The effects of the structure of sterols on the development of Heliothis zea

Ritter, Karla S.; Nes, William R.

doi:10.1016/0022-1910(81)90021-4

Cited by 35 publications

(34 citation statements)

References 13 publications

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“…The work reported here implies that, unlike what has been found for a variety of other biological functions of sterols (13,(31)(32)(33)(34)(35)(36)(37), recognition of the side chain is minimal in the various processes (absorption, transport, etc.) that govern feedback inhibition.…”

Section: Discussionmentioning

confidence: 68%

Inhibition of hepatic cholesterol synthesis in mice by sterols with shortened and stereochemically varied side chains.

Erickson¹,

Nes²

1982

Proc. Natl. Acad. Sci. U.S.A.

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Philadelphia, Pennsylvania 19104 Communicated by E. H. Ahrens, Jr., May 5, 1982 ABSTRACT Mice were fed cholesterol or various other sterols for 26 hr, after which the amount of hepatic cholesterol synthesis was measured in a cell-free system. The following sterols were as effective as cholesterol itself in, depressing the conversion of acetate into sterol: pregn-5.en-3.&ol, which lacks an isohexyl group on C-20; (E)-17(2G)-dehydrocholesterol, in which the isohexyl group is fixed to the right; (E)-20(22)-dehydrocholesterol, in which C-23 is oriented away from the nucleus; and 20-epicholesterol. Moreover, when the isohexyl group was fixed to the left in (Z)-17(20)-dehydrocholesterol, this dietary sterol, identified in the liver, caused notonly a depression in the conversion ofacetate into sterols but also-a depression in the conversion of both mevalonate and squalene into sterols. The incorporation of acetate into fatty acids was not depressed, nor did the (Z)-sterol appear to have a generalized effect on membranous enzymes,, because the activity of glucose-6-phosphatase was unaffected. Thus, feedback inhibition was retained when .the stereochemistry of cholesterol's side chain was drastically changed and even after the nearly complete removal of the side chain. This implies that the side chain is only minimally recognized by the mechanisms involved in. feedback inhibition.The influence of the size, shape, and polarity of sterols on the biological function of these compounds has been the subject of many investigations. Among them have been studies with fungi and protozoa on the significance of chirality at C-20 and of the spatial orientation of C-22 on the ability of sterols to promote growth of anaerobic Saccharomyces cerevisiae (1), to induce oospore formation in Phytophthora cactorum (2, 3), and to be dehydrogenated by Tetrahymena pyriformis (4, 5). In all three of these cases the natural (20R) configuration (6-9) was found to be essential. Similarly obligatory was the ability of the sterol, to have C-22 oriented to the right in the usual view of the molecule (C-18 and C-19 toward the observer and ring Ato the left) and simultaneously to have no bulk larger than a H atom in front.-Orientation of C-22 to the right is known to occur in the crystalline state (6, 7). A reason why this should be the more stable form has been suggested (4) and correlated (4, 5) with the biological properties (1-5).In the present investigation we have examined this stereochemical problem in mammals. The functional parameter used for quantitation was inhibition of hepatic cholesterol synthesis brought about by short-term feedback from sterol in the diet of mice. Because, unlike the results with the single-celled organisms, we found biological activity required neither the (20R) configuration nor the ability of C-22 to lie on the right, it appeared that the receptors involved in feedback did not recognize the cholesterol side chain. In order to explore this further, we extended our studies to sterols with side chains smaller than...

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Section: Discussionmentioning

confidence: 68%

Inhibition of hepatic cholesterol synthesis in mice by sterols with shortened and stereochemically varied side chains.

Erickson¹,

Nes²

1982

Proc. Natl. Acad. Sci. U.S.A.

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“…There was evidence that the larvae convert A7-and A'-sterols to cholesterol, because (1) minor quantities of cholesterol were present in varying amounts when the insects were fed these sterols, and (2) cholesterol was not found to be a contaminant of the dietary ingredients. Although some of this cholesterol may have been derived from maternal sterols, the contribution of transovarially derived sterols to the sterol pool of the sixth instar is probably quite small and doesn't explain why the amounts of cholesterol found in these experiments varied from < 1% to 19%.…”

Section: Discussionmentioning

confidence: 97%

“…Larvae of H. zeu were reared individually on artificial diets, which contained no plant material but were supplemented with different sterols (15 mgllOO ml diet) as described previously [1,2].…”

Section: H Zeamentioning

confidence: 99%

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Metabolism of Δ⁰‐, Δ⁵‐, and Δ⁷‐Sterols by Larvae of Heliothis zea

Ritter

1983

Arch Insect Biochem Physiol

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Heliothis zea was reared on artificial diets containing A5-sterols (cholesterol, campesterol, or sitosterol), A'-sterols (lathosterol, epifungisterol, or spinasterol), or A'-sterols (cholestanol, epicoprostanol, carnpestanol, or sitostanol) in order to determine how different dietary sterols affect the type of sterols present in the tissues of the late-sixth-instar larva. Although all of the dietary sterols (except epicoprostanol) supported the growth of the larvae, not all of the sterols were metabolized to the same end products. In each case, at least 80% of the sterols in the tissues of the larvae retained the same nucleus as that of the dietary sterol, indicating that H. zea carries out very little metabolism of ring B of A5-, A7-, and A'-sterols. The larvae dealkylated the A' -, A'-, and A'-alkylsterols to 24desalkylsterols, but a greater percentage of the A5-alkylsterols were metabolized in this manner. The sterols present as free sterols in the larva were also present as esterifed sterols which accounted for 2-4% of the total sterols. Therefore, the sterol composition of the tissues of H. zea can be altered by varying the dietary sterols.

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“…as Manduca sexta, Tribolium confusum [5], HeZiothis zea [6], and Diatraea grandiosella [n, to name only a few representative species. It has also been shown that development in a number of species, including M .…”

Section: Introductionmentioning

confidence: 99%

25‐Azasteroid inhibition of development and conversion of C₂₈ and C₂₉ phytosterols to cholesterol in Spodoptera litura (F.)

Kuthiala

Agarwal

Thompson

et al. 1987

Arch Insect Biochem Physiol

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Larvae of Spodoptera litura (F.) grown on an artificial diet completed larval development in 19.2 days and attained a maximum weight of 873.2 mg. When fed dietary concentrations of 50 ppm of 25-azacholesterol or 10 ppm of 25-azacholestane, the larval developmental period increased to 28.4 and 23.4 days, and the larval weights were 447.5 and 542.3 mg, respectively. Both compounds induced distinct melanization effects and caused production of larval-pupal intermediates and severe mortality. Treatments with concentrations of 50 ppm or more of either azasteroid caused a decline in pupal period and earlier eclosion and emergence of abnormal adults. Egg laying and hatchability decreased with increasing concentrations of azasteroids in the larval diets.When 1 pprn or more of 25-azasteroid is added to the artificial diet, the insect larvae contain identifiable amounts of desmosterol, in addition to cholesterol, campesterol, and sitosterol, which are present in Spodoptera grown on artificial diet alone. Desmosterol accumulation in the insect body is due to an inhibition of the AZ4-sterol reductase by 25-azasteroids. An increase in the concentration of these azasteroids in the diet results in an increase in sitosterol concentration and simultaneous reduction in the cholesterol levels due to inhibition of conversion of sitosterol. This inhibition appears to be more pronounced with 25-azacholestane treatment than with 25-azacholesterol.

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The effects of the structure of sterols on the development of Heliothis zea

Cited by 35 publications

References 13 publications

Inhibition of hepatic cholesterol synthesis in mice by sterols with shortened and stereochemically varied side chains.

Inhibition of hepatic cholesterol synthesis in mice by sterols with shortened and stereochemically varied side chains.

Metabolism of Δ⁰‐, Δ⁵‐, and Δ⁷‐Sterols by Larvae of Heliothis zea

25‐Azasteroid inhibition of development and conversion of C₂₈ and C₂₉ phytosterols to cholesterol in Spodoptera litura (F.)

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The effects of the structure of sterols on the development of Heliothis zea

Cited by 35 publications

References 13 publications

Inhibition of hepatic cholesterol synthesis in mice by sterols with shortened and stereochemically varied side chains.

Inhibition of hepatic cholesterol synthesis in mice by sterols with shortened and stereochemically varied side chains.

Metabolism of Δ0‐, Δ5‐, and Δ7‐Sterols by Larvae of Heliothis zea

25‐Azasteroid inhibition of development and conversion of C28 and C29 phytosterols to cholesterol in Spodoptera litura (F.)

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Metabolism of Δ⁰‐, Δ⁵‐, and Δ⁷‐Sterols by Larvae of Heliothis zea

25‐Azasteroid inhibition of development and conversion of C₂₈ and C₂₉ phytosterols to cholesterol in Spodoptera litura (F.)