Mono- and digalactosyldiacylglycerol composition of dinoflagellates. V. The galactolipid profile ofAlexandrium tamarense(Dinophyceae) during the course of infection by the parasitic syndinian dinoflagellateAmoebophryasp.

Abstract

Amoebophrya is a parasitic, syndinian dinoflagellate genus that must infect another host dinoflagellate in order to reproduce. Work by Park et al. [Mar. Ecol. Prog. Ser., 227: 281-292 (2002)] has led to the hypothesis that Amoebophrya's development within a host cell nucleus disrupts the flow of genetic information involved in plastidial function. The possibility that genetic disruption by this parasite could lead to alterations in plastidial lipid composition during the course of an infection has not yet been elucidated. Our primary objective in this lipidomic study was to examine the chloroplast membrane galactolipid composition of Alexandrium tamarense infected by an Amoebophrya species in order to determine whether infection of A. tamarense causes a phenotypic alteration in the composition of mono-and digalactosyldiacylglycerol (MGDG and DGDG, respectively), two galactolipids that comprise the majority of photosynthetic membranes. Our secondary objective was to determine if non-photosynthetic Amoebophrya sp. either incorporated host cell MGDG and DGDG, and/or itself produced forms of MGDG and DGDG, as has been observed previously in heterotrophic apicomplexan parasites distantly related to Amoebophrya. We found that, despite development of Amoebophrya sp. within the nucleus, the composition of A. tamarense MGDG and DGDG did not change throughout the infection process. The predominant forms of these galactolipids were 18:5/18:4 (sn À 1/snÀ2) and 20:5/18:4 DGDG, which were present at similar abundances in both an uninfected host and a host late in the infection process just prior to release of Amoebophrya sp. dinospores. Amoebophrya sp. did not possess appreciable amounts of any forms of MGDG and DGDG.

Lipidomic profile in three species of dinoflagellates ( Amphidinium carterae , Cystodinium sp., and Peridinium aciculiferum ) containing very long chain polyunsaturated fatty acids

“…Both 28:7 and 28:8 acids were found only in the fraction of phospholipids, not in glycolipids (Leblond and Dahmen, 2012) such as MGDG, DGDG, and SQDG, which, on the contrary, contained 18:4 and 18:5 with the major molecular species 18:4/18:5-MGDG and 18:4/18:5-DGDG (Leblond et al, 2015). These findings indicate that the C28 fatty acids are located and probably synthesized in the cytoplasm or in an organelle other than the chloroplast, whereas the C 18 fatty acids e 18:4n-3 and 18:5n-3 -are glycolipid constituents apparently synthesized within the chloroplast.…”

Mono- and digalactosyldiacylglycerol composition of dinoflagellates. VII. Evidence against galactolipid production and plastid presence in the heterotrophic, basal dinoflagellate, Oxyrrhis marina

“…The relative abundance of each lipid was determined from the peak heights of individual sodium adducts of MGDG and DGDG. Based on our work in Leblond & Dahmen (2012), the detection limit for our analysis of MGDG and DGDG is 1 pg cell -1 .…”

“…Subsequent studies have examined the forms of MGDG and DGDG in cold-adapted, peridinin-containing dinoflagellates (Gray et al, 2009b) and how temperature affects these lipids in the Cluster 2 dinoflagellate genus, Pyrocystis , and have determined that Amoebophrya sp. developing as a parasite within the dinoflagellate Alexandrium tamarense, does not appear to produce or incorporate any forms of MGDG and DGDG (Leblond & Dahmen, 2012). Additional work in this series has examined the biochemical relationship between peridinin-containing dinoflagellates and the photosynthetic alveolate, Chromera velia (Dahmen et al, 2013), the closest photosynthetic relative to apicomplexan parasites.…”