Dataset: Grazing experiment 6: cell lipids

The phytoplankton Rhodomonas sp. CCMP 755 was grown semi-continuously in atmosphere controlled chambers at three different CO2 treatment concentrations; Ambient (400ppmv), Moderate (750ppmv), and High (1000ppmv).  Cultures were diluted daily starting day 4 with pre-equilibrated media containing f/50 nutrients.  Some of the culture removed was used to evaluate chemical parameters.  Samples for lipid mass were collected on day 16.  Samples were filtered onto muffled glass fiber filters, wrapped in muffled foil and flash frozen on dry ice.  Samples were then stored at    -80° C until analysis.  Filters were transferred to a tissue grinder containing 1.9 ml of 1:2 v/v CHCl3: MeOH and 0.125 ml deionized water.  Filters were homogenized with the solution and transferred to a clean glass culture tube and vortexed for 1 minute.  Samples were then sonicated in a water bath at room temperature for 10 minutes and then centrifuged at 2000 rpm for 10 minutes.  The supernatant was then transferred to another glass culture tube and 0.625 ml of CHCl3 and 0.625 ml deionized water were added and then centrifuged another 10 minutes.  The samples were now separated into two phases and the bottom organic phase was collected using a Pasteur pipet and transferred to a pre-weighed glass culture tube.  Samples were evaporated with nitrogen gas to dryness and weighed to determine total cellular lipid mass.