Project description:Relatively little is known about the presence and regulation of pathways involved in nutrient acquisition in the brown tide forming alga, Aureococcus anophagefferens. In this study, Long-SAGE (Serial Analysis of Gene Expression) was used to profile the A. anophagefferens transcriptome under nutrient replete (control), and nitrogen (N) and phosphorus (P) deficiency with the goal of understanding how this organism responds at the transcriptional level to varying nutrient conditions. This approach has aided A. anophagefferens genome annotation efforts and identified a suite of genes up-regulated by N and P deficiency, some of which have known roles in nutrient metabolism. Genes up-regulated under N deficiency include an ammonium transporter, an acetamidase/formamidase, and two peptidases. This suggests an ability to utilize reduced N compounds and dissolved organic nitrogen, supporting the hypothesized importance of these N sources in A. anophagefferens bloom formation. There are also a broad suite of P-regulated genes, including an alkaline phosphatase, and two 5’-nucleotidases, suggesting A. anophagefferens may use dissolved organic phosphorus under low phosphate conditions. These N- and P-regulated genes may be important targets for exploring nutrient controls on bloom formation in field populations.
Project description:Relatively little is known about the presence and regulation of pathways involved in nutrient acquisition in the brown tide forming alga, Aureococcus anophagefferens. In this study, Long-SAGE (Serial Analysis of Gene Expression) was used to profile the A. anophagefferens transcriptome under nutrient replete (control), and nitrogen (N) and phosphorus (P) deficiency with the goal of understanding how this organism responds at the transcriptional level to varying nutrient conditions. This approach has aided A. anophagefferens genome annotation efforts and identified a suite of genes up-regulated by N and P deficiency, some of which have known roles in nutrient metabolism. Genes up-regulated under N deficiency include an ammonium transporter, an acetamidase/formamidase, and two peptidases. This suggests an ability to utilize reduced N compounds and dissolved organic nitrogen, supporting the hypothesized importance of these N sources in A. anophagefferens bloom formation. There are also a broad suite of P-regulated genes, including an alkaline phosphatase, and two 5’-nucleotidases, suggesting A. anophagefferens may use dissolved organic phosphorus under low phosphate conditions. These N- and P-regulated genes may be important targets for exploring nutrient controls on bloom formation in field populations. Aureococcus anophagefferens CCMP 1984 was obtained from the Provasoli-Guillard Center for the Culture of Marine Phytoplankton (CCMP). The cultures were grown at 18C on a 14 h:10 h light:dark cycle (140 µmol quanta m-2 s-1). Nitrogen- and phosphate-replete (883 µM NO3- and 36.3 µM PO43-) cells, –N (40 µM NO3-) cells, and –P (1 µM PO43-) cells were grown in autoclaved L1 media with no Si (Guillard and Hargraves 1993), prepared using 0.2 µm filtered Vineyard Sound seawater. Vitamins (thiamine, biotin, and B12) were sterile filtered and added to the media after autoclaving. Replete cells were harvested during mid log phase of growth, while –N and –P cells were harvested at the onset of stationary phase when N or P was depleted.
Project description:Understanding strategy of nitrate and urea assimilation in a Chinese strain of Aureococcus anophagefferens through RNA-seq analysis
