While DGATs have long been thought

While DGATs have long been thought to be associated with the ER membrane, recent reports have indicated that DGATs could also be localised to mitochondria-associated membranes in mice (Stone et al., 2009) and there is growing evidence that there may be an independent TAG biosynthesis pathway in the chloroplasts of C. reinhardtii, based on studies of sta6 mutants which are defective in starch biosynthesis (Fan et al., 2011, Goodson et al., 2011). This may mean that there are different DGAT splice forms or multiple DGAT isoforms with different subcellular targeting peptides. If these hypotheses turn out to be true, TAG biosynthesis in algae could prove much more complicated than currently thought, and taking this into account for future metabolic engineering efforts will be crucial. The capability to modify algal species to produce high levels of designer biofuels or high-value lipid compounds on-demand will be highly reliant on basic research into both the enzymes involved in the biosynthesis pathways, as well as transcription factors involved in controlling the expression of these genes. While the lack of fully sequenced algal genomes is currently seen as a major obstacle to research into potential industrial production algal strains, new methods are currently being developed to sidestep such research Bufalin (Guarnieri et al., 2011). Refinement of this technique could potentially enable large throughput screening of productive algal strains combined with the ability to elucidate the details of TAG biosynthesis for each individual algal species.
Conclusion Determining whether the multiple putative algal DGAT isoforms are functional DGATs via biochemical assays will be vital in our effort to genetically engineer algae to produce TAG on a large enough scale to make biodiesel production viable. As can be seen in O. tauri, it is possible that different DGAT2 isoforms may have different substrate preferences, which could lead to differential accumulation of TAG species. This may be a possible reason for the presence of multiple DGATs in unicellular algae. For the moment, we cannot discount the possibility that some of the algal DGAT2s may be MGATs or other members of the DGAT2 family and we will need to conduct biochemical assays on isolated DGAT2 proteins to determine their enzymatic characteristics. Moreover, an understanding of the relationship between the various DGAT activities and that of other enzymes of fatty acid and TAG biosynthesis such as PDAT as well as the regulatory controls operating on the pathway will be a vital step forward towards systematic genetic engineering of the TAG biosynthesis pathway.
Acknowledgements This work was supported by a Yousef Jameel Scholarship, administrated by the Cambridge Trusts. We are grateful to our colleagues, Dr. Sam Brockington and Dr. Matt Davey for contributing to fruitful discussion concerning phylogenetics and lipid metabolism respectively.
Introduction Psoralea corylifolia L. (Leguminosae), which called “Bu-Gu-Zhi” in China is an annual herbaceous plant distributed widely in Southeast Asia. Its seeds, known as Psoraleae Fructus, are traditionally used for the treatment of spermatorrhea, pollakiuria, asthma, and nephritis. A number of chemical constituents, including flavonoids, meroterpenes, bakuchiol and coumarins, have been isolated from this plant. Some of these compounds displayed a wide range of biological activities such as antioxidant [1], antibacterial [2], antiplatelet [3], anti-inflammatory [4], antidepressant-like [5], immunomodulatory and antitumor properties [6]. However, to the best of our knowledge, there is few report of the seeds of P. corylifolia eliciting glycosidase inhibition. Therefore, we consider about the preliminary study on DGAT activity of P. corylifolia.