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Biomedical subjects

R W Rinne

Publications and source records attributed to R W Rinne.

18 recordsLinked to original sources
PubMed1988

Protein Synthesis during Natural and Precocious Soybean Seed (Glycine max [L.] Merr.) Maturation.

Protein synthesis was studied during precocious and natural soybean seed (Glycine max [L.] Merr.) maturation. Developing seeds harvested 35 days after flowering were precociously matured through controlled dehydration. Total soluble proteins and proteins labeled with [(35)S]methionine were extracted from control, developing seeds and from precociously and naturally matured seeds and were analyzed by one-dimensional PAGE and fluorography. The results demonstrated that several polypeptides which were designated "mature polypeptides," were synthesized de novo during precocious and natural seed maturation. Two of these polypeptides, 31 and 128 kilodalton in mass, also stained intensely with Coomassie blue, suggesting their abundant accumulation during seed maturation. Results from in vitro translation experiments showed that the mRNAs corresponding to these "maturation polypeptides" accumulated during precocious maturation and in naturally matured seeds, but not in seeds freshly harvested 35 days after flowering (control). The role of the "maturation polypeptides" is currently unknown; however, their presence and that of their corresponding mRNAs was coincident with the ability of matured seeds to establish seedling growth. This study has demonstrated that precocious seed maturation treatments may be extremely useful for investigations of metabolic events and molecular control mechanisms affecting soybean seed maturation.

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PubMed1986

A Comparison of Oleic Acid Metabolism in the Soybean (Glycine max [L.] Merr.) Genotypes Williams and A5, a Mutant with Decreased Linoleic Acid in the Seed.

The metabolism of oleoyl coenzyme A (CoA) was examined in developing seed from two soybean (Glycine max [L.] Merr.) genotypes: Williams, a standard cultivar and A5, a mutant containing nearly twice the oleic acid (18:1) content of Williams. The in vitro rates of esterification of oleoyl-CoA to lysophosphatides by acyl-CoA: lysophosphatidylcholine acyltransferase was similar in both genotypes and lysophosphatidyl-ethanolamine was a poor substrate. Crude extracts desaturated exogenous [1-(14)C]dioleoyl phosphatidylcholine at 14% of the rate achieved with [1-(14)C]oleoyl-CoA, and 50 micromolar lysophosphatidylcholine. The desaturase enzyme also required NADH for full activity. Extracts from Williams contained 1.5-fold more oleoyl phosphatidylcholine desaturase activity, on a fresh weight basis, than did A5 and appeared to have a similar affinity for oleoyl-CoA. There was 1.2- to 1.9-fold more linoleic acid (18:2) in phosphatidylcholine from Williams than from A5, measured at two stages of development, but both genotypes had a similar distribution of fatty acids in the one and two positions. Phosphatidylethanolamine in A5 contained relatively more linoleic acid (18:2) in the one position than did Williams. The increased oleic acid (18:1) content in A5 appeared to be a result of decreased rates of 18:1 desaturation of oleoyl-phosphatidylcholine in this genotype.

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PubMed1986

Changes in Soybean (Glycine max [L.] Merr.) Glycerolipids in Response to Water Stress.

Soybean (Glycine max [L.] Merr.) plants with the first trifoliate leaf fully expanded were exposed to 4 and 8 days of water stress. Leaf water potentials dropped from -0.6 megapascal to -1.7 megapascals after 4 days of stress; then to -3.1 megapascals after 8 days without water. All of the plants recovered when rewatered. The effects of short-term drought stress on triacylglycerol, diacylglycerol, phospholipid, and galactolipid metabolism in the first trifoliate leaves was determined. Leaf triacylglycerol and diacylglycerol content increased 2-fold during the first 4 days of stress and returned to control levels 3 days after rewatering. The polar lipid fraction, which contained phospholipids and galactolipids, changed little during this time. The linolenic acid (18:3) content of the triacylglycerol and diacylglycerol increased 25% during stress and the polar lipid 18:3 content decreased 15%. The pattern of glycerolipid labeling, after applying [2-(14)C]acetate to intact leaves was altered by water stress. After 4 days of water stress the radioactivity of phosphatidic acid + phosphatidylinositol, phosphatidylcholine, triacylglycerol, and diacylglycerol increased between 4 and 9% (compared to control plans) while radioactivity of phosphatidylethanolamine, monogalactosyldiglyceride, and digalactosyldiglyceride decreased 2 to 11%. These data indicated that increased levels of triacylglycerol and diacylglycerol observed during water stress were attributed to de novo synthesis rather than breakdown or reutilization of existing glycerolipids and fatty acids.

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PubMed1978

Lipid molecular species composition in developing soybean cotyledons.

The fatty acid composition of triglyceride and phospholipids in developing soybean cotyledons (Glycine max L., var. "Harosoy 63") was analyzed at several stages of growth between 30 and 70 days after flowering. Changes observed in fatty acid composition within each lipid class were related to the levels of lipid molecular species present in the oil. Thirteen molecular species of triglyceride were identified in developing cotyledons, however three of these groups: trilinolenic, dilinolenic-monolinoleic, and linolenic-linoleic-oleic triglycerides, were not found in the mature seed. In immature cotyledons, trioleic and trilinoleic triglycerides accounted for 50% of the structures found; the level of these molecules decreased to 24.9% in the mature seed. The dilinoleic-monolinolenic triglycerides increased from 0.4 to 23.4% during cotyledon development. Changes in triglyceride composition were compared to the levels of molecular species for each phospholipid class. Dilinoleic and monosaturated monolinoleic phospholipid species were dominant in all phospholipid classes throughout development.

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PubMed1978

Studies on the metabolism of lipid molecular species in immature soybean cotyledons.

Metabolism of lipid molecular species in soybean cotyledons (Glycine max [L.] Merr. var. "Harosoy 63") was determined from incorporation studies with radioactive acetate and glycerol. Lipid synthetic activity was highest in immature cotyledons at 30 days after flowering. Distinct differences in labeling patterns of molecular species within lipid classes demonstrated that selective utilization of diglyceride intermediates occurred in complex lipid biosynthesis in soybean. The phospholipid molecular species in this tissue that displayed the highest turnover rates had the following acyl combinations: saturate-linoleic and dioleic in phosphatidic acid; saturate-oleic in phosphatidylinositol and phosphatidylethanolamine; dioleic in phosphatidylcholine; oleic-dilinoleic in N-acylphosphatidylethanolamine. Saturate-dilinoleic, oleic-dilinoleic, trioleic, and trilinoleic structures were rapidly synthesized species of triglyceride in immature soybean cotyledons.

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PubMed1976

Effect of freezing and cold storage on phospholipids in developing soybean cotyledons.

Freezing of plant tissue adversely affects lipid composition. Immature soybean cotyledons (Glycine max L. Merr.) var. "Harosoy 63" were frozen with liquid N(2), dry ice, or stored in a freezer (-20 C) before lipid extraction. The effects of freezing temperature, thawing rate, and cold storage on the lipid composition of frozen tissue revealed significantly higher levels of phosphatidic acid, and diminished levels of phosphatidylcholine, phosphatidylethanolamine, and N-acylphosphatidylethanolamine from the control. Regardless of freezing temperature, phosphatidic acid levels increased from 4.7 mole% to nearly 50 mole% of the total phospholipid when frozen tissues were stored 10 days at -20 C. During the same period, N-acylphosphatidylethanolamine decreased from 54.1 mole% to 6.6 mole% phospholipid. At least 8 mole% of the phosphatidic acid increase occurred during slow thawing of the frozen tissues. In autoclaved samples, phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine, and N-acylphosphatidylethanolamine levels were not different from the control. Labeling of the lipid-glycerol with (3)H, and fatty acids with (14)C, demonstrated the degradation product was primarily phosphatidic acid. Apparently enzymic destruction of the phospholipids occurred during freezing, cold storage, and thawing.

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PubMed1976

Studies on lipid synthesis and degradation in developing soybean cotyledons.

The metabolic activity of individual lipid classes found in developing soybean cotyledons (Glycine max.) is estimated by determining the degradation rate of the compound under given conditions. Pulse-labeling and dual substrate labeling are used to evaluate this parameter. These studies indicate first order decay kinetics for phosphatidic acid, phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine, N-acyl-phosphatidylethanolamine, diglyceride, and zero order kinetics for triglyceride in cotyledons var. "Harosoy 63" at 30 days after flowering. Decay coefficients for acyl groups and lipid-glycerol moieties within specific lipid classes from either method are comparable. Half-life (t((1/2))) calculations from the decay coefficients indicate extremely rapid turn-over rates (0.08 to 3.4 hours at 25 C) and suggest similar turnover rates of acyl groups and lipid-glycerol in diglyceride and all phospholipids except N-acylphosphatidylethanolamine where acyl groups are replaced independent of the glycerol moiety. These experiments reveal not only different metabolic activity between lipid components of soybean cotyledons, but also describe a new method for measuring lipid turnover in plants.

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PubMed1976

Involvement of phospholipids in triglyceride biosynthesis by developing soybean cotyledons.

The incorporation of phospholipids specifically labeled with glycerol-2(3)H and acyl-(14)C by whole cell tissues of developing soybean cotyledons (Glycine max L.) reveals that phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine, N-acylphosphatidylethanolamine, and phosphatidic acid can be metabolized to diglyceride. The diglyceride formed may be recylced into phospholipid or acylated to triglyceride. Diglyceride from phosphatidic acid and phosphatidylethanolamine is used readily in triglyceride biosynthesis compared to the other phospholipids. Incorporation of N-acylphosphatidylethanolamine having [9-10-(3)H(N)]oleic acid esterified at sn-3 in cotyledons shows rapid acyltransfer of (3)H into triglyceride and therefore N-acylphosphatidylethanolamine appears to participate in triglyceride biosynthesis as an acyl donor. These studies emphasize phospholipid metabolism in developing soybean cotyledons is a dynamic process which plays a key role in triglyceride formation.

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PubMed1975

Citrate cleavage enzymes from developing soybean cotyledons: incorporation of citrate carbon into Fatty acids.

Data are presented which demonstrate a citrate cleavage enzyme in the supernatant of a developing soybean (Glycine max L. Merr., var. Harosoy 63) cotyledon homogenate following a 126,000g spin for 2 hours. Activity of the enzyme was observed directly in the supernatant enzyme preparation and in a desalted supernatant preparation by measuring the formation of acetylhydroxamate. Acetylhydroxamate production was dependent on citrate and coenzyme A. The reaction increased with time, citrate, and coenzyme A concentrations.Involvement of the enzyme in lipid synthesis was investigated by the incorporation of carbon from citrate-1,5-(14)C into fatty acids. Incorporation shows a pH optimum at 8.5, a temperature optimum at 30 C, and a dependence on ATP and coenzyme A. The reaction is linear throughout the range of extract concentrations tested and is linear as a function of time for 1 hour. Isotope was distributed primarily in unsaturated fatty acids.

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PubMed1974

Phospholipids in the developing soybean seed.

The distribution of phospholipids in developing soybean seeds [Glycine max (L.) Merr., var. "Chippewa 64," "Harosoy 63," "Wayne," and "Clark 63"] was followed. From 30 to 60 days after flowering expressed as mole per cent of phospholipid phosphorus phosphatidic acid decreased from 14.8 to 9.1; phosphatidylinositol increased from 0 to 9.1; phosphatidylcholine increased from 8.2 to 9.8; phosphatidylethanolamine increased from 5.3 to 8.6; phosphatidylglycerol increased from 3.2 to 4.8; diphosphatidylglycerol increased from 2.7 to 4.1; and N-acylphosphatidylethanolamine decreased from 65.8 to 54.6. However, from 60 days after flowering to maturity, phosphatidic acid decreased to 0; phosphatidylinositol increased roughly 2-fold; phosphatidylcholine increased roughly 4.7-fold; phosphatidylethanolamine increased 3-fold; N-acylphosphatidylethanolamine decreased 11-fold; whereas phosphatidylglycerol and diphosphatidylglycerol remained essentially constant. Percentages of individual phospholipid species were not statistically different between any two varieties at a given time period.Immature soybean cotyledons incubated with (14)C-acetate or -pyruvate demonstrated rapid incorporation into the phospholipid fraction. N-acylphosphatidylethanolamine was found to account for nearly 70% of the total radioactivity incorporated by the total polar lipid fraction and greater than 30% of the total radioactivity added.

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PubMed1969

Biosynthesis of Fatty acids by a soluble extract from developing soybean cotyledons.

Fractionation of developing soybean cotyledons into cellular components demonstrates that most of the activity necessary to incorporate acetate-1-(14)C into lipid remains in the supernatant from a 198,000g spin for 1 hr. The system studied is dependent upon ATP, CoA, and CO(2). Concentrations of ATP greater than 4 x 10(-3)m are inhibitory, while 1 x 10(-4)m CoA is needed for optimal activity. Avidin inhibition of acetate incorporation into lipid could be reversed by biotin. Studies indicated that NADPH is a better source of reducing power than NADH. The system studied is inhibited by p-chloromercuribenzoic acid and this inhibition can be reversed by an excess of GSH. The system studied shows maximum activity in tris buffer at pH 8.6 or in glycine buffer, pH 9.4.The distribution of acetate into the various fatty acids is greatly influenced by the temperature of incubation. Cooler incubation temperatures favor the distribution of acetate into the more unsaturated fatty acids.

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PubMed1969

Influence of age and sulfur metabolism on ATP sulfurylase activity in the soybean and a survey of selected species.

ATP sulfurylase activity varied greatly among different leaves on the soybean plant [Glycine max (L.) Meer.], and high levels of activity did not appear in the leaves until the seedlings were about 3 weeks old. In general, leaves from the top of the plant had a higher activity than leaves from the bottom of the plant. A much greater activity was found in soybean leaves than in soybean roots. The absence of sulfate in the nutrient solution resulted in higher enzyme activity in leaves from young plants and in lower activity in leaves from older plants. Over the growing season, however, ATP sulfurylase activity appeared to be related to sulfur content of the leaf. Several other plant species also had measurable levels of ATP sulfurylase.

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