Xiuqin Sun

First Institute of Oceanography, Qingdao, Shandong Sheng, China

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Publications (15)27.5 Total impact

  • Article: Screen and effect analysis of immunostimulants for sea cucumber, Apostichopus japonicus
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    ABSTRACT: Immunostimulants may improve disease resistance of aquaculture animals by promoting the nonspecific immunity response of the organisms. Five types of saccharides, including chitosan, yeast polysaccharide, burdock oligosaccharide, seaweed polysaccharide and lentinus edodes polysaccharide, were screened for potential use as immunostimulants by using spectrophotometry. The saccharides were injected into Apostichopus japonicus, a sea cucumber, and the lysozyme and superoxide dismutase (SOD) activities of the coelomic fluid and epidermal slime were monitored in six consecutive days. The results show that the lysozyme activity of the animal’s coelomic fluid was significantly stimulated on day 2, day 4 and day 6 after the injection of the saccharides (P<0.05). The effects of chitosan and yeast polysaccharide were the most notable. The lysozyme activity of the epidermal slime was significantly increased by chitosana, yeast polysaccharide, seaweed polysaccharide, and burdock oligosaccharide on day 1 and day 2 after the injection (P<0.05). The SOD activity of the coelomic fluid was significantly promoted by the saccharides on day 2 and day 4 post-injection (P<0.05), while the SOD activity of the epidermal slime increased on day 2. These findings indicate that chitosan and yeast polysaccharide are the most effective immunostimulants and potential healthy anti-disease feedstuff for A. japonicus.
    Chinese Journal of Oceanology and Limnology 04/2012; 27(1):80-84. · 0.50 Impact Factor
  • Article: Proteomic aspects of infection by lymphocystis disease virus in Japanese flounder (Paralichthys olivaceus)
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    ABSTRACT: To reveal the key factor in self-healing from LCDV (lymphocystis disease virus)-infected Japanese flounder (Paralichthys olivaceus), serum proteins from self-healing and sick Japanese flounder were separated by two-dimensional electrophoresis to screen differentially expressed proteins. Protein spots demonstrating changes greater than two-fold in the expression level were digested and further identified in capillary liquid chromatography tandem mass spectrometry (LC-MS/MS). Two immunity-relevant proteins were thus identified as transferrin and the complement component C3 of Japanese flounder. These findings suggest that the two proteins may play important roles in the self-healing of lymphocystis in Japanese flounder. This is an important theoretical foundation to promote self-healing in LCDV-infected Japanese flounder by improving their innate immunity. KeywordJapanese flounder– Paralichthys olivaceus –lymphocystis disease–proteomics–serum
    Chinese Journal of Oceanology and Limnology 04/2012; 29(3):603-608. · 0.50 Impact Factor
  • Article: Histochemical localization and characterization of AKP, ACP, NSE, and POD from cultured Apostichopus japonicus
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    ABSTRACT: We investigated the distribution of four enzymes involved in the immune response of Apostichopus japonicus. We collected samples of the tentacles, papillate podium, integument, respiratory tree, and digestive tract and stained them for acid phosphatase (ACP), alkaline phosphatase (AKP), non-specific esterase (NSE) and peroxidase (POD) activity. The distribution and content of ACP, AKP, NSE, and POD differed among the tissues. The coelomic epithelium of the tentacle, papillate podium, and integument and the mucous layer of respiratory tree were positive for ACP activity. The coelomic epithelium and cuticular layer of the tentacle, papillate podium, and integument and the mucous layer and tunica externa of the respiratory tree and digestive tract stained positive or weakly positive for AKP activity. Almost all the epithelial tissues stained positive, strongly positive, or very strongly positive for NSE activity. The cuticular layer of the tentacle and integument and the mucous layer, tunica submucosa, and tunica externa of the respiratory tree and digestive tract stained positive for POD activity. We hypothesize that these enzymes play a role in the immune response in A. japonicus.
    Chinese Journal of Oceanology and Limnology 04/2012; 27(3):550-554. · 0.50 Impact Factor
  • Article: Characterization of defensin gene from abalone Haliotis discus hannai and its deduced protein
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    ABSTRACT: Defensin is one of preserved ancient host defensive materials formed in biological evolution. As a regulator and effector molecule, it is very important in animals’ acquired immune system. This paper reports the defensin gene from the mixed liver and kidney cDNA library of abalone Haliotis discus hannai Ino. Sequence analysis shows that the gene sequence of full-length cDNA encodes 42 mature peptides (including six Cys), molecular weight of 4 323 Da, and pI of 8.02. Amino acid sequence homology analysis shows that the peptides are highly similar (70% in common) to other insects defensin. Because of a typical insect-defensin structural character of mature peptide in the secondary structure, the polypeptide named Haliotis discus defensin (hd-def), a novel of antimicrobial peptides, belongs to insects defensin subfamily. The RT-PCR result of Haliotis discus defensin shows that the gene can be expressed only in the hepatopancreas by Gram-negative and positive bacteria stimulation, which is ascribed to inducible expression. Therefore, it is revealed that the Haliotis discus defensin gene expression was related to the antibacterial infection of Haliotis discus hannai Ino. Keywordgene expression-abalone defensin (hd-def)- Haliotis discus hannai
    Chinese Journal of Oceanology and Limnology 04/2012; 26(4):375-379. · 0.50 Impact Factor
  • Article: Distribution and expression in vitro and in vivo of DNA vaccine against lymphocystis disease virus in Japanese flounder (Paralichthys olivaceus)
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    ABSTRACT: Lymphocystis disease, caused by the lymphocystis disease virus (LCDV), is a significant worldwide problem in fish industry causing substantial economic losses. In this study, we aimed to develop the DNA vaccine against LCDV, using DNA vaccination technology. We evaluated plasmid pEGFP-N2-LCDV1.3 kb as a DNA vaccine candidate. The plasmid DNA was transiently expressed after liposome transfection into the eukaryotic COS 7 cell line. The distribution and expression of the DNA vaccine (pEGFP-N2-LCDV1.3kb) were also analyzed in tissues of the vaccinated Japanese flounder by PCR, RT-PCR and fluorescent microscopy. Results from PCR analysis indicated that the vaccine-containing plasmids were distributed in injected muscle, the muscle opposite the injection site, the hind intestine, gill, spleen, head, kidney and liver, 6 and 25 days after vaccination. The vaccine plasmids disappeared 100 d post-vaccination. Fluorescent microscopy revealed green fluorescence in the injected muscle, the muscle opposite the injection site, the hind intestine, gill, spleen, head, kidney and liver of fish 48 h post-vaccination, green fluorescence did not appear in the control treated tissue. Green fluorescence became weak at 60 days post-vaccination. RT-PCR analysis indicated that the mcp gene was expressed in all tested tissues of vaccinated fish 6–50 days post-vaccination. These results demonstrate that the antigen encoded by the DNA vaccine is distributed and expressed in all of the tissues analyzed in the vaccinated fish. The antigen would therefore potentially initiate a specific immune response. the plasmid DNA was injected into Japanese flounder (Paralichthys olivaceus) intramuscularly and antibodies against LCDV were evaluated. The results indicate that the plasmid encoded DNA vaccine could induce an immune response to LCDV and would therefore offer immune protection against LCD. Further studies are required for the development and application of this promising DNA vaccine.
    Chinese Journal of Oceanology and Limnology 04/2012; 28(1):67-74. · 0.50 Impact Factor
  • Article: Halomonas daqiaonensis sp. nov., a moderately halophilic, denitrifying bacterium isolated from a littoral saltern.
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    ABSTRACT: Two novel gram-negative, oxidase- and catalase-positive, rod-shaped bacterial strains, designated YCSA28(T) and YCSA39, were isolated from sediment of Daqiao saltern, Jimo, Qingdao, on the east coast of China. The two strains grew optimally at 28-30 °C, at pH 7.5 and in the presence of 7-8 % (w/v) NaCl. They were assigned to the genus Halomonas, class Gammaproteobacteria, based on 16S rRNA gene sequence analysis. The major cellular fatty acids of the two strains were C(18 : 1)ω7c (42.9 %), C(16 : 0) (23.1 %) and C(16 : 1)ω7c/ω6c (18.0 %), and Q-9 was the major ubiquinone. The G+C content of the DNA of strains YCSA28(T) and YCSA39 was 63.7 and 63.9 mol%, respectively. The predominant respiratory lipoquinone, cellular fatty acid profiles and DNA G+C content of strains YCSA28(T) and YCSA39 were consistent with those of recognized species of the genus Halomonas. Levels of DNA-DNA relatedness between strains YCSA28(T) and YCSA39, between YCSA28(T) and Halomonas ventosae Al12(T), and between YCSA39 and H. ventosae Al12(T) were 95, 45 and 50 %, respectively. Together, these data indicated that strains YCSA28(T) and YCSA39 represent a single novel species of the genus Halomonas, for which the name Halomonas daqiaonensis sp. nov. is proposed. The type strain is YCSA28(T) ( = CGMCC 1.9150(T)  = NCCB 100305(T)  = MCCC 1B00920(T)).
    INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 07/2011; 61(Pt 7):1612-6. · 2.11 Impact Factor
  • Article: Marinobacter daqiaonensis sp. nov., a moderate halophile isolated from a Yellow Sea salt pond.
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    ABSTRACT: A Gram-negative, oxidase- and catalase-positive, moderately halophilic strain, designated YCSA40(T), was isolated from sediment of Daqiao saltern in Qingdao, on the east coast of China. Growth occurred at 10-45 °C, at pH 5-9 and with 1-15% NaCl. Strain YCSA40(T) showed the highest 16S rRNA gene sequence similarity to Marinobacter segnicrescens SS011B1-4(T) (97%) and M. gudaonensis SL014B61A(T) (96.9%) and 16S rRNA gene sequence phylogenetic analysis assigned the isolate to the genus Marinobacter. Strain YCSA40(T) contained C(18:1)ω9c (34.8%), C(16:0) (11.6%), C(19:0) cyclo ω10c/C(19:1)ω6c (10.5%), C(16:1)ω9c (8.4%), C(17:0) (6.3%) and C(12:0) 3-OH (5.8%) as the predominant fatty acids. The DNA G+C content was 60.8 mol% and the major ubiquinone was Q-9. These chemotaxonomic characters were all consistent with membership of the genus Marinobacter. DNA-DNA relatedness between the isolate and M. segnicrescens CGMCC 1.6489(T), M. gudaonensis CGMCC 1.6294(T) and other type strains of species of the genus Marinobacter was ≤30%. On the basis of the aforementioned data, it was concluded that strain YCSA40(T) represents a novel species of the genus Marinobacter, for which the name Marinobacter daqiaonensis sp. nov. is proposed. The type strain is YCSA40(T) (=CGMCC 1.9167(T) =NCCB 100308(T) =LMG 25365(T)).
    INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 02/2011; 61(Pt 12):3003-8. · 2.11 Impact Factor
  • Article: Sunxiuqinia elliptica gen. nov., sp. nov., a member of the phylum Bacteroidetes isolated from sediment in a sea cucumber farm.
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    ABSTRACT: Three novel aerobic, elliptic bacteria, designated DQHS4(T), DQHS8 and DQHS15, were isolated from sediment of a seashore pond for sea cucumber culture in Jimo, Qingdao, on the east coast of China. Cells were Gram-, oxidase- and catalase-negative. All three strains grew at 15-42 °C, pH 5-9 and NaCl concentrations between 0.5 and 10%. DNA-DNA hybridization experiments revealed high (>85%) relatedness among the three novel isolates and suggested that the strains constitute a single species. Comparative 16S rRNA gene sequence analysis indicated that these bacteria had less than 90% similarity to all described species of the phylum Bacteroidetes; the closest relative of the three isolates was Prolixibacter bellariivorans F2(T), sharing only 89.6% sequence similarity. The major cellular fatty acids were iso-C(17:0) 3-OH (19.8-20.0%), iso-C(15:0) (16.9-17.3%), anteiso-C(17:1) B and/or iso-C(17:1) I (7.4-8.7%), C(17:0) 2-OH (8.4%), anteiso-C(15:0) (8.2-8.6%) and C(17:1)ω6c (5.6-6.0%). The major respiratory quinone was menaquinone-7 (MK-7) and the DNA G+C content was 41.8-43.5 mol%. Based on the distinct phylogenetic position and the combination of genotypic, phenotypic and chemotaxonomic characteristics, these three strains were considered to represent a novel species of a new genus in the phylum Bacteroidetes, for which the name Sunxiuqinia elliptica gen. nov., sp. nov. is proposed. The type strain of Sunxiuqinia elliptica is DQHS4(T) (=CGMCC 1.9156(T) =NCCB 100301(T) =LMG 25367(T)).
    INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 01/2011; 61(Pt 12):2885-9. · 2.11 Impact Factor
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    Article: Isolation and Characterization of a Phosphate-Solubilizing Halophilic Bacterium Kushneria sp. YCWA18 from Daqiao Saltern on the Coast of Yellow Sea of China.
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    ABSTRACT: Phosphate-solubilizing bacteria (PSB) function in soil phosphorus cycle, increasing the bioavailability of soil phosphorus for plants. Isolation and application of salt-tolerant or halophilic PSB will facilitate the development of saline-alkali soil-based agriculture. A moderately halophilic bacterium was isolated from the sediment of Daqiao saltern on the eastern coast of China, which also performs phosphate-solubilizing ability. The bacterium was assigned to genus Kushneria according to its 16S rRNA gene sequence, and accordingly named as Kushneria sp. YCWA18. The fastest growth was observed when the culturing temperature was 28°C and the concentration of NaCl was 6% (w/v). It was founds that the bacterium can survive at a concentration of NaCl up to 20%. At the optimum condition, the bacterium solubilized 283.16 μg/mL phosphorus in 11 days after being inoculated in 200 mL Ca(3)(PO(4))(2) containing liquid medium, and 47.52 μg/mL phosphorus in 8 days after being inoculated in 200 mL lecithin-containing liquid medium. The growth of the bacterium was concomitant with a significant decrease of acidity of the medium.
    Evidence-based Complementary and Alternative Medicine 01/2011; 2011:615032. · 4.77 Impact Factor
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    Article: Immune Efficacy of a Genetically Engineered Vaccine against Lymphocystis Disease Virus: Analysis of Different Immunization Strategies.
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    ABSTRACT: Here, we report the construction of a vaccine against lymphocystis disease virus (LCDV) using nucleic acid vaccination technology. A fragment of the major capsid protein encoding gene from an LCDV isolated from China (LCDV-cn) was cloned into an eukaryotic expression vector pEGFP-N2, yielding a recombinant plasmid pEGFP-N2-LCDV-cn0.6 kb. This plasmid was immediately expressed after liposomal transfer into the Japanese flounder embryo cell line. The recombinant plasmid was inoculated into Japanese flounder via two routes (intramuscular injection and hypodermic injection) at three doses (0.1, 5, and 15 μg), and then T-lymphopoiesis in different tissues and antibodies raised against LCDV were evaluated. The results indicated that this recombinant plasmid induced unique humoral or cell-mediated immune responses depending on the inoculation route and conferred immune protection. Furthermore, the humoral immune responses and protective effects were significantly increased at higher vaccine doses via the two injection routes. Plasmid pEGFP-N2-LCDV0.6 kb is therefore a promising vaccine candidate against LCDV in Japanese flounder.
    Evidence-based Complementary and Alternative Medicine 01/2011; 2011:729216. · 4.77 Impact Factor
  • Article: Identification of the pathogens associated with skin ulceration and peristome tumescence in cultured sea cucumbers Apostichopus japonicus (Selenka).
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    ABSTRACT: The aquaculture of sea cucumbers Apostichopus japonicus (Selenka) has developed rapidly in China in recent years, but is increasingly affected by diseases such as skin ulceration and peristome tumescence. Previous studies on the pathogens causing these diseases focused largely on bacterial causes. In December 2008, we isolated four dominant bacterial species from lesions present in A. japonicus with the aforementioned diseases, from a farm in Yangkou (Qingdao, China). With two of these bacterial species, experimental infection of healthy A. japonicus resulted in the same disease symptoms that occurred in naturally infected A. japonicus. These two species were identified as Pseudoalteromonas sp. and Pseudoalteromonas tetraodonis. The early symptoms of infection for these bacterial species were ulcer spots on the dorsal skin and abdominal parapodia, followed by an increase in the number of ulcer spots or their merging into larger spots. Additionally, we isolated a spherical virus 100-250nm in diameter and with a bilayer capsule, from A. japonicus with another disease from four different farms. By experimental infection with crude extracts of the virus, healthy laboratory-acclimatized A. japonicus developed the same symptoms as in natural infected cases. The early symptoms of viral infection comprised a decrease in tentacle activity, decay of dorsal papillate podia, peristome tumescence and abdominal ulceration. Our study demonstrates that the bacteria and virus were both responsible for skin ulceration and peristome tumescence in A. japonicus, but resulted in different early disease symptoms.
    Journal of Invertebrate Pathology 11/2010; 105(3):236-42. · 2.06 Impact Factor
  • Article: Cohaesibacter marisflavi sp. nov., isolated from sediment of a seawater pond used for sea cucumber culture, and emended description of the genus Cohaesibacter.
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    ABSTRACT: A Gram-negative, catalase-negative, oxidase-positive, rod-shaped bacterium, strain DQHS21(T), was isolated from sediment of a seawater pond used for sea cucumber culture at Jimo in Qingdao province on the east coast of China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain DQHS21(T) belonged to the genus Cohaesibacter, sharing the highest sequence similarity (96.1 %) with Cohaesibacter gelatinilyticus CL-GR15(T), while the similarity to other strains was below 93.0 %. The cellular fatty acids consisted mainly of C(18 : 1)ω7c (60.7 %), C(18 : 0) (17.8 %), C(16 : 0) (8.5 %) and summed feature 3 (C(16 : 1)ω7c and/or iso-C(15 : 0) 2-OH; 6.0 %), which together accounted for 93 % of the total fatty acids. Ubiquinone 10 was the major quinone. The G+C content of the chromosomal DNA of strain DQHS21(T) was 55.2 mol%. The combined genotypic and phenotypic data showed that strain DQHS21(T) represents a novel species of the genus Cohaesibacter, for which the name Cohaesibacter marisflavi sp. nov. is proposed, with the type strain DQHS21(T) ( = CGMCC 1.9157(T)  = NCCB 100300(T)).
    INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY 04/2010; 61(Pt 4):762-6. · 2.11 Impact Factor
  • Article: Chitosan microspheres as candidate plasmid vaccine carrier for oral immunisation of Japanese flounder (Paralichthys olivaceus).
    Jiyuan Tian, Juan Yu, Xiuqin Sun
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    ABSTRACT: Oral DNA-based immunotherapy is a new treatment option for fish immunisation in intensive culture. However, because of the existence of the nucleases and severe gastrointestinal conditions, DNA-based vaccines can be hydrolyzed or denatured. In our laboratory, a plasmid DNA (pDNA) containing major capsid protein (MCP) gene of lymphocystis disease virus (LCDV) was prepared, and then pDNA was encapsulated in chitosan microspheres through an emulsion-based methodology. The yield, loading percent and encapsulation efficiency of microspheres were 93.6%, 0.3% and 94.5%, respectively. Scanning electron microscopy (SEM) showed that pDNA-loaded microspheres yielded a spherical shape with smooth surfaces. The disproportion of super-coiled to open circle and linear pDNA suggested that high transfection efficiencies of pDNA in microspheres were retained. The cumulative release of pDNA showed that chitosan microspheres were resistant to degradation in simulated gastrointestinal tract environment. The release profile at PBS buffer (pH 7.4) displayed that pDNA-loaded chitosan microspheres had a release up to 42 days after intestinal imbibition. RT-PCR showed that RNA containing information of MCP gene existed in various tissues 10-90 days post-vaccination. SDS-PAGE and immunofluorescent images indicated that pDNA expressed MCP in tissues of fish 10-90 days after oral administration. In addition, indirect ELISA displayed that the immune responses of sera were positive (O.D.> or =0.3) from week 1 to week 16 for fish vaccinated with microspheres, in comparison with fish vaccinated with naked pDNA. Data obtained suggested that chitosan microspheres were promising carriers for oral pDNA vaccine. Because this encapsulation technique was easy to operate and immunisation efficacy of microspheres loaded with pDNA was significant, it had potential to be used in drug delivery applications.
    Veterinary Immunology and Immunopathology 08/2008; 126(3-4):220-9. · 2.08 Impact Factor
  • Article: The formulation and immunisation of oral poly(DL-lactide-co-glycolide) microcapsules containing a plasmid vaccine against lymphocystis disease virus in Japanese flounder (Paralichthys olivaceus).
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    ABSTRACT: Nucleic acid-based immunotherapy is a new treatment option for fish immunisation in intensive culture. However, DNA-based vaccines would be hydrolyzed or denaturized because of the existence of nucleases and severe gastrointestinal conditions. Poly(DL-lactide-co-glycolide) (PLGA) microcapsules, loaded with plasmid DNA (pDNA) against lymphocystis disease virus (LCDV), were prepared by modified water in oil in water (W/O/W) double emulsion method in our laboratory. Encapsulation efficiency, loading percent and diameter of microcapsules were 78-88%, 0.5-0.7% and less than 10 mum, respectively. In simulated gastric fluid (SGF), less than 10% of pDNA was released from microcapsules in 12 h, and about 6.5% of pDNA was released in 12 h in simulated intestinal fluid (SIF). The content of the supercoiled of pDNA in microcapsules and control was 80% and 89% respectively, which indicated that a little supercoiled pDNA degradation occurred during encapsulation. RT-PCR showed that lots of RNA containing information of MCP gene existed in all tissues of fish vaccinated with microcapsules 10-90 days after oral administration. SDS-PAGE and immunoblots, as well as immunofluorescence images, displayed that major capsid protein (MCP) of LCDV was expressed in tissues of fish vaccinated with pDNA-loaded microcapsules. In addition, indirect enzyme-linked immunosorbent assay (ELISA) showed that the immune responses of sera were positive (O.D> or =0.3) from week 1 to week 24 for fish vaccinated with microcapsules, in comparison with fish vaccinated with naked pDNA. Our results suggested that PLGA microcapsules were promising oral carriers for pDNA delivery. This encapsulation technique had potential for drug delivery applications due to its ease of operation and notable immunisation efficacy.
    International Immunopharmacology 07/2008; 8(6):900-8. · 2.38 Impact Factor
  • Article: Cloning and expression of prion protein encoding gene of flounder ( Paralichthys olivaceus )
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    ABSTRACT: The prion protein (PrP) encoding gene of flounder (Paralichthys olivaceus) was cloned. It was not interrupted by an intron. This gene has two promoters in its 5′ upstream, indicating that its transcription may be intensive, and should have an important function. It was expressed in all 14 tissues tested, demonstrating that it is a house-keeping gene. Its expression in digestion and reproduction systems implies that the possible prions of fish may transfer horizontally.
    Chinese Journal of Oceanology and Limnology 01/2008; 26(1):50-53. · 0.50 Impact Factor

Institutions

  • 2012
    • First Institute of Oceanography
      Qingdao, Shandong Sheng, China
    • Ocean University of China
      Qingdao, Shandong Sheng, China
  • 2011
    • State Oceanic Administration
      Qingdao, Shandong Sheng, China
  • 2008
    • Ocean University of Qingdao
      Qingdao, Shandong Sheng, China
    • Qingdao Agricultural University
      Qingdao, Shandong Sheng, China