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Acyl-CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) catalyzes the last reaction in the acyl-CoA-dependent biosynthesis of triacylglycerol (TAG). DGAT activity resides mainly in DGAT1 and DGAT2 in eukaryotes and bifunctional wax ester synthase-diacylglycerol acyltransferase (WSD) in bacteria, which are all membrane-bound proteins but exhibit no sequence homology to each other. Recent studies also identified other DGAT enzymes such as the soluble DGAT3 and diacylglycerol acetyltransferase (EaDAcT), as well as enzymes with DGAT activities including defective in cuticular ridges (DCR) and steryl and phytyl ester synthases (PESs). This review comprehensively discusses research advances on DGATs in prokaryotes and eukaryotes with a focus on their biochemical properties, physiological roles, and biotechnological and therapeutic applications. The review begins with a discussion of DGAT assay methods, followed by a systematic discussion of TAG biosynthesis and the properties and physiological role of DGATs. Thereafter, the review discusses the three-dimensional structure and insights into mechanism of action of human DGAT1, and the modeled DGAT1 from Brassica napus. The review then examines metabolic engineering strategies involving manipulation of DGAT, followed by a discussion of its therapeutic applications. DGAT in relation to improvement of traits of farmed animals is also discussed along with DGATs in various other eukaryotic organisms. [ABSTRACT FROM AUTHOR]

Highlights: [•] Molecular markers to determine sources of organic matter in waters is reviewed. [•] Human and animal wastes are distinguishable by fecal sterols and bile acids. [•] Artificial sweeteners identify input of human wastewater. [•] LC–MS should facilitate analysis of molecular markers in environmental studies. [ABSTRACT FROM AUTHOR]

Abstract: Oil crops are a very important agricultural commodity. Demand for such oils is rising steadily (at more than 5% per year over the last half century). Although the majority of plant oils are used for food or animal feed, there is increasing interest in their use as renewable chemicals for industry. Because of the demonstrated demand for oils and finite agricultural land, attention is focussing on improving productivity. Genetic manipulation of crop plants needs a knowledge of the biosynthetic pathways concerned and how they are regulated. Although there are different ways to acquire much information, metabolic flux and metabolic control analyses are ways to provide quantitative assessments. In this review we describe our experiments using metabolic control analysis on important crops – oil palm, oilseed rape, olive and soybean. Such research provides information for future informed genetic manipulations and we give a successful example of this in oilseed rape (Brassica napus L.). [Copyright &y& Elsevier]

Abstract: When compared to other organisms, plants are atypical with respect to isoprenoid biosynthesis: they utilize two distinct and separately compartmentalized pathways to build up isoprene units. The co-existence of these pathways in the cytosol and in plastids might permit the synthesis of many vital compounds, being essential for a sessile organism. While substrate exchange across membranes has been shown for a variety of plant species, lack of complementation of strong phenotypes, resulting from inactivation of either the cytosolic pathway (growth and development defects) or the plastidial pathway (pigment bleaching), seems to be surprising at first sight. Hundreds of isoprenoids have been analyzed to determine their biosynthetic origins. It can be concluded that in angiosperms, under standard growth conditions, -phytyl moieties, -triterpenes and -carotenoids are made nearly exclusively within compartmentalized pathways, while mixed origins are widespread for other types of isoprenoid-derived molecules. It seems likely that this coexistence is essential for the interaction of plants with their environment. A major purpose of this review is to summarize such observations, especially within an ecological and functional context and with some emphasis on regulation. This latter aspect still requires more work and present conclusions are preliminary, although some general features seem to exist. [Copyright &y& Elsevier]

Abstract: Prospective epidemiological surveys and numerous animal studies have shown an important role for dietary docosahexaenoic acid (DHA) in healthy brain function and reducing the risk of dementia. The evidence for this is summarised and some further experiments of our own are described. For the experimentation we have used the Tg2576 mouse, which is a well known model of amyloid pathology and cognitive impairment as seen in Alzheimer''s disease. We found that, while brain levels of DHA showed a positive correlation with behaviour and a negative correlation with insoluble β-amyloid (1-40), the general benefits of DHA-enriched diets were not as great as have sometimes been reported in the literature. This may be due to either the age of the animals we tested and/or the fact that we examined the effects of DHA supplementation against a normal healthy control diet condition, unlike previous studies, in order to mimic dietary supplement use in the human population. In addition, we point to some ways in which biotechnology could be used to supplement the world''s supply of omega-3 PUFAs (especially DHA) since there is an increasing shortage of such compounds for dietary consumption. [Copyright &y& Elsevier]

Abstract: Eukaryotic algae are a very diverse group of organisms that are key components of ecosystems ranging from deserts to the Antarctic. They account for over half of the primary production at the base of food chains. The lipids of different classes are varied and contain unusual compounds not found in other phyla. In this short review, we introduce the major cellular lipids and their fatty acids and then describe how the latter (particularly the polyunsaturated fatty acids, PUFAs) are synthesised. The discovery of different elongases and desaturases important for PUFA production is detailed and their application for biotechnology described. Finally, the potential for algae in commercial applications is discussed, particularly in relation to the production of very long chain PUFAs and biofuel. [Copyright &y& Elsevier]

Abstract: Two lipoxygenase isoforms from olive callus cultures were separated from each other. Acetone powders were made to stabilise activity and remove lipids. Separation was then achieved by salt precipitation and ion-exchange chromatography. Both isoforms had comparable activity with linoleic and α-linolenic acid substrates, a basic pH optimum and had molecular masses of around 95kDa. The callus extracts preferentially formed the 13-hydroperoxy products, in keeping with the pattern of volatile derivatives found in olive tissues and oils derived therefrom. [Copyright &y& Elsevier]

Abstract: We evaluated the ability of heavy metals (copper, lead) to alter lipid metabolism in four algal lichen photobionts following short term exposure. Metal concentrations (10μM) were equivalent to environmentally relevant levels that have been reported to have effects on intact algae. The algae were grown under normal or deficient phosphate conditions to assess any interactions with the heavy metal stress. Given the frequent sensitivity of lichens to copper and lead, there were surprisingly small changes on lipid metabolism, as assessed by radiolabelling from [1-14C]acetate. The main effects, which were seen in a number of cases, were an overall inhibition of total lipid labelling and a relative increase in the labelling of triacylglycerols in the non-polar fraction. Both of these changes can be viewed as reflecting general toxicity of heavy metals. The Coccomyxa photobiont species were more sensitive than Trebouxia species, which fits with the general distribution of the latter in lichens inhabiting harsh environments. [Copyright &y& Elsevier]

Abstract: Eukaryotic algae are a very diverse group of organisms which inhabit a huge range of ecosystems from the Antarctic to deserts. They account for over half the primary productivity at the base of the food chain. In recent years studies on the lipid biochemistry of algae has shifted from experiments with a few model organisms to encompass a much larger number of, often unusual, algae. This has led to the discovery of new compounds, including major membrane components, as well as the elucidation of lipid signalling pathways. A major drive in recent research have been attempts to discover genes that code for expression of the various proteins involved in the production of very long-chain polyunsaturated fatty acids such as arachidonic, eicosapentaenoic and docosahexaenoic acids. Such work is described here together with information about how environmental factors, such as light, temperature or minerals, can change algal lipid metabolism and how adaptation may take place. [Copyright &y& Elsevier]

Tamoxifen is the hormonal treatment of choice in women who have hormone-dependent breast cancer and its efficacy in those women considered to have a high risk of developing breast cancer, has also been established. γ linolenic acid (GLA) has been shown to decrease the invasion of breast cancer and recent studies have demonstrated that GLA can enhance the oestrogen receptor down-regulation induced by tamoxifen. However, tamoxifen is associated with serious side-effects due mainly to systemic delivery, and targeted delivery of both tamoxifen and GLA would be highly beneficial. This work was a preliminary study for the development of a transcutaneous system to simultaneously deliver both tamoxifen and GLA directly to the breast. Full thickness human skin was dosed with 500 μl saturated solution of tamoxifen in borage oil (25% GLA) and the simultaneous permeation of the two actives determined. There was rapid flux with minimal lag time, the cumulative permeation at 24 h was 764.3±94.2 μg cm−2 for GLA and 5.44±0.67 μg cm−2 for tamoxifen: the latter being comparable to the amount of tamoxifen associated with cancerous breast tissue from a 20 mg oral dose. The ratio of GLA/tamoxifen permeated at different timepoints was quite consistent, both in terms of mass (mean 138, S.D. 15.1) and mols (mean 184, S.D. 20.3). It was determined that 2.5 molecules of GLA were associated with each molecule of tamoxifen in the permeation process, equating to a solvation cage of three molecules of triacylglycerol. This study has demonstrated the feasibility of administering simultaneously tamoxifen and GLA using borage oil as vehicle, which warrants further investigation as a novel topical two-component system in relation to or prophylaxis of those perceived at high risk of developing breast cancer. The study also provides further evidence of the permeation of solvated complexes across skin, rather than discrete penetrant molecules. [Copyright &y& Elsevier]

Arthritis is a common disease in which the end-point results in joint replacement surgery. This article reviews the use of nutraceuticals as alternative treatments for pathological manifestations of arthritic disease. The efficacy of fish oils (e.g. cod liver oil) in the diet has been demonstrated in several clinical trials, animal feeding experiments and in vitro models that mimic cartilage destruction in arthritic disease. In addition, there is some evidence for beneficial effects of other nutraceuticals, such as green tea, herbal extracts, chondroitin sulphate and glucosamine. However, in most cases, there is little scientific evidence at the cellular and molecular levels to explain their mechanisms of action. [Copyright &y& Elsevier]

All ecologists are familiar with uncertainty, at least at the level of whether they should reject a null hypothesis. Uncertainty is, however, pervasive and its characterization is essential if we are to understand our effects on ecosystems. Traditional fisheries management has a poor track record for confronting uncertainty, but most management authorities are now committed to a precautionary approach. As a result, some of the most interesting methods for taking account of uncertainty in ecological systems have been developed by fisheries scientists. These methods evaluate the relative performance of different management procedures with the use of mathematical and statistical models that synthesize knowledge and speculation about the system of interest. Recent advances in computer-intensive statistics have made it possible to combine this approach with model fitting, so that the uncertainties and risks associated with different outcomes of management can be quantified. We show how this methodology can be applied to a range of ecological problems where the advice that scientists provide to decision makers is likely to be clouded by uncertainty. [Copyright &y& Elsevier]

Brassica oilseed species are the third most important in the world, providing approximately 15 % of the total vegetable oils. Three species (Brassica rapa, B. juncea, B. napus) dominate with B. napus being the most common in Canada, China and Europe. Originally, B. napus was a crop producing seed with high erucic acid content, which still persists today, to some extent, and is used for industrial purposes. In contrast, cultivars which produce seed used for food and feed are low erucic acid cultivars which also have reduced glucosinolate content. Because of the limit to agricultural land, recent efforts have been made to increase productivity of oil crops, including Brassica oilseed species. In this article, we have detailed research in this regard. We have covered modern genetic, genomic and metabolic control analysis approaches to identifying potential targets for the manipulation of seed oil content. Details of work on the use of quantitative trait loci, genome-wide association and comparative functional genomics to highlight factors influencing seed oil accumulation are given and functional proteins which can affect this process are discussed. In summary, a wide variety of inputs are proving useful for the improvement of Brassica oilseed species, as major sources of global vegetable oil. [ABSTRACT FROM AUTHOR]

Changes in grey seal (Halichoerus grypus) serum thyroid hormones with age, sex and during lactation were investigated. Concentrations were related to polychlorinated biphenyl (PCB) uptake and exposure in pups and females. There was no effect of sex or stage of lactation on either free or total thyroxine (T4) and triiodothyronine (T3), but significant age-related variability was seen. Pupshad significantly higher concentrations of total T4 than adults (p <0.0001) and serum levels declined with age. In general, there was nosignificant relationship between PCB exposure to pups through femalemilk or between PCB blubber concentrations and thyroid hormone levels, when the effect of age was controlled for. However, the ratio T3:T4 was significantly correlated with the concentration of one congener, CB169 (p = 0.048), when stage of lactation was used as a covariate. In conclusion, serum thyroid hormone levels may be less useful biomarkers of contaminant exposure in seals than other biochemical measures. Although concentrations vary predictably with age, other factors, such as condition and nutritional status, may compromise their usefulness in assessing contaminant-induced hormone disruption in pinnipeds. [ABSTRACT FROM AUTHOR]