Reference Tree and Environmental Sequence Diversity of Labyrinthulomycetes


Published in The Journal of Eukaryotic Microbiology.

Reference Tree and Environmental Sequence Diversity of Labyrinthulomycetes

Jingwen Pan, Javier del Campo, Patrick J. Keeling

Labyrinthulomycetes are heterotrophic stramenopiles that are ubiquitous in a wide range of both marine and freshwater habitats and play important roles in decomposition of organic matter. The diversity and taxonomy of Labyrinthulomycetes has been studied for many years, but we nevertheless lack both a comprehensive reference database and up-to-date phylogeny including all known diversity, which hinders many global insights into their ecological distribution and the relative importance of various subgroups in different environments. Here, we present a curated reference database and a phylogenetic tree of Labyrinthulomycetes small subunit ribosomal RNA (SSU or 18S rRNA) data. Based on this created reference database, we analyzed high-throughput environmental sequencing data, revealing many previously unknown environmental clades and exploring the ecological distribution of various subgroups. Particularly, a number of newly identified environmental clades that are widespread in the open ocean. Comparing the manually curated reference database to existing tools for identification of environmental sequences (e.g. PR2 or SILVA databases) suggests that the curated database provides a higher degree of specificity and a lower frequency of misidentification. The phylogenetic framework and database will be a useful tool for future ecological and evolutionary studies.

Ecological and evolutionary significance of novel protist lineages


Published in the European Journal of Protistology as part of the VII European Congress of Protistology special issue

Ecological and evolutionary significance of novel protist lineages

Javier del Campo, Laure Guillou, Elisabeth Hehenberger, Ramiro Logares, Purificación López-García, Ramon Massana

Environmental molecular surveys targeting protist diversity have unveiled novel and uncultured lineages in a variety of ecosystems, ranging from completely new high-rank lineages, to new taxa moderately related to previously described organisms. The ecological roles of some of these novel taxa have been studied, showing that in certain habitats they may be responsible for critical environmental processes. Moreover, from an evolutionary perspective they still need to be included in a more accurate and wider understanding of the eukaryotic tree of life. These seminal discoveries promoted the development and use of a wide range of more in-depth culture-independent approaches to access this diversity, from metabarcoding and metagenomics to single cell genomics and FISH. Nonetheless, culturing using classical or innovative approaches is also essential to better characterize this new diversity. Ecologists and evolutionary biologists now face the challenge of apprehending the significance of this new diversity within the eukaryotic tree of life.

From photosynthetic algae to obligate intracellular parasites

F5.largePublished in eLife

Chromerid genomes reveal the evolutionary path from photosynthetic algae to obligate intracellular parasites

Yong H Woo, Hifzur Ansari, Thomas D Otto, Christen M Klinger, Martin Kolisko, Jan Michálek, Alka Saxena, Dhanasekaran Shanmugam, Annageldi Tayyrov, Alaguraj Veluchamy, Shahjahan Ali, Axel Bernal, Javier del Campo, Jaromír Cihlář, Pavel Flegontov, Sebastian G Gornik, Eva Hajdušková, Aleš Horák, Jan Janouškovec, Nicholas J Katris, Fred D Mast, Diego Miranda-Saavedra, Tobias Mourier, Raeece Naeem, Mridul Nair, Aswini K Panigrahi, Neil D Rawlings, Eriko Padron-Regalado, Abhinay Ramaprasad, Nadira Samad, Aleš Tomčala, Jon Wilkes, Daniel E Neafsey, Christian Doerig, Chris Bowler, Patrick J Keeling, David S Roos, Joel B Dacks, Thomas J Templeton, Ross F Waller, Julius Lukeš, Miroslav Oborník, Arnab Pain

The eukaryotic phylum Apicomplexa encompasses thousands of obligate intracellular parasites of humans and animals with immense socio-economic and health impacts. We sequenced nuclear genomes of Chromera velia and Vitrella brassicaformis, free-living non-parasitic photosynthetic algae closely related to apicomplexans. Proteins from key metabolic pathways and from the endomembrane trafficking systems associated with a free-living lifestyle have been progressively and non-randomly lost during adaptation to parasitism. The free-living ancestor contained a broad repertoire of genes many of which were repurposed for parasitic processes, such as extracellular proteins, components of a motility apparatus, and DNA- and RNA-binding protein families. Based on transcriptome analyses across 36 environmental conditions, Chromera orthologs of apicomplexan invasion-related motility genes were co-regulated with genes encoding the flagellar apparatus, supporting the functional contribution of flagella to the evolution of invasion machinery. This study provides insights into how obligate parasites with diverse life strategies arose from a once free-living phototrophic marine alga.