24 May 2019
Marine parasite survives without key genes
Published online 24 April 2019
Scientists discover a thriving marine parasite lacking genes in its mitochondria
The cells of most life forms contain energy-producing mitochondria that have unique genetic material, in addition to that found in a cell’s nucleus. Researchers have now discovered an exception to this rule in the dinoflagellate Amoebophrya ceratii, a single-celled, free-floating marine parasite that has functional mitochondria, but without any genetic material.
A team from Germany, Egypt, France, Canada, the United Kingdom and the Czech Republic sequenced the parasite’s complete genome to find it had virtually no genes in its mitochondria.
The finding can help better understand the evolutionary history of dinoflagellates and their relatives such as the malaria-causing parasite, says co-author Ahmed Moustafa, an associate professor of bioinformatics at the American University in Cairo, Egypt.
Amazingly, the parasite had a drastically reduced number of genes in its plastid too, a cellular organelle that aids in photosynthesis, rendering it defunct.
The plastid DNA in most dinoflagellates contains 14 genes. Amoebophrya ceratii has one remnant plastid gene. The reduction in genes in its mitochondria is even more striking. While some of its relatives contain at least three mitochondrial genes, the parasite has none.
Amoebophrya ceratii needs energy when it forms a large number of dinospores, the free-floating stage of its life cycle that seeks out a new host to invade. The researchers say the parasites utilise specific genes in the cells’ nuclei to keep their mitochondria functional and producing energy.
John, U. et al. An aerobic eukaryotic parasite with functional mitochondria that likely lacks a mitochondrial genome. Sci. Adv. 5, eaav1110 (2019).