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Protistology ■ 43
Results from the Tara Oceans metabarcoding study revealed that a significant fraction of the plankton in the sunlit ocean is constituted by diplonemid flagellates, a poorly known group of heterotrophic excavate protists. In an analysis of V9 18S rDNA metabarcodes from planktonic communities collected in 123 globally distributed stations, diplonemids emerge as a highly abundant and extremely diverse group that lacks geographic structuring but displays strong vertical separation. Uniquely among planktonic eukaryotes, taxonomic identification of diplonemids is far from saturation. They are more abundant in polar regions and deeper waters, yet their biological function in the ocean — the largest ecosystem of our biosphere - remains unknown. We are attempting to isolate and culture new marine diplonemids in order to sequence their genomes, analyze their ultrastructure and establish protocols for their genetic manipulation. By this combined approach, we hope to shed more light on these „new kids on the block".
THE SMALL SUBUNIT rRNA GENE SEQUENCE OF THE CHONOTRICH CHILODO-CHONA CARCINI JANKOWSKI, 2007 CONFIRMS CHONOTRICHS AS A DYSTERIID-DERIVED CLADE (PHYLLOPHARYNGEA, CILIOPHORA) Lynn D.H.
Department of Integrative Biology, University of Guelph, Guelph, ON Canada N1G 2W1 [email protected]
The chonotrichs are sessile ciliated protozoa ectosymbiotic on the body parts of a variety of crustaceans. They have long been considered a separate group because their sessile habit has resulted in the evolution of a very divergent body form and reproductive strategy compared to free-living ciliates. In the mid-20th Century, the free-living dysteriid cyrtophorian ciliates were proposed as a potential sister clade because the chonotrich bud or daughter cell showed similarities during division morphogenesis (i.e. ontogeny) to these free-living dysteriids. A single small subunit (SSU) rRNA gene sequence is available for the chonotrich Isochona sp. However, its authenticity has been questioned in the recent literature, and the placement of this sequence within the dysteriid clade has added to this controversy. In this report, the SSUrRNA gene sequence of the chonotrich Chilodochona carcini ectosymbiotic on the green crab Carcinus maenas is provided. Topology testing of the SSUrRNA gene phylogeny constructed by Bayesian Inference robustly supports the sister-group relationship of Isochona sp. and C. carcini, the monophyly of
these two chonotrichs, and the divergence of the chonotrich clade within the dysteriid clade.
MAPPING THE HIDDEN DIVERSITY OF FREE LIVING FRESH WATER CILIATES FROM DELHI REGION, INDIA Makhija S.1, Abraham J.S.1, Somasundaram S.1, Toteja R.1, Gupta R.2
1 - Acharya Narendra Dev College, University ofDelhi, Delhi, India
2 - Maitreyi College, University ofDelhi, Delhi, India [email protected]
India, with 2.4% of the world's area, has over 8% of the world's total biodiversity, making it one ofthe 12 mega diversity countries in the world. Despite this richness, the data concerning ciliate diversity from India is rather scarce. We at University of Delhi have been involved in the morphological and molecular taxonomy of ciliates from freshwater bodies namely from Okhla Bird Sanctuary, Sanjay Lake, Pond at Rajghat in Delhi region. A large number of species from different classes have been observed from these water samples namely from genus Tetmemena, Stylonychia, Laurentiella, Euplotes, Aspidisca, Paraurostyla, Gastrostyla, Pseudourostyla, Urostyla, Oxytricha and Uroleptus from class Spirotrichea; Blepharisma, Spirostomum and Stentor from class Heterotrichea; Paramecium, Frontonia, Vorticella and Cyclidium from class Oligohymenophorea; Litonotus, Dileptus, Didinium and Lacrymaria from class Litostomatea; Colpoda from class Colpodea; Chilodonella from class Phyllopharyngea; Loxodes from class Karyorelectia; and Coleps from class Prostomatea have been identified by live cell observations, protargol staining, silver staining and morphometric measurements. In the present study, we describe in detail few species from the subclass Stichotrichia and Hypotrichea. There is difficulty in understanding the phylogenetic relationship between different species of these group based solely on morphological markers. Therefore, we are trying to look into both morphological and multiple molecular markers like SSU- rRNA, ITS 1, ITS2 , hsp70 and histone genes and we could depict morphological and molecular congruence in the species from subclass Stichotrichia and Hypotrichea.
GLOBAL SHIFTS IN GENE EXPRESSION PROFILES ACCOMPANIED WITH ENVIRONMENTAL CHANGES IN CNIDARIAN-DINOFLAGELLATE ENDOSYMBIOSIS Maruyama S.1, Aihara Y.2, Yamaguchi T.3, Yama-guchi K.4, Shigenobu S.4, Takahashi H.3, Kawata M.1, Ueno N.3, Minagawa J.2
44 • "PROTIST—2016
1 - Department of Environmental Life Sciences, Tohoku University, Japan
2 - Division of Environmental Photobiology, National Institute for Basic Biology, Japan
3 - Division of Morphogenesis, National Institute for Basic Biology, Japan
4 - Functional Genomics Facility, National Institute for Basic Biology, Japan [email protected]
Stable endosymbiotic relationship between cnida-rian animal and dinoflagellate Symbiodinium spp. is a prerequisite for sustaining coral reef ecosystem. Recent studies have shown that elevated seawater temperature can cause collapse of endosymbiosis by expulsion of the symbiotic algae from cnidarians, which is known as 'bleaching', and subsequent mass mortality. However, the technical difficulty in maintaining and using corals as material in laboratory has hampered further understanding of the molecular biology of the cnidarian-dinofla-gellate endosymbiosis. Here we show transcriptomic analyses using the symbiotic sea anemone Exaiptasia pallida (formerly Aiptasiaspp.), an emerging model cnidarian, in multiple culture conditions. The genome-wide gene expression profiles were analyzed by mapping the RNAseq reads from symbiotic and experimental apo-symbiotic anemones onto the host and endosymbiont genome sequences. A large portion of the genes differentially expressed in response to light and elevated temperature in the symbiotic and apo-symbiotic anemones was not overlapped and, in a number of cases, different members in a single gene family were activated between the symbiotic and apo-symbiotic anemones. These suggest that the anemones use distinct gene sets to respond to environmental changes depending on the symbiosis states with Symbiodinium. From the endosymbiont side, several photosynthesis-related genes associated with the photosystem II core assembly were detected to be down-regulated under the heat condition in hospite, which potentially affect the photodamage-induced stress responses. Overall, our data suggest that the endosymbiosis with Symbiodinium substantially affect the host's transcriptional profiles, potentially leading to the altered ecological contribution to the environment.
CHLOROPLAST DIVISION OF TETRASEL-MIS SP. IN THE FOOD VACUOLE OF MIXO-TROPHIC ALGAE RAPAZA VIRIDIS Maruyama M.1, Miyagishima S.2, Suzaki T.3, Kashiyama Y.14
1 - Fukui University of Technology
2 - National Institute of Genetics
3 - Kobe University
4 - Ritsumeikan University [email protected]
Rapaza viridis is a euglenoid that always possesses chloroplasts in cells without exception. R. viridis requires not only light but also a specific strain of green algae (Tetraselmis sp.) as its prey for their survival/growth, hence apparently being of obligate mixotrophy. Nonetheless, the degradative process of chloroplasts of the prey was barely observed. Furthermore, only trace amount of 132,173-cyclopheophorbide enols (CPEs), the non-phototoxic catabolites of chlorophylls, was produced along with the predation, indicating that only a small proportion of chlorophylls was actually discarded from the ingested chloroplasts. We thus investigated cell dynamics regarding ingested chloroplasts in R. viridis to understand the fate of the chloroplasts and chlorophylls contained therein. Unlike other phycophagic euglenoids, decrement of chlorophyll fluorescence from the ingested chloroplasts was rarely observed, and any evidence for digestive degradation of the chloroplasts was not recognized. Furthermore, the chloro-plastic eye-spots of Tetraselmis sp. became dispersed several hours after the ingestion and eventually disappeared. In the next hours, interestingly, the ingested chloroplasts became subdivided into more than several pieces with various sizes. Within a day, the unique, rough appearance of chloroplasts of Tetraselmis sp. in the DIC image became insignificant and changed into a rather smooth appearance that is no more distinguishable from those originally possessed by R. viridis. Afterward, the number of "chloroplasts" per cell began to decrease, suggesting progress of R. viridis cell divisions at this stage. We discuss the mechanism for the observed chloroplast division and the origin of "chloroplasts" of R. viridis.
HETEROGENEITY IN NUTRIENT UPTAKE BY INDIVIDUAL DINOFLAGELLATE CELLS REVEALED USING NanoSIMS Matantseva O.1, Vogts A.2, Voss M.2, Skarlato S.1
1 - Institute ofCytology RAS, St. Petersburg, Russia
2 - Institute for Baltic Sea Research Warnemuende, Germany
Dinoflagellates are one of the most successful groups of marine protists. Many photosynthetic dinoflagellates can utilize not only inorganic, but also organic compounds as nutrients, which is advantageous in eutrophied coastal zones. Therefore, nutritional physiology of these organisms receives much scientific attention. Usually it is studied by bulk approaches; however, the use of
