Antioxidant properties of evening primrose seed extracts.

The antioxidant activity of extracts of evening primrose seeds (SE) and a commercially extracted filter cake (FC) were determined. The SE and FC were extracted with methanol/water (9:1) followed by evaporation and concentration. Extracts were tested in a bulk oil system and an oil-in-water emulsion using safflower oil as the major source of lipids. The antioxidant activity of the extracts was compared to that of a control and to that of butylated hydroxytoluene (BHT), singly, and in combination. Antioxidant activity was measured by the co-oxidation of beta-carotene, an oxidative stability instrument, conjugated dienes, and headspace analysis of hexanal. The SE extract had greater antioxidant activity than the FC extract. The SE extract was more effective in controlling the oxidation in the oil-in-water model system than in the bulk oil system. The activity of SE was concentration dependent, and at higher concentrations the SE was as effective as BHT, but it required higher concentrations because of its lack of purity. Synergism between SE and BHT was demonstrated in both model systems.

Growth of Cucurbita maxima L. plants in the presence of the cycloartenol synthase inhibitor U18666A.

Squash, like other Cucurbitaceae, have unique sterol profiles that offer an excellent opportunity to examine the relationship between sterol biosynthesis and plant growth. To determine the effect of sterol biosynthesis inhibition on squash growth, Cucurbita maxima seedlings with and without cotyledons were subjected to increasing concentrations of the cycloarternol synthase (EC 5.4.99.8) inhibitor 3 beta-(2-diethylaminoethoxy)androstenone (U18666A). Inhibition of shoot growth was concentration-dependent (from 0, 2, 5, 10, and 20 microM); plants with intact cotyledons grew to 26.4, 23.7, 21.6, 20.0, and 15.6 cm, respectively, at the above inhibitor concentrations, compared to 25.5, 19.4, 17.0, 12.0, and 11 cm for plants with severed cotyledons. In plants with severed cotyledons, 10 and 20 microM U18666A caused rapid necrosis of the first two, newly emerged, primary leaves, and halted new leaf formation. Secondary root formation was initially affected at all inhibitor concentrations regardless of whether cotyledons were present or not. Vegetative tissue showed a decrease in the accumulation of the major squash sterol, 7,22-stigmastadienol, accompanied by increased accumulation of minor sterol components. Sterol profiles in cotyledons were unaltered. The data show that sterols are crucial for maintaining plant growth and viability, but do not address the cotyledonary effect on growth with respect to sterol biosynthesis.

Two-dimensional electrophoresis and densitometric analysis of solubilized bovine sperm plasma membrane proteins detected by silver staining and radioiodination.

Bovine sperm plasma membranes were extracted with deoxycholate and subjected to two-dimensional gel electrophoresis. Proteins were visualized either by silver staining or autoradiography using 125I. When 1.5-2.0 micrograms of protein extract was applied to the first-dimension get, 250 spots could be detected by autoradiography. Thirty micrograms of protein was required to obtain spot visualization using silver strain, revealing more than 500 spots on the gel. These data establish the limit under which two-dimensional electrophoresis can be used in conjunction with flow cytometric sorting of sperm for the analysis of possible sex-specific membrane differences. The necessity of orienting sperm as they past the laser in the cell sorting system reduces throughput; thus, the number of sperm sorted within a given time is limited. It is suggested that autoradiography will allow the flow cytometer to be used in a time-efficient manner. Longer sorting times would be required to obtain sufficient sample to analyze total protein composition.

Gas chromatographic analysis of intact steryl esters in wild type Saccharomyces cerevisiae and in an ester accumulating mutant.

The steryl ester faction from wild type and mutant strains of the yeast Saccharomyces cerevisiae was analyzed without saponification by a non-polar capillary gas chromatographic column. When expressed as microgram ester/mg dry wt, the total ester fraction remained constant or declined slightly from log to stationary phase in the wild type. In the mutant the decrease was more dramatic. No individual ergosteryl ester species was dominant throughout the culture cycle in the wild type. A compound tentatively identified as zymosteryl palmitate was the most prevalent ester in wild type log phase cells, ergosta-5,7-dienyl palmitate and ergosta-5,7-dienyl palmitoleate were the major esters in stationary cells. In the mutant strain, ergosteryl esters of palmitate, palmitoleate, oleate, and stearate were the major ester components throughout the culture cycle. Like the wild type, however, the mutant showed an increase in the proportion of ergosta-5,7-dienyl esters in the stationary phase of the culture cycle. The data did not indicate a sterol/fatty acid specificity during the culture cycle.

Pleiotropic mutations in Saccharomyces cerevisiae affecting sterol uptake and metabolism.

Sterol uptake control mutants (upc-) have been isolated via ethylmethanesulfonate mutagenesis from wild-type Saccharomyces cerevisiae. These mutants are heme and sterol competent but possess the ability to accumulate exogenous sterol(s) under aerobic conditions. Previous studies demonstrate sterol uptake only in a hem-, erg- background; however, the Upc- strains described here are Hem+ and do not require exogenous sterol for growth. We were unable to obtain viable hem+, erg-, upc+ recombinants; such combinations appear to be lethal. Isolates of Upc mutants demonstrated different levels of sterol uptake, and sterol analysis revealed a broad phenotypic range with regard to amounts and accumulation of ergosterol and non-ergosterol sterols. Assays of acyl CoA: ergosterol acyltransferase and sterol ester hydrolase showed no apparent difference in activity between Upc mutants and the wild type.

Sterol composition during the life cycle of the soybean and the squash.

Sterol analyses were performed on soybeans and squash at intervals throughout the life cycle from seed to mature seed-bearing plant. The sterols of the soybean (24-methyl-cholesterol, stigmasterol and sitosterol) increased in quantity from that in the seed in each stage examined except for a pause or decrease prior to flowering and a decrease at senescence. Individual sterols remained in the same proportion to each other and changes in content were similar in roots and shoots. In the squash a much more complicated sterol mixture was found, composed primarily of C-7 unsaturated sterols characteristic of Cucurbitaceae. Sterol composition also increased during the life cycle except for approximately two wk in the preflowering to early flowering period. The data indicate low synthesis or high turnover of sterols (or both) in these plants in the weeks at or just prior to flowering.