Maira Maselli, 1 , * Konstantinos Anestis, 2 , † Kerstin Klemm, 2 , † Per Juel Hansen, 1 and Uwe John 2 , 3


1Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
2Alfred-Wegener-Institute, Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
3Helmholtz Institute for Functional Marine Biodiversity, Oldenburg, Germany
Edited by: Jean-David Grattepanche, Temple University, United States
Reviewed by: Ravi Toteja, University of Delhi, India; Jun Gong, Sun Yat-sen University, China
*Correspondence: Maira Maselli, [email protected]
†These authors have contributed equally to this work
This article was submitted to Aquatic Microbiology, a section of the journal Frontiers in Microbiology
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Cell Biology


Many marine ciliate species retain functional chloroplasts from their photosynthetic prey. In some species, the functionality of the acquired plastids is connected to the simultaneous retention of prey nuclei. To date, this has never been documented in plastidic Strombidium species. The functionality of the sequestered chloroplasts in Strombidium species is thought to be independent from any nuclear control and only maintained via frequent replacement of chloroplasts from newly ingested prey. Chloroplasts sequestered from the cryptophyte prey Teleaulax amphioxeia have been shown to keep their functionality for several days in the ciliate Strombidium cf. basimorphum. To investigate the potential retention of prey genetic material in this ciliate, we applied a molecular marker specific for this cryptophyte prey. Here, we demonstrate that the genetic material from prey nuclei, nucleomorphs, and ribosomes is detectable inside the ciliate for at least 5 days after prey ingestion. Moreover, single-cell transcriptomics revealed the presence of transcripts of prey nuclear origin in the ciliate after 4 days of prey starvation. These new findings might lead to the reconsideration of the mechanisms regulating chloroplasts retention in Strombidium ciliates. The development and application of molecular tools appear promising to improve our understanding on chloroplasts retention in planktonic protists.



Samples were inspected using the Olympus BX50 microscope equipped with a CoolLED pE-300 light source on 400 × magnification with appropriate wavelengths for DAPI (excitation, 350 nm; emission, 450 nm), Alexa488 (excitation, 480 nm; emission, 530 nm), and chloroplast fluorescence (excitation, 600 nm; emission, 650 nm).

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The pE-300white is a popular illuminator for everyday fluorescent screening and analysis with simple operatation and individual irradiance control of each LED channel.

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Frontiers in Microbiology

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