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Molecular diversity of summer plankton picoeukaryotes in the White Sea

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· “PROTIST–2016”
- Lomonosov Moscow State University, Moscow,
- Institute for Biology of Inland Waters, Russian
Academy of Sciences, Borok, Russia
- University of British Columbia, Department of
Botany, Vancouver, BC, Canada
Protists are ubiquitous, but the factors influencing
their diversity and biogeography are poorly understood. We use a comprehensive database on
the marine benthic heterotrophic flagellate (HF)
morphospecies to explore the worldwide patterns
in their diversity and distribution in comparison
with predictions of the Ubiquity model (UM) and
Moderate Endemicity model (MEM). Number
of known HF morphospecies was limited (even if
considering the rates of descriptions), and local-toglobal diversity ratio was relatively high (10-25%).
Regional diversity was highly correlated with the
investigation effort, indicating considerable underexploration. Regional endemics were few (not over
19% of total richness), and many morphospecies
were widespread or even cosmopolitan. No obvious
latitudinal trend in HF diversity was detected. By
species composition, the regions were distinctly
arranged into three groups according to cold,
temperate and warm waters, but not in accordance
with geographical distances. This distribution
pattern was most likely explained by contemporary
climate (temperature) but did not suggest clear
geographical barriers for dispersal. Therefore, the
HF morphospecies are less concordant with the
MEM predictions but closer to the UM than other
(larger) protists. (In)consistency between the
distributional patterns obtained from genetic- and
morphology-based data are briefly discussed.
This study was supported by Russian Foundation for
Basic Research (grants № 15-04-02245 to AA and
№ 14-04-00553, 15-29-02518 to DT).
Belevich T.A. 1, Ilyash L.V. 1, Milyutina I.A. 2,
Logacheva M.D.2, Goryunov D.V.2, Troitsky A.V.2
- Lomonosov Moscow State University, Faculty of
- Belozersky Institute of Physico-Chemical Biology,
Lomonosov Moscow State University
Picoeukaryotes (protists < 2 µm) play an important
role in marine ecosystems, although knowledge of
their diversity and ecosystem functioning is limited.
The White Sea is located in the sub-Arctic zone.
However, its abiotic conditions are characterized by
a number of features typical of the Arctic seas. In this
study, the molecular diversity of picoeukaryotes in
July 2014 in Kandalaksha Bay (the White Sea) was
examined using conventional filter fractionation and
Illumina sequencing. In < 2 µm size fraction 186
taxa were revealed that included some nanoplankton
(2–20 µm) and even microplankton (>20 µm) taxa.
Plankton assemblage was prevailed by autotrophs
(>57% of all sequences). Putative picoeukaryotic
autotrophs were mostly dominated by three genus:
Micromonas sp., Bathycoccus sp. and Ostreococcus
sp. (35% of all sequences). Putative heterotrophic
picoeukaryote assemblage was more diverse and
was presented by marine stramenopiles (MAST,
Labyrinthulomycetes), Amoebozoa, Cercozoa
and picozoa. Illumina sequencing revealed some
new groups and genus of nano- and microplankton
organisms which have been never detected in the
White Sea. Our study revealed that diversity of
picoeukaryotes in summer in the sub-Arctic White
Sea corresponds to that of the other Arctic seas, such
as the Beaufort and Norwegian Seas.
Beliavskaia A., Kiselev A., Rautian M.
Saint Petersburg State University
Among Paramecium species P. putrinum is one of
the best identifiable. Most important discriminative
features are small cell size (70-140 µm), single big
micronucleus (MI) and very special contractile
vacuole (CV) represented as set of small vacuoles.
We have studied several clones from different
collecting sites that were characterized by all features
mentioned above but with unusual habitus. Detailed
analysis revealed several very specific characteristics
of these clones. Usually the cells are bigger up to 120140 µm. Their single MI has got “chromosomal”
structure. Contractile vacuole differs from typical
P. putrinum one. It has got short channels and is
similar to CV of P. nephridiatum, or P. polycarium.
Holospora-like bacterium found in P. putrinum do
not infect “atypical” strains. Finally the sequence of
cytochrome c oxidase subunit I gene has only 86%
identity with the one of P. putrinum, which is much
higher than difference between different P. putrinum
syngens. Taking in account all above, we propose
new species “Candidatus Paramecium ossipovi”.
Scientific research was performed at the Center for
Culturing Collection of Microorganisms and Center
for Molecular and Cell Technologies of Research
park of St. Petersburg State University.
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sea, plankton, picoeukaryotes, molecular, diversity, white, summer
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