The metabolism of stigmasterol and cholesterol by Paramecium aurelia

Conner, Robert L.; Landrey, Josephine R.; Kaneshiro, Edna S.; Wagtendonk, W. J. Van

doi:10.1016/0005-2760(71)90176-7

Cited by 22 publications

(12 citation statements)

References 21 publications

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“…For Paramecium, an apparent link between growth support and fatty acyl esterification of sterols has been reported (Conner et al, 1971). This would clearly favour a hypothesis involving essential sterols in the transport, metabolism or transacylation of fatty acids.…”

Section: Discussionmentioning

confidence: 92%

“…1 depicts the influence of exogenous stigmasterol concentration on the growth of P. tetraurelia in monoxenic culture. In these experiments, stigmasterol and its metabolite, 7-dehydrostigmasterol (Conner et al, 1971 ;Whitaker & Nelson, 1987), served as both the bulk membrane sterol and the nutritionally required phytosterol. Under this condition, near maximal growth was realized at an exogenous stigmasterol concentration of 5.0 yg ml-l (Pitt, 1980).…”

Section: Culturesmentioning

confidence: 99%

“…The nutritional requirement for sterol was described 30 years ago, when it was found that only a small group of structurally similar phytosterols support growth (Conner et al, 1953;Conner & van Wagtendonk, 1955). One subsequent report has addressed the question of why specific phytosterols are required for growth of Paramecium (Conner et al, 1971). An apparent link between growth support and fatty acyl esterification of sterols was demonstrated.…”

Section: Introductionmentioning

confidence: 99%

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Sterol Synergism in Paramecium tetraurelia

Whitaker

Nelson

1988

Microbiology

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Paramecium tetraurelia is a naturally occurring sterol auxotroph with an absolute nutritional requirement for one of a small group of structurally related phytosterols. We report here a quantitative study demonstrating that a low, otherwise sub-supportive, concentration ( x 0.020-0.050 pg ml-l) of an essential phytosterol (stigmasterol) is adequate for growth of this ciliate, provided that a second, relatively non-specific sterol is available at a higher concentration (1.0p.g ml-*) to allow for membrane biosynthesis. This phenomenon, referred to as sterol synergism, has been observed in a broad taxonomic range of organisms, with the conclusion that small amounts of specific sterols are required to perform some previously unknown, vital metabolic or regulatory function. Paramecium promises to be an excellent model organism for the elucidation of essential sterol function.

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Section: Discussionmentioning

confidence: 92%

Section: Culturesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sterol Synergism in Paramecium tetraurelia

Whitaker

Nelson

1988

Microbiology

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“…Apart from free sterols esterified ones have been reported from the protozoan Paramecium (Conner et al, 1971) up to mammalian brains (Eto & Suzuki, 1971). In molluscs, the composition of sterols and the potential capacity of synthesizing sterols in various representatives have been fairly well documented (review: Voogt, 1972a).…”

mentioning

confidence: 99%

Biosynthesis and composition of sterols and sterol esters in the land snail Cepaea nemoralis (L.) (gastropoda, pulmonata, stylommatophora)

Horst¹,

Voogt²

1972

Comparative Biochemistry and Physiology Part B: Comparative Bio

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Abstract--1. The biosynthesis and composition of sterols and sterol esters were studied in the land snail Cepaea nemoralis after injection of Na-l-14C -a~tate.2. Free and esterified sterols appeared to be synthesized by the animals, whilst the specific radioactivity of the sterols from the esters was found to be higher than that of the free sterols after incubation for 48 hr.3. The composition of sterols in both fractions was not significantly different. 4. The fatty acid moiety of the sterol esters appeared to be labeled as well and involved about sixty components, which are summarized from myristic acid onwards.

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“…Interestingly, however, Paramecium tetraurelia does not have C-24 dealkylation activity(Conner et al, 1971) and requires phytosterols(Whitaker and Nelson, 1987). Overall, sterol metabolism in T. thermophila seems to be the evolutionary product of a fascinating combination of gene losses (e.g., typical eukaryotic genes involved in sterol biosynthesis) combined with acquisition of bacterial genes to allow for synthesis of unusual compounds, with potentially novel mechanisms of sterol modification.…”

Section: Studies On Membrane Lipids In Tetrahymenamentioning

confidence: 99%