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Protist communities in water and sediment of a Sea cucumber farming system

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Protistology
3
- University of South Bohemia, Faculty of Science,
370 05 České Budějovice, Czech Republic
4
- Institute of Microbiology ASCR, Centrum Agaltech,
379 01 Třeboň, Czech Republic
kika.zahonova@gmail.com
Euglena longa, a close relative of the photosynthetic
model alga Euglena gracilis, possesses an enigmatic
non-photosynthetic plastid. Its genome has retained a gene for the large subunit of the enzyme
RuBisCO (rbcL). Here we provide new data
illuminating the putative role of RuBisCO in E.
longa. We demonstrated that the E. longa RBCL
protein sequence is extremely divergent compared
to its homologs from the photosynthetic relatives,
suggesting a possible functional shift upon the loss
of photosynthesis. Similarly to E. gracilis, E. longa
harbors a nuclear gene encoding the small subunit
of RuBisCO (RBCS) as a precursor polyprotein
comprising multiple RBCS repeats, one of which is
highly divergent. Both RBCL and the RBCS proteins
are synthesized in E. longa, but their abundance
is very low compared to E. gracilis. No RBCS
monomers could be detected in E. longa, suggesting
that processing of the precursor polyprotein is
inefficient in this species. The abundance of RBCS
is regulated post-transcriptionally. Indeed, blocking
the cytoplasmic translation by cycloheximide
has no immediate effect on the RBCS stability in
photosynthetically grown E. gracilis, but in E. longa,
the protein is rapidly degraded. E. longa appears to
lack the chaperone RBCX essential for assembly
of a conventional RuBisCO complex. Altogether,
our results revealed signatures of evolutionary
degradation of RuBisCO in E. longa and suggest that
its role in this species may be rather unorthodox.
PROTIST COMMUNITIES IN WATER AND
SEDIMENT OF A SEA CUCUMBER FARMING SYSTEM
Zhang Q., Tan S., Gong J.
Laboratory of Microbial Ecology and Matter Cycles,
Yantai Institute of Coastal Zone Research, Chinese
Academy of Science, Yantai, China
jgong@yic.ac.cn
Little is known about the distinctive communities
of uncultured protsit within the aquaculture ecosystem. In this work, the planktonic and benthic protist
communities in a sea cucumber farming system
were simultaneously investigated on three sampling
dates. Analyses of SSU rRNA gene libraries of six
samples revealed 108 eukaryotic taxonomic units,
among which 17.5% were rare. Stramenopiles
and Alveolata are predominant groups in both
sediment and water samples. Dinophyta, Rhizaria
and parasitic Mesomycetozoa were only detected
· 91
in water samples. Parasitic Apicomplexa were
found frequently from both water and sediment
samples. Based on terminal-restriction fragment
length polymorphisms, distinct succession and
contrasting protist community structure was found
among temporal samples and between planktonic
and benthic habitats. Redundancy analysis indicated
that the temprature, concentration of dissolved
phosphate, and N:Si in surface water were the most
significant abiotic variables shaping the planktonic
communities. This study indicates that temprature
and stoichiometric ratios play important roles in
driving succession of protist communities, and
parasitic protist could be early examed by molecular
technologies for the farming pools.
This work was supported by projects from NSFC
(No. 313018680) and Scientific Development
Program of Yantai (No. 2014ZH073).
MAKE PERCISE IDENTIFICAITON USING
DNA TAXONOMY TECHNIQUES FOR CLOSELY RELATED EUPLOTES CONGENERS
(PROTOZOA, CILIOPHORA) WITH HIGHLY
PHENOTYPIC PLASTICITY
Zhao Y.1, Yi Z.2, Song W.3
1
- Research Center for Eco-Environmental Sciences,
Chinese Academy of Sciences, Beijing 100085, China
2
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitor, School of Life Science, South
China Normal University, Guangzhou 510631, China
3
- Laboratory of Protozoology, Institute of Evolution
& Marine Biodiversity, Ocean University of China,
Qingdao 266003, China
yanzhao@rcees.ac.cn
Ciliated protists constitute astounding diversity
and play crucial role in different biotopes yet
still incompletely characterized microbes. DNA
barcoding is promising to address this dilemma.
This molecular technique based on COX 1 gene
has become a routine method for animal organism
identification and taxonomic clarification. This
common region also can distinguish ciliates species,
but has not displayed universality, and establishing
a standardized DNA barcoding system for ciliated
protists is still confronted with many difficulties
and challenges. Here, we collected the species-rich
taxon Euplotes from brackish and fresh waters. In the
framework of traditional classification system, the
Euplotes spp. with available morphological features
can provide a useful template against which to test
the accuracy of DNA-based taxonomy. Using >30
samples, we have assessed the most common COX
1 region and the alternative SSU-V4, SSU-V9,
LSU-D1/D2, ITS1, ITS2 markers. And SSU-V9,
LSU-D1/D2 and ITS1 could distinguish the most
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sea, protist, water, farming, cucumber, system, communities, sediments
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