Fat Metabolism in Higher Plants

Harwood, John L.; Stumpf, P.K.

doi:10.1104/pp.46.4.500

Cited by 60 publications

(12 citation statements)

References 42 publications

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“…TLC-FID separation of PL revealed that PC was the major PL (70% of total) of borage seeds prior to germination ( Table 6). PC is also the major PL in seeds of alfalfa (Medicago sativa) (20), pea (Pisum sativum) (14,44), barley (Hordeum vulgare) (19), saf- flower (Carthamus tinctorius) (8), and soybean (Glycine max) (42). PS and PE were coeluted and their total made up the nextlargest fraction.…”

Section: Resultsmentioning

confidence: 99%

Lipid components of borage (Borago officinalis L.) seeds and their changes during germination

Senanayake

Shahidi

2000

J Americ Oil Chem Soc

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The changes in composition of total and neutral lipids (NL) as well as glycolipids (GL) and phospholipids (PL) of borage (Borago officinalis L.) seeds, germinated in the dark at 25°C for 10 d, were studied. Total lipids constituted 34.0% of the dry matter of borage seeds. During germination, the content of total lipids was decreased by 95%. NL accounted for 95.7% of total lipids prior to germination and were composed of triacylglycerols (TAG; 99.1%), diacylglycerols (DAG; 0.06%), monoacylglycerols (MAG; 0.02%), free fatty acids (FFA; 0.91%), and sterols (0.02%). The content of TAG was significantly (P ≤ 0.05) decreased, while that of other components, such as MAG and FFA, significantly (P ≤ 0.05) increased during germination. However, the content of DAG did not change. GL and PL accounted for 2.0 and 2.3% of total lipids, respectively, and their contents significantly (P ≤ 0.05) increased as germination proceeded. The thin layer chromatography-flame-ionization detection studies showed that phosphatidylcholine (PC; 69.7%) was the major PL present. The total content of phosphatidylserine (PS) and phosphatidylethanolamine (PE), which were coeluted, was 18.2%; phosphatidic acid (PA) was present at 11.2% of the total PL fraction. Lysophosphatidylcholine was detected at 0.9%. The proportion of PC, PS, and PE significantly (P ≤ 0.05) decreased during germination, but that of PA increased (P ≤ 0.05) markedly. The fatty acid composition of lipid fractions changed as germination proceeded. The predominant fatty acids of total lipids, NL, and GL were linoleic and linolenic acids, while those of PL were linoleic and palmitic acids. The present study demonstrated that the overall changes of lipids seen in borage seeds during germination agree well with results for other oilseeds. Changes in lipid compositions during germination result from the formation of tissues and metabolic interconversion of lipid classes. Rapid changes in lipid composition during seed germination may enhance the nutritional value of the sprouts.Paper no. 9128 in JAOCS 77, 55-61 (January 2000).a As a weight percentage of total NL. Mean ± SD of triplicate determinations. Means within a row with different roman superscript letters are significantly different (P ≤ 0.05). ND, not detected; for other abbreviation see Table 1.

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Section: Resultsmentioning

confidence: 99%

Lipid components of borage (Borago officinalis L.) seeds and their changes during germination

Senanayake

Shahidi

2000

J Americ Oil Chem Soc

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“…If CH indeed penetrated and inhibited protein synthesis in the same cells synthesizing these enzymes, the increases in activities of OMP pyrophosphorylase, OMP decarboxylase, and probably of cytidine deaminase during germination are likely due to activation rather than actual synthesis. Enzymes capable of fatty acid formation (8) and an amylopectin-1,6-glucosidase (11) similarly increase in activity in cotyledons of germinating peas without being synthesized de novo. However, assuming the only important effect of CH upon increase of uridine hydrolase activity resulted from inhibition of protein formation, this enzyme probably arises at least in part from de novo synthesis.…”

Section: Discussionmentioning

confidence: 99%

“…No influences upon respiration were observed after exposure to 50 pg of CH per ml. Harwood and Stumpf (8) studied the influence of various concentrations of CH up to 1 mg/ml upon water absorption, fatty acid synthesis, and leucine-14C incorporation into protein of whole pea seeds during the first 24 hr of germination. CH had no effect on imbibition, consistent with our unpublished data, but leucine incorporation during the first 24 hr of germination was inhibited about 78% by 10 or 25 ,ug of CH per ml.…”

Section: Discussionmentioning

confidence: 99%

Development of Pyrimidine-metabolizing Enzymes in Cotyledons of Germinating Peas

Ross¹,

Murray²

1971

Plant Physiol.

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Mechanisms controlling conversion of orotic acid-6-'4C to uridine-5'-phosphate in cotyledons of germinating Alaska peas (Pisum sativum L.) were investigated. The content of 5-phosphoribosyl-l-pyrophosphate was very low in dry seeds, increased to a maximum after about 12 hours of imbibition, and then rapidly declined. Orotidine-5'-phosphate pyrophosphor. ylase and orotidine-5'-phosphate decarboxylase activities more than doubled during the first 24 hours of germination and then also decreased. These results do not account for the continuous increases of orotate anabolism in such cotyledons as we observed previously. The initial increases in activities of these two enzymes were unaffected by cycloheximide, while the subsequent decreases were less rapid in the presence of this inhibitor. Activities of cotyledonary cytidine deaminase and uridine hydrolase also increased during imbibition, but the activity of only the latter showed a decrease after imbibition was completed. Cycloheximide inhibited the initial rapid increase in uridine hydrolase activity but had little effect on its subsequent decline. Cycloheximide had only slight inhibitory effects on the development of cytidine deaminase activity during the first 62 hours. The evidence suggests that uridine hydrolase might be synthesized de novo during the first few days of germination, but that the other three enzymes might not be.We previously observed that "C-labeled orotic acid and uridine were converted into various pyrimidine nucleotides and RNA in cotyledons of germinating Alaska peas (15). This incorporation was more extensive in seeds germinated about 1 week than in those germinated for lesser times. It was suggested that the increasing capacity of the seeds to convert orotate into RNA might be due to an increase of OMP-pyrophosphorylase activity or of PRPP, a necessary substrate for this enzyme. Decarboxylation of OMP appeared to be nonlimiting at all germination stages, since no "C-labeled OMP was ever detected in the cotyledons. On the contrary, orotate-"C accumulated in seeds which only weakly converted it into RNA. The present report describes results indicating that both OMP pyrophosphorylase and OMP decarboxylase become increasingly active in pea cotyledons during the first 24 to 36 hr of germination, but their activities then decrease. The decreases but not the increases in enzyme activities are inhibited by CH, a known inhibitor of protein synthesis. The effects of CH on protein synthesis and on the development of cytidine deaminase and uridine hydrolase, two enzymes suspected to be involved in the metabolism of RNA stored in the cotyledons, are also described. MATERIALS AND METHODSGerminaton. Pea (Pisum sativiuim L., cv. Alaska) seeds were germinated under conditions designed to minimize bacterial contamination. Seeds were shaken in 1.0% (w/v) NaOCl for 3 min and rinsed extensively in sterile water. Twenty seeds were then spread over the surface of three layers of Whatman No. 1 filter paper in 9-cm Petri dishes. The Petri dishes and filt...

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“…plates with chloroform/methanol/acetic acid (200: 100: 1, by vol.) and were identified after paper chromatography of their deacylated derivatives (Dawson, 1960) and acid hydrolysates (Harwood & Stumpf, 1970). Amounts of acyl lipids were determined from their fatty acid content.…”

Section: Lipid Extraction and Analysismentioning

confidence: 99%

Changes in the acyl lipid composition of photosynthetic bacteria grown under photosynthetic and non-photosynthetic conditions

Russell¹,

Harwood²

1979

Biochemical Journal

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The acyl lipids and their constituent fatty acids were studied in the photosynthetic bacteria Rhodospirillum rubrum, Rhodopseudomonas capsulata and Rhodopseudomonas sphaeroides, which were grown under photosynthetic and non-photosynthetic conditions. The major lipids were found to be phosphatidylethanolamine, phosphatidylglycerol and cardiolipin in each bacterium. The two Rhodopseudomonas species also contained significant quantities of phosphatidylcholine. Other acyl lipids accounted for less than 10% of the total. On changing growth conditions from non-photosynthetic to photosynthetic a large increase in the relative proportion of phosphatidylglycerol was seen at the expense of phosphatidyl-ethanolamine. In Rhodospirillum rubrum the fatty acids of the major phospholipids showed an increase in the proportion of palmitate and stearate and a decrease in palmitoleate and vaccenate on changing growth conditions to photosynthetic. In contrast, the exceptionally high levels (>80%) of vaccenate in individual phospholipids of Rhodopseudomonas capsulata and Rhodopseudomonas sphaeroides were unaffected by changing growth conditions to photosynthetic. Analysis of the lipids of chromatophores, isolated from the three bacteria, showed that these preparations were enriched in phosphatidylglycerol. The large increase in this phospholipid, seen during growth under photosynthetic conditions, appeared, therefore, to be due to a proliferation of chromatophore membranes. Possible roles for acyl lipids in the formation and function of the photosynthetic apparatus of bacteria are discussed.

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Fat Metabolism in Higher Plants

Cited by 60 publications

References 42 publications

Lipid components of borage (Borago officinalis L.) seeds and their changes during germination

Lipid components of borage (Borago officinalis L.) seeds and their changes during germination

Development of Pyrimidine-metabolizing Enzymes in Cotyledons of Germinating Peas

Changes in the acyl lipid composition of photosynthetic bacteria grown under photosynthetic and non-photosynthetic conditions

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