PANGAEA_987865 Relative proportions of sterols in Melosira assemblages, and subsequently isolated unialgal cultures collected in June 2023 during the RV Kronprins Haakon cruise 2023-1 in Fram Strait Leu, Eva; Šupraha, Luka; Graeve, Martin; Fahl, Kirsten; Müller, Anja; Müller, Juliane; Lunden, Jonas; Woll, Matthias; Kohlbach, Doreen Relative proportions of sterols in Melosira assemblages, and subsequently isolated unialgal cultures collected in June 2023 during the RV Kronprins Haakon cruise 2023-1 in Fram Strait 2026-01-07 PANGAEA Dataset https://doi.pangaea.de/10.1594/PANGAEA.987865 Investigator Eva Leu eva.leu@akvaplan.niva.no Earth Science Event label Station label Type of study Sample code/label DEPTH, water Depth comment Genus, unique identification Genus, unique identification (Semantic URI) Genus, unique identification (URI) 24-Methylcholesta-5,22E-dien-3beta-ol 24-methylcholest-5-en-3beta-ol 3beta-Stigmast-5-en-3-ol Cholesta-5,24-dien-3beta-ol Date/time start, experiment Date/time end, experiment Experimental treatment Treatment: temperature Treatment: salinity Treatment: nitrate Treatment: silicate Treatment: phosphate geoscientificInformation AO2023-1 AO2023-1_MA1 Arctic microalgae Hand pump Melosira Standard cultivation Sterols trophic markers Reference in WoRMS Gas chromatograph-mass spectrometer Unialgal cultures cultivation Kronprins Haakon 2023-06-18 2023-06-18 Complete 78.9397 78.9397 -2.1387 -2.1387 0.0 m (DEPTH, water) 0.0 m (DEPTH, water) access rights needed CC-BY-4.0: Creative Commons Attribution 4.0 International (License comes into effect after moratorium ends) English PANGAEA Data Publisher for Earth & Environmental Science https://www.pangaea.de/ Data Center Contact Michael Diepenbroek info@pangaea.de

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Bremen Bremen 28359 Germany online 171 data points text/tab-separated-values Kohlbach, Doreen; Kunisch, Erin H; Graeve, Martin; Fahl, Kirsten; Müller, Anja; Müller, Juliane; Lunden, Jonas; Woll, Matthias; Leu, Eva (submitted): Melosira arctica: algal superfood or nutritional dead-end for Arctic grazers? Elementa - Science of the Anthropocene Folch, Jordi; Lees, M; Sloane Stanley, G H (1957): A simple method for the isolation and purification of total lipides from animal tissues. Journal of Biological Chemistry, 226(1), 497-509, https://doi.org/10.1016/S0021-9258(18)64849-5 Stein, Ruediger; Frederichs, Thomas; Fahl, Kirsten; Geibert, Walter; Matthiessen, Jens; Niessen, Frank; Vogt, Christoph; Sassenroth, Cynthia; Bazhenova, Evgenia A (2025): A 430 kyr record of ice-sheet dynamics and organic-carbon burial in the central Eurasian Arctic Ocean. Nature Communications, 16(1), 3822, https://doi.org/10.1038/s41467-025-59112-7

During the AO2023-1 expedition (1-21 June 2023), Melosira assemblages were collected using a handpump at a sampling site in Fram Strait. In addition to performing physiological measurements and filtering the material for trophic markers (fatty acids, stable isotope ratios of fatty acids, sterols and highly branched isoprenoids (HBIs), living material was brought back to Akvaplan-niva in Oslo and two strains were established as unialgal cultures. The cultures are maintained in artificial seawater-based L1 medium at 4°C and 25 µmol m-2 s-1 light with a 16:8 L:D cycle. Lipids were extracted from freeze-dried samples following the method of Folch et al. (1957), using a dichloromethane/methanol mixture (2:1, v/v) in a sonication bath. Thereafter, lipids were saponified with 20% potassium hydroxide in water/methanol (1:9). Sterols were extracted with hexane, purified by open-column chromatography with SiO2 and eluted with methanol. Sterol fractions were derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). Sterols were analyzed with gas chromatography–mass spectrometry (Agilent 7890B, Agilent Technologies), equipped with a DB-1ms column (30 m length, 0.25 mm internal diameter, 0.25 μm film thickness) and an Agilent 5977A MSD, following Stein et al. (2025). The temperature program ranged from 60°C to 320°C. Sterols were quantified using an internal standard (androstanol). Sterol analysis was conducted to complement datasets on fatty acid proportions and fatty acid stable isotope compositions. Collectively, the datasets enable a detailed characterization of the biochemical composition of different Melosira arctica-dominated algal assemblages from the Arctic Ocean, and a comparison with a unialgal culture of this important species. ** For all details see the full metadata description at "https://doi.pangaea.de/10.1594/PANGAEA.987865"!

http://en.wikipedia.org/wiki/Fram_Strait Fram Strait https://doi.org/10.1016/S0021-9258(18)64849-5 A simple method for the isolation and purification of total lipides from animal tissues https://doi.org/10.1038/s41467-025-59112-7 A 430 kyr record of ice-sheet dynamics and organic-carbon burial in the central Eurasian Arctic Ocean https://npolar.no/en/kronprins-haakon/ Kronprins Haakon https://www.marinespecies.org Reference in WoRMS DIF 9.4 2026-01-07 2026-02-15