Parasite of the Month

Amoebophrya ceratii

KEY FACTS:

A. ceratii is haploid, with V-shaped permanently condensed chromosomes during most of its life cycle. Genomes are rather small (hundreds of Mb) compared with other dinoflagellates (∼3–245 Gb).

Genes are grouped into unidirectional clusters, and mRNAs are trans-spliced. In two strains, introns were predominantly non-canonicals (differing from the GT-AG motif) and partly composed of introners acting as transposable elements.

The complex III of the oxidative phosphorylation (OXPHOS) pathway is

DISEASE FACTS:

Infection occurs either in the nucleus or cytoplasm. Once inside the host, the A. ceratii nutrition mode starts with osmotrophy and then shifts to phagotrophy. Predigested host chromosomes are sucked into feeding tubes and consumed in food vacuoles.

During the infection, the host is ‘zombified’: it still swims, with functional mitochondria and chloroplasts, despite the complete digestion of its nucleus. The energy produced by the host organelles likely benefits the parasitoid.

The lifespan of

TAXONOMY AND CLASSIFICATION:

PHYLUM: Myzozoa

CLASS: Dinoflagellata

ORDER: Syndiniales

FAMILY: Amoebophryidae

GENUS: Amoebophrya

SPECIES: A. ceratii (species complex composed of multiple cryptic species)

Acknowledgments

This research is funded by the ANR (ANR-21-CE02-0030-01 EPHEMER). Electron microscopy images were provided by Sophie Lepanse (MERIMAGE platform, Station Biologique of Roscoff) and Gérard Prensier (in memory). Estelle Bigeard (Station Biologique of Roscoff) is in charge of parasitic strains within the Roscoff Culture Collection (RCC).

Declaration of interests

The authors declare no competing interests.