Project description:In the absence of light, the heterotrophic microalga Crypthecodinium cohnii accumulates lipids rich in docosahexaenoic acid (DHA). However, limited genetic data restricts understanding of its metabolism, especially DHA synthesis with ethanol. Next-generation sequencing identified numerous transcripts for fatty acid and carbohydrate production. qRT-PCR confirmed increased expression of genes linked to energy, carbohydrate, lipid, terpenoid, and polyketide metabolism. Upregulation of genes in ethanol metabolism, fatty acid synthesis, glycerophospholipid, and pyruvate pathways raised acetyl-CoA and key metabolite precursors.
Project description:To overcome the inhibition caused by the fermentation supernatant in the late fermentation stage of docosahexaenoic acid (DHA)-producing Crypthecodinium cohnii, fermentation supernatant-based adaptive laboratory evolution (FS-ALE) was conducted. The cell growth and DHA productivity of the evolved strain (FS280) obtained after 280 adaptive cycles corresponding to 840 days of evolution were increased by 161.87% and 311.23%, respectively, at 72 h under stress conditions and increased by 19.87% and 51.79% without any stress compared with the starting strain, demonstrating the effectiveness of FS-ALE.
Project description:Chlorella sp. HS2 is a halotolerant microalga exhibiting relatively high biomass productivity and substantially high lipid accumulation in marine growth media, which suggests this alga as an important crop for industrial algal cultivation systems. To determine pathways leading to HS2's acclimation responses to salt stress, we performed RNA-seq analysis with triplicated cultures grown in freshwater and marine media at both exponential and stationary growth phases. We then run de novo assembly to obtain HS2 transcriptome, which in turn was annotated and processed to extract dysregulated pathways. Results showed a large proportion of down-regulated genes, for instance photosynthesis and TCA pathways. Photosynthesis appeared, however, to recover at the stationary phase, while the general down-regulation pattern was maintained.
Project description:Thraustochytrids of the genera Schizochytrium and Aurantiochytrium accumulate oils rich in the essential, marine n3 fatty acid docosahexaenoic acid (DHA). DHA production in Aurantiochytrium sp T66 was studied with the aim to provide more knowledge about factors that affect the DHA-productivities and the contributions of the two enzyme systems used for fatty acid synthesis in thraustochytrids, fatty acid synthetase (FAS) and PUFA-synthase. Fermentations with nitrogen starvation, which is well-known to initiate lipid accumulation in oleaginous organisms, were compared to fermentations with nitrogen in excess where lipid accumulation was obtained by oxygen limitation. The specific productivities of fatty acids originating from FAS were considerably higher under nitrogen starvation than with nitrogen in excess, while the specific productivities of DHA were the same at both conditions. Global transcriptome analysis showed significant up-regulation of FAS under N-deficient conditions, while the PUFA-synthase genes were only marginally upregulated. Neither of them was upregulated under O2-limitation where nitrogen was in excess, suggesting that N-starvation mainly affects the FAS and may be less important for the PUFA-synthase. The transcriptome analysis also revealed responses likely to be related to the generation of reducing power (NADPH) for fatty acid synthesis.
Project description:The molecular mechanisms through which dihydroartemisinin (DHA) induces immunomodulation in vivo remain unclear. Herein, DHA-regulated proteins and their phosphorylation profiles were identified and characterized, in the spleens of mice, using proteomics and phosphoproteomic approaches. We found that DHA upregulates proliferation-associated protein (cyclin-dependent kinases, Ki67, and mini-chromosome maintenance and proliferating cell nuclear antigen) expression via modulation of mitogen-activated protein kinase (MAPK) - activator protein 1 (AP-1) signaling pathway activity. In addition, DHA promoted the proliferation of CD4 T naïve, proliferated CD25+CD4+ T-cells, and BrdU+ interferon (IFN)-γ-producing CD8+ T cells. These predicted mechanisms of action were then validated in a Plasmodium berghei ANKA-infected mouse model of malaria and a cyclophosphamide-induced immunosuppression model. Collectively, the findings of this study, for the first time, provide robust evidence that DHA induced the expansion of the splenic T-cell pool through MAPK-AP1 signaling. The data provided in-depth knowledge in the mechanism of DHA-mediated immunomodulation.
