Separation and identification of lipids in the photosynthetic cousins of Apicomplexa Chromera velia and Vitrella brassicaformis.

The alveolate algae Chromera velia and Vitrella brassicaformis (chromerids) are the closest known phototrophic relatives to apicomplexan parasites. Apicomplexans are responsible for fatal diseases of humans and animals and severe economic losses. Availability of the genome sequences of chromerids together with easy and rapid culturing of C. velia makes this alga a suitable model for investigating elementary biochemical principals potentially important for the apicomplexan pathogenicity. Such knowledge allows us to better understand processes during the evolutionary transition from a phototrophy to the parasitism in Apicomplexa. We explored lipidomes of both algae using high-performance liquid chromatography with mass spectrometry or gas chromatography with flame ionization detection. A single high-performance liquid chromatography with mass spectrometry analysis in both ionization modes was sufficient for the separation and semi-quantification of lipids in chromerid algae. We detected more than 250 analytes belonging to five structural lipid classes, two lipid classes of precursors and intermediates, and triacylglycerols as storage lipids. Identification of suggested structures was confirmed by high-resolution mass spectrometry with an Orbitrap mass analyzer. An outstandingly high accumulation of storage triacylglycerols was found in both species. All the investigated aspects make C. velia a prospective organism for further applications in biotechnology.

Budding of the Alveolate Alga Vitrella brassicaformis Resembles Sexual and Asexual Processes in Apicomplexan Parasites.

Ease of cultivation and availability of genomic data promoted intensive research of free-living phototrophic relatives of apicomplexans, i.e. Chromera velia and Vitrella brassicaformis. Chromera and Vitrella differ significantly in their physiology, morphology, phylogenetic position and genomic features, but Vitrella has not gained as much attention. Here we describe two types of Vitrella zoosporangia. One contains zoospores surrounded by roughly structured matter, with an intracytoplasmic axoneme predicted to develop into a mature flagellum upon spore release, similarly to Plasmodium microgametes; in the second type, cells concurrently bud off the center of the sporangium, surrounded by smooth matter, and flagella develop extracellularly. This process of budding is reminiscent of microsporogenesis as seen in Toxoplasma. We suggest one (or both) of these processes generates gamete-like flagellate progeny. Based on live staining, fusion of zoospores does occur in cultures of V. brassicaformis. We failed to find an apical structure similar to the pseudoconoid in any life stage. V. brassicaformis may therefore either represent an ancestral state lacking an apical complex or has lost the apical complex secondarily. We propose that the common ancestor of Apicomplexa and "chrompodellids" exhibited a complex life cycle, which was reduced in chromerids and colpodellids as dictated by their environment.