Publications by authors named "Dapeng Xu"

56 Publications

Correspondence between DOM molecules and microbial community in a subtropical coastal estuary on a spatiotemporal scale.

Environ Int 2021 Apr 23;154:106558. Epub 2021 Apr 23.

State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, College of Ocean and Earth Sciences, Xiamen University, Xiang'an Campus, Xiang'an South Road, Xiamen 361102, China; Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiang'an Campus, Xiang'an South Road, Xiamen 361102, China. Electronic address:

Dissolved organic matter (DOM) changes in quantity and quality over time and space, especially in highly dynamic coastal estuaries. Bacterioplankton usually display seasonal and spatial variations in abundance and composition in the coastal regions, and influence the DOM pool via assimilation, transformation and release of organic molecules. The change in DOM can also affect the composition of bacterial community. However, little is known on the correspondence between DOM molecules and bacterial composition, particularly through a systematic field survey. In this study, the spatiotemporal signatures of microbial communities and DOM composition in the subtropical coastal estuary of Xiamen are investigated over one and half years. The co-occurrence analysis between bacteria and DOM suggested microorganisms likely transformed the DOM from a relatively high (>400 Da) to a low (<400 Da) molecular weight, corresponding to an apparent increase in overall aromaticity. This might be the reason why microbial transformation renders "dark" organic matter visible in mass spectrometry due to more efficient ionization of microbial metabolites, as well as photodegradation processes. K- and r-strategists exhibited different correlations with two-size categories of DOM molecules owing to their different lifestyles and responses to environmental nutrient conditions. A comparison of the environmental variables and DOM composition with the microbial communities showed that the environmental/DOM variations played a more important role in shaping the microbial communities than vice versa. This study sheds light on the interactions between microbial populations and DOM molecules at the spatiotemporal scale, improving our understanding of microbial roles in marine biogeochemical cycles.
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http://dx.doi.org/10.1016/j.envint.2021.106558DOI Listing
April 2021

Water mass shapes the distribution patterns of planktonic ciliates (Alveolata, Ciliophora) in the subtropical Pearl River Estuary.

Mar Pollut Bull 2021 Apr 14;167:112341. Epub 2021 Apr 14.

State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China; Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen 361102, China. Electronic address:

Ciliates comprise essential components of microzooplankton in diverse marine environments. However, the extent to which environmental variables shape the distribution of planktonic ciliates in complex estuarine systems remains unclear. Here, 52 samples were collected from the Pearl River Estuary, China to reveal the influence of environmental variables on planktonic ciliate communities. Distinct community compositions of ciliates were found in three identified water masses: Pearl River diluted water mass, South China Sea surface water mass, and South China Sea bottom water mass. Significant differences in abundance, biomass, cell size, and oral diameter structure of ciliates were also detected among the three water masses. The partial Mantel test showed that water mass (as represented by water temperature and salinity) surpassed other environmental variables to be the primary factor driving the dynamics of the ciliate community. This study revealed the controlling mechanisms of planktonic ciliate communities in a subtropical, hydrographically complex estuarine ecosystem.
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http://dx.doi.org/10.1016/j.marpolbul.2021.112341DOI Listing
April 2021

The Calcium Phosphate Modified Titanium Implant Combined With Platelet-Rich Plasma Treatment Promotes Implant Stabilization in an Osteoporotic Model.

J Craniofac Surg 2021 Mar-Apr 01;32(2):603-608

Department of Oral and Maxillofacial Surgery, Yantai Stomatological Hospital Affiliated to Binzhou Medical College, Yantai, China.

Abstract: Osteoporosis as a kind of systemic bone metabolic disease has become one of the most prevalent diseases among the middle- and old-age, characterized with low bone mass and disruptive osseous microenvironment. The poor bone condition both in quantity and quality makes it daunting for osteoporotic patients who are submitted to dental implantation, joint replacement therapy, or orthopedic surgery. Since calcium phosphate (CaP) and platelet-rich plasma (PRP) treatment, all have improving the effect on bone regeneration. Inspired by this fact, the authors introduced a kind of novel implant with CaP modified surface by HPT (hydrothermal & pressure) treatment in this study. After producing, the authors tested its physicochemical properties through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS) and contact-angle measurement. Then the authors desired to investigate the effect of this CaP-modified implant on bone regeneration and stabilization maintenance combined with PRP treatment by establishing an osteoporotic rat model. After 3 months of surgery, the authors collected all the specimens and evaluated new bone formation by micro-computed tomography (micro-CT) analysis, biomechanical test, and histologic assessment. All the results in vivo experiment showed the CaP modified implant combined with PRP treatment could improve the osteoinductive effect under osteoporotic condition, leading to better maintenance for stabilization between bone and implant interface, which might be rendered as a promising clinical method for osteoporotic patients when they receive orthopedic surgeries.
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http://dx.doi.org/10.1097/SCS.0000000000006836DOI Listing
March 2021

Biogeographical Distribution and Community Assembly of Active Protistan Assemblages Along an Estuary to a Basin Transect of the Northern South China Sea.

Microorganisms 2021 Feb 10;9(2). Epub 2021 Feb 10.

State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China.

Marine protists are essential for globally critical biological processes, including the biogeochemical cycles of matter and energy. However, compared with their prokaryotic counterpart, it remains largely unclear how environmental factors determine the diversity and distribution of the active protistan communities on the regional scale. In the present study, the biodiversity, community composition, and potential drivers of the total, abundant, and rare protistan groups were studied using high throughput sequencing on the V9 hyper-variable regions of the small subunit ribosomal RNA (SSU rRNA) along an estuary to basin transect in the northern South China Sea. Overall, Bacillariophyta and Cercozoa were abundant in the surface water; heterotrophic protists including Spirotrichea and marine stramenopiles 3 (MAST-3) were more abundant in the subsurface waters near the heavily urbanized Pearl River estuary; Chlorophyta and Pelagophyceae were abundant at the deep chlorophyll maximum depth, while Hacrobia, Radiolaria, and Excavata were the abundant groups in the deep water. Salinity, followed by water depth, temperature, and other biological factors, were the primary factors controlling the distinct vertical and horizontal distribution of the total and abundant protists. Rare taxa were driven by water depth, followed by temperature, salinity, and the concentrations of PO. The active protistan communities were mainly driven by dispersal limitation, followed by drift and other ecological processes.
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http://dx.doi.org/10.3390/microorganisms9020351DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7916720PMC
February 2021

Elevated Contribution of Low Nucleic Acid Prokaryotes and Viral Lysis to the Prokaryotic Community Along the Nutrient Gradient From an Estuary to Open Ocean Transect.

Front Microbiol 2020 15;11:612053. Epub 2020 Dec 15.

State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Institute of Marine Microbes and Ecospheres, Xiamen University, Xiamen, China.

Prokaryotes represent the largest living biomass reservoir in aquatic environments and play a crucial role in the global ocean. However, the factors that shape the abundance and potential growth rate of the ecologically distinct prokaryotic subgroups [i.e., high nucleic acid (HNA) and low nucleic acid (LNA) cells] along varying trophic conditions in the ocean remain poorly understood. This study conducted a series of modified dilution experiments to investigate how the abundance and potential growth rate of HNA and LNA prokaryotes and their regulating factors (i.e., protozoan grazing and viral lysis) change along a cross-shore nutrient gradient in the northern South China Sea. The results showed that the abundance of both HNA and LNA cells was significantly positively correlated with the abundance of heterotrophic nanoflagellates and viruses, whereas only HNA abundance exhibited a significant positive correlation with nutrient level. With a decreasing nutrient concentration, the potential growth rate of the HNA subgroup declined significantly, while that of the LNA subgroup was significantly enhanced, leading to an elevated relative potential growth rate of the LNA to HNA subgroup under decreasing nutrient levels. Furthermore, our data revealed different regulatory roles of protozoan grazing and viral lysis on the HNA and LNA subgroups, with HNA suffering higher mortality pressure from grazing than from lysis in contrast to LNA, which experienced equivalent pressures. As the nutrient levels declined, the relative contribution of lysis to the mortality of the HNA subgroup increased significantly, in contrast to the insignificant change in that of the LNA subgroup. Our results indicated the elevated role of LNA cells in the prokaryotic community and the enhanced viral lysis pressure on the total prokaryotes under oligotrophic conditions. This implies a weakened efficiency of carbon cycling within the microbial loop and enhanced viral lysis to shunt more carbon and energy flow in the future ocean, in which oligotrophication will be strengthened due to global warming.
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http://dx.doi.org/10.3389/fmicb.2020.612053DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7793805PMC
December 2020

Genetic Diversity, Community Assembly, and Shaping Factors of Benthic Microbial Eukaryotes in Dongshan Bay, Southeast China.

Front Microbiol 2020 23;11:592489. Epub 2020 Dec 23.

State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.

Microbial eukaryotes are pivotal components of marine ecosystems. However, compared with the pelagic environments, the diversity distribution and the driving mechanisms of microbial eukaryotes in the marine sediments have rarely been explored. In this study, sediment cores were collected along a transect from inner to outer Dongshan Bay, Southeast China. By combining high throughput sequencing of small-subunit (SSU) rRNA gene with measurements on multiple environmental variables, the genetic diversity, community structure and assembly processes, and environmental shaping factors were investigated. Alveolata (mainly Ciliophora and Dinophyceae), Rhizaria (mainly Cercozoa), and Stramenopiles (mainly Bacillariophyta) were the most dominant groups in terms of both relative sequence abundance and operational taxonomic unit (OTU) richness. Grain size composition of the sediment was the primary factor determining the alpha diversity of microbial eukaryotes followed by sediment depth and heavy metal, including chromium (Cr), zinc (Zn), and plumbum (Pb). Geographic distance and water depth surpassed other environmental factors to be the primary factors shaping the microbial eukaryotic communities. Dispersal limitation was the primary driver of the microbial eukaryotic communities, followed by drift and homogeneous selection. Overall, our study shed new light on the spatial distribution patterns and controlling factors of benthic microbial eukaryotes in a subtropical bay which is subjected to increasing anthropogenic pressure.
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http://dx.doi.org/10.3389/fmicb.2020.592489DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7785585PMC
December 2020

Spatial distribution of the microzooplankton communities in the northern South China Sea: Insights into their function in microbial food webs.

Mar Pollut Bull 2021 Jan 11;162:111898. Epub 2020 Dec 11.

State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen 361102, China.

The spatial distribution of microzooplankton in the northern South China Sea was investigated in March 2016. Microzooplankton communities were dominated by cyclotrichids, aloricate oligotrichs, and choreotrichs within ciliates and the order Gymnodiniales within dinoflagellates. Microzooplankton abundance varied between 60 and 166,520 cells L, with higher values in the coastal diluted water, and microzooplankton biomass exhibiting a similar pattern. High densities of Akashiwo cf. sanguinea were found in the upper waters along the coast, and mixotrophs dominated the communities in all the water masses. A canonical analysis of principal coordinates showed that the spatial patterns of microzooplankton communities could be clearly discriminated in the different water masses. Our findings provide insights into the functioning of microzooplankton and the potential risk of harmful Akashiwo cf. sanguinea algal blooms in coastal waters. In addition, our study provides evidence for using microzooplankton communities as potential indicators of water masses in complex marine systems.
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http://dx.doi.org/10.1016/j.marpolbul.2020.111898DOI Listing
January 2021

Top-down controls on nutrient cycling and population dynamics in a model estuarine photoautotroph-heterotroph co-culture system.

Mol Ecol 2021 01 6;30(2):592-607. Epub 2020 Dec 6.

State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, College of Ocean and Earth Sciences, Xiamen University, Xiamen, People's Republic of China.

Viral lysis and protistan grazing are thought to be the major processes leading to microbial mortality in aquatic environments and thus regulate community diversity and biogeochemical cycling characteristics. Here, we studied nutrient cycling and bacterial responses to cyanophage-mediated photoautotroph lysis and ciliate predation in a model Synechococcus-heterotroph co-culture system. Both viral lysis and Euplotes grazing facilitated the transformation of organic carbon from biomass to dissolved organic matter with convention efficiencies of 20%-26%. The accumulation of ammonium after the addition of phages and ciliates suggested the importance of recycled NH occurred in the interactions between Synechococcus growth and heterotrophic bacterial metabolism of photosynthate. The slower efficiency of P mineralization compared to N (primarily ammonium) indicated that P-containing organic matter was primarily integrated into bacterial biomass rather than being remineralized into inorganic phosphate under C-rich conditions. In the cyanophage addition treatment, both Fluviicola and Alteromonas exhibited rapid positive responses to Synechococcus lysing, while Marivita exhibited an apparent negative response. Further, the addition of Euplotes altered the incubation system from a Synechococcus-driven phycosphere to a ciliate-remodelled zoosphere that primarily constituted grazing-resistant bacteria and Euplotes symbionts. Top-down controls increased co-culture system diversity and resulted in a preference for free-living lifestyles of dominant populations, which was accompanied by the transfer of matter and energy. Our results indicate top-down control was particularly important for organic matter redistribution and inorganic nutrient regeneration between photoautotrophs and heterotrophs, and altered bacterial lifestyles. This study consequently sheds light on marine biogeochemical cycling and the interaction networks within these dynamic ecosystems.
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http://dx.doi.org/10.1111/mec.15750DOI Listing
January 2021

The Calcium Phosphate Modified Titanium Implant Combined With Platelet-Rich Plasma Treatment Promotes Implant Stabilization in an Osteoporotic Model.

J Craniofac Surg 2020 Nov 12. Epub 2020 Nov 12.

Department of Oral and Maxillofacial Surgery, Yantai Stomatological Hospital Affiliated to Binzhou Medical College, Yantai, China.

Osteoporosis as a kind of systemic bone metabolic disease has become one of the most prevalent diseases among the middle- and old-age, characterized with low bone mass and disruptive osseous microenvironment. The poor bone condition both in quantity and quality makes it daunting for osteoporotic patients who are submitted to dental implantation, joint replacement therapy, or orthopedic surgery. Since calcium phosphate (CaP) and platelet-rich plasma (PRP) treatment, all have improving the effect on bone regeneration. Inspired by this fact, the authors introduced a kind of novel implant with CaP modified surface by HPT (hydrothermal & pressure) treatment in this study. After producing, the authors tested its physicochemical properties through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS) and contact-angle measurement. Then the authors desired to investigate the effect of this CaP-modified implant on bone regeneration and stabilization maintenance combined with PRP treatment by establishing an osteoporotic rat model. After 3 months of surgery, the authors collected all the specimens and evaluated new bone formation by micro-computed tomography (micro-CT) analysis, biomechanical test, and histologic assessment. All the results in vivo experiment showed the CaP modified implant combined with PRP treatment could improve the osteoinductive effect under osteoporotic condition, leading to better maintenance for stabilization between bone and implant interface, which might be rendered as a promising clinical method for osteoporotic patients when they receive orthopedic surgeries.
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http://dx.doi.org/10.1097/SCS.0000000000006836DOI Listing
November 2020

Contrasting Community Composition of Active Microbial Eukaryotes in Melt Ponds and Sea Water of the Arctic Ocean Revealed by High Throughput Sequencing.

Front Microbiol 2020 3;11:1170. Epub 2020 Jun 3.

Division of Polar Ocean Science, Korea Polar Research Institute, Incheon, South Korea.

Melt ponds (MPs), form as the result of thawing of snow and sea ice in the summer, have lower albedo than the sea ice and are thus partly responsible for the polar amplification of global warming. Knowing the community composition of MP organisms is key to understanding their roles in the biogeochemical cycles of nutrients and elements. However, the community composition of MP microbial eukaryotes has rarely been studied. In the present study, we assessed the microbial eukaryote biodiversity, community composition, and assembly processes in MPs and surface sea water (SW) using high throughput sequencing of 18S rRNA of size-fractionated samples. Alpha diversity estimates were lower in the MPs than SW across all size fractions. The community composition of MPs was significantly different from that of SW. The MP communities were dominated by members from Chrysophyceae, the ciliate classes Litostomatea and Spirotrichea, and the cercozoan groups Filosa-Thecofilosea. One open MP community was similar to SW communities, which was probably due to the advanced stage of development of the MP enabling the exchange of species between it and adjacent SW. High portions of shared species between MPs and SW may indicate the vigorous exchange of species between these two major types of environments in the Arctic Ocean. SW microbial eukaryote communities are mainly controlled by dispersal limitation whereas those of MP are mainly controlled by ecological drift.
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http://dx.doi.org/10.3389/fmicb.2020.01170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7291953PMC
June 2020

Spatial distribution patterns of planktonic ciliate communities in the East China Sea: Potential indicators of water masses.

Mar Pollut Bull 2020 Jul 17;156:111253. Epub 2020 May 17.

State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen 361102, China. Electronic address:

The spatial distribution of planktonic ciliates over the coastal and continental shelf of the East China Sea were investigated using quantative protargol staining. Aloricate oligotrichs and choreotrichs were dominant in terms of species number, abundance and biomass. Ciliate densities varied between 3 and 2688 cells L with higher values occurring in the coastal water and the mixing water than in the Yellow Sea coastal water and the Taiwan warm water. Ciliate biomass exhibited a similar pattern as abundance. A canonical analysis of principal coordinates demonstrated that the spatial patterns of ciliate community structure could be clearly discriminated in different water masses. Diversity parameters showed strong relationships with spatial changes in ciliate communities and might serve as predictors of water mass in future studies. Our findings provide evidence for using ciliate communtiy composition, supplemented with dominant species and diversity parameters, as potential indicators of water masses in complex marine environments.
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http://dx.doi.org/10.1016/j.marpolbul.2020.111253DOI Listing
July 2020

LC-MS/MS method for simultaneous determination of rivaroxaban and metformin in rat plasma: application to pharmacokinetic interaction study.

Bioanalysis 2019 Dec;11(24):2269-2281

School of Pharmacy, Institute of Materia Medica, The Fourth Military Medical University, Xi'an 710032, PR China.

A reliable, sensitive and simple LC-MS/MS method has been established and validated for the quantitation of rivaroxaban (RIV) and metformin (MET) in rat plasma. The procedure of method validation was conducted according to the guiding principles of EMA and US FDA. At the same time, the method was applied to pharmacokinetic interactions study between RIV and MET for the first time. When RIV and MET coadministered to rats, pharmacokinetic parameters of MET like AUC, AUC and C had statistically significant increased. t of RIV was prolonged without affecting t obviously and C was inhibited significantly (p < 0.05) by comparison to the single group. The results indicated that drug-drug interactions occurred when the coadministration of RIV and MET.
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http://dx.doi.org/10.4155/bio-2019-0230DOI Listing
December 2019

Nonmineralized and Mineralized Silk Fibroin/Gelatin Hybrid Scaffolds: Chacterization and Cytocompatibility In Vitro for Bone-Tissue Engineering.

J Craniofac Surg 2020 Mar/Apr;31(2):416-419

Department of Oral and Maxillofacial Surgery, Yantai Stomatological Hospital Affiliated to Binzhou Medical College, Yantai, China.

In this study, nonmineralized silk fibroin/gelatin (SF/G) hybrid scaffolds and the mineralized SF/G/hydroxyapatite (SF/G/HA) hybrid scaffolds were fabricated using vacuum freeze-drying method and biomineralization technique. The morphology and mechanical properties of the 2 hybrid scaffolds were characterized. Furthermore, the cytotoxic profiles of the hybrid scaffolds were investigated in vitro by seeding the human osteoblast cells (hFOB1.19). The 2 hybrid scaffolds were both highly porous and the pore sizes of the SF/G as well as SF/G/HA hybrid scaffolds were 260 ± 58 μm and 210 ± 35 μm, respectively. Compared with the SF/G hybrid scaffold, the SF/G/HA hybrid scaffolds exhibited significantly enhanced compressive strength and modulus. Significant early cell adhesion and proliferation on the SF/G hybrid scaffolds were observed, while SF/G/HA hybrid scaffolds effectively improved osteogenic differentiation of hFOB1.19 after 10 days of coculture. The results confirmed that the 2 hybrid scaffolds were both cytocompatible and had almost no negative effects on the hFOB1.19 in vitro. However, the SF/G/HA hybrid scaffolds tended to be more promising for application in bone-tissue engineering with good mechanical property and osteogenic differentiation.
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http://dx.doi.org/10.1097/SCS.0000000000006020DOI Listing
July 2020

Integrated Space-Time Dataset Reveals High Diversity and Distinct Community Structure of Ciliates in Mesopelagic Waters of the Northern South China Sea.

Front Microbiol 2019 24;10:2178. Epub 2019 Sep 24.

Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen, China.

Little is known about diversity distribution and community structure of ciliates in mesopelagic waters, especially how they are related to spatial and temporal changes. Here, an integrative approach, combining high-throughput cDNA sequencing and quantitative protargol stain, was used to analyze ciliate communities collected temporally along a transect from coastal to oceanic regions at depths ranging from the surface to 1000 m. The mesopelagic zone exhibited comparable alpha diversity to surface water which was consistent over temporal variation, with high diversity occurring at the interface with the euphotic zone. Comparison with the northeastern and the western Pacific Ocean revealed consistency of this vertical distribution of ciliates across oceanic basins. Mesopelagic ciliates harbored distinct community structure without significant seasonal differences, with the vertical variations driven largely by members of the classes Spirotrichea and Oligohymenophorea. Operational taxonomic units (OTUs) affiliated with Scuticociliatia, Astomatida and Apostomatida, members of which are known to be bacterivorous and/or commensal/parasitic species, were more abundant in mesopelagic waters than above, implying they are an important component of food webs in the mesopelagic zone. A combination of depth, geographic distance and environment shaped the ciliate communities, with depth being the most influential factor. Phylogenetic null modeling analysis further indicated that 57.1 and 33.3% of mesopelagic community variation was governed by dispersal limitation and heterogeneous selection, respectively, probably due to the marked biochemical and physical gradients down the water column. This suggests that ciliate community structure in the mesopelagic zone is mainly controlled by stochastic processes. Collectively, this study reports mesopelagic ciliates exhibited high diversity and distinct community structure across spatiotemporal scales and informs the processes mediating ciliate assembly in the mesopelagic zone. These should be fully considered in future studies to build a more comprehensive understanding of mesopelagic microbial assemblages.
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http://dx.doi.org/10.3389/fmicb.2019.02178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6768975PMC
September 2019

Adhesion, biological corrosion resistance and biotribological properties of carbon films deposited on MAO coated Ti substrates.

J Mech Behav Biomed Mater 2020 01 23;101:103448. Epub 2019 Sep 23.

Key Laboratory of Marine New Materials and Related Technology, Zhejiang Key Laboratory of Marine Materials and Protection Technology, Ningbo Institute of Material Technology & Engineering, Chinese Academy of Sciences, Ningbo, 315201, China. Electronic address:

A thin diamond-like carbon (DLC) film, a graphite-like carbon (GLC) film and a thick diamond-like carbon (PE-DLC) film are deposited on the micro arc oxidation (MAO) coated pure titanium substrates using a hybrid ion beam deposition system, magnetron sputtering and plasma enhanced chemical vapor deposition, respectively. The microstructure, adhesion, biological corrosion resistance and biotribological properties were determined. The results showed that the three duplex coatings presented uneven surface features and increased binding force. The binding force of the duplex coatings was strongly affected by the bonding strength between the MAO coating and Ti substrate. Although the roughness Ra of the three duplex coatings was high, their friction coefficients were small (under 0.22) in the SBF solution. The MAO/DLC and MAO/GLC coatings showed an excellent tribological behavior and corrosion resistance in the SBF solution.
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http://dx.doi.org/10.1016/j.jmbbm.2019.103448DOI Listing
January 2020

Phylogeny and Genetic/Morphological Variation of Strombidinopsis minima-like Species (Ciliophora: Choreotrichia).

J Eukaryot Microbiol 2020 01 8;67(1):115-124. Epub 2019 Oct 8.

Department of Oceanography, Inha University, Incheon, 22212, Korea.

Six isolates of mineral-enveloped Strombidinopsis minima-like species were collected from the coastal waters across several regions in Korea. Morphological observations and molecular analyses were performed. The ribosomal DNA sequences (including small subunit ribosomal DNA, internal transcriber spacer 1-5.8S ribosomal DNA-internal transcriber spacer 2; and part of large subunit ribosomal DNA) of these six isolates were compared. Their morphological characteristics were also compared with those of S. minima populations reported. The marked genetic differences (with a similarity range of 96.85-98.48%) in SSU rDNA among these S. minima-like entities suggest the existence of multiple species. This finding is also supported by morphological variations detected in this study and reported in the literature (e.g. 15-32 collar membranelles in different populations). In addition, S. minima-like species are clustered with S. batos and S. sinicum, and therefore, our SSU rDNA results support previous results suggesting that the genus Strombidinopsis is not monophyletic in origin. Further collection of morphological and molecular data may facilitate the determination of a new genus carrying mineral-enveloped Strombidinopsis species.
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http://dx.doi.org/10.1111/jeu.12761DOI Listing
January 2020

Study on the Relationship between Seed Absorbed Dose and Seed Composition of Cf Neutron Source Irradiated Bean Seed.

Sci Rep 2019 07 3;9(1):9635. Epub 2019 Jul 3.

School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China.

This study aims to further identify the biological effects of neutron-irradiated plants and provides insights into the mutation breeding of such plants. In this study, the neutron irradiation device designed by our institute was used to analyze the relationship between the seed components in different legume crops and their neutron absorption dose rate, fission gamma absorption dose rate, and induced gamma absorption dose rate. The results show that the effect sizes of the components on the neutron absorbed dose rate are as follows: ash > fat > moisture > carbohydrate > protein. The effect sizes of the components on the absorbed dose rate of fission gamma are as follows: ash > moisture > fat > carbohydrate > protein. There is a positive correlation between fission gamma absorbed dose rate and the weight of ash, water and fat, while a negative correlation with carbohydrate and protein. However, the linear relationship between each component and the absorbed dose rate of induced gamma is not significant, this needs to be identified by further researches. Based on the results of the present study, we conclude that the neutron absorbed dose can be calculated without taking into account the fat composition of bean crop seeds (except for soybean seeds) in the process of mutation breeding induced by radiation. In special cases where the accuracy requirement of the dose rate is not high, it is possible to use protein instead of legume crop seeds for neutron absorption dose calculations.
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http://dx.doi.org/10.1038/s41598-019-45829-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6610101PMC
July 2019

Taxonomy and phylogeny of two poorly studied genera of marine oligotrich ciliates including descriptions of two new species: Cyrtostrombidium paraboreale sp. n. and Apostrombidium orientale sp. n. (Ciliophora: Spirotrichea).

Eur J Protistol 2019 Aug 16;70:1-16. Epub 2019 May 16.

Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China. Electronic address:

Although it is widely recognized that oligotrich ciliates are the dominant constituent of microzooplankton communities and perform key functions in energy flow and material cycling in marine microbial food webs, knowledge of their diversity is scant. In the present study, we investigate the oligotrich genera, Cyrtostrombidium and Apostrombidium, with emphasis on their morphology and evolutionary relationships. Three isolates were collected from coastal waters of northern and southern China including two new species, viz., Cyrtostrombidium paraboreale sp. n., Apostrombidium orientale sp. n., and Apostrombidium pseudokielum Xu et al., 2009. Cyrtostrombidium paraboreale sp. n. is characterized by possessing 64-98 cytopharyngeal rods and two macronuclear nodules. Apostrombidium orientale sp. n. is characterized by its somatic kinety consisting of five fragments including a horizontally orientated subterminal fragment and possessing conspicuously long dorsal cilia. Apostrombidium pseudokielum is redescribed based on the new population and a re-examination of the type material. Phylogenetic analyses were performed for the subclass Oligotrichia, incorporating SSU rRNA gene sequences of the three species investigated here. The results indicate that the genus Cyrtostrombidium is monophyletic with C. paraboreale sp. n. occupying the basal position. The genus Apostrombidium is not monophyletic as Varistrombidium kielum is nested within it.
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http://dx.doi.org/10.1016/j.ejop.2019.05.001DOI Listing
August 2019

Fractal theory and controllable preparation of centimeter level silver nanowire arrays and their application in melamine detection as SERS substrates.

Spectrochim Acta A Mol Biomol Spectrosc 2019 Oct 28;221:117184. Epub 2019 May 28.

School of Materials Science and Chemical Engineering, Xi'an Technological University, Xi'an 710032, People's Republic of China. Electronic address:

Silver nanowire arrays as surface-enhanced Raman scattering (SERS) substrates were prepared by a solid-state ionics method under the direct current electric field (DCEF) and used to rapidly detect melamine in aqueous solutions. The arrangement density and surface roughness of the prepared silver nanowire arrays are significantly different upon a change in the impressed current intensity. The growth mechanism of silver nanowire arrays was associated with the apical growth advantage and the irregular electrode interface. When the current intensity was 4 μA and 10 μA, the fractal dimension of silver nanowire arrays was 1.66 and 1.49, the diameters of nanowires ranged from 90 to 130 nm and 90 to 170 nm, and many densely arranged and regularly arranged silver nanoparticles lie in the prepared nanowire arrays, respectively. The result shows that there were more silver nanostructures and surface roughness under 4 μA DCEF. The Raman signal intensity of melamine molecule shows that the prepared SERS substrate exhibited a high sensitivity. The proposed method allow us detect melamine with a limit of 10 mol/L and 10 mol/L, which are lower than the safety limit estimated by the US food and Drug Administration. With its facile material synthesis, simple detection procedure and low detection concentration, this silver nanowire arrays with high surface roughness indicates a strong potential detection technique in the field of food safety.
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http://dx.doi.org/10.1016/j.saa.2019.117184DOI Listing
October 2019

Closed Loop Recycling of Electric Vehicle Batteries to Enable Ultra-high Quality Cathode Powder.

Sci Rep 2019 Feb 7;9(1):1654. Epub 2019 Feb 7.

Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, MA, 01609, USA.

The lithium-ion battery (LIB) recycling market is becoming increasingly important because of the widespread use of LIBs in every aspect of our lives. Mobile devices and electric cars represent the largest application areas for LIBs. Vigorous innovation in these sectors is spurring continuous deployment of LIB powered devices, and consequently more and more LIBs will become waste as they approach end of life. Considering the significant economic and environmental impacts, recycling is not only necessary, but also urgent. The WPI group has successfully developed a closed-loop recycling process, and has previously demonstrated it on a relatively small scale 1 kg spent batteries per experiment. Here, we show that the closed-loop recycling process can be successfully scaled up to 30 kg of spent LIBs from electric vehicle recycling streams, and the recovered cathode powder shows similar (or better) performance to equivalent commercial powder when evaluated in both coin cells and single layer pouch cells. All of these results demonstrate the closed-loop recycling process has great adaptability and can be further developed into industrial scale.
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http://dx.doi.org/10.1038/s41598-018-38238-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6367435PMC
February 2019

Pigmented microbial eukaryotes fuel the deep sea carbon pool in the tropical Western Pacific Ocean.

Environ Microbiol 2018 10 2;20(10):3811-3824. Epub 2018 Oct 2.

Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystem, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China.

Phototrophic microbial eukaryotes dominate primary production over large oceanic regions. Due to their small sizes and slow sinking rates, it is assumed they contribute relatively little to the downward export of organic carbon via the biological pump. Therefore, the community structure of phototrophic cells in the deep ocean has long been overlooked and remains largely unknown. In this study, we used an integrative approach, including epifluorescence microscopy, sequencing of 18S rRNA and photosystem-II psbA gene transcripts, to investigate phototrophic microbial eukaryotes in samples collected from the tropical Western Pacific Ocean. It was found that: (i) pigmented nano-sized eukaryotes (PNEs) are ubiquitous in the deep Western Pacific Ocean down to 5000 m depth; (ii) the PNE community is dominated by cells 2-5 μm in size; (iii) their abundance is significant, averaging 4 ± 1 (± s.e.) cells ml in waters below 1000 m which is comparable to that of heterotrophic nanoflagellates; (iv) the active pigmented microbial eukaryotes in the deep waters are highly diverse and dominated by Haptophyta followed by Chlorophyta and Bacillariophyta; (v) PNEs in deep waters were likely transported from surface ocean by various fast-sinking mechanisms, thus contributing to the biological pump and fuelling the deep-sea communities by supplying fresh organic carbon.
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http://dx.doi.org/10.1111/1462-2920.14396DOI Listing
October 2018

Changes in community structure of active protistan assemblages from the lower Pearl River to coastal Waters of the South China Sea.

Eur J Protistol 2018 Apr 31;63:72-82. Epub 2018 Jan 31.

State Key Laboratory of Marine Environmental Science, Institute of Marine Microbes and Ecospheres, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China. Electronic address:

Protists make up an important component of aquatic ecosystems, playing crucial roles in biogeochemical processes on local and global scales. To reveal the changes of diversity and community structure of protists along the salinity gradients, community compositions of active protistan assemblages were characterized along a transect from the lower Pearl River estuary to the open waters of the South China Sea (SCS), using high-throughput sequencing of the hyper-variable V9 regions of 18S rRNA. This study showed that the alpha diversity of protists, both in the freshwater and in the coastal SCS stations was higher than that in the estuary. The protist community structure also changed along the salinity gradient. The relative sequence abundance of Stramenopiles was highest at stations with lower salinity and decreased with the increasing of salinity. By contrast, the contributions of Alveolata, Hacrobia and Rhizaria to the protistan communities generally increased with the increasing of salinity. The composition of the active protistan community was strongly correlated with salinity, indicating that salinity was the dominant factor among measured environmental parameters affecting protistan community composition and structure.
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http://dx.doi.org/10.1016/j.ejop.2018.01.004DOI Listing
April 2018

Comparative study on the incision healing of the palatal mucosa by using Er:YAG laser or traditional scalpel in the SD rats.

Lasers Med Sci 2018 Jul 22;33(5):1019-1024. Epub 2018 Jan 22.

Department of Implantology, Yantai Stomatological Hospital, No. 142 North Great Street, Zhifu District, Yantai, 264001, Shandong Province, People's Republic of China.

The aim of this study was to compare the histology of wound healing following incisions with the scalpel or the Er:YAG laser in the palatal mucosa of SD rats. Two types of wounds were performed with the stainless steel scalpel or the Er:YAG laser in the palatal mucosa of SD rats, while the adjacent untreated palatal mucosa was chosen as control. Rats were sacrificed on day 1, day 3, day 7, and day 30 post-surgery. Biopsy samples from each wound were examined and the expression of IL-1ß and TGF-ß1 was determined by enzyme-linked immunosorbent assay (ELISA). The early postoperative incision of the scalpel group had obvious bleeding and swelling, while the laser wound mainly covered the surface of white pseudomembrane. The infiltration of neutrophils and lymphocytes in the stroma of the scalpel incision was more than that of the laser group. Compared to the laser group, 1 and 3 days after operation, the TGF-β1 content of the scalpel group were significantly increased (P = 0.032 and 0.019). Seven days after operation, the TGF-β1 content of two groups was decreased. TGF-β1 expression of control group was obviously increased (P > 0.05); 1, 3, and 7 days after operation, the traditional scalpel amount of IL-1β expression was significantly higher than that of control group (P = 0.000, 0.000, and 0.001). Postoperative day 1, IL-1β expression of laser group and control group had no significant difference (P = 0.572). Three days after operation, IL-1β expression of laser incision was increased and was significantly higher than that in control group (P = 0.032), however lower than the scalpel group (P = 0.03). Seven days after operation, the IL-1β expression of two groups had no significant difference (P = 0.333); however, the IL-1β expression of two groups were significantly higher than that of the control group (P = 0.02 and 0.001). Compared to the traditional scalpel, the incision of Er:YAG laser has smaller inflammation reaction, more pseudomembrane coverage, and minimal damage of the mucoperiosteal tissue.
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http://dx.doi.org/10.1007/s10103-018-2450-8DOI Listing
July 2018

Spontaneous fetal femoral fracture: a case report and literature review.

J Int Med Res 2018 Mar 14;46(3):1282-1287. Epub 2018 Jan 14.

Department of Paediatric Surgery, Nanjing Medical University, Affiliated 261546 Wuxi People's Hospital , Wuxi, Jiangsu Province, China.

Spontaneous fetal femoral fractures are uncommon in the paediatric setting. The major clinical presentations of a spontaneous fetal femoral fracture are femoral angulation, shortness of the femur and even a marked fracture line. This case report describes a spontaneous fetal femoral fracture of the right femur, which was detected by routine ultrasonography during the 19 week of gestation in a 24-year-old woman. On routine follow-up visits, the angulation of the right femur in the fetus gradually improved. A caesarean section was undertaken at 39 weeks +5 days of gestation and an X-ray was taken on the second day after birth, which showed that the fracture had healed and the callus had been absorbed. The lengths of the two femurs of the baby were not equal; the right femur was 84 mm, which was 11 mm shorter than the left femur. In cases like this, postnatal follow-up is essential so that an operation can be carried out in a timely manner when the deformity is apparent.
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http://dx.doi.org/10.1177/0300060517744923DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5972261PMC
March 2018

Marked seasonality and high spatial variation in estuarine ciliates are driven by exchanges between the 'abundant' and 'intermediate' biospheres.

Sci Rep 2017 08 25;7(1):9494. Epub 2017 Aug 25.

Department of Life Sciences, Natural History Museum, London, SW7 5BD, UK.

We examined the spatial and temporal variability of ciliate community in a subtropical estuary by rRNA and rDNA-based high throughput sequencing of 97 samples collected along the entire salinity gradient at two-month intervals in 2014. Community divided statistically into three groups: freshwater (salinity < 0.5‰), oligohaline and mesohaline (0.5‰ < salinity < 18‰), and polyhaline and euhaline (18‰ < salinity < 40‰). Across all three groups, salinity explained most of the community variability. Within each group, seasonal shifts in community formed cool (spring and winter) and warm (summer and autumn) subgroups, indicating that spatial variability overrode seasonal changes in determining community composition. Cool and warm groups showed opposite associations with temperature and prey proxies, suggesting distinct seasonal niche separation. The community reassembly of cool and warm groups was essentially due to transitions between intermediate (with relative abundance of 0.01-1%) and abundant (with relative abundance > 1%) OTUs. Further analyses demonstrated that the intermediate group not only encompassed comparable OTU richness to that of the total community and maintained high metabolic activity but also had the highest proportion in transition, either to abundance or rarity, thus offering a first view on how it varies across space and time and revealing the essential role it played in maintaining stability and functionality within the community.
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http://dx.doi.org/10.1038/s41598-017-10308-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5573402PMC
August 2017

Microbial Eukaryote Diversity and Activity in the Water Column of the South China Sea Based on DNA and RNA High Throughput Sequencing.

Front Microbiol 2017 14;8:1121. Epub 2017 Jun 14.

Department of Life Sciences, Natural History MuseumLondon, United Kingdom.

To study the diversity and metabolic activity of microbial eukaryotes in the water column of the South China Sea, genomic DNA and RNA were co-extracted from samples collected down to bathyal depth at two sites. V9 regions of both SSU rRNA gene and its transcript (cDNA) were amplified and sequenced using high throughput sequencing. Our study revealed: (1) DNA and RNA datasets showed significant differences in microbial eukaryote community composition, with the variability between the two datasets for the same sample exceeding that between samples within each dataset, indicating that nucleic acid source overrode environmental factors in determining the composition of microeukaryotes; (2) despite the differences in community composition between the two datasets, both DNA and RNA revealed similar depth-related distribution patterns of microbial eukaryotes; (3) using the ratio of RNA: DNA as a proxy of relative metabolic activity, a depth-related pattern was found for the relative metabolic activity of some but not all groups of microbial eukaryotes, with the highest activity for the groups with depth-related pattern usually found in the middle water layers; and (4) the presence of live and active photoautotrophic microbial eukaryotes in the deep ocean was confirmed, indicating that they play an important role in controlling the deep-sea organic carbon pool. Overall, our study sheds light on the diversity and activity of microbial eukaryotes in the water column of a tropical oligotrophic ocean and their potential contributions in the downward transportation of organic material from the surface ocean to the deep via the biological pump.
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http://dx.doi.org/10.3389/fmicb.2017.01121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5469884PMC
June 2017

Solid-state ionics method fabricated centimeter level CuAu alloy nanowires: Application in SERS.

J Colloid Interface Sci 2017 Aug 8;500:150-154. Epub 2017 Apr 8.

School of Materials Science and Chemical Engineering, Xi'an Technological University, Xi'an 710032, People's Republic of China. Electronic address:

CuAu alloy nanowires were prepared by a solid-state ionics method under a direct current electric field (DCEF) using fast ionic conductor RbCuClI films. The surface morphology, chemical composition and crystal structures of the CuAu alloy nanowires were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. Raman enhancement performance of the CuAu alloy nanowires substrates was detected by Rhodamine 6G (R6G) aqueous solutions as probe molecules. Long-range disorder and short-range order CuAu alloy nanowires with the length of 1 cm were prepared by a solid-state ionics method. The nanowires were bamboo-shaped and the diameters of nanowires ranged from 40 to 100nm. The molar ratio of Cu to Au is 16:1. The crystal structure of the CuAu alloy nanowires is crystallized. A part of Cu and Au formed AuCu alloy structure. The limiting concentrations of R6G for the prepared CuAu alloy nanowires SERS substrates is 10mol/L.
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http://dx.doi.org/10.1016/j.jcis.2017.04.025DOI Listing
August 2017

Distribution and Diversity of Microbial Eukaryotes in Bathypelagic Waters of the South China Sea.

J Eukaryot Microbiol 2017 05 12;64(3):370-382. Epub 2016 Oct 12.

Department of Life Sciences, Natural History Museum, London, SW7 5BD, United Kingdom.

Little is known about the biodiversity of microbial eukaryotes in the South China Sea, especially in waters at bathyal depths. Here, we employed SSU rDNA gene sequencing to reveal the diversity and community structure across depth and distance gradients in the South China Sea. Vertically, the highest alpha diversity was found at 75-m depth. The communities of microbial eukaryotes were clustered into shallow-, middle-, and deep-water groups according to the depth from which they were collected, indicating a depth-related diversity and distribution pattern. Rhizaria sequences dominated the microeukaryote community and occurred in all samples except those from less than 50-m deep, being most abundant near the sea floor where they contributed ca. 64-97% and 40-74% of the total sequences and OTUs recovered, respectively. A large portion of rhizarian OTUs has neither a nearest named neighbor nor a nearest neighbor in the GenBank database which indicated the presence of new phylotypes in the South China Sea. Given their overwhelming abundance and richness, further phylogenetic analysis of rhizarians were performed and three new genetic clusters were revealed containing sequences retrieved from the deep waters of the South China Sea. Our results shed light on the diversity and community structure of microbial eukaryotes in this not yet fully explored area.
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http://dx.doi.org/10.1111/jeu.12372DOI Listing
May 2017

Multi-gene-based phylogenetic analysis of oligotrich ciliates with emphasis on two dominant groups: Cyrtostrombidiids and strombidiids (Protozoa, Ciliophora).

Mol Phylogenet Evol 2016 12 28;105:241-250. Epub 2016 Aug 28.

Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao 266003, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266003, China. Electronic address:

Phylogenetic analyses of ciliated protists are frequently based on single molecular markers, usually the small subunit ribosomal RNA gene (SSU rDNA), despite the well-known limitations of this approach. Here, 78 new sequences of three linked genes (SSU rDNA, ITS1-5.8S rDNA-ITS2, LSU rDNA) were characterized and applied to phylogenetic analyses of oligotrichs (s. str.). It was found that: (1) three taxa, that is tontoniids, pelagostrombidiids and cyrtostrombidiids should be split from the family Strombidiidae (s. l.), which supports Agatha's classification based on morphological characters; (2) the families Tontoniidae and Cyrtostrombidiidae are both monophyletic whereas Strombidiidae is polyphyletic; (3) the positions of the families Cyrtostrombidiidae and Pelagostrombidiidae varied in different trees although with low support values; (4) the close relationship between Varistrombidium and Apostrombidium is confirmed, which updates the evolutionary hypothesis for oligotrichs based on ciliary patterns; and (5) two relatively stable clades were found in the family Strombidiidae.
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http://dx.doi.org/10.1016/j.ympev.2016.08.019DOI Listing
December 2016

The All-Data-Based Evolutionary Hypothesis of Ciliated Protists with a Revised Classification of the Phylum Ciliophora (Eukaryota, Alveolata).

Sci Rep 2016 04 29;6:24874. Epub 2016 Apr 29.

Institute of Evolution &Marine Biodiversity, Ocean University of China, Qingdao 266003, China.

The phylum Ciliophora plays important roles in a wide range of biological studies. However, the evolutionary relationships of many groups remain unclear due to a lack of sufficient molecular data. In this study, molecular dataset was expanded with representatives from 55 orders and all major lineages. The main findings are: (1) 14 classes were recovered including one new class, Protocruziea n. cl.; (2) in addition to the two main branches, Postciliodesmatophora and Intramacronucleata, a third branch, the Mesodiniea, is identified as being basal to the other two subphyla; (3) the newly defined order Discocephalida is revealed to be a sister clade to the euplotids, strongly suggesting the separation of discocephalids from the hypotrichs; (4) the separation of mobilids from the peritrichs is not supported; (5) Loxocephalida is basal to the main scuticociliate assemblage, whereas the thigmotrichs are placed within the order Pleuronematida; (6) the monophyly of classes Phyllopharyngea, Karyorelictea, Armophorea, Prostomatea, Plagiopylea, Colpodea and Heterotrichea are confirmed; (7) ambiguous genera Askenasia, CyclotrichiumParaspathidium and Plagiocampa show close affiliation to the well known plagiopyleans; (8) validity of the subclass Rhynchostomatia is supported, and (9) the systematic positions of Halteriida and Linconophoria remain unresolved and are thus regarded as incertae sedis within Spirotrichea.
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http://dx.doi.org/10.1038/srep24874DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4850378PMC
April 2016