Variations in structures and distributions of C25 highly branched isoprenoid (HBI) alkenes in cultures of the diatom, Haslea ostrearia (Simonsen)

摘要: Abstract The highly branched isoprenoid (HBI) alkenes of three batch cultures the diatom Haslea ostrearia have been examined and occurrence C 25 tri-, tetra- pentaenes confirmed. Growth outside at ambient temperature, under natural sunlight, in May (6 days) June (10 days) 1995 monitoring HBI concentrations samples collected daily stored frozen, revealed that greater HBIs ( ca 6500 fg cell −1 ) were produced than a much earlier stage growth. Furthermore, more unsaturated (predominantly tetraene rather triene). reasons for these differences are present unknown future investigations effect irradiance, salinity other environmental variables required. Such experiments may allow various distributions alga sediments to be better understood and, like some polyunsaturated lipids, become useful palaeoenvironmental indicators. Two previously unreported alkenes, 2,6,10,14-tetramethyl-7-(3-methylpent-4-enyl)pentadec-2,5,9,13-ene (GC retention index, 2201 DB-1 2,6,10,14-tetramethyl-7-(3-methylene pent-4-enyl)pentadec-2,5,9,13-ene RI, 2248 from culture grown October/November 1993 frozen over year, also isolated characterised by 13 1 H NMR, epoxide derivatisation mass spectrometry. structural characterisation studies should aid our understanding geochemical fate widely distributed hydrocarbons.