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Protistology ■ 25
THE PARASITIC ASSIMILATION FROM DIATOMS BY APLANOCHYTRIUM (THRAUS-TOCHYTRIIDAE, LABYRINTHULEA, STRA-MENOPILES) Hamamoto Y.12, Honda D.32
1 - Graduate School of Natural Science, Konan University, Japan
2 - Institute for Integrative Neurobiology, Konan University, Japan
3 - Faculty of Science and Engineering, Konan University, Japan [email protected] Thraustochytrids inhabit the ocean all over the world and have been recognized as important eukaryotic decomposers in the marine ecosystem. The monitoring works have suggested that they obtain nutrients from the terrestrial organic matter at estuarine areas. On the other hand, the habitat ofthe thraustochytrids is spread over the coastal areas, in which there are almost no influences from terrestrial fields. This suggests that the nutrition source of the thraustochytrids in the coastal areas is the detritus of phytoplankton. In this study, we investigated the assimilation of the thraustochytrids from diatoms, which are important primary pro-ducers in the coastal areas. First, we examined growth tests of the thraustochytrids under the 2-membered culture condition with Skeletonema diatoms. As the result, Aplanochytrium strains have quite higher growth than 8 other genus-level groups of the thraustochytrids. Observation under light microscopy showed that the vegetative cells of Aplanochytrium extended the pseudopod-like ectoplasmic nets to the diatom cells, and then chloroplasts ofthe diatoms shrank and bleached. It was suggested that the thraustochytrids play the role as not only decomposers but also "predators". Moreover, Aplanochytrium cells pulled the diatom cells and made aggregates, which are suited to be baits for juvenile fishes. It is possible that the food chain pathway of the Aplanochytrium has a large impact on the marine ecosystem because there are few steps in the food chain between the producers and the higher consumers.
A RE-INVESTIGATION OF THE PELAGO-PHYTE GENUS SARCINOCHRYSIS USING MATERIAL COLLECTED FROM THE TYPE LOCALITY
Han K.Y.1, Melkonian M.2, Andersen R.A.3, Graf L.1, Pérez Reyes C.4, Yoon H.S.1
1 - Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea
2 - Botany Department, Cologne Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany
3 - Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250 USA
4 - Spanish Bank of Algae — Marine Biotechnology Center (BEA-CBM), University of Las Palmas de Gran Canaria, Muelle de Taliarte s/n, 35214, Telde, Las Palmas, Gran Canaria, Spain [email protected]
Modern systematists use molecular markers to identify and distinguish species; however, many microalgae were described before gene sequencing was invented and the holotype was often an ink drawing. Cryptic speciation and biogeographic isolation are potential problems when anchoring an old species name with a modern gene sequence. Therefore, to avoid possible confusion caused by a misidentified microalgal culture from a different locality, the best approach is to sequence genes from the alga re-collected from the type locality. The marine alga Sarcinochrysis marina was described in 1930 by Geitler from the Canary Islands, Spain; Geitler used two cultures in his study, but these cultures no longer exist. Sarcinochrysis marina is the oldest genus in the Pelagophyceae. We re-isolated S. marina from the type locality near Las Palmas, Gran Canaria. Furthermore, we included additional Pelagophyceae strains that were obtained from culture collections. We produced a total of 109 sequences, representing the nuclear-encoded SSU rRNA and the plastid encoded rbcL, psaA, psaB, psbA, and psbC genes. The sequences were used to infer maximum likelihood phylogenetic trees. We anchored the genus Sarcinochrysis using the Las Palmas isolate, and we discovered several undescribed genera and species that are morphologically similar to Sarcinochrysis.
UNEXPECTED DIVERSITY OF THE PECULIAR GENUS CRENEIS (EXCAVATA: HETE-ROLOBOSEA) Hanouskova P., Cepicka Ivan Department ofZoology, Charles University in Prague, Prague, Czech Republic [email protected],
Creneis is a recently (2014) discovered genus of marine anaerobic heteroloboseids. Its only species, C. carolina, displays several uncommon features including amoeboid flagellates with a single flagel-lum, a multiflagellate form with ca. 14 flagella and the unique structure ofits flagellar apparatus. Therefore, its affiliation to Heterolobosea is recognizable only thanks to the results ofmolecular-phylogenetic analyses. Creneis was described on the basis of a single isolate and has never been observed again. We have established six marine Creneis strains in culture. According to the morphology and SSU rRNA gene
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sequences, our strains represent five novel species of Creneis. The species morphologically differ from each other as well as from C. carolina; the diagnostic features include the cell size, character of the flagellum, type and arrangement of pseudopodia, and character of the uroid and uroidal adhesive filaments. At least three new species are able to form the fast-swimming "multiflagellate" form, which, however, possesses only four or five flagella. Our results show that Creneis is a widespread and diverse lineage of anaerobic protists. Because six known species (including C. carolina) are represented by only seven strains, its true diversity is certainly much higher.
PREDATORY CAPABILITIES OF THE FILA-STEREAN CAPSASPORA OWCZARZAKI REVEALS ITS POTENTIAL FOR A FREE-LIVING LIFESTYLE
Harcet M.12, Lopez-Escardo D.1, Sebe-Pedros A.13, Ruiz-Trillo I.1-4-5
1 - Multicellgenome lab, Institut de biologia evolutiva (UPF-CSIC) Pssg. de la Barceloneta 37-49. 08003 Barcelona (Spain)
2 - Division of molecular biology, Ruder Boskovic Institute, Bijenicka cesta 54, 10 000Zagreb, Croatia
3 - Department of Computer Science and Applied Mathematics, Weizmann Institute ofScience, Rehovot 76100, Israel
4 - Institucio Catalana de Recerca i Estudis Avancats, Pg Lluis Companys 23, 08010 Barcelona, Spain
5 - Departament de Genetica, Universitat de Barcelona, 08028 Barcelona, Spain [email protected]
Capsaspora owczarzaki is one of only two known members of Filasterea — a group of protists closely related to animals. Due to its phylogenetic position, complex life cycle, and wide gene repertoire, it has become an important non-model organism in evolutionary studies, especially on the origin of animals. C. owczarzaki was isolated from several strains of freshwater snail Biomphalaria glabrata. However, it remains unclear whether it is an obligate symbiont or it can have a free-living lifestyle. In order to answer this question, we tested the interaction of C. owczarzaki with bacteria (Enterobacter aerogenes), with other unicellular eukaryotes (Dyctiostelium discoideum and Acanthamoeba castellani), and with
B. glabrata embryonic (BGE) cells. The interactions were observed and documented by microscopy. In addition, we followed the growth of C. owczarzaki in the presence of these organisms. We found that
C. owczarzaki is able to grow on a diet consisting
only of bacteria. Furthermore, it efficiently kills and consumes Dictyostelium discoideum and BGE cells, and ingests material from live Acathamoeba castellanii. We performed RNAseq of C. owczarzaki fed by the organisms mentioned before and found distinct expression profiles for each food type. Our results strongly suggest that C. owczarzaki is not an obligate snail symbiont, but rather an opportunistic predatory organism able to feed on a variety of food types. This research increases the knowledge on the diversity of lifestyles among unicellular holozoans, and has implications on our understanding of the origin of animals.
MORPHOLOGY OF TWO SPECIES OF THE THECATE DINOFLAGELLATE GENUS BLE-PHAROCYSTA EHRENBERG (DINOPHYTA) FROM THE TROPICAL MEXICAN PACIFIC Hernández-Becerril David Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México [email protected] Species ofthe thecate dinoflagellate genus Blepharo-cysta Ehrenberg are usually globose, spherical to ovoid, and lack a depressed cingulum and sulcus, typical of most dinoflagellates. The five recognized Blepharocysta species are truly marine planktonic forms and are mainly distributed in tropical and subtropical areas. During an oceanographic cruise along tropical coasts of the Mexican Pacific, net phytoplankton samples yielded a number oftropical forms of dinoflagellates, including two Blepharocysta species: Blepharocysta paulseni and B. splendor-maris. Both species were studied by LM and SEM and the general morphology previously described in the literature was confirmed, although the theca ornamentation was observed in detail. The cell shape, more ovoid in Blepharocysta splendormaris and more spherical in B. paulseni, the development of sulcal and theca ornamentation lists, with Blepharocysta paulseni having more reduced lists and a higher pores density, appear as the morphological characters separating both species. Additionally, Blepharocysta splendormaris has been found not only in tropical areas, but also in Antarctic waters. These two species (and probably all Blepharocysta species) showed no chloroplasts and are supposedly heterotrophic. Comparison among all species ofthe genus was made, emphasizing the shape and relative size ofthe cells, the development and ornamentation of the sulcal lists, tabulation and ornamentation of the theca, and the general distribution.
