamate. These results show that appreciable transaminase activity remains in the permeabilized cells and support earlier data indicating the presence of a branched NAD-to-cytochrome oxidase system. These results also provide preliminary information on the sensitivity of the two branches to Ca++, hyperosmolality, and Krebs cycle intermediates.

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“…In L. major the rates of decarboxylation of acetate, alanine, glycerol, and glucose are appreciably less in early stationary phase cells than in log phase promastigotes [15], whereas the rate of oxidation of fatty acids increases [2]. The ability to oxidize leucine is now shown to also decrease during the transition from log to mid-stationary phase.…”

Section: Discussionmentioning

confidence: 95%

“…To begin to understand the catabolism of leucine in L. donovani, the rate of I4CO, formation from [ I -I4C]-and [U-14C]leucine and from [ 1 -14C]a-ketoisocaproate was examined. Earlier studies have shown that the rates of oxidation of alanine, glucose, and acetate were lower in L. major promastigotes from early stationary phase cultures than from cultures in the late log phase [ 15,161. The rate of I4CO2 release from 14C-labeled fatty acids, however, increased with culture age, although the increase was generally small in cells from midstationary phase cultures [2].…”

mentioning

confidence: 89%

Oxidation of Leucine by Leishmania donovani

Blum

1991

The Journal of Protozoology

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The metabolism of leucine by Leishmania donovani was investigated. Washed promastigotes were incubated with [1-14C]- or [U-14C]leucine or [1-14C]alpha-ketoisocaproate (KIC) and 14CO2 release was measured. The amount of KIC-derived acetyl-CoA oxidized in the citric acid cycle was computed. Promastigotes from mid-stationary phase cultures oxidized each of these labeled substrates less rapidly than cells from late log phase cultures, and significantly less acetyl-CoA derived from KIC oxidation was oxidized in the citric acid cycle. Glucose was a stronger inhibitor than was acetate of CO2 formation in the citric acid cycle in log phase promastigotes, but the reverse was observed in cells from mid-stationary phase. Alanine also inhibited leucine catabolism, but glutamate had little effect. Acute hypo-osmotic stress did not affect leucine catabolism, but hyper-osmotic stress caused appreciable inhibition of leucine oxidation. Cells grown under hypo- or hyper-osmotic conditions showed no changes in the effects of hypo- or hyper-osmotic stress on leucine catabolism, i.e. L. donovani is not an osmoconformer with respect to leucine metabolism. Leucine utilization in L. donovani was insensitive to a number of drugs that affect leucine metabolism in mammalian cells, indicating that the leucine pathway in L. donovani is not regulated in the same manner as in mammalian cells.

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Effects of oxygen concentration on the intermediary metabolism of Leishmania major promastigotes

Cited by 27 publications

References 22 publications

Evaluation of a Microculture Method for Isolation of Leishmania Parasites from Cutaneous Lesions of Patients in Peru

Evaluation of a Microculture Method for Isolation of Leishmania Parasites from Cutaneous Lesions of Patients in Peru

Oxidation of Alanine, Acetate, Glutamate, and Succinate by Digitonin‐Permeabilized Leishmania major Promastigotes

Oxidation of Leucine by Leishmania donovani

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