Cold-induced metabolic conversion of haptophyte di- to tri-unsaturated C37 alkenones used as palaeothermometer molecules

Kitamura, Eri; Kotajima, Tomonori; Sawada, Ken; Suzuki, Iwane; Shiraiwa, Yoshihiro

doi:10.1038/s41598-018-20741-2

Cited by 11 publications

(4 citation statements)

References 45 publications

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“…The difference in δ 2 H ratios between the two alkenones is known to be quite variable (D'Andrea et al, ; Schwab & Sachs, ; van der Meer et al, ; Wolhowe et al, ). The C 37:3 is synthesized from the C 37:2 , and at colder temperatures there is a lower relative abundance of the C 37:2 (Endo et al, ; Kitamura et al, ). Normally, the synthesis of C 37:3 from a C 37:2 causes a depletion of the C 37:3 , leaving the C 37:2 relatively enriched, since desaturation is associated with isotopic depletion (Chikaraishi et al, ).…”

Section: Resultsmentioning

confidence: 99%

Paleosensitivity of Hydrogen Isotope Ratios of Long‐Chain Alkenones to Salinity Changes at the Chile Margin

Weiss

Bar

Stolwijk

et al. 2019

Paleoceanog and Paleoclimatol

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Hydrogen isotope ratios of long-chain alkenones (δ 2 H C37 ratios) have been shown to correlate with salinity in several culture studies. However, it is uncertain how applicable the δ 2 H C37 -salinity relationship is to reconstruct past salinity. The δ 2 H C37 ratios were measured on sediments from a drill core (ODP site 1234) at the Chilean Margin covering the last~150 kyr. High δ 2 H C37 values corresponded to glacial time periods and interglacial periods are characterized by lower δ 2 H C37 values, aligning with δ 18 O ratios measured on planktonic foraminifera from the same core. Effects of parameters such as species composition, the δ 2 H-δ 18 O relationship used for ice volume corrections, and nutrient-or light-controlled growth rate, did not appear to significantly alter δ 2 H C37 ratios at ODP 1234. We used linear regression equations from batch culture experiments, marine surface sediments, and suspended particulate organic matter to quantitatively characterize salinity changes over the last~150 kyr at ODP 1234. However, most of these equations yielded larger salinity shifts than previously suggested, a phenomenon also observed for other δ 2 H C37 records. This suggests that the paleosensitivity of δ 2 H C37 ratios to salinity was larger in the geologic record than has been observed in any modern environment or laboratory settings, or that glacial to interglacial salinity shifts might have been larger than currently believed.

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Section: Resultsmentioning

confidence: 99%

Paleosensitivity of Hydrogen Isotope Ratios of Long‐Chain Alkenones to Salinity Changes at the Chile Margin

Weiss

Bar

Stolwijk

et al. 2019

Paleoceanog and Paleoclimatol

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“…and E. huxleyi under ocean-related global change scenarios ( Table 2). The low availability or absence of dietary sterols has been shown to constrain growth, reproduction and survival in Daphnia (Martin-Creuzburg et al, 2005;Martin-Creuzburg and von Elert, 2009a), and development and egg production in copepods (Hassett, 2004;Klein-Breteler et al, 2005). The potential influence of sterol deficiency on ecosystem functioning is the reduction of carbon transfer efficiency across autotroph-herbivore interface, leading to a low production of higher trophic levels (von Elert et al, 2003;Martin-Creuzburg and von Elert, 2009b).…”

Section: Implications For Ecology and Biogeochemistrymentioning

confidence: 99%

“…Long-chain alkenones are major lipids produced only by certain species of haptophytes, e.g., oceanic species Emiliania huxleyi and Gephyrocapsa oceanica (Conte et al, 1995;Volkman et al, 1980c) and coastal species Isochrysis galbana (reviewed by Conte et al, 1994). Alkenones in E. huxleyi are believed to be used for energy storage (Eltgroth et al, 2005;Epstein et al, 2001), while little is known about the entire biosynthetic pathway of alkenones and their evolutionary and ecological functions (Rontani et al, 2006;Kitamura et al, 2018). Alkenones may have fitness and trophic benefit for their producers, because these unusual lipids are not only more photostable than other neutral lipids such as triacylglycerols, but also resistant to digestion, perhaps making alkenone producers less suitable for grazers (Eltgroth et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Ocean-related global change alters lipid biomarker production in common marine phytoplankton

Bi¹,

Ismar-Rebitz²,

Sommer³

et al. 2020

Preprint

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Abstract. Global change concurrently alters multiple environmental factors, with uncertain consequences for marine ecosystems. Lipids, in their function as trophic markers in food webs and organic matter source indicators in water column and sediments, provide a tool for reconstructing the complexity of global change effects. It remains unclear how ongoing changes in multiple environmental drivers affect the production of key lipid biomarkers in marine phytoplankton. Here, we tested the responses of sterols, alkenones and fatty acids (FAs) in the diatom Phaeodactylum tricornutum, the cryptophyte Rhodomonas sp. and the haptophyte Emiliania huxleyi under a full-factorial combination of three temperatures (12, 18 and 24 °C), three N : P supply ratios (molar ratios 10 : 1, 24 : 1 and 63 : 1) and two pCO2 levels (560 and 2400 µatm) in semi-continuous culturing experiments. Overall, N and P deficiency had a stronger effect on per-cell contents of sterols, alkenones and FAs than warming and enhanced pCO2. Specifically, P deficiency caused an overall increase in biomarker production in most cases, while N deficiency, warming and high pCO2 caused non-systematic changes. Under future ocean scenarios, we predict an overall decrease in carbon-normalized contents of sterols and polyunsaturated fatty acids (PUFAs) in E. huxleyi and P. tricornutum, and a decrease in sterols but an increase in PUFAs in Rhodomonas sp. Variable contents of lipid biomarkers indicate a diverse carbon allocation between marine phytoplankton species in response to changing environments. Thus, it is necessary to consider the changes in key lipids and their consequences for food web dynamics and biogeochemical cycles, when predicting the influence of global change on marine ecosystems.

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“…The relative abundance of the C37:3 and C37:2 alkenones are strongly coupled to temperature, with higher amounts of the C37:2 at higher temperatures (Prahl and Wakeham, 1987). The C37:3 is synthesized from the C37:2 by a desaturation step (Rontani et al, 2006;Endo et al, 2018;Kitamura et al, 2018), which occurs less often at higher temperatures. Desaturation is associated with 2 H depletion (Chikaraishi et al, 2004), thus it follows that the C37:3 alkenone should be more depleted than its C37: 2 5 precursor, as observed here (Fig.…”

Section: Effects Of Temperature For T Lutea Alkenonesmentioning

confidence: 99%

Impact of metabolic pathways and salinity on the hydrogen isotope ratios of haptophyte lipids

Weiss

Chivall

Kasper

et al. 2019

Preprint

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Hydrogen isotope ratios of biomarkers have been shown to reflect water isotope ratios, and in some cases correlate significantly with salinity. The δ 2 H-salinity relationship is best studied for long-chain alkenones, biomarkers for haptophyte 20 algae, and is known to be influenced by a number of different environmental parameters. It is not fully known why δ 2 H ratios of lipids retain a correlation to salinity, and whether this is a general feature for other lipids produced by haptophyte algae.Here, we analyzed δ 2 H ratios of three fatty acids, brassicasterol, long-chain C37 alkenones and phytol from three different haptophyte species grown over a range of salinities. Lipids synthesized in the cytosol, or relying on precursors of cytosolic origin, show a correlation between their δ 2 H ratios and salinity. In contrast, biosynthesis in the chloroplast, or utilizing 25 precursors created in the chloroplast, yields lipids that do not show a correlation between δ 2 H ratios and salinity. This leads to the conclusion that location of metabolism is the first-order control on the salinity signal retained in δ 2 H ratios of certain lipids.Additionally, we found that δ 2 H ratios of alkenones from batch cultures of the Group II haptophyte species Tisochrysis lutea correlate positively with temperature, contrary to findings from cultures of Group III haptophytes, but retain a similar response to nutrient availability in line with other Group III haptophytes. 30 Biogeosciences Discuss., https://doi.

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Cold-induced metabolic conversion of haptophyte di- to tri-unsaturated C37 alkenones used as palaeothermometer molecules

Cited by 11 publications

References 45 publications

Paleosensitivity of Hydrogen Isotope Ratios of Long‐Chain Alkenones to Salinity Changes at the Chile Margin

Paleosensitivity of Hydrogen Isotope Ratios of Long‐Chain Alkenones to Salinity Changes at the Chile Margin

Ocean-related global change alters lipid biomarker production in common marine phytoplankton

Impact of metabolic pathways and salinity on the hydrogen isotope ratios of haptophyte lipids

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