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Biomedical subjects

C Grunwald

Publications and source records attributed to C Grunwald.

33 records · Page 2Linked to original sources
PubMed1973

Effect of Light on Mevalonic Acid Incorporation into the Phytosterols of Nicotiana tabacum L. Seedlings.

Mevalonic acid-2-(14)C was readily incorporated into the free, esterified, and glycosidic sterol fractions of tobacco (Nicotiana tabacum L. var. Burley 21) seedlings. The time course of mevalonic acid-2-(14)C incorporation was different for the various individual sterols. Campesterol and sitosterol (group I) became radioactive as the free sterol and subsequently as the steryl ester. The reverse order was observed for cholesterol and stigmasterol (group II). Light stimulated the incorporation of mevalonic acid-2-(14)C into the group I free sterols and during the first 6 to 9 hours into the steryl esters of group II. The increase in specific radioactivity of the group II steryl esters was followed by a decline. Based on time course studies it is suggested that the group II steryl esters turn over rapidly and that light influences the rate of turnover.

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PubMed1972

Sterol Changes during Germination of Nicotiana tabacum Seeds.

The identity, composition, and concentration of the total, free, esterified, and glycosidic sterol fractions were determined during germination of tobacco seeds. The total, free, and esterified sterols increased, with stigmasterol and campesterol accounting for most of the increase. Steryl glycosides decreased during germination, and stigmasteryl and sitosteryl glycosides showed the largest decrease. During germination, sitosterol was the major sterol in all fractions but stigmasterol and campesterol showed the greatest changes. The fatty acid composition of the steryl esters and acylated steryl glycosides most closely resembled the di- and triglycerides.

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PubMed1971

Changes in Sterol Composition during Greening of Etiolated Barley Shoots.

THE FOLLOWING STEROLS WERE IDENTIFIED IN BARLEY SHOOTS: stigmasterol, beta-sitosterol, campesterol, and cholesterol. The total sterol content of green and etiolated tissue was 2.84 and 3.20 milligrams per gram dry weight, respectively. The free sterols accounted for most of the difference in total sterol content. The sterol ester, sterol glycoside, and acylated sterol glycoside contents of green and etiolated barley shoots were essentially the same. Etiolated tissue had twice as much total beta-sitosterol as stigmasterol, while green tissue had equal amounts of these two sterols. The campesterol and cholesterol content was the same in green and etiolated tissue. This same sterol composition pattern held true for the free, glycosidic, and acylated glycosidic sterols; however, the sterol ester fraction had a completely different composition pattern. The esterified stigmasterol content was quite low in green and etiolated tissue, and campesterol was the second largest esterfied sterol component in etiolated tissue. Etiolated barley seedlings exposed to light had a shift in the ratio of free stigmasterol to beta-sitosterol in favor of stigmasterol; however, no correlation was observed between chlorophyll synthesis and shift in sterol composition.

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PubMed1970

Grafting and gibberellin effects on the growth of tall and dwarf peas.

Tall peas var. Alaska and dwarf peas var. Progress No. 9 were grafted onto their own roots or reciprocally grafted to determine the rootstock effect on the growth of the stem. In all cases the grafted stems grew the same as their ungrafted controls regardless of which rootstock they were grown on. When similarly grafted plants were supplied with gibberellic acid, good graft unions did not inhibit its translocation. This evidence supports the thesis that the mechanism controlling stem growth in peas is located in the stem and that the roots have no direct control over this mechanism.

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PubMed1970

Sterol distribution in intracellular organelles isolated from tobacco leaves.

All membrane-containing fractions isolated from tobacco leaves contained free sterols, sterol glycosides, and sterol esters. The three sterol forms increased, on a dry weight basis, with a decrease in particle size. The supernatant fraction contained only trace amounts of sterol. The major sterols in all cellular fractions, in the order of decreasing amounts, were: stigmasterol, beta-sitosterol, campesterol, and cholesterol. The 500g pellet contained the largest percentage of free sterol, while the 46,000g pellet contained the largest percentage of esterified sterol. The individual sterol composition of the free sterol and sterol glycoside fraction was very similar; however, the composition of the sterol ester fraction varied widely among intracellular fraction. The intracellular distribution pattern of cholesterol-(14)C added to the isolation medium provided evidence that the intracellular sterol distribution pattern is not an artifact. These results support the suggestion that sterols in plant cells may have a physiological function associated with membranes.

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PubMed1968

Effect of sterols on the permeability of alcohol-treated red beet tissue.

Alcohols and hydrogen peroxide altered the permeability of membranes of Beta vulgaris root cells. Generally alcohols increased the permeability of membranes without going through an induction period except methanol which required a 10- to 15-hour induction period. The membrane effect of methanol could be inhibited with CaCl(2), cholesterol, beta-sitosterol, and stigmasterol. Cholesterol was the most effective inhibitor, followed by beta-sitosterol and stigmasterol; and at the same concentration, the sterols were more effective than CaCl(2), the classic membrane stabilizer.Ergosterol increased the methanol-initiated betacyanin leakage. Since none of the tested sterols reversed the betacyanin efflux induced by hydrogen peroxide, the sterols do not apparently act as antioxidants. The results are explained in terms of sterol-phospholipid interaction, based on stereochemistry and charge distribution.

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