Simultaneous Effects of Light Intensity and Phosphorus Supply on the Sterol Content of Phytoplankton

Sterol profiles of microalgae and their change with environmental conditions are of great interest in ecological food web research and taxonomic studies alike. Here, we investigated effects of light intensity and phosphorus supply on the sterol content of phytoplankton and assessed potential interactive effects of these important environmental factors on the sterol composition of algae. We identified sterol contents of four common phytoplankton genera, Scenedesmus, Chlamydomonas, Cryptomonas and Cyclotella, and analysed the change in sterol content with varying light intensities in both a high-phosphorus and a low-phosphorus approach. Sterol contents increased significantly with increasing light in three out of four species. Phosphorus-limitation reversed the change of sterol content with light intensity, i.e., sterol content decreased with increasing light at low phosphorus supply. Generally sterol contents were lower in low-phosphorus cultures. In conclusion, both light and phosphorus conditions strongly affect the sterol composition of algae and hence should be considered in ecological and taxonomic studies investigating the biochemical composition of algae. Data suggest a possible sterol limitation of growth and reproduction of herbivorous crustacean zooplankton during summer when high light intensities and low phosphorus supply decrease sterol contents of algae

STEROLS OF TETRASELMIS (PRASINOPHYCEAE)

1. Sterols were identified from 11 isolates of Tetraselmis, a unicellular Prasinophyte alp used frequently as food in mariculture. 2. The principal sterol in eight isolates was either 24-methylenecholesterol or 24-methylcholesterol; the latter was determined to be campesterol in all cases. 3. Campesterol is the first 24alpha sterol to be reported in the Prasinophyceae. 4. In the remaining three isolates, cholesterol was the principal sterol with smaller amounts of 24-methylenecholesterol and campesterol present; in two of these strains total sterol approached 3% of dry weight. 5. This is the first report of cholesterol as the principal sterol of a Prasinophyte; the C28 sterols found in Tetraselmis are the dominant sterols in most Prasinophyceae studied to date

MS-DIAL: data-independent MS/MS deconvolution for comprehensive metabolome analysis

Data-independent acquisition (DIA) in liquid chromatography tandem mass spectrometry (LC-MS/MS) provides more comprehensive untargeted acquisition of molecular data. Here we provide an open-source software pipeline, MS-DIAL, to demonstrate how DIA improves simultaneous identification and quantification of small molecules by mass spectral deconvolution. For reversed phase LC-MS/MS, our program with an enriched LipidBlast library identified total 1,023 lipid compounds from nine algal strains to highlight their chemotaxonomic relationships