Showing papers by "John L. Harwood published in 1987"
TL;DR: The relative acyl lipid composition of both leaflets of the thylakoid membrane indicates that the lamellar structure is strongly favored in the inner monolayer, whereas the outer one presents a metastable character which allows the probable coexistence of both lamellars and non-lamellar phases.
Abstract: The transmembrane distribution of monogalactosyldiacylglycerol and digalactosyldiacylglycerol was determined in chloroplast thylakoids from a range of temperate climate plants. These plants included dicotyledons, monocotyledons, C16:3 and C18:3 plants and herbicide-resistant species. In all the thylakoids examined monogalactosyldiacylglycerol was enriched in the outer leaflet (53–65%) while digalactosyldiacylglycerol was highly enriched in the inner leaflet (78–90%). The non-bilayer forming monogalactosyldiacylglycerol represented 55–81% of the total acyl lipids of the outer monolayer. The relative acyl lipid composition of both leaflets of the thylakoid membrane indicates that the lamellar structure is strongly favored in the inner monolayer, whereas the outer one presents a metastable character which allows the probable coexistence of both lamellar and non-lamellar phases. The consequence of this asymmetry for the stability and function of the thylakoid membrane is discussed.
47 citations
TL;DR: The data indicate that extracellular dipalmitoyl-phosphatidylcholine, the major component of pulmonary surfactant, is not catabolized at the alveolar surface, although the initial distribution of the removed phospholipid complex may change in relation to the enlarged heterogenous free cell population.
Abstract: Naturally prepared radiolabelled pulmonary surfactant can be rapidly cleared from the alveolar surface to the lung tissue after intratracheal instillation into experimental rats This clearance is both time- and dose-dependent, a large dose (10 mg/animal) becoming associated with lung tissue more rapidly than a smaller more physiological dose (075 mg/animal) The data indicate that extracellular dipalmitoyl-phosphatidylcholine, the major component of pulmonary surfactant, is not catabolized at the alveolar surface Alveolar free cells (mainly macrophages) appear to play a minor role in surfactant clearance Quartz-induced phospholipidosis does not lead to an alteration in the rate of bulk surfactant clearance from the alveolar surface, although the initial distribution of the removed phospholipid complex may change in relation to the enlarged heterogenous free cell population
11 citations
TL;DR: The lipid content and metabolism of five algae was studied and fatty acid methyl esters (FAME) formed from the lipids were analysed by g.1.c.
Abstract: Marine macroalgae are a diverse and abundant group of plants, but many aspects of their metabolism are poorly understood. Marine algal lipids show variations from those of higher plants, and marked differences occur amongst algal divisions. Marine algae have a wide range of polyunsaturated fatty acids (PUFA’s) and some unusual lipids (Jamieson & Reid, 1972; Pohl & Zurheide, 1979~; Smith & Harwood, 1984). The lipid content and metabolism of five algae (Fucus vesiculosus, Ascophyllum nodosum: Phaeophyceae, Chondrus crispus, Polysiphonia lanosa: Rhodophyceae, and Enteromorpha intestinalis: Chlorophyceae) was studied. Samples of algae were collected from sites on the S. Wales coast. Lipids were extracted by the method of Garbus et al. (1963) as modified by Smith et al. (1982), and identified by co-chromatography with standards on t.1.c. and staining reactions. Fatty acid methyl esters (FAME) formed from the lipids were analysed by g.1.c. and quantified using an internal standard. Identifications were confirmed using
6 citations
01 Jan 1987
TL;DR: De novo fatty acid synthesis in plant tissues appears to be catalysed by the operation of a high molecular weight (multifunctional protein) acetyl-CoA carboxylase and a Type II fatty acid synthetase.
Abstract: De novo fatty acid synthesis in plant tissues appears to be catalysed by the operation of a high molecular weight (multifunctional protein) acetyl-CoA carboxylase and a Type II fatty acid synthetase. Elongation of the product of the synthetase, or of endogenous acids, is catalysed by Type III fatty acid synthetases with malonyl-CoA as the source of the additional carbons.
3 citations
01 Jan 1987
TL;DR: Studies with the plant growth-promoting compound, indol-3-y1 acetic acid (IAA), using the third internode region of pea stems, have shown that in the presence of IAA the incorporation of [Me-14 C]choline into phosphatidylcholine was reduced within one hour of treatment, due to a change in the activity of cytidylyltransferase.
Abstract: Phosphatidylcholine is the major phospholipid of the non-photosynthetic membranes of higher plants1, and its main route of synthesis is via the CDP-base pathway2 Studies with the plant growth-promoting compound, indol-3-y1 acetic acid (IAA), using the third internode region of pea (Pisum sativum L) stems, have shown that in the presence of IAA the incorporation of [Me-14 C]choline into phosphatidylcholine was reduced within one hour of treatment3 This was shown to be due to a change in the activity of cytidylyltransferase
1 citations
01 Jan 1987
TL;DR: The effect of light, temperature and heavy metals on lipid metabolism in the brown alga Fucus serratus and how it is affected by environmental factors is studied.
Abstract: Little is known about lipid metabolism in marine algae and how it is affected by environmental factors. This is in spite of the fact that these organisms constitute a large part of the Plant Kingdom. The work up to 1979 has been summarized1. Recent work has studied the effect of light, temperature and heavy metals on lipid metabolism in the brown alga Fucus serratus 2.
1 citations
01 Jan 1987
TL;DR: The oleaginous yeast, Rhodotorula gracilis, is capable of accumulating large amounts of storage lipid when grown under nitrogen-limiting conditions, and the major fatty acids present in the acyl lipids have been shown to be palmitic, stearic, oleic, linoleic and α-linolenic acids.
Abstract: The oleaginous yeast, Rhodotorula gracilis (CBS 3043) is capable of accumulating large amounts of storage lipid when grown under nitrogen-limiting conditions. The storage lipids produced under these conditions are located in intracellular storage vesicles, and are primarily triacylglycerols. The major fatty acids present in the acyl lipids have been shown to be palmitic, stearic, oleic, linoleic and α-linolenic acids; indicating the presence of Δ9, A12 and Δ15 desaturase enzymes.
1 citations
1 citations
1 citations