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Showing papers by "John L. Harwood published in 2013"


Journal ArticleDOI
TL;DR: Temperature sensing and how responses to heat stress are not necessarily dependent on denatured proteins are discussed, and it is clear that membrane lipids have a pivotal function.

147 citations


Book ChapterDOI
01 Jan 2013
TL;DR: An overview of lipid composition and lipid metabolism in algae with a special emphasis on the production of algal oils and/or their metabolism for biofuel applications is given.
Abstract: Algae exhibit superior attributes to terrestrial crop plants as bioenergy sources. Many algae accumulate substantial amounts of non-polar lipids, mostly in the form of triacylglycerols or hydrocarbons, and these levels may reach up to 20–50 % of dry cell weight. These oleaginous species have been considered as promising sources of oil for biofuels, such as surrogates of gasoline, kerosene and diesel. In spite of several technical limitations associated with existing technologies in the production of economically-viable algal oil, further research in this area is needed and such studies will clearly benefit from a better understanding of lipid metabolism and accumulation in algal cells. At present, relatively little information is available on lipid biosynthesis and its regulation in algae. Moreover, the lack of information about control mechanisms for the lipid synthesis in different algal species limits our attempts to manipulate lipid metabolism in algae. However, some promising achievements in genetic and metabolic manipulations in higher plants are useful examples/directions to follow. In the present chapter we give an overview of lipid composition and lipid metabolism in algae with a special emphasis on the production of algal oils and/or their metabolism for biofuel applications.

64 citations


Journal ArticleDOI
TL;DR: Recent studies suggest that engineering of seed oil content can be guided using methods in metabolic analysis, and manipulation of specific steps in storage lipid biosynthesis using genetic engineering has resulted in transgenic lines of Brassica napus with increased seedOil content.
Abstract: Increasing the seed oil content of Brassica species and other major oilseed crops is of paramount importance in maintaining a future supply of vegetable oil for a growing global population. Currently, commercially-available Brassica species with enhanced seed oil content have all been developed through plant breeding. Many quantitative trait loci including gene interactions are involved in the control of seed oil content. Despite this complexity, manipulation of specific steps in storage lipid biosynthesis using genetic engineering has resulted in transgenic lines of Brassica napus with increased seed oil content. Recent studies suggest that engineering of seed oil content can be guided using methods in metabolic analysis.

35 citations


Journal ArticleDOI
TL;DR: Metabolic control analysis is used to provide information about major oil crops such as oilseed rape, oil palm, olive, and soybean and this knowledge has been used to inform genetic manipulation for crop improvement.
Abstract: Plant oils are a very valuable agricultural commodity. They are currently mainly used (>80%) for food and animal feed but, increasingly, they have utility as renewable sources of industrial feedstocks or biofuel. Because of finite agricultural land, the best way to increase availability (in order to match demand) is by improving productivity. To do this requires a knowledge of metabolism and its regulation. Various methods have been used to provide information but only systems biology can yield quantitative data about complete metabolic pathways. We have used metabolic control analysis to provide information about major oil crops such as oilseed rape, oil palm, olive, and soybean. Such knowledge has then been used to inform genetic manipulation for crop improvement.

31 citations


Journal ArticleDOI
TL;DR: This is the first study to demonstrate directly that host resource depletion caused by endemic infection could affect epidemic disease transmission and recommend that future studies of epidemic transmission should take greater account of endemic co-infections.
Abstract: Endemic, low-virulence parasitic infections are common in nature. Such infections may deplete host resources, which in turn could affect the reproduction of other parasites during co-infection. We aimed to determine whether the reproduction, and therefore transmission potential, of an epidemic parasite was limited by energy costs imposed on the host by an endemic infection. Total lipids, triacylglycerols (TAG) and polar lipids were measured in cockroaches (Blattella germanica) that were fed ad libitum, starved or infected with an endemic parasite, Gregarina blattarum. Reproductive output of an epidemic parasite, Steinernema carpocapsae, was then assessed by counting the number of infective stages emerging from these three host groups. We found both starvation and gregarine infection reduced cockroach lipids, mainly through depletion of TAG. Further, both starvation and G. blattarum infection resulted in reduced emergence of nematode transmission stages. This is, to our knowledge, the first study to demonstrate directly that host resource depletion caused by endemic infection could affect epidemic disease transmission. In view of the ubiquity of endemic infections in nature, future studies of epidemic transmission should take greater account of endemic co-infections.

23 citations


Journal ArticleDOI
TL;DR: Different ways of obtaining information on how oil accumulation is regulated are discussed with an emphasis on metabolic control analysis, which has been well‐illustrated by its application to help raise yields in oilseed rape.

22 citations


Book ChapterDOI
01 Jan 2013
TL;DR: Olive oil contains a mixture of triacylglycerols (TAGs) plus minor components that give the oil its properties and organoleptic characteristics as mentioned in this paper, and the TAGs from olive oil are synthesized through a complex process that involves fixation of carbon dioxide, the production of sugars that are transported to the developing fruits and their breakdown through glycolysis to produce intermediates that are imported into the plastids and finally converted to acetyl-CoA.
Abstract: Virgin olive oil (VOO) is a natural product extracted from fresh olive fruits by physical means without any chemical transformation. Olive oil contains a mixture of triacylglycerols (TAGs) plus minor components that give the oil its properties and organoleptic characteristics. TAGs from olive oil are synthesized through a complex process that involves fixation of carbon dioxide, the production of sugars that are transported to the developing fruits, and their breakdown through glycolysis to produce intermediates that are imported into the plastids and finally converted to acetyl-CoA. In green fruits (like olive) a part of this carbon can also be fixed in the fruits themselves. The acetyl-CoA is converted to malonyl-CoA, which is used for fatty acid synthesis in cycles of elongation that take place within the plastids. The fatty acid products are converted to acyl-CoA derivatives, exported to the cytosol, and then utilized for lipid assembly in the endoplasmic reticulum. The TAG products are finally stored in oil vesicles that increase in size during fruit maturation. The aroma of VOO is caused by a variety of volatile compounds. This fraction is quantitatively small when compared with TAGs but determines the organoleptic quality of the oil. Analysis of olive volatiles reveals a high content of six-carbon aldehydes and alcohols typically synthesized by the lipoxygenase (LOX) pathway. This pathway involves the release of polyunsaturated fatty acids (linoleic and linolenic) from olive fruit cell membranes and their oxygenation by LOX activity. The resulting hydroperoxides are then cleaved by the enzyme hydroperoxide lyase to produce oxoacids and volatile aldehydes that can then be reduced to alcohols by the action of endogenous alcohol dehydrogenases. The relative activities of these enzymes during fruit maturation and olive oil processing determine the volatile composition of the oil. The more recent advances in these aspects of olive fruit metabolism are described in the review.

16 citations