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FEMS Microbiol Lett. 2017 Jul 3;364(12). doi: 10.1093/femsle/fnx117.

Assessing phagotrophy in the mixotrophic ciliate Paramecium bursaria using GFP-expressing yeast cells.

Author information

1
Department of Biology, Faculty of Education, Hirosaki University, Hirosaki 036-8560, Japan.
2
Research Core for Interdisciplinary Sciences, Okayama University, Okayama 700-8530, Japan.

Abstract

We used cells of the yeast Saccharomyces cerevisiae expressing green fluorescent protein (GFP) as fluorescently labelled prey to assess the phagocytic activities of the mixotrophic ciliate Paramecium bursaria, which harbours symbiotic Chlorella-like algae. Because of different fluorescence spectra of GFP and algal chlorophyll, ingested GFP-expressing yeast cells can be distinguished from endosymbiotic algal cells and directly counted in individual P. bursaria cells using fluorescence microscopy. By using GFP-expressing yeast cells, we found that P. bursaria altered ingestion activities under different physiological conditions, such as different growth phases or the presence/absence of endosymbionts. Use of GFP-expressing yeast cells allowed us to estimate the digestion rates of live prey of the ciliate. In contrast to the ingestion activities, the digestion rate within food vacuoles was not affected by the presence of endosymbionts, consistent with previous findings that food and perialgal vacuoles are spatially and functionally separated in P. bursaria. Thus, GFP-expressing yeast may provide a valuable tool to assess both ingestion and digestion activities of ciliates that feed on eukaryotic organisms.

KEYWORDS:

GFP; Paramecium bursaria; algal endosymbiosis; ciliate; phagotrophic protists; yeast

PMID:
28591835
DOI:
10.1093/femsle/fnx117
[Indexed for MEDLINE]

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