Upcoming

On our upcoming DinoSphere seminar will be on July 14th at 9 AM (PDT) / 6 PM (CEST), featuring Victoria (Noodin) Jacko-Reynolds (University of British Columbia, Canada) and Leïla Jacquot (Biology Centre CAS, Czechia). 

Zoom link: https://unibas.zoom.us/launch/jc/67793459223 

Meeting ID: 677 9345 9223

Passcode: 916415

A phylogenetic investigation into the plastid evolutionary parallelisms within myzozoan parasites - Victoria (Noodin) Jacko-Reynolds (University of British Columbia, Canada)

The loss of photosynthesis often marks the beginning of the transition from a free-living photosynthetic flagellate towards parasitism in the long history of the sister lineages, apicomplexans and dinoflagellate otherwise known as myzozoans. Following the loss of photosynthesis, myzozoan plastids have been repeated reduced to cryptic plastids, relying solely on metabolic functioning such as FeS clustering, fatty acid biosynthesis and heme production. In rare cases, the plastid genome and organelle are lost outright, as seen in the apicomplexan, Cryptosporidium and dinoflagellate, Hematodinium. Here, Noodin presents work from their PhD dissertation of two lineages of parasites, the apicomplexan corallicolid and the dinoflagellate Blastodinium as systems to understand further trends during the transition to parasitism. Corallicolids are parasites of cnidarians and have retained chlorophyll biosynthesis genes despite having lost photosynthetic ability, through phylogenomic analyses, the phylogenomic position of corallicolids indicates multiple parallel losses of the chlorophyll biosynthesis pathway across the history of apicomplexa. On the other hand, members of Blastodinium are actively photosynthetic whereas one known species have completely lost ability to photosynthesize. Here, we investigate trends in the loss of photosynthesis across the first transcriptomes of Blastodinium. As these two lineages of parasite are uncultured, rigorous sampling, single-cell transcriptomics, and phylogenetics are used to provide a genomic snapshot of plastid retention and evolutionary parallelisms. 

From freshwater and marine habitats to the laboratory: exploring kleptoplastidic dinoflagellates - Leïla Jacquot (Biology Centre CAS, Czechia)

Kleptoplastidic dinoflagellates can be used as models to study plastid endosymbiosis – the process of how free-living algae have been converted into the photosynthetic organelles found in extant plants and algae. By transiently utilizing functional plastids retained from their prey (so-called kleptoplasts), kleptoplastidic taxa potentially represent intermediate stages in the process of plastid endosymbiosis. Their diversity remain understudied, suggesting significant potential for the discovery of novel lineages. We focused initially on exploring lakes around the city (České Budějovice, Czech Republic) to isolate the unarmoured dinoflagellate Nusuttodinium aeruginosum, a freshwater species known to be kleptoplastidic. This dinoflagellate has been described to feed on the cryptophyte Chroomonas sp. and to retain the plastid from its prey up to several weeks, maintaining photosynthetic activity during this period. Here, we highlight challenges and their solutions faced during isolation and cultivation of N. aeruginosum from the environment. Our analyses of ITS/16S sequencing show that the dinoflagellate can feed on a Chroomonas sp. strain obtained from culture collection and can retain plastids from more than one Chroomonas species in the environment. Given that dinoflagellate diversity is substantially higher in marine habitats than in freshwater, we extended our investigation to the Mediterranean Sea (Villefranche-sur-Mer), where potential candidates for kleptoplasty were manually isolated for host and prey taxonomic identification.