@article {kusch_dead_2019, title = {Dead in the Water: The Vicious Cycle of Blanks During Natural Level 14 C Manipulation of Marine Algal Cultures}, journal = {Frontiers in Marine Science}, volume = {6}, year = {2019}, note = {Publisher: Frontiers}, abstract = {Authentic biomarker standards were obtained from algal cultures in an attempt to accurately determine blank C added during sample processing for compound-specific radiocarbon analysis. Emiliania huxleyi and Thalassiosira pseudonana were grown under manipulated Δ14C dissolved inorganic carbon (DIC) levels and chlorophyll a and either alkenones (E. huxleyi) or low molecular weight (LMW) alkanoic acids (T. pseudonana) were isolated from the respective biomass using preparative liquid chromatography (LC), wet chemical techniques or preparative gas chromatography, respectively. DI14C in the seawater medium was determined pre- and post-growth. Biomarker Δ14C values mostly agree within 1-2? analytical uncertainties. In those cases where biomarker Δ14C values differ significantly, chlorophyll a is up to 104{\textperthousand} more 14C-depleted than alkenones or LMW alkanoic acids, consistent with a larger LC blank compared to the other purification methods. However, in the majority of experimental setups pre- and post-growth DIC Δ14C values seem to be compromised by an unknown and variable blank C contribution. DIC Δ14C values deviate strongly from the anticipated Δ14C values (by up to ca. 560{\textperthousand}), pre- and post-growth Δ14C values differ significantly (by up to ca. 460{\textperthousand}), and changes are not unidirectional. Accordingly, since the substrate Δ14C value cannot unequivocally be constrained, blank C contributions for the different biomarker purification methods cannot be accurately calculated. This study illustrates the challenges and problems of producing authentic standards that are not readily commercially available and exemplifies how a laborious and time-consuming culturing approach may enter a vicious cycle of blank C contamination hampering accurate blank C determination.}, keywords = {Algal cultures, Alkanoic acids, alkenones, Authentic standards, Blank, chlorophyll a, Compound-specific radiocarbon analysis, natural level 14 C manipulation, rcc1238}, issn = {2296-7745}, doi = {10.3389/fmars.2019.00780}, url = {https://www.frontiersin.org/articles/10.3389/fmars.2019.00780/full}, author = {Kusch, Stephanie and Benthien, Albert and Richter, Klaus-Uwe and Rost, Bj{\"o}rn and Mollenhauer, Gesine} } @article {Rokitta2016, title = {P- and n-depletion trigger similar cellular responses to promote senescence in eukaryotic phytoplankton}, journal = {Frontiers in Marine Science}, volume = {3}, number = {July}, year = {2016}, note = {tex.mendeley-tags: 2016,RCC1217,RCC126}, month = {jun}, keywords = {2016, rcc1217, RCC126}, issn = {2296-7745}, doi = {10.3389/fmars.2016.00109}, url = {http://journal.frontiersin.org/article/10.3389/fmars.2016.00109 http://journal.frontiersin.org/Article/10.3389/fmars.2016.00109/abstract}, author = {Rokitta, Sebastian D. and von Dassow, Peter and Rost, Bj{\"o}rn and John, Uwe} } @article {Schaum2015, title = {Environmental stability affects phenotypic evolution in a globally distributed marine picoplankton}, journal = {The ISME Journal}, year = {2015}, note = {tex.mendeley-tags: oth95,rcc1107,rcc1108,rcc1114,rcc1558,rcc1645,rcc1662,rcc410,rcc422,rcc434,rcc501,rcc675,rcc747,rcc789,rcc809,rcc810}, pages = {1{\textendash}10}, abstract = {Marine phytoplankton can evolve rapidly when confronted with aspects of climate change because of their large population sizes and fast generation times. Despite this, the importance of environment fluctuations, a key feature of climate change, has received little attention{\textemdash}selection experiments with marine phytoplankton are usually carried out in stable environments and use single or few representatives of a species, genus or functional group. Here we investigate whether and by how much environmental fluctuations contribute to changes in ecologically important phytoplankton traits such as C:N ratios and cell size, and test the variability of changes in these traits within the globally distributed species Ostreococcus. We have evolved 16 physiologically distinct lineages of Ostreococcus at stable high CO2 (1031{\textpm}87 ??atm CO2 , SH) and fluctuating high CO2 (1012{\textpm}244 ??atm CO2 , FH) for 400 generations.We find that although both fluctuation and high CO2 drive evolution, FH- evolved lineages are smaller, have reduced C:N ratios and respond more strongly to further increases in CO2 than do SH-evolved lineages. This indicates that environmental fluctuations are an important factor to consider when predicting how the characteristics of future phytoplankton populations will have an impact on biogeochemical cycles and higher trophic levels in marine food webs.}, keywords = {oth95, rcc1107, RCC1108, RCC1114, RCC1558, rcc1645, rcc1662, rcc410, rcc422, RCC434, rcc501, rcc675, rcc747, RCC789, RCC809, rcc810}, issn = {1751-7362}, doi = {10.1038/ismej.2015.102}, url = {http://www.nature.com/doifinder/10.1038/ismej.2015.102}, author = {Schaum, C-Elisa and Rost, Bj{\"o}rn and Collins, Sin{\'e}ad} } @article {Rokitta2011, title = {Transcriptome analyses reveal differential gene expression patterns between the life-cycle stages of Emiliania huxleyi (Haptophyta) and reflect specialization to different ecological niches}, journal = {Journal of Phycology}, volume = {47}, number = {4}, year = {2011}, note = {Publisher: Blackwell Publishing Ltd tex.mendeley-tags: 2011,rcc,sbr?hyto?ppo}, pages = {829{\textendash}838}, abstract = {Coccolithophores, especially the abundant, cosmopolitan species Emiliania huxleyi (Lohmann) W. W. Hay et H. P. Mohler, are one of the main driving forces of the oceanic carbonate pump and contribute significantly to global carbon cycling, due to their ability to calcify. A recent study indicates that termination of diploid blooms by viral infection induces life-cycle transition, and speculation has arisen about the role of the haploid, noncalcifying stage in coccolithophore ecology. To explore gene expression patterns in both life-cycle stages, haploid and diploid cells of E. huxleyi (RCC 1217 and RCC 1216) were acclimated to limiting and saturating photon flux densities. Transcriptome analyses were performed to assess differential genomic expression related to different ploidy levels and acclimation light intensities. Analyses indicated that life-cycle stages exhibit different properties of regulating genome expression (e.g., pronounced gene activation and gene silencing in the diploid stage), proteome maintenance (e.g., increased turnover of proteins in the haploid stage), as well as metabolic processing (e.g., pronounced primary metabolism and motility in the haploid stage and calcification in the diploid stage). Furthermore, higher abundances of transcripts related to endocytotic and digestive machinery were observed in the diploid stage. A qualitative feeding experiment indicated that both life-cycle stages are capable of particle uptake (0.5 ??m diameter) in late-stationary growth phase. Results showed that the two life-cycle stages represent functionally distinct entities that are evolutionarily shaped to thrive in the environment they typically inhabit.}, keywords = {2011, endocytosis, Life-cycle stages, microarray, quantitative RT-PCR, rcc, SBR$_\textrmP$hyto$_\textrmE$PPO, sbr?hyto?ppo, transcriptome profiling}, doi = {10.1111/j.1529-8817.2011.01014.x}, url = {http://dx.doi.org/10.1111/j.1529-8817.2011.01014.x}, author = {Rokitta, Sebastian D and de Nooijer, Lennart J and Trimborn, Scarlett and de Vargas, Colomban and Rost, Bj{\"o}rn and John, Uwe} }