Free-living core dinoflagellates are commonly infected by members of two parasitic clades that are themselves closely related to dinoflagellates, the marine alveolates and perkinsids. These parasites are abundant and ecologically important, but most species have been difficult to observe directly or cultivate, so our knowledge of them is usually restricted to environmental 18S rRNA gene sequences, as genome-scale molecular data are not available for most species. Here, we report the finding of several of these parasites infecting free-living dinoflagellates.
View Article and Find Full Text PDFDinoflagellates are an abundant and diverse group of protists representing a wealth of unique biology and ecology. While many dinoflagellates are photosynthetic or mixotrophic, many taxa are heterotrophs, often with complex feeding strategies. Compared to their photosynthetic counterparts, heterotrophic dinoflagellates remain understudied, as they are difficult to culture.
View Article and Find Full Text PDFChlorophyll c is a key photosynthetic pigment that has been used historically to classify eukaryotic algae. Despite its importance in global photosynthetic productivity, the pathway for its biosynthesis has remained elusive. Here we define the CHLOROPHYLL C SYNTHASE (CHLCS) discovered through investigation of a dinoflagellate mutant deficient in chlorophyll c.
View Article and Find Full Text PDFMicrobial eukaryotes are important components of marine ecosystems, and the Marine Alveolates (MALVs) are consistently both abundant and diverse in global environmental sequencing surveys. MALVs are dinoflagellates that are thought to be parasites of other protists and animals, but the lack of data beyond ribosomal RNA gene sequences from all but a few described species means much of their biology and evolution remain unknown. Using single-cell transcriptomes from several MALVs and their free-living relatives, we show that MALVs evolved independently from two distinct, free-living ancestors and that their parasitism evolved in parallel.
View Article and Find Full Text PDFWarnowiid dinoflagellates contain a highly complex camera-eye-like structure called the ocelloid that is composed of different organelles resembling parts of metazoan eyes, including a modified plastid that serves as the retinal body. The overall structure of the ocelloid has been investigated by microscopy; because warnowiids are not in culture and are rare in nature, we know little about their function. Here, we generate single-cell transcriptomes from 18 warnowiid cells collected directly from the marine environment representing all 4 known genera and 1 previously undescribed genus, as well as 8 cells from a related lineage, the polykrikoids.
View Article and Find Full Text PDFDinoflagellates are a diverse protist group possessing many unique traits. These include (but are not limited to) expansive genomes packaged into permanently condensed chromosomes, photosynthetic or cryptic plastids acquired vertically or horizontally in serial endosymbioses, and a ruffle-like transverse flagellum attached along its length to the cell. When reconstructing character evolution, early branching lineages with unusual features that distinguish them from the rest of the group have proven useful for inferring ancestral states.
View Article and Find Full Text PDFDinoflagellates possess many cellular characteristics with unresolved evolutionary histories. These include nuclei with greatly expanded genomes and chromatin packaged using histone-like proteins and dinoflagellate-viral nucleoproteins instead of histones, highly reduced mitochondrial genomes with extensive RNA editing, a mix of photosynthetic and cryptic secondary plastids, and tertiary plastids. Resolving the evolutionary origin of these traits requires understanding their ancestral states and early intermediates.
View Article and Find Full Text PDFAn amendment to this paper has been published and can be accessed via a link at the top of the paper.
View Article and Find Full Text PDFDiverse microbial ecosystems underpin life in the sea. Among these microbes are many unicellular eukaryotes that span the diversity of the eukaryotic tree of life. However, genetic tractability has been limited to a few species, which do not represent eukaryotic diversity or environmentally relevant taxa.
View Article and Find Full Text PDFWhile light limitation can inhibit bloom formation in dinoflagellates, the potential for high-intensity photosynthetically active radiation (PAR) to inhibit blooms by causing stress or damage has not been well-studied. We measured the effects of high-intensity PAR on the bloom-forming dinoflagellates Alexandrium fundyense and Heterocapsa rotundata. Various physiological parameters (photosynthetic efficiency F /F , cell permeability, dimethylsulfoniopropionate [DMSP], cell volume, and chlorophyll-a content) were measured before and after exposure to high-intensity natural sunlight in short-term light stress experiments.
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