Diacylglycerol acyltransferase (DGAT) is a key for the synthesis of triacylglycerol (TAG) from diacylglycerol in the unicellular green alga Chlamydomonas reinhardtii.Acetyl-CoA carboxylase (ACCase) and fatty acid synthase (FAS) are responsible for the synthesis of fatty acids. We found the TAG and fatty acid synthesis related genes in C. reinhardtii, including five DGAT (DGAT1 (JGI 184281), DGAT2 (JGI 400751), DGAT3 (JGI 285889), DGAT4 (JGI 141301), and DGAT5 (JGI 190539)), three £] ketoacyl-ACP reductase isoforms ( (JGI 153976), (JGI 153976), and (JGI 194728)) and two £] ketoacyl-ACP synthase isofroms ( (JGI 139619) and (JGI 205887)) for FAS, and ACC £\ (NCBI XP_001696945.1), ACC £] (NCBI XP_001703187.1) and ACC biotin carboxylase ( NCBI XP_001702319.1)) for ACCase in C. reinhardtii. This investigation designed the primers of the above genes to determine whether acetate influences their mRNA expression levels in cell-wall less strain CC400 in the nitrogen starvation condition. The results showed that the absence of nitrogen in the medium triggered the lipid accumulation for the strains of CC400 in the condition of 50 £gE light. DGAT3 mRNA levels were increased by nitrogen starvation. For the FAS genes, in the strain of CC400 showed no increased mRNA levels upon exposure to nitrogen starvation. The mRNA levels of ACC£\, ACC £] and ACC biotin carboxylase were more or less decreased by nitrogen starvation in CC400 strains. Thus, the responses of DGAT gene expression to acetate supplement were checked. The absence of acetate from the medium partly inhibited the nitrogen starvation induced increases in lipid and DGAT3 mRNA levels, and the mRNA levels of DGAT1 and DGAT2 in the nitrogen starvation condition. However, DGAT4 mRNA levels were significantly induced by the absence of acetate from the medium. In conclusion, the present study demonstrate that acetate is required for the nitrogen starvation induced DGAT3 gene expression (mRNA levels) and lipid accumulation in C. reinhardtii.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0901110-011346 |
| Date | 01 September 2010 |
| Creators | Wu, Pei-shan |
| Contributors | Yi-Ting Hsu, Lu-Te Chuang, Tse-Min Lee |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0901110-011346 |
| Rights | not_available, Copyright information available at source archive |
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