NSC228155 br Acknowledgments Authors acknowledge financial s

Acknowledgments Authors acknowledge financial support from the National Natural Science Foundation of China (31402274, 31172389), the Special Project of Marine Renewable Energy from the State Oceanic Administration (SHME2011SW02), China Postdoctoral Science Foundation (2014M551381) and Shanghai Universities First-class Discipline Project of Marine Sciences.
Introduction For industrial uses, fatty acids with hydroxy, epoxy or unusual positions of desaturation are desired (Meier zu Beerentrup and Röbbelen, 1987). Castor oil containing up to 90% ricinoleic NSC228155 (12-hydroxyoleic acid) is obtained from Ricinus communis L. (Euphorbiaceae) and it is traded in quantity. Kleiman et al. (1965) in a survey of euphorb seed oils identified one species with a high content (60%) of vernolic acid (12,13-epoxyoleic acid): Euphorbia lagascae Spreng. Baumann et al. (1988) also listed Euphorbia lathyris L., the caper spurge, as a potential new industrial crop due to its high content of oleic acid (80–90%). Oilseed crops with unusual fatty acids can be developed either by domestication of wild species (Pascual-Villalobos et al., 1994) or by genetic transformation of existing ones (Murphy, 1993). Transforming the gene that is responsible for the production of the functional group (e.g. hydroxy or epoxy) into an established oilseed crop (e.g. rape or sunflower) is not sufficient to obtain a high expression and accumulation of the unusual fatty acid in the transgenic plant (Broun and Somerville, 1997). But, as reported by Kinney et al. (1998), a greater amount of such fatty acids could be achieved by storing them in triacylglycerols (TAG). The enzyme that catalyses the synthesis of TAG from diacylglycerol (DAG) is the acyl-CoA: 1,2-diacylglycerol acyltransferase (DGAT) and it is intimately associated with membranes. It has also been suggested that the selectivity of a DGAT of any particular crop for its native substrate is a limiting factor in the flexibility to incorporate other fatty acids (Wiberg et al., 1994, He et al., 2004b). Murphy (1993) indicated that DGAT appears to have a relatively low substrate specificity towards a variety of acyl-CoAs compared with other acyltransferases that are involved in earlier steps of lipid synthesis. Possibly there are similarities among euphorb plant species but extraction of the enzymes present in the microsomal fraction is needed for testing their preferences for substrates. Although R. communis, E. lathyris and E. lagascae belong to the same family, the DGAT activity of their microsomal preparations has not been compared. The objective of this work was to test in vitro the preferences for oleoyl-CoA and 1,2–diolein, which are the predominant native substrates in E. lathyris and to compare with the microsomes of R. communis and E. lagascae.
Materials and methods
Results and discussion Table 1 summarizes the results of Reaction 1, where [14C] oleoyl-CoA was used as acyl donor and no acyl receptors were added. DGAT activity was detected in most of the preparations since the label was incorporated into TAG, except in R. communis H22 E (both incubation times) or E. lathyris ELAT E (6d) possibly because there was not endogenous DAG.