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Helena Filipsson, foto Erik Thor

Helena Filipsson

Professor

Helena Filipsson, foto Erik Thor

Kleptoplastidic benthic foraminifera from aphotic habitats : insights into assimilation of inorganic C, N and S studied with sub-cellular resolution

Författare

  • Thierry Jauffrais
  • Charlotte LeKieffre
  • Magali Schweizer
  • Emmanuelle Geslin
  • Edouard Metzger
  • Joan M. Bernhard
  • Bruno Jesus
  • Helena L. Filipsson
  • Olivier Maire
  • Anders Meibom

Summary, in English

The assimilation of inorganic compounds in foraminiferal metabolism compared to predation or organic matter assimilation is unknown. Here, we investigate possible inorganic-compound assimilation in Nonionellina labradorica, a common kleptoplastidic benthic foraminifer from Arctic and North Atlantic sublittoral regions. The objectives were to identify the source of the foraminiferal kleptoplasts, assess their photosynthetic functionality in light and darkness and investigate inorganic nitrogen and sulfate assimilation. We used DNA barcoding of a ~ 830 bp fragment from the SSU rDNA to identify the kleptoplasts and correlated transmission electron microscopy and nanometre-scale secondary ion mass spectrometry (TEM-NanoSIMS) isotopic imaging to study 13C-bicarbonate, 15N-ammonium and 34S-sulfate uptake. In addition, respiration rate measurements were determined to assess the response of N. labradorica to light. The DNA sequences established that over 80% of the kleptoplasts belonged to Thalassiosira (with 96%–99% identity), a cosmopolitan planktonic diatom. TEM-NanoSIMS imaging revealed degraded cytoplasm and an absence of 13C assimilation in foraminifera exposed to light. Oxygen measurements showed higher respiration rates under light than dark conditions, and no O2 production was detected. These results indicate that the photosynthetic pathways in N. labradorica are not functional. Furthermore, N. labradorica assimilated both 15N-ammonium and 34S-sulfate into its cytoplasm, which suggests that foraminifera might have several ammonium or sulfate assimilation pathways, involving either the kleptoplasts or bona fide foraminiferal pathway(s) not yet identified.

Avdelning/ar

  • Kvartärgeologi

Publiceringsår

2019

Språk

Engelska

Sidor

125-141

Publikation/Tidskrift/Serie

Environmental Microbiology

Volym

21

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

Wiley-Blackwell

Ämne

  • Oceanography, Hydrology, Water Resources
  • Natural Sciences
  • Biological Sciences

Status

Published

Projekt

  • Svenska kalkskaliga mikroorganismer i franska akvarier

ISBN/ISSN/Övrigt

  • ISSN: 1462-2912