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Protistology ■ 45
modern single-cell tools significantly advances our knowledge in this field. We used stable isotope tracers, isotope ratio mass spectrometry and nanoscale secondary ion mass spectrometry (NanoSIMS) to investigate concurrent uptake of nitrate and urea by dinoflagellates Prorocentrum minimum at the population and single-cell levels. Although bulk and averaged single-cell measurements revealed similar relationships between the urea and nitrate uptake, NanoSIMS disclosed significant heterogeneity in nutritional activity of individual cells. Dinoflagellates readily consumed urea even if this nutrient was new to the cells, but some cells took it up at a 9-folds higher rate than others. Furthermore, sudden urea input resulted in overall 30-40% suppression ofthe nitrate uptake. However, a closer look with NanoSIMS showed that in 30% of cells nitrate consumption was completely inhibited, whereas in other cells it might be not suppressed. We conclude that even sporadic inputs of urea to coastal ecosystems are likely to have a prominent effect on P. minimum populations. Physiological heterogeneity among individual dinoflagellate cells can represent a so far overlooked strategy towards ecological success. Funded by the Russian Science Foundation, project 16-14-10116 (to OM, SS) and Federal Ministry of Education and Research, grant BMBF 03F0626A (to AV, MV).
TRENDS IN ENDOSYMBIOTIC GENE TRANSFER ON PLASTID METABOLIC PATHWAYS IN DINOFLAGELLATES WITH NON-CANONICAL PLASTIDS Matsuo E.1, Inagaki Y.12
1 - Graduate School of Life and Environmental Sciences, University of Tsukuba
2 - Center for Computational Sciences, University of Tsukuba
yinagai@gmail.com
The major photosynthetic dinoflagellates possess red algal-derived plastids, but some minor lineages established non-canonical plastids derived from phylogenetically diverse eukaryotic algae. Dinoflagellates Karlodinium veneficum and Lepidodinium chlorophorum, which bear non-canonical plastids derived from haptophyte- and green algal endosymbionts, respectively, and their nuclear genomes contain genes encoding plastidal proteins that are likely transferred from the genomes ofthe endosymbiont algae (endosymbiotic gene transfer, EGT). Although EGT is generally considered to be an essential step in transforming an endosymbiotic alga into a plastid, it has yet to be fully understood to what extent metabolic functions in the Karlodinium and Lepidodinium plastids rely
on endosymbiotically acquired proteins. We here surveyed nucleus-encoded plastidal proteins in Karlodinium and Lepidodinium, and investigated the origins of the proteins involved in two metabolic pathways localized in the plastid. Chlorophyll a biosynthetic pathway in the two species appeared to be reorganized in different ways. The pathway in Karlodinium was found to be occupied by proteins acquired from the haptophyte endosymbiont, while 'laterally derived' proteins, which were acquired from diverse eukaryotes rather than the green algal endosymbiont, comprise the pathway in Lepidodinium. In contrast, the majority of proteins which were detected in isoprene biosynthetic pathway in Karlodinium or Lepidodinium were derived from host dinoflagellate, suggesting that switch from the canonical to non-canonical plastids barely triggered reorganization of this particular pathway in the two species. In this talk, we discuss biological reasons for the marked difference in the impact of gene transfer between the two metabolic pathways in Karlodinium and Lepidodinium.
LAGENOPHRYS PATINA (CILIOPHORA: PERITRICHIA: LAGENOPHRYIDAE) ATTACHED TO TWO MEXICAN POPULATIONS OF HYALELLA AZTECA (CRUSTACEA: AM-PHIPODA): STATISTICAL APPROACH TO PROBE SITE PATTERN PREFERENCE ON HOST
Mayén-Estrada R.1, Macip-Ríos R.2, Hermoso-Salazar M.3, Romero-Niembro V.M.1
1 - Lab. Protozoología, Depto. Biol. Comparada, Fac. Ciencias, Universidad Nacional Autónoma de México, Circuito Ext. s/núm. Ciudad Universitaria, C. P. 04510, Ciudad de México, Mexico
2 - ENES Morelia, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No.8701, Col. Ex Hacienda de San José de la Huerta, C.P. 58190 Morelia, Michoacán, Mexico
3 - Departamento de Biología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito Ext. s/núm. Ciudad Universitaria, C. P. 04510, Ciudad de México, Mexico romaraf@gmail.com
Members of genus Lagenophrys are obligate symbiotic peritrichs of crustaceans, however the pattern of distribution on corporal surface varies according to involved species. To demonstrate with statistical tests the preference for an amphipod body region or appendage to attach, two Hyalella azteca populations were collected in two Mexican lakes, Xochimilco Lake and Cuitzeo Lake, and density and prevalence of Lagenophrys patina on host surface were calculated. We used a contingency table and
