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  • 2015-2019  (9)
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  • 1
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    Formation and mosaicity of coccolith segment calcite of the marine algae Emiliania huxleyi (2018)
    Wiley
    In:  Journal of Phycology, 54 (1). pp. 85-104.
    Details
    Publication Date: 2021-02-08
    Description: Coccolithophores belong to the most abundant calcium carbonate mineralizing organisms. Coccolithophore biomineralization is a complex and highly regulated process, resulting in a product that strongly differs in its intricate morphology from the abiogenically produced mineral equivalent. Moreover, unlike extracellularly formed biological carbonate hard tissues, coccolith calcite is neither a hybrid composite, nor is it distinguished by a hierarchical microstructure. This is remarkable as the key to optimizing crystalline biomaterials for mechanical strength and toughness lies in the composite nature of the biological hard tissue and the utilization of specific microstructures. To obtain insight into the pathway of biomineralization of Emiliania huxleyi coccoliths, we examine intracrystalline nanostructural features of the coccolith calcite in combination with cell ultrastructural observations related to the formation of the calcite in the coccolith vesicle within the cell. With TEM diffraction and annular dark-field imaging, we prove the presence of planar imperfections in the calcite crystals such as planar mosaic block boundaries. As only minor misorientations occur, we attribute them to dislocation networks creating small-angle boundaries. Intracrystalline occluded biopolymers are not observed. Hence, in E. huxleyi calcite mosaicity is not caused by occluded biopolymers, as it is the case in extracellularly formed hard tissues of marine invertebrates, but by planar defects and dislocations which are typical for crystals formed by classical ion-by-ion growth mechanisms. Using cryo-preparation techniques for SEM and TEM, we found that the membrane of the coccolith vesicle and the outer membrane of the nuclear envelope are in tight proximity, with a well-controlled constant gap of ~4 nm between them. We describe this conspicuous connection as a not yet described interorganelle junction, the “nuclear envelope junction”. The narrow gap of this junction likely facilitates transport of Ca2+ ions from the nuclear envelope to the coccolith vesicle. On the basis of our observations, we propose that formation of the coccolith utilizes the nuclear envelope–endoplasmic reticulum Ca2+-store of the cell for the transport of Ca2+ ions from the external medium to the coccolith vesicle and that E. huxleyi calcite forms by ion-by-ion growth rather than by a nanoparticle accretion mechanism.
    Type: Article , PeerReviewed
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  • 2
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    Long-term dynamics of adaptive evolution in a globally important phytoplankton species to ocean acidification (2016)
    AAAS (American Association for the Advancement of Science)
    In:  Science Advances, 2 (7). e1501660-e1501660.
    Details
    Publication Date: 2019-10-17
    Description: Marine phytoplankton may adapt to ocean change, such as acidification or warming, because of their large population sizes and short generation times. Long-term adaptation to novel environments is a dynamic process, and phenotypic change can take place thousands of generations after exposure to novel conditions. We conducted a long-term evolution experiment (4 years = 2100 generations), starting with a single clone of the abundant and widespread coccolithophore Emiliania huxleyi exposed to three different CO2 levels simulating ocean acidification (OA). Growth rates as a proxy for Darwinian fitness increased only moderately under both levels of OA [+3.4% and +4.8%, respectively, at 1100 and 2200 μatm partial pressure of CO2 (Pco2)] relative to control treatments (ambient CO2, 400 μatm). Long-term adaptation to OA was complex, and initial phenotypic responses of ecologically important traits were later reverted. The biogeochemically important trait of calcification, in particular, that had initially been restored within the first year of evolution was later reduced to levels lower than the performance of nonadapted populations under OA. Calcification was not constitutively lost but returned to control treatment levels when high CO2–adapted isolates were transferred back to present-day control CO2 conditions. Selection under elevated CO2 exacerbated a general decrease of cell sizes under long-term laboratory evolution. Our results show that phytoplankton may evolve complex phenotypic plasticity that can affect biogeochemically important traits, such as calcification. Adaptive evolution may play out over longer time scales (〉1 year) in an unforeseen way under future ocean conditions that cannot be predicted from initial adaptation responses.
    Type: Article , PeerReviewed
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  • 3
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    Swift thermal reaction norm evolution in a key marine phytoplankton species (2016)
    Wiley
    In:  Evolutionary Applications, 9 (9). pp. 1156-1164.
    Details
    Publication Date: 2019-09-23
    Description: Temperature has a profound effect on the species composition and physiology of marine phytoplankton, a polyphyletic group of microbes responsible for half of global primary production. Here, we ask whether and how thermal reaction norms in a key calcifying species, the coccolithophore Emiliania huxleyi, change as a result of 2.5 years of experimental evolution to a temperature ≈2°C below its upper thermal limit. Replicate experimental populations derived from a single genotype isolated from Norwegian coastal waters were grown at two temperatures for 2.5 years before assessing thermal responses at 6 temperatures ranging from 15 to 26°C, with pCO2 (400/1100/2200 μatm) as a fully factorial additional factor. The two selection temperatures (15°/26.3°C) led to a marked divergence of thermal reaction norms. Optimal growth temperatures were 0.7°C higher in experimental populations selected at 26.3°C than those selected at 15.0°C. An additional negative effect of high pCO2 on maximal growth rate (8% decrease relative to lowest level) was observed. Finally, the maximum persistence temperature (Tmax) differed by 1–3°C between experimental treatments, as a result of an interaction between pCO2 and the temperature selection. Taken together, we demonstrate that several attributes of thermal reaction norms in phytoplankton may change faster than the predicted progression of ocean warming.
    Type: Article , PeerReviewed
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  • 4
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    Long-term dynamics of adaptive evolution in a globally important phytoplankton species to ocean acidification (2016)
    American Association for the Advancement of Science
    Details
    Publication Date: 2016-07-29
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science
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  • 5
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    Long-term adaptation of the coccolithophore Emiliania huxleyi to ocean acidification and global warming (2016)
    Details
    Publication Date: 2022-11-02
    Description: This Thesis summarizes the adaptive effects of ocean acidification and global warm on the coccolithophore Emiliania huxleyi. The adaptive effects were experimentally assessed in a long term evolutionary experiment. After 2100 asexual generations of selection to CO2 the fitness (growth rate) increased slightly over time under 1100 µatm pCO2. Under 2200 µatm pCO2 the fitness advantage of 5% at 500 generations remained unchanged. The phenotypic trait of calcification was partly restored within 500 generations. Thereafter, calcification was reduced in response to selection. The reduction of calcification was not constitutively, as the calcite per cell quotas were restored when assessed with 400 µatm pCO2. Temperature adaptation occurred independently of ocean acidification levels. The fitness increase in growth rate due was up to 16% in populations adapted to high temperature and high CO2 compared to not adapted cells under selection conditions. The ratio of particular inorganic (PIC) and organic carbon (PIC:POC) recovered to their initial ratio after temperature adaptation, even under elevated CO2. Cells evolved to a smaller size accompanied by a reduction in POC-content. Production rates were restored to values under present-day ocean conditions, owing to adaptive evolution in growth rate. Temperature adaptation increased the effect on persisting CO2 adaptation in growth rate. The immediate physiological effect on PIC per cell was diminished compared to the lower temperature treatment, and so were the adaptive effects. Temperature adaptation reduced the negative effects of ocean acidification. Both adaptations were necessary to receive the full fitness effect under high-temperature-high-CO2-conditions. As consequence both adaptive effects are additive. Global warming may reduce the adverse effects of ocean acidification on E. huxleyi populations. My results show further, that marine phytoplankton may evolve changes in the plastic response under future ocean conditions.
    Type: Thesis , NonPeerReviewed
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  • 6
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    Long-term dynamics of adaptive evolution in a globally important coccolithophore to ocean acidification: timeseries growth rates (2015)
    PANGAEA
    Details
    Publication Date: 2023-10-23
    Keywords: Carbon dioxide, partial pressure; DATE/TIME; Growth rate; Number of batch; Replicate; Temperature, water
    Type: Dataset
    Format: text/tab-separated-values, 26184 data points
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  • 7
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    Long-term dynamics of adaptive evolution in a globally important coccolithophore to ocean acidification (2015)
    PANGAEA
    In:  Supplement to: Schlüter, Lothar; Lohbeck, Kai T; Gröger, Joachim P; Riebesell, Ulf; Reusch, Thorsten B H (2016): Long-term dynamics of adaptive evolution in a globally important phytoplankton species to ocean acidification. Science Advances, 2(7), e1501660-e1501660, https://doi.org/10.1126/sciadv.1501660
    Details
    Publication Date: 2023-10-23
    Description: Recent evolution experiments have revealed that marine phytoplankton may adapt to global change, for example to ocean warming or acidification. Long-term adaptation to novel environments is a dynamic process and phenotypic change can take place thousands of generations after exposure to novel conditions. Using the longest evolution experiment performed in any marine species to date (4 yrs, = 2100 generations), we show that in the coccolithophore Emiliania huxleyi, long-term adaptation to ocean acidification is complex and initial phenotypic responses may revert for important traits. While fitness increased continuously, calcification was restored within the first 500 generations but later reduced in response to selection, enhancing physiological declines of calcification in response to ocean acidification. Interestingly, calcification was not constitutively reduced but revealed rates similar to control treatments when transferred back to present-day CO2 conditions. Growth rate increased with time in controls and adaptation treatments, although the effect size of adaptation assessed through reciprocal assay experiments varied. Several trait changes were associated with selection for higher cell division rates under laboratory conditions, such as reduced cell size and lower particulate organic carbon content per cell. Our results show that phytoplankton may evolve phenotypic plasticity that can affect biogeochemically important traits, such as calcification, in an unforeseen way under future ocean conditions.
    Keywords: BIOACID; Biological Impacts of Ocean Acidification
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    Format: application/zip, 3 datasets
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  • 8
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    Long-term dynamics of adaptive evolution in a globally important coccolithophore to ocean acidification: timeseries cell size (2015)
    PANGAEA
    Details
    Publication Date: 2023-10-23
    Keywords: Carbon dioxide, partial pressure; Cell size; DATE/TIME; Number of batch; Replicate; Temperature, water
    Type: Dataset
    Format: text/tab-separated-values, 20383 data points
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  • 9
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    Long-term dynamics of adaptive evolution in a globally important coccolithophore to ocean acidification: timeseries carbonate (2016)
    PANGAEA
    Details
    Publication Date: 2024-03-15
    Keywords: Alkalinity, total; Aragonite saturation state; Bicarbonate ion; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, particulate; Carbon, inorganic, particulate, per cell; Carbon, organic, particulate; Carbon, organic, particulate, per cell; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, partial pressure; Cell, diameter; Chromista; Emiliania huxleyi; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Generation; Growth, relative; Growth/Morphology; Haptophyta; Laboratory experiment; Laboratory strains; Light intensity; Nitrogen, organic, particulate, per cell; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Organisms; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Particulate inorganic carbon/particulate organic carbon ratio; Pelagos; pH; Phytoplankton; Replicate; Salinity; Single species; Species; Temperature, water
    Type: Dataset
    Format: text/tab-separated-values, 5172 data points
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