Data for: Carbon and nitrogen uptake through photosynthesis and feeding by photosymbiotic Acantharia (Radiolaria)

Underlying and extended data for the publication: “Carbon and nitrogen uptake through photosynthesis and feeding by photosymbiotic Acantharia”  (https://doi.org/10.12688/openreseurope.14983.1)

Background: Mixotrophy, combining phagotrophy and photoautotrophy in order to acquire nutrients and energy, is a widespread trophic mode in marine protist plankton. Acantharia (Radiolaria) are ubiquitous, but still uncultured oceanic protists. Many of them are mixoplanktic by endosymbiotic relations with microalgae. Here we aimed at quantitatively assess phototrophy (inorganic nutrients) and phagotrophy (organic nutrients) of photosymbiotic Acantharia, to understand their physiology, and thereby improve integrations of mixotrophy into ecological models of oceanic ecosystems.

Methods: Freshly collected Acantharia were incubated with stable isotopes of inorganic carbon and nitrogen to determine photosynthetic uptake rates. Grazing experiments (prey disappearance) were done with different algal cultures as potential food organisms to measure the contribution of prey ingestion to the acantharian metabolism. Fluorescently (and isotopically) labelled prey was used to verify prey uptake, qualitatively.

Results/Conclusions:  Carbon uptake rates were unaffected by the nitrogen source (i.e., nitrate or ammonium). Total carbon inorganic uptake rate was 1112±82 pgC h^-1 Acantharia^‑1, 22.3±1.6 pgC h^-1 symbiont cell^-1assuming 50 symbionts per Acantharia, at ~155-μmol photons m⁻² s⁻¹ irradiance. The Acantharia studied could use both inorganic ammonium and nitrate, but ammonium was taken up at a ~5 times higher rate. Prey ingestion of the haptophyte, Isochrysis galbana, was detected using labelled algae. Significant grazing by Acantharia could only be established on the dinoflagellate Effrenium voratum, with a grazing rate of 728 prey Acantharia^‑1 hour^-1 (i.e., ~56.3 ngC h^-1, 46% of total holobiont carbon content) at a ratio of 1.06x10⁴ prey predator^-1. Daily photosynthetic carbon uptake rates made up ~14.5% of the total holobiont carbon content (0.9% hourly).
The extent to which photosynthates are used and assimilated by the acantharian cell and/or if it is used for catabolic processes to obtain energy is still to be studied. Isotopic ratios further suggests seasonal differences in the usage of each trophic mode.

Underlying data(sets):

• EAIRMS_data_for_Acantharia-Table1_Table2_Figure1_ETable3.xlsx:
  Isotopic data of the Acanhtaria photosynthetic C and N uptake experiments. The sheet titled '...Export.wke' is the raw machine outputs; 'standards TCD' and 'standard IRMS' are the isolated data for respectively the TCD and IRMS of the standards; 'samples TCD' and 'samplesIRMS' are the isolated data for respectively the TCD and IRMS of the samples; 'Results' sheet makes the calculation on the data for the samples accounting for the standards; the 'statistics delta' sheet gives the statistics and test.

• Flowcytometry_data-Grazing_rates-Table3.xlsx:
  Cell count data of prey items used for acantharian grazing experiments. The sheets are labeled by RCC culture number, each sheet gives the flowcytometry data and calculations for ingestion rate. The 'Results table' sheet provides an overview of ingestion rates.

• Photosynthetic_rates_and_chla_summary_of_algal_culture_data.xlsx:
  Photosynthetic rates of Phaeocystis cultures as measured using ¹⁴C techniques, and the Chl-a concentrations of relevant cultures.

• Imaging_data-Acantharia_grazing.zip: 
  This is data of the fluorescence confocal microscopy and is organised by experimental time point. It includes the .tif files used in the manuscript and the original .lif files of the Leica microscope. The .lif data for time points T60 and T240 also contain images that have not been illustrated in the manuscript and do not come accompanied by a .tif file.

Extended data:

Extended data overview:

• Extended_data_Text_Figures_Tables.docx:
  Supplementary information to “Carbon and nitrogen uptake through photosynthesis and feeding by photosymbiotic Acantharia”. Contains all figures, tables, and legends. Figures are also separately available in this dataset. This contains extended data and preliminary experiments on Acantharia (Radiolaria), as well as, extra experiments and data of Collodaria (Radiolaria).

Extended data figures:

• E Fig 1 cells.tiff

• E fig 2 photo exp design 2022.png

• E fig 3 feeding exp design.png

• E fig 4 PAM supp image.png

• E fig 5- nonsymbiotic Acantharia.tif

• E fig 6 Acantharia prelimn d13C Graph exl outlier.png

• E Fig 7 - Acantharia SI-prey feeding graph

• E fig 8- Graph collodaria d15N.png

• Fig2-3D reconstruction video simulation-Acantharia T60_cell_1_stained.avi

Extended data tables:

• E table 1 - Culture information.xlsx

• E Table 2 - medium specifics.xlsx

Extended data (raw) datasets:

• Extended_data-PAM raw data.xlsx:
  Microscope PAM Data underlying E Fig 4

• Extended_data-isotopic values september 2018 Collodaria and Acantharia.xlsx:
  Isotopic values of Collodaria and Acantharia samples from September 2018; data underlying E Fig 6

• Extended_data-EAIRMS data Collodaria -april2019-reprocessed25-9-2019_E fig 8.xlsx:
  Isotopic data of Collodaria, underlying data for E Fig 8.
  The sheet titled '...excel_2.wke' is the raw ÍRMS machine outputs; 'sample peaks' and 'ref peaks' are the isolated data for respectively the samples and machine references; 'sample peaks (cleaned)' is the data of the samples run cleaned to include only the numbers needed; 'standards' and 'Samples' are the data for respectively the standards and samples of the IRMS run; The 'Samples'  sheet makes the calculation on the data for the samples accounting for the standards; the 'samples overview' sheet gives an overview of the delta values.

• Extended_data-Isotopically labeled prey plus Acantharia_EAIRMS_and_Flowcyto_prey_count_data_E Fig7.xlsx
  The sheet titled '...excel_2.wke' is the raw ÍRMS machine outputs; 'sample peaks' and 'ref peaks' are the isolated data for respectively the samples and machine references; 'sample peaks (cleaned)' is the data of the samples run cleaned to include only the numbers needed; 'standards' and 'samples' are the data for respectively the standards and samples of the IRMS run; The 'samples' sheet makes the calculation on the data for the samples accounting for the standards; the 'samples radiolaria' sheet isolates the data for our Acantharia samples gives and gives an overview of the delta values. The last sheet ' prey cell counts' is the flowcytometry count data of the prey.

• Image_data-Acantharia_grazing.zip
  Photographs taken of the grazing experiments