Salinity Acclimation Induces Reduced Energy Metabolism,Osmotic Pressure Regulation and Transcriptional Reprogramming in Hypotrichida Ciliate Gastrostyla setifera

Coastal and estuarine protists are frequently exposed to salinity undulation.While the tolerance and stress responses of microalgae to salinity have been extensively studied,there have been scarce studies on the physiological response of heterotrophic protists to salinity stressing.In this study,we investigated the physiological response of the heterotrophic ciliate Gastrostyla setifera to a salinity of 3,via a transcriptomic approach.The first transcriptome of genus Gastrostyla was obtained utilizing a group of manually isolated ciliate individuals(cells)and RNA-seq technique.The completeness of the transcriptome was verified.Differentially expressed gene(DEG)analysis was performed among the transcriptomes of G.setifera acclimated in saline water(salinity 3)and those cultured in fresh water.The results demonstrated a significant alternation in gene transcription,in which the ciliate exhibits a transcripttomic acclimation in responding salinity stressing.The up-regulated DEGs were enriched in the pathways of cytoskeleton proteins,membrane trafficking,protein kinases and protein phosphatases.These may represent enhanced functions of ion transport,stress response and cell protections.Pathways involved in energy metabolism and biosynthesis were markedly down-regulated,reflecting decreased cell activity.Particularly,we detected significantly down-regulated genes involved in several pathways of amino acid catabolism,which may lead to accumulation of amino acids in the ciliate cell.Amino acid could act as compatible solutes in the cytoplasm to maintain the osmotic balance in saline water.Overall,this work is an initial exploration to the molecular basis of the heterotrophic protist responding to salinity stressing.The result sheds light on the mechanisms of enhancement of cell protection,reduction of cell activity,and osmotic pressure regulation in ciliates acclimated to salinity.

Molecular diversity and biogeography of benthic ciliates in the Bohai Sea and Yellow Sea

This study explored the molecular diversity and biogeography of benthic ciliates in Chinese marginal seas, the Bohai Sea(BHS), North Yellow Sea(NYS) and South Yellow Sea(SYS). From a previous 18S rRNA gene pyrosequencing dataset of the benthic microeukaryotes, we retrieved the sequences affiliated with phylum Ciliophora and analyzed alpha and beta diversities of ciliate communities. We found that BHS had the highest ciliate operational taxonomic unit(OTU) richness than NYS and SYS, whereas the richness was not significantly different between summer and winter. Among all the measured environmental variables, water depth showed consistently the strongest correlations with alpha diversities. Overall, the class Spirotrichea(mostly Choreotrichia and unassigned lineages within the class) dominated the communities in terms of both relative proportion of sequences(77.0%) and OTU richness(66.5%). OTU-level ciliate community structure was significant different among the three basins, but not between the seasons. Structurally, significant differences in relative proportion among the basins were detected for the class Litostomatea, but not for other classes. Partial Mantel tests demonstrated that water depth difference was more important than geographic and environment distances in shaping the community structure of benthic ciliates in the studied area. About 60% OTUs were not assigned at a class or order level and at least 45% OTUs shared a sequence similarity no more than 97% with the described species, indicating a great potential for ciliate species discovery in the offshore sediments. Compared with previous morphology-based surveys, the spatial pattern of ciliate diversity(decreasing from NYS to SYS) is also identified in the present study. Nevertheless, structurally, the dominant class appeared to be Spirotrichea in the sequencing dataset, which differs from previous morphology-based results(dominance of classes Prostomatea and Karyorelictea in biomass). The potential causes for the discrepancies between molecular and morphological findings are also discussed.

Latitudinal changes (6°S-20°N) of summer ciliate abundance and species compositions in surface waters from the Java Sea to the South China Sea

Ciliates play a curial role in energy transfer from pico- and nano-phytoplankton to mesozooplankton in marine ecosystems. In order to visualize their geographical distributions from the Java Sea to the South China Sea （6~S to 20~N）, the authors investigated the ciliate abundance and species composition in sur- face waters during May 18 to 27 of 2010. The ciliate abundance decreased latitudinally from 3 080 ind./L （~6~S） to 40 ind./L （-~3~N）, and then increased to 1 180 ind./L （-~ 16~N） at the end of the survey. A total of 22 ciliates belonging to 15 genera were identified with the tintinnids accounted for 50% （11 species）; and the species number showed a same spatial change as the ciliate abundance. Moreover, the Strombidium oc- cupied over 50% of total ciliate abundance in most stations and Mesodiniurn and Tintinnopsis contributed to about 18.7% and 11.4%, respectively. In particular, our results indicate that the geographical changes in ciliate abundance were positively regulated by larger nano- and micro-phytoplankton biomass, rather than smaller pico-phytoplankton in the investigated waters.

Complementary DNA sequencing (cDNA): an eff ective approach for assessing the diversity and distribution of marine benthic ciliates along hydrographic gradients

The Yellow Sea Cold Water Mass(YSCWM)is a distinct hydrographic phenomenon of the Yellow Sea,and the distribution pattern of meio-and macrobenthos diff ers inside and outside of the YSCWM.However,such a pattern has never been observed in the microbenthic ciliate communities.Therefore,we hypothesized that benthic ciliates followed a similar distribution pattern as meio-and macrobenthos,but this pattern has not been uncovered by morphological methods.We evaluated the diversity and distribution of benthic ciliates at fi ve stations along hydrographic gradients across the YSCWM and adjacent shallow water by using morphology and DNA and complementary DNA(cDNA)high-throughput sequencing of the V4 region of 18S rRNA gene.Results showed that the diversity of benthic ciliates detected by DNA(303 OTUs),and the cDNA(611 OTUs)sequencing was much higher than that detected by the morphological method(79 species).Morphological method detected roughly diff erent ciliate communities inside and outside of the YSCWM,but without statistical signifi cance.No clear pattern was obtained by DNA sequencing.In contrast,cDNA sequencing revealed a distinct distribution pattern of benthic ciliate communities like meioand macrobenthos,which coincided well with the results of the environmental parameter analysis.More than half of the total sequences detected by DNA sequencing belonged to planktonic ciliates,most(if not all)of which were recovered from historic DNA originating through the sedimentation of pelagic forms because none of them were observed morphologically.The irrelevant historic DNA greatly infl uenced the recovery of rare species and thus limited the understanding of the benthic ciliate diversity and distribution.Our research indicates that the methods used have signifi cant eff ects on the investigation of benthic ciliate communities and highlights that cDNA sequencing has great advantages in estimating the diversity and distribution of benthic ciliates,as well as the potential for benthic environmental assessments.

Difference of planktonic ciliate communities of the tropical West Pacific, the Bering Sea and the Arctic Ocean

Ciliates are important components in planktonic food webs,but our understanding of their community structures in different oceanic water masses is limited.We report pelagic ciliate community characteristics in three seas:the tropical West Pacific,the Bering Sea and the Arctic Ocean.Planktonic ciliate abundance had"bimodal-peak","surface-peak"and"DCM(deep chlorophyll a maximum layer)-peak"vertical distribution patterns in the tropical West Pacific,the Bering Sea and the Arctic Ocean,respectively.The abundance proportion of tintinnid to total ciliate in the Bering Sea(42.6%)was higher than both the tropical West Pacific(7.8%)and the Arctic Ocean(2.0%).The abundance proportion of small aloricate ciliates(10–20μm size-fraction)in the tropical West Pacific was highest in these three seas.The Arctic Ocean had higher abundance proportion of tintinnids in larger LOD(lorica oral diameter)size-class.Proportion of redundant species increased from the Arctic Ocean to the tropical West Pacific.Our result provided useful data to further understand ecology roles of planktonic ciliates in different marine habitats.

Taxonomy, Morphology and Phylogeny of a New Oligotrich Ciliate-Omegastrombidium hongkongense n. sp.(Protozoa: Ciliophora) from Clear Water Bay, Hong Kong

One new marine oligotrich ciliate, Omegastrombidium hongkongense n. sp., was isolated from a bloom of Noctiluca scuntillans near Port Shelter, Hong Kong. The morphology and infraciliature of this new species were studied on both living and protargol-stained specimens. Its phylogenetic position was discussed based on the sequence of the small subunit r RNA gene. O. hongkongense is different from its congeners with special characters. The cells are usually heart-shaped, and the cell size usually is(20–35) ×(20–30) μm in vivo. Its deep buccal cavity extends obliquely to about 1/2 of cell length. It shows prominent apical protrusion. The adoral zone of membranelles is divided into 17–19 collar membranelles and four buccal membranelles. It has one ball-like macronucleus. The girdle kinety forms a closed loop which obliquely surrounds the body. The ventral kinety and thigmotactic membranelles are not observed. The SSU r RNA sequence of O. hongkongense was close to those of Strombidium paracalkinsi and Varistrombidium kelum with approximately 99% similarity. In the phylogenetic trees, O. hongkongense can be grouped with O. elegans and V. kielum species with very low support(16% ML).

Ciliated hepatic foregut cyst:an increasingly diagnosed condition

BACKGROUND:Ciliated foregut cysts of the liver are rare, with only 96 cases diagnosed since the first description in 1857.They are being increasingly diagnosed recently;the majority of the cases have been reported in the last 15 years. Although they bear a close resemblance to the simple cyst of the liver which has essentially a benign course,ciliated hepatic foregut cysts(CHFCs)can progress to malignancy with devastating consequences.It is imperative that this group of conditions be diagnosed and treated adequately. DATA SOURCES:This review includes discussion of the data from all the 96 reported cases from English and non-English literature.Analysis of the incidence rates, embryogenesis,growth,clinical features,risk of malignancy and the prognosis are highlighted systematically.The roles of various diagnostic modalities including ultrasound, CT,MRI,fine needle aspiration cytology(FNAC), immunohistochemistry and surgery are further discussed. RESULTS:The mean age of patients with CHFC was 48± 12 years.The male/female ratio was 1.1∶1.The majority of patients with CHFC(62%)were asymptomatic,and the common mode of presentation was right upper abdominal pain.The cysts occurred in the left lobe in 51 patients, with sole location in segmentⅣin 44,and in the right lobe in 26.The average size of the cysts was 3.6±2.12 cm. The majority of the cysts were unilocular,and only 7 cases were multilocular.Cyst contents were described as viscous or mucinous in 73 patients,whereas bilious fluid was noted in 3.Large cysts having squamous carcinoma were cited in 3 patients,and 2 had extensive squamous metaplasia without malignancy.Others had benign histopathology. CONCLUSIONS:Clinicians have become increasingly aware of CHFC.Imaging alone is not diagnostic per se, but when considered in the context of the global picture does provide important clues to the diagnosis.FNAC is diagnostic by the presence of the ciliated columnar aspirate but lacks sensitivity.Infantile presentation is usually accompanied by biliary communication and mandates a different surgical approach.The demonstration of malignant transformation in 3 cases and its fatal course emphasizes the need for surgical resection in all cases once the diagnosis is made.

Morphological Studies on Four Brackish Water Ciliates of the Class Spirotrichea(Protista, Ciliophora)

We reinvestigate the morphology of two oligotrich and two hypotrich ciliates collected from the coasts of north and south China, viz., Parallelostrombidium obesum Liu et al., 2015, Spirostrombidium apourceolare Liu et al., 2013, Protogastrostyla pulchra(Pereyaslawzewa, 1886) Gong et al., 2007, and Uncinata bradburyae(Gong et al., 2001) Luo et al., 2015. All the populations match well with the original samples identified in previous studies. Supplemental taxonomic data were supplied for these four species of the new populations. The species Parallelostrombidium obesum is characterised by its dorsal-ventrally flattened body shape with anterior and posterior ends transversely truncating, as well as two thigmotactic membranelles and girdle kinety that spirals around the cell one and a half times. Spirostrombidium apourceolare is characterised by its elongate ellipsoidal and dorsal-ventrally flattened body shape, two thigmotactic membranelles, about 11-27 ovoid macronuclear nodules, and girdle kinety that spirals around the cell twice with two undulations. Protogastrostyla pulchra is characterised by its elongate body shape and unique, caudally located food vacuole. Based on the new populations, we described the smaller cortical granules, clustered around dorsal bristles for the first time. The new population of Uncinata bradburyae shares the diagnostic features with the type population, which include prominent beak-like projection in anterior region, the conspicuous gap of adoral zone, proximalmost adoral membranelles distinctly elongated, and infraciliature.

Divisional morphogenesis in the marine ciliate Anteholosticha manca (Kahl,1932) Berger,2003 (Ciliophora:Urostylida)

The cortical development and macronuclear evolution of the marine hypotrichous ciliate Anteholosticha manca, collected from the coastal waters near Qingdao, China, were investigated using the protargol impregnation method. The morphogenesis of A. manca is generally typical for the genus, and can be characterized as the following features ： （ 1 ） in the proter, a new oral primordium is formed on the bottom （beneath the pellicle） of the buccal cavity, disorganization of the parental undulating membranes do not contribute to the formation of this primordium ; （2） FVT-cirral anlagen in both dividers develop independently, and very likely only a few midventral cirri join in the formation of these primordia; （ 3 ） both marginal row and dorsal kinety anlagen develop intrakinetally within the parental structure; （4） at the middle stage, macronuclear segments fuse together to form a single mass as observed in most of its related forms.

Diversity of oligotrich ciliates(Ciliophora, Spirotrichea) in the northern coast of South China Sea as revealed in LSU rDNA sequences

Although the taxonomy of oligotrich ciliates has been widely investigated,yet the species diversity remains poorly known.We newly designed a pair of oligotrich-specific LSU rDNA primers covering the 600-bp D1/D2 region,and it was effective for detecting oligotrich species.Using the primers,we constructed the cloning libraries to investigate the species diversity of oligotrichs in the northern coastal waters of the South China Sea.In total,165 oligotrich sequences were obtained from five widely separated sampling sites.Sixty operational taxonomic units(OTUs)were obtained at 99%similarity threshold,and low-abundance OTUs with no more than two sequences contributed most of these(about 78%).Our findings are consistent with previous morphological studies,Strombidium was found the most abundant and widely distributed genus in this area.In addition,the BLAST search in the NCBI database resulted in 95%OTUs matching with named oligotrich species in similarity below 99%.Therefore,oligotrich morphospecies diversity has been underestimated as low-abundance species,and the LSU rDNA oligotrich sequence database needs to be better promoted.

Morphological studies of six free-living spirotrichean ciliates (Protozoa： Ciliophora) with three new records from the coastal South China Sea

The living morphology and infraciliature of six spirotrichous ciliates collected from the coastal South China Sea were investigated using live observation and protargol impregnation. These are Euplotes woodruffi Gaw, 1939, Hemigastrostyla enigmatica （Dragesco and Dragesco-Kerneis, 1986） Song and Wilbert, 1997, Neourostylopsis flavicana （Wang et al., 2011） Chen et al., 2013, Protogastrostyla pulchra （Perejaslawzewa, 1886） Gong et al., 2007, Pseudoamphisiella alveolata （Kahl, 1932） Song and Warren, 2000, and PseudokahlieUa marina （Foissner et al., 1982） Berger et al., 1985. Among these, Protogastrostyla pulchra, Pseudoamphisiella alveolata and PseudokahlieUa marina are reported from the South China Sea for the first time, which manifest obvious differences apart from other Chinese populations. As new contribution, the detailed description of isolates from mangrove habitat of E. woodruffi and 1t. enigmatica, and aquaculture pond isolate of N.flavicana, are present.

SPECIES COMPOSITION AND SEASONAL DENSITY DYNAMICS OF CILIATED PROTOZOA IN BAOAN LAKE WITH PARTICULAR REFERENCE TO THE SUBMERGED MACROPHYTES

From April 1996 to October 1997, regular samplings were carried out monthly at 8 stations in a macrophytic basin of Baoan Lake. From the water samples, 47 genera, 96 species of ciliata were identified. Stations covered with macrophytes had greater number of ciliate species and higher percentage of sessile species. The mixotroph Strombidium viride bearing algal endosymbionts dominated numerically the whole ciliate communities; most of the other dominants were bactivores. Total ciliate density in Lake Baoan was 6170-34310 ind./L. The seasonal density fluctuations of the dominant species populations were also investigated. Maximum abundances were observed in spring and winter during the decay of macrophytes and minimum densities were observed during the summer months of luxuriant macrophytes growth.

Observations on a magnetotactic bacteria-grazing ciliate in sediment from the intertidal zone of Huiquan Bay,China

Magnetotactic bacteria(MTB)are a group of prokaryotes having the ability to orient and swim along geomagnetic field lines because they contain intracellular magnetosomes that are synthesized through a biomineralization process.Magnetosomes have recently also been found in unicellular eukaryotes,which are referred to as magnetically responsive protists(MRPs).The magnetosomes have three origins in MRPs.In this study,we characterized a MTB-grazing ciliated MRP that was magnetically collected from intertidal sediment of Huiquan Bay,Qingdao,China.Based on 18S rRNA gene sequence analysis,the ciliated MRP was tentatively identified as Uronemella parafi lificum HQ.Using transmission electron microscopy,we observed that magnetosomes having 2-3 shapes were randomly distributed within this ciliate.Energydispersive X-ray spectroscopy and high-resolution transmission electron microscopy images of the magnetosomes were consistent with them being composed of magnetite.Magnetosomes having the same shape and mineral composition were also detected in MTB that occurred in the same environment as the ciliated MRP.Statistical analysis showed that the size and shape of the magnetosomes in the ciliated MRP were similar to those in MTB.The results suggest that this ciliated MRP can graze,ingest,and digest various types of MTB.It is certainly worth noting that this is the first record of MRPs in Asian aquatic sediment and suggesting they might be widely distributed.These results also support the assertion that MRPs probably contribute to the ecological cycles of iron,and expand possibilities for research into the mechanism of magnetoreception in eukaryotes.

Morphology and SSU rD NA Sequence Analysis of Two Hypotrichous Ciliates(Protozoa, Ciliophora, Hypotrichia) Including the New Species Metaurostylopsis parastruederkypkeae n.sp.

The morphology and phylogeny of two hypotrichous ciliates, Metaurostylopsis parastruederkypkeae n. sp. and Neourostylopsis flavicana(Wang et al., 2011) Chen et al., 2013 were investigated based on morphology, infraciliature and the small subunit(SSU) ribosomal RNA gene(r RNA) sequence. The new species, M. parastruederkypkeae n. sp. was identified according to its characteristics: body shape ellipsoidal, size about(165–200) ×(45–60) μm in vivo, cell color reddish; two types of cortical granules including wheat grain-like and yellow-greenish larger ones along the marginal cirri rows and dorsal kineties and dot-like and reddish smaller ones, grouped around marginal cirri on ventral side and arranged in short lines on dorsal side; 26–41 adoral membranelles; three frontal and one parabuccal, five to seven frontoterminal, one buccal, and three to six transverse cirri; seven to thirteen midventral pairs; five to nine unpaired ventral cirri, five to seven left and three to five right marginal rows; and three complete dorsal kineties. Phylogenetic analysis based on SSU r DNA sequences showed that both Metaurostylopsis and Neourostylopsis are monophyletic. As the internal relationship between and within both genera are not clear, further studies on the species in these two genera are necessary. The key characteristics of all known twelve Metaurostylopsis-Apourostylopsis-Neourostylopsis species complex were updated.

Planktonic ciliate trait structure variation over Yap,Mariana,and Caroline seamounts in the tropical Western Pacific Ocean

Trait structure is increasingly used in plankton ecology to understand diversity and biogeography.However,our knowledge of micro zooplankton(e.g.planktonic ciliates)trait structure and its variation with hydrography is limited.In this study,we analyzed planktonic ciliate trait structure in waters with different hydrography and deep Chlorophyll a maximum(DCM)layers over three seamounts:Yap,Mariana,and Caroline seamounts.Mariana seamount had a lower surface temperature than the Yap and Caroline seamounts.DCM layers over Mariana and Caroline seamounts were deeper than Yap seamount.There was a weak upwelling in upper 50 m around top of Mariana seamount.The ciliate distribution showed bimodal pattern(high abundance appeared in the surface and DCM layers)over three seamounts.At surface layer,the large size-fraction(>30μm)abundance proportion to aloricate ciliate over Yap seamount(44.4%)was higher than Mariana(32.8%)and Caroline(36.1%)seamounts.For tintinnid abundance proportion to total ciliate,Mariana(12.0%)and Caroline(11.5%)seamounts at about 100-m depth were higher than that of Yap seamount(6.4%).Vertically,tintinnid could be divided into 4 groups over the three seamounts.At30-m depth,group I(species occurring from surface to 100 m only)was dominant component over Yap and Caroline seamounts,while group IV(species occurring at every depth)changed into dominant component over Mariana seamount,the weak upwelling might be the reason.Salpingella faurei was the top dominant species,which corresponded to deeper DCM layers over Mariana and Caroline seamounts.Our results showed that the upwelling and the deeper DCM could influence the planktonic ciliate trait structure.

Ciliated hepatic foregut cyst with high intra-cystic carbohydrate antigen 19-9 level

A ciliated hepatic foregut cyst(CHFC)is a rare foregut developmental malformation usually diagnosed in adulthood.Five percent of reported cases of CHFC transform into squamous cell carcinoma.We report the presentation,evaluation,and surgical management of a symptomatic 45-year-old male found to have a 6.2 cm CHFC.Contrast tomography-guided fine-needle aspirationdemonstrated columnar,ciliated epithelium consistent with the histologic diagnosis of CHFC.The intracystic levels of carbohydrate antigen(CA)19-9 and carcinoembryonic antigen(CEA)were extremely high(978118U/m L and 973μg/L,respectively).Histologically,the wall of the cyst showed characteristic pseudopapillae lined with a ciliated stratified columnar epithelium,underlying smooth muscle,an outer fibrous layer and no atypia.Immunohistochemistry for CA19-9 and CEA was positive.This is the first case report of a CHFC in which levels of CA 19-9 and CEA were measured.Our findings suggest that a large sized multilocular cyst and elevated cyst CA19-9 and CEA levels do not exclude a CHFC from consideration in the diagnosis.CHFCs should be included in the differential diagnosis of hepatic lesions.Accurate diagnosis of a CHFC is necessary given its potential for malignant transformation,and surgical excision is recommended.

Comparative Evaluation on Combined Ecotoxic Effects of Nitrofurazone and NH_(4)Cl Using Two Ciliated Protists as Model Organisms:Population Dynamics and Growth Rates

Ecotoxic effects of antibiotics or ammonium have been confirmed independently in aquatic animals,but few studies have investigated their combined effects.In aquaculture ecosystems,these pollutants frequently coexist,and often in high concentrations.In this study,the combined effects of antibiotic nitrofurazone and NH4 Cl on the population dynamics and growth rates of two species of ciliated protists,Euplotes vannus and Pseudokeronopsis rubra,were investigated.Profiles of the dose-responses were visualized,and interactions between the two pollutants were quantified by the response surface method(RSM).Results showed that 1)the dynamics of the population growth differed significantly between the testd ciliates and varied with the concentrations of the pollutants;2)the relative growth rate(RGR)of both ciliates decreased significantly with increased pollutant concentrations,while the difference in RGR between the two ciliates was not significant;3)RSM analysis demonstrated an additive effect of nitrofurazone and NH4 Cl on the RGR in both ciliates.In brief,ecotoxic effects can be caused by nitrofurazone and ammonium independently on the two test ciliates,and such effects can be strengthened when they present at the same time.These findings offer a valuable reference for evaluating combined ecotoxic effects caused by multiple pollutants in aquaculture ecosystems.

Differences in planktonic ciliate spatial distribution in spring and autumn in the southern Yellow Sea

Seasonal variation of marine plankton spatial distribution is important in understanding the biological processes in the ocean.In this study,we studied spatial distribution of planktonic ciliate abundance and biomass in the central deep area（station depth greater than 60 m） and the coastal shallow area（station depth less than 60 m） of the southern Yellow Sea（32°–36.5°N,121°–125°E） in spring（April） and autumn（October–November） of 2006.Our results showed that both ciliate abundance and biomass in the surface waters were higher in spring（（1 490±2 336）ind./L;（4.11±7.81） μg/L） than in autumn（（972±823） ind./L;（1.11±1.18） μg/L,calculated by carbon）.Ciliate abundance and biomass in the surface waters of the coastal shallow area were similar in spring and autumn.However,in the central deep area,those values were much higher in spring（（1 878±2 893） ind./L;（5.99±10.10）μg/L） than in autumn（（738±373） ind./L;（0.74±0.76） μg/L）.High values of ciliate abundance and biomass occurred in the central deep area in spring and in the coastal shallow area in autumn.Mixotrophic ciliate Laboea strobila was abundant in the central deep area in spring,when a phytoplankton bloom occurred.However,in autumn,L.strobila was abundant in the coastal shallow area.Boreal tintinnid Ptychocyli obtusa was found in spring.Both L.strobila and P.obtusa were concentrated in the surface waters when their abundance was more than 1 000 ind./L.Peaks of these species were in the subsurface waters when their abundance was less than 400 ind./L.This study showed that both high abundance and biomass of ciliates occurred in different areas in southern Yellow Sea seasonally.

On four closely related hypotrichous ciliates(Protozoa,Ciliophora,Spirotrichea):molecular characters,interspecific relationships and phylogeny defined with multigene sequence information

In order to clarify the phylogeny and relationships of the most confused hypotrichous ciliates,Holosticha-complex,four closely related holostichids（five populations）,Holosticha bradburyae,H.diademata,Anteholosticha sp.,and A.manca,were compared and analyzed using ITS2 secondary structures,ITS1-5.8S-ITS2 region and SSrRNA gene sequences.The ITS1-5.8S-ITS2 region sequences of these four species were first sequenced,and they shared sequence identities ranging from 68.0% to 90.1%,while two populations of Anteholosticha sp.differed in three nucleotides（sequence identity 99.8%）.There were several minor differences among ITS2 secondary structures of these species,while two populations of Anteholosticha sp.had the identical secondary structure.Phylogenetic trees inferred from the ITS1-5.8S-ITS2 region sequences of stichotrichs using multiple algorithms（Neighbor-Joining,Maximum Parsimony and Bayesian） revealed similar topologies.The results show that：（1） Holosticha bradburyae and H.diademata firmly clustered together with strong bootstrap supports,forming a sister clade with Anteholosticha sp.,（2） Anteholosticha appeared to be a paraphyletic assemblage,in which the morphotype A.manca was more closely related to Diaxonella trimarginata than to its congener Anteholosticha sp.Phylogenetic analyses based on the SSrRNA gene and the combined sequences of SSrRNA gene and ITS1-5.8S-ITS2 region revealed the similar relationships between Holosticha and Anteholosticha,nevertheless their positions within the subclass Stichotrichia differed from each other inferred from different genes.

Spatial distribution of aloricate ciliates in the stratified water of the Cosmonaut and Cooperation Seas in the Southern Ocean

Aloricate ciliates are the main component of microzooplankton.They play important roles in the circulation of materials and flow of energy in marine pelagic ecosystems.To determine the distribution pattern and structure of the aloricate ciliate community in vertically stratified waters of the Southern Ocean,we collected data on aloricate ciliates in the Cosmonaut and Cooperation Seas during the 36th Chinese National Antarctic Research Expedition.The ranges of aloricate ciliate abundance and biomass were 5-3097 ind·L^(-1)and 0.01-11.40μg C·L^(-1),respectively.Vertically,the average abundance of aloricate ciliates decreased from the surface to 200 m,while biomass was highest in the 50-m layer.The importance of aloricate ciliates<20μm increased along the depth gradient.Their contribution to total abundance increased from 13.04%in the surface layer to 73.71% in the 200-m layer.This is the first study to explore the distribution characteristics of the aloricate ciliate community in a stratified water column of the Southern Ocean.Our results will be helpful for understanding the variation in the pelagic community in waters of the Southern Ocean with intensified stratification.