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John L. Harwood

Bio: John L. Harwood is an academic researcher from Cardiff University. The author has contributed to research in topics: Lipid metabolism & Fatty acid. The author has an hindex of 60, co-authored 420 publications receiving 16081 citations. Previous affiliations of John L. Harwood include John L. Scott & Spanish National Research Council.


Papers
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Journal ArticleDOI
TL;DR: The effect of irrigation with saline water on oil quality was studied in the two olive cultivars Koroneiki and Mastoidis, which are the main varieties grown extensively on the island of Crete, and showed that increased NaCl levels in irrigation water resulted in a decrease in oil content in the fruits and an increase in total phenols and their secoiridoid derivatives in olive oils from harvested fruits.
Abstract: The effect of irrigation with saline water on oil quality was studied in the two olive ( Olea europaea L) cultivars Koroneiki and Mastoidis, which are the main varieties grown extensively on the island of Crete Plants (5 years old) were grown outdoors in containers, filled with freely drained light soil Four treatments were applied, differing in the NaCl added to the irrigation water as follows: 0 (control) 50, 100, and 150 mM NaCl Drip irrigation was applied regularly, during the dry season (from April to October) Plants in all treatments were irrigated when the soil-water potential reached -40 kPa at a depth of 30 cm Data showed that increased NaCl levels in irrigation water resulted in a decrease in oil content in the fruits and an increase in total phenols and their secoiridoid derivatives in olive oils from harvested fruits Furthermore, changes also took place in the composition of fatty acids and triacylglycerol molecular species The extent of alterations was different for the two varieties and greater in cv Koroneiki This fitted with agronomic evidence that cv Koroneiki is less saline-tolerant than cv Mastoidis

28 citations

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TL;DR: Heterotrophic olive callus was characterized by its ability to accumulate triacylglycerol rich in oleate, a situation comparable to developing olive fruit and acyl lipid composition varied according to the state of differentiation and to incubation temperature.
Abstract: Differentiation in olive callus cultures was induced by changing the plant growth regulator content, particularly 2,4-dichlorophenoxyacetic acid, in the growth media at 25 o C. These cultures have been maintained for an extended period with low polyploid nuclei levels. Analysis of olive callus cultures indicated that the acyl lipid composition varied according to the state of differentiation and to incubation temperature. Heterotrophic olive callus was characterized by its ability to accumulate triacylglycerol rich in oleate, a situation comparable to developing olive fruit. In fact, oleate-rich triacylglycerol was enhanced in heterotrophic callus cultured at 35 o C

27 citations

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TL;DR: The relative sensitivity of very long chain fatty acid synthesis to thiocarbamates in potato tuber provides further evidence that these herbicides reduce cuticular wax by inhibiting fatty acid elongation.

27 citations

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TL;DR: Changes in the relative labelling of triacylglycerols (TAGs) and DAGs in embryos of different ages suggested that diacyl glycerol acyltransferase (DAGAT) could exert significant flux control during periods of rapid lipid synthesis.

27 citations

Journal ArticleDOI
01 Jan 1972-Lipids
TL;DR: In this article, a method for the rapid and comprehensive subcellular fractionation of plant tissue using a combination of differential and discontinuous Ficoll gradient centrifugation is described.
Abstract: A method is described for the rapid and comprehensive subcellular fraction-ation of plant tissue using a combination of differential and discontinuous Ficoll gradient centrifugation. The procedure has been used to study the synthesis of fatty acids from acetate-1-14C or malonyl CoA-1,3-14C, by fractions of germinating pea and lupin seeds and developing avocado fruit, castor bean and safflower seeds. Particle free supernatants of seeds synthesize fatty acids from14C-malonyl CoA in the presence of added cofactors. Since acetyl CoA carboxylase activity is absent the utilization of14C-acetate by these fractions is minimal. Other particulate fractions show different activities depending on seed types. Active fractions include the low speed particulate of pea and lupin, the pea microsomes, the avocado mesocarp chloroplasts, and the fat fractions of castor bean and safflower. Individual fractions produce characteristic patterns of acids; especially noteworthy is oleic acid biosynthesis by soluble enzymes of castor bean and safflower from14C-malonyl CoA. Some characteristics of the avocado supernatant, pea supernatant, and castor bean fat fraction synthesizing systems are compared. As a result of these studies, generalizations derived from work with mammalian or bacterial systems cannot be applied to higher plants.

27 citations


Cited by
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Yusuf Chisti1
TL;DR: As demonstrated here, microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels.

9,030 citations

Journal ArticleDOI
TL;DR: In this article, the transesterification reaction is aected by molar ratio of glycerides to alcohol, catalysts, reaction temperature, reaction time and free fatty acids and water content of oils or fats.

4,902 citations

Journal ArticleDOI
TL;DR: The current understanding of IFN‐γ ligand, receptor, ignal transduction, and cellular effects with a focus on macrophage responses and to a lesser extent, responses from other cell types that influence macrophages function during infection are reviewed.
Abstract: Interferon-gamma (IFN-gamma) coordinates a diverse array of cellular programs through transcriptional regulation of immunologically relevant genes. This article reviews the current understanding of IFN-gamma ligand, receptor, signal transduction, and cellular effects with a focus on macrophage responses and to a lesser extent, responses from other cell types that influence macrophage function during infection. The current model for IFN-gamma signal transduction is discussed, as well as signal regulation and factors conferring signal specificity. Cellular effects of IFN-gamma are described, including up-regulation of pathogen recognition, antigen processing and presentation, the antiviral state, inhibition of cellular proliferation and effects on apoptosis, activation of microbicidal effector functions, immunomodulation, and leukocyte trafficking. In addition, integration of signaling and response with other cytokines and pathogen-associated molecular patterns, such as tumor necrosis factor-alpha, interleukin-4, type I IFNs, and lipopolysaccharide are discussed.

3,589 citations

Journal ArticleDOI
TL;DR: A brief summary of the current knowledge on oleaginous algae and their fatty acid and TAG biosynthesis, algal model systems and genomic approaches to a better understanding of TAG production, and a historical perspective and path forward for microalgae-based biofuel research and commercialization are provided.
Abstract: Microalgae represent an exceptionally diverse but highly specialized group of micro-organisms adapted to various ecological habitats. Many microalgae have the ability to produce substantial amounts (e.g. 20-50% dry cell weight) of triacylglycerols (TAG) as a storage lipid under photo-oxidative stress or other adverse environmental conditions. Fatty acids, the building blocks for TAGs and all other cellular lipids, are synthesized in the chloroplast using a single set of enzymes, of which acetyl CoA carboxylase (ACCase) is key in regulating fatty acid synthesis rates. However, the expression of genes involved in fatty acid synthesis is poorly understood in microalgae. Synthesis and sequestration of TAG into cytosolic lipid bodies appear to be a protective mechanism by which algal cells cope with stress conditions, but little is known about regulation of TAG formation at the molecular and cellular level. While the concept of using microalgae as an alternative and renewable source of lipid-rich biomass feedstock for biofuels has been explored over the past few decades, a scalable, commercially viable system has yet to emerge. Today, the production of algal oil is primarily confined to high-value specialty oils with nutritional value, rather than commodity oils for biofuel. This review provides a brief summary of the current knowledge on oleaginous algae and their fatty acid and TAG biosynthesis, algal model systems and genomic approaches to a better understanding of TAG production, and a historical perspective and path forward for microalgae-based biofuel research and commercialization.

3,479 citations