Elucidating lipid metabolism in Chlamydomonas

Keith P. Alden1, Hui Qing Lim1, Gerald Goh1, Rajoshi Ghosh1, Markus R. Wenk2, and Neil D. Clarke1

1) Genome Institute of Singapore, Biopolis, Singapore 138672 2) Department of Biochemistry, National University of Singapore, Singapore 117597

Algae can potentially produce 10 to 100 times more triacylglycerides (TAGs) per hectare than crops such as rapeseed or soybean, and can be grown on non-arable land or in extremes of pH or salinity. Despite their huge potential as a feedstock for fuel production very little is known about the regulation of lipid metabolism in algae. In order to develop an understanding of lipid metabolism in green algae we are taking a systems biology approach using the model organism, Chlamydomonas reinhardtii. We have developed a high-throughput lipid assay for screening cells grown under differing conditions. This screen was used to identify a nutrient starvation regime that produced high levels of TAGs which we later used for transcriptome analysis with microarray and RNAseq. In order to characterize the genes of interest from our transcriptome analyses we have been utilising microRNA mediated gene expression knockdown followed by phenotype array analysis and mass spectrometry of lipid extracts to identify chain lengths and degrees of saturation from the knockdown strains. This has allowed us to begin generating a database of lipid-relevant Chlamydomonas genes, and to map these genes to particular steps in metabolic pathways.

e-mail address of presenting author: aldenk@gis.a-star.edu.sg