%0 Journal Article %J Harmful Algae %D 2022 %T Mixotrophy in the bloom-forming genus Phaeocystis and other haptophytes %A Koppelle, Sebastiaan %A López-Escardó, David %A Brussaard, Corina P.D. %A Huisman, Jef %A Philippart, Catharina J.M. %A Massana, Ramon %A Wilken, Susanne %K RCC1130 %K RCC1303 %K rcc1383 %K RCC1455 %K RCC1486 %K RCC1523 %K RCC1537 %K RCC918 %X Phaeocystis is a globally widespread marine phytoplankton genus, best known for its colony-forming species that can form large blooms and odorous foam during bloom decline. In the North Sea, Phaeocystis globosa typically becomes abundant towards the end of the spring bloom, when nutrients are depleted and the share of mixo­ trophic protists increases. Although mixotrophy is widespread across the eukaryotic tree of life and is also found amongst haptophytes, a mixotrophic nutrition has not yet been demonstrated in Phaeocystis. Here, we sampled two consecutive Phaeocystis globosa spring blooms in the coastal North Sea. In both years, bacterial cells were observed inside 0.6 – 2% of P. globosa cells using double CARD-FISH hybridizations in combination with laser scanning confocal microscopy. Incubation experiments manipulating light and nutrient availability showed a trend towards higher occurrence of intracellular bacteria under P-deplete conditions. Based on counts of bacteria inside P. globosa cells in combination with theoretical values of prey digestion times, maximum ingestion rates of up to 0.08 bacteria cell− 1 h− 1 were estimated. In addition, a gene-based predictive model was applied to the transcriptome assemblies of seven Phaeocystis strains and 24 other haptophytes to assess their trophic mode. This model predicted a phago-mixotrophic feeding strategy in several (but not all) strains of P. globosa, P. antarctica and other haptophytes that were previously assumed to be autotrophic. The observation of bacterial cells inside P. globosa and the gene-based model predictions strongly suggest that the phago-mixotrophic feeding strategy is widespread among members of the Phaeocystis genus and other haptophytes, and might contribute to their remarkable success to form nuisance blooms under nutrient-limiting conditions. %B Harmful Algae %V 117 %P 102292 %G eng %U https://linkinghub.elsevier.com/retrieve/pii/S1568988322001202 %R 10.1016/j.hal.2022.102292 %0 Journal Article %J eLife %D 2017 %T Chimeric origins of ochrophytes and haptophytes revealed through an ancient plastid proteome %A Dorrell, Richard G %A Gile, Gillian %A McCallum, Giselle %A Méheust, Raphaël %A Bapteste, Eric P %A Klinger, Christen M %A Brillet-Guéguen, Loraine %A Freeman, Katalina D %A Richter, Daniel J %A Bowler, Chris %K 2017 %K RCC1486 %K RCC1523 %K RCC1537 %K RCC1587 %K SBR$_\textrmP$hyto$_\textrmE$PPO %X Plastids are supported by a wide range of proteins encoded within the nucleus and imported from the cytoplasm. These plastid-targeted proteins may originate from the endosymbiont, the host, or other sources entirely. Here, we identify and characterise 770 plastid-targeted proteins that are conserved across the ochrophytes, a major group of algae including diatoms, pelagophytes and kelps, that possess plastids derived from red algae. We show that the ancestral ochrophyte plastid proteome was an evolutionary chimera, with 25% of its phylogenetically tractable nucleus-encoded proteins deriving from green algae. We additionally show that functional mixing of host and plastid proteomes, such as through dual-targeting, is an ancestral feature of plastid evolution. Finally, we detect a clear phylogenetic signal from one ochrophyte subgroup, the lineage containing pelagophytes and dictyochophytes, in plastid-targeted proteins from another major algal lineage, the haptophytes. This may represent a possible serial endosymbiosis event deep in eukaryotic evolutionary history. %B eLife %V 6 %P 1–45 %8 may %G eng %U http://elifesciences.org/lookup/doi/10.7554/eLife.23717 %R 10.7554/eLife.23717 %0 Journal Article %J Protist %D 2011 %T Integrative taxonomy of the pavlovophyceae (haptophyta) : a reassessment %A Bendif, E M %A Probert, I %A Hervé, A %A Billard, C %A Goux, D %A Lelong, C %A Cadoret, J P %A Véron, B %K 2011 %K ASSEMBLE %K rcc %K RCC1523 %K rcc1524 %K rcc1525 %K RCC1526 %K RCC1527 %K RCC1528 %K RCC1529 %K RCC1530 %K RCC1531 %K RCC1532 %K RCC1533 %K RCC1534 %K RCC1535 %K RCC1536 %K RCC1537 %K RCC1538 %K RCC1539 %K RCC1540 %K RCC1541 %K RCC1542 %K RCC1543 %K RCC1544 %K RCC1545 %K RCC1546 %K RCC1548 %K RCC1549 %K RCC1551 %K RCC1552 %K RCC1553 %K RCC1554 %K RCC1557 %K SBR$_\textrmP$hyto$_\textrmE$PPO %X The Pavlovophyceae (Haptophyta) contains four genera (Pavlova, Diacronema, Exanthemachrysis and Rebecca) and only thirteen characterised species. Considering the importance of members of this class, we constructed molecular phylogenies inferred from sequencing of ribosomal gene markers with comprehensive coverage of the described diversity and using type strains when available add on culture strains. Moreover, the morphology and ultrastructure of 12 of the described species was re-examined and the pigment signatures of many culture strains were determined. The molecular analysis revealed that sequences of all described species differed, although those of Pavlova gyrans and P. pinguis were nearly identical, these potentially forming a single cryptic species complex. Four well-delineated genetic clades were identified, one of which included species of both Pavlova andDiacronema. Unique combinations of morphological/ultrastructural characters were identified foreach of these clades. The ancestral pigment signature of the Pavlovophyceae consisted of a basic set of pigments plus MV chl cPAV, the latter being entirely absent in the Pavlova + Diacronema clade and supplemented by DV chl cPAV in part of the Exanthemachrysis clade. Based on this combination of characters, we propose a taxonomic revision of the class, with transfer of several Pavlova species to an emended Diacronema genus. The evolution of the class is discussed in the context of the phylogenetic reconstruction presented. %B Protist %V 162 %P 738–761 %G eng %R 10.1016/j.protis.2011.05.001