Involvement of phosphatidate phosphatase in the biosynthesis of triacylglycerols in Chlamydomonas reinhardtii

Lipid biosynthesis is essential for eukaryotic cells, but the mechanisms of the process in microalgae remain poorly understood. Phosphatidic acid phosphohydrolase or 3-sn-phosphatidate phosphohydrolase(PAP) catalyzes the dephosphorylation of phosphatidic acid to form diacylglycerols and inorganic orthophosphates. This reaction is integral in the synthesis of triacylglycerols. In this study, the mRNA level of the PAP isoform CrPAP2 in a species of Chlamydomonas was found to increase in nitrogen-free conditions. Silencing of the CrPAP2 gene using RNA interference resulted in the decline of lipid content by 2.4%–17.4%. By contrast, over-expression of the CrPAP2 gene resulted in an increase in lipid content by 7.5%–21.8%. These observations indicate that regulation of the CrPAP2 gene can control the lipid content of the algal cells. In vitro CrPAP2 enzyme activity assay indicated that the cloned CrPAP2 gene exhibited biological activities.

The Roles of acyI-CoA： Diacylglycerol Acyltransferase 2 Genes in the Biosynthesis of Triacylglycerols by the Green Algae Chlamydomonas reinhardtii

Dear Editor, Triacylglycerols （triglycerides） （TAGs）, as the major storage forms of energy, mainly are stored in adipocytes, myocytes, enterocytes, hepatocytes, and mammary epithelial cells in mammals, oilseeds in plants, and lipid droplets in microorgan- isms （Yen et al., 2008）. Aside from energy storage, TAGs have essential functions in multiple physiological processes. In plants, TAGs are crucial for seed oil accumulation, germina- tion, and seedling development （Zhang et al., 2005, 2009）. Notably, TAGs derived from plants and microorganisms could serve as the feedstock for biofuels production （Deng et al., 2009）. Therefore, understanding of the molecular basis of TAGs bio- synthesis and storage is of considerable economic importance.

In vitro Transient Expression System of Latex C-serum was used for Analysis of Hevein Promoter in Response to Abscisic Acid in Hevea brasiliensis

Hevein has been found to be an essential element in coagulation of rubber particles in latex of rubber trees. In a previous study, we cloned a 1 241-bp fragment of a 5＇ upstream region of the hevein gene by genome walking. This fragment was analyzed by a 5＇ end nested deletion method in the present study, fused with a uidA （gus） gene to produce a series of tested constructs, which were transferred into C-serum of latex and the Gus activities were detected. Results showed that the fragment from -749 to -292 was sufficient for expression of gus gene in latex, and the fragment from -292 to -168 was crucial in response to abscisic acid inducement. In a transient transgenic test of rubber leaf with particle bombardment, construct Hev749 conferred gus-specific expression in veins, in which the latex tubes mainly distributed. This implies that the fragment from -749 to -292 was laticiferous-specific.