5 
The origin of the dinoflagellate plastid

Abstract

The peridinin pigmented dinoflagellate chloroplasts are the result of a secondary endosymbiotic event between a photosynthetic eukaryote and a dinoflagellate.Dinoflagellate chloroplast and nuclear evolution were independent before this endosymbiotic event. To reconstruct the evolution of the dinoflagellate chloroplast, phylogenies were constructed with a chloroplast gene psbB. The gene phylogeny should reflect the evolution of the chloroplast and indicate the plastid donor lineage. Gene sequences derived from the dinoflagellate chloroplast were extremely divergent but suggested that the plastid donor could have been a haptophyte. In an attempt to find better genes for analysis and to further understand gene transfer about 4900 randomly selected expressed genes were sequenced from two dinoflagellates, Lingulodinium polyedra and Amphidinium carterae. From these genes, thirty typically plastid-encoded genes were found, including eight otherwise known only from plastid genomes. Based on poly-A tails, gene families, and leader sequences these genes appear to be nuclearencoded in dinoflagellates. This result suggests that dinoflagellate chloroplasts may have the smallest protein-coding potential yet known. These genes and the partially sequenced chloroplast genome of a haptophyte were used in a phylogenetic analysis. There is strong conflict between genes encoded in the chloroplast and those in the nucleus. The chloroplast genes suggest relationship between haptophyte and dinoflagellate plastids, while the nuclear-encoded genes suggest a relationship with heterokonts. Chromophyte plastid monophyly is supported by these data but the single origin of the chromophyte plastid from red algae does not mean that the host lineages are monophyletic. These results are consistent with at least two different scenarios: either dinoflagellates and haptophytes independently acquired a plastid from the heterokonts, or dinoflagellates acquired their plastids from haptophtyes, who in turn acquired their plastids from heterokonts. The evolutionary rate of the remaining plastid-encoded genes was compared with formerly plastid-encoded genes. These relative rate tests revealed strong incongruence between minicircle genes, formerly plastid-encoded genes and genes that were likely to have been acquired from the nucleus of the plastid donor lineage.

Substitutional editing of transcripts from genes of cyanobacterial origin in the dinoflagellate Ceratium horridum

“…Peridinin‐containing dinoflagellates are not only enigmatic for their genomic organization and the use of a type II RuBisCO, but also because of their unusual minicircles and the high amount of nucleus‐encoded genes for plastid functions [18,19]. Our results expand this list of aberrant characters of peridinin‐containing dinoflagellates by the detection of RNA editing of cyanobacterial‐derived genes, which prior to our findings was exclusively reserved for land plants [26].…”

“…Examples for this are the high amount of permanently condensed nuclear DNA in most species [9,10], the lack of histone proteins and consequently of nucleosomes [11–13], proteins encoded as polyproteins [14,15], and, in the case of peridinin‐containing dinoflagellates, a proteobacterial‐like nuclear encoded type II RuBisCO [16,17]. As recently shown, dinoflagellates are furthermore the “champions” in successfully transferring genes from the plastid into the cell nucleus [18,19]. Whether the plastids of peridinin‐containing dinoflagellates, surrounded by an envelope of three membranes, evolved through secondary or tertiary endosymbiosis remains controversial to date [7,20,21].…”

Estudio taxonómico y ecológico de los dinoflagelados planctónicos del orden Peridiniales de la Bahía de Acapulco con énfasis en las familias Diplopsaliaceae y Protoperidiniaceae

“…Actualmente este término se usa para referirse a un grupo de organismos eucariontes microscópicos, planctónicos que están emparentados con los Alveolados (Apicomplejos y Ciliados), porque poseen un anfiesma con vesículas anfiesmales (Fensome et al, 1993;Van den Hoeck et al, 1995;Hackett et al, 2004;Adl et al, 2005). Como con los Cromistas porque tienen mitocondrias con crestas tubulares (Cavalier-Smith, 1999; Bachvaroff, 2003;Patron et al, 2004). Que exhiben una gran diversidad morfológica y funcional, donde a pesar de que predominan las formas unicelulares flageladas, que poseen un aparato flagelar que comprende dos flagelos disimiles, uno longitudinal, y otro transversal (Fensome et al, 1993; Van den Hoeck et al, 1995) (Fig.…”

“…También ocurren, formas ameboideas no flageladas, cocoides, palmeloides o formadoras de filamentos, que si bien, no parecen presentar semejanza con los dinoflagelados típicos (Fig. 1), sus relaciones, se han comprobado con base en las características de la células reproductivas flageladas, conocidas como dinosporas (zoosporas) (Graham y Wilcox, 2000), o bien a través de sus secuencias moleculares (Bachvaroff, 2003;Hackett et al, 2004 ), e incluso ocurre un cloroplasto temporal derivado de Cryptophyta (Dinophysis spp.). El otro 49 % de las especies de dinoflagelados son heterótrofas, las cuales predominan en el medio marino (Gómez, 2012a), expresa diferentes estrategias: Auxotrofía, fagotrofía, mizocitosis y organotrofía, e incluso mixotrofía (Gaines y Elbrächter, 1987).…”

“…99). Mensualmente la riqueza de especies de Peridiniales varió de 5-43 espeies, el mes más diverso fue marzo de 2010 (23-43) y el menos diverso fue julio (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24).…”