Xiao-Lin Liu

Chinese Academy of Fishery Sciences, 北江, Zhejiang Sheng, China

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Publications (7)17.67 Total impact

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    ABSTRACT: The study isolated 224 bacteria from the intestine of Apostichopus japonicus, then selected and identified three of the bacteria (HS1, HS7, and HS10) which demonstrated amylase, lipase, and protease production capacity as candidate probiotics for sea cucumbers. The three potential probiotics showed no pathogenicity both in haemolytic assays on sheep blood agar plates and after immersing sea cucumbers in a suspension of the bacteria. To reveal the effects of these three potential probiotics on the innate immunity of sea cucumbers, total coelomocyte counts, respiratory burst activity, superoxide dismutase activity, lysozyme activity, acid phosphatase activity, and phagocytic activity by coelomocytes were examined after feeding with four different diets for up to 28 days. Also the specific growth rate and survival rate were investigated after a 60-day feeding trial. Sea cucumbers were fed with 4 diets: one control, three diets supplemented with 1 × 10(9) cell g(-1) of HS1, HS7, and HS10 for 28-60 days. Results showed that sea cucumbers fed diets containing HS1, HS7, and HS10 had led to an enhanced cellular and humoral immune response, notably higher total coelomocytes counts, respiratory burst activity, lysozyme activity, acid phosphatase activity, and phagocytic activity, as recorded during the four weeks of probiotics administration. On the other hand, the survival rate among dietary treatments ranged from 90.71 to 97.97% with significant improvement (P < 0.05) compared to that of the control; and the growth rate observed in the sea cucumbers fed HS1 and HS7 showed sharp increases after 60 days feeding. The present study confirmed the potential beneficial effects of Pseudoalteromonas elyakovii HS1, Shewanella japonica HS7, and Vibro tasmaniensis HS10 as dietary probiotics in A. japonicus.
    Fish &amp Shellfish Immunology 04/2014; · 2.96 Impact Factor
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    ABSTRACT: The effects of single or combined use of dietary Shewanella haliotis D4, Bacillus cereus D7 and Aeromonas bivalvium D15, isolated from the gut of shrimp, were assessed on the growth, innate immunity and disease resistance of Pacific white shrimp (Litopenaeus vannamei). Shrimp was fed 28 days by five experimental diets — i) control diet with no probiotics, ii) three probiotic diets, i.e. feed supplemented with 107 cell g− 1 of D4 (D4 diet), D7 (D7 diet) and D15 (D15 diet), and iii) mixed diet comprising of strains D4, D7 and D15 at a ratio of 2:1:1, dosed at 107 cell g− 1. Results showed that growth of shrimp, i.e. final weight, weight gain, percent weight gain and specific growth rate, was improved after 28-days of feeding regime with probiotics compared to the control. Respond of several non-specific immune parameters of groups fed probiotics was also enhanced; i.e. diet D4 and D15 led to significant enhancement of both respiratory burst and superoxide dismutase activities than that of control. Moreover, the respiratory burst activity was also enhanced by mixed diet at the end of 28 days. All probiotic groups were able to increase acid phosphatase activity of shrimp between days 7 and 21. Moreover, the expression of prophenoloxidase and < beta>-1, 3-glucan-binding protein was significantly up regulated in shrimp fed D4 and D15 diets compared to control group, but penaeidin 3 expression up regulated significantly only with mixed diet after 28 days. The cumulative mortality of shrimp, experimentally challenged with Vibrio harveyi, was reduced in groups fed probiotics, i.e. D4 = 36.67%, D7 = 41.67%, D15 = 13.33% and mixed = 11.67%, respectively, than that of controls (43.33%) after 10 days of post-infection. Overall, the results of this study indicated the potential of using probiotics to improve growth, immunity and disease resistance of white shrimp.
    Aquaculture. 01/2014; s 428–429:141–149.
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    ABSTRACT: The study isolated 224 bacteria from the intestine of Apostichopus japonicus, then selected and identified three of the bacteria (HS1, HS7, and HS10) which demonstrated amylase, lipase, and protease production capacity as candidate probiotics for sea cucumbers. The three potential probiotics showed no pathogenicity both in haemolytic assays on sheep blood agar plates and after immersing sea cucumbers in a suspension of the bacteria. To reveal the effects of these three potential probiotics on the innate immunity of sea cucumbers, total coelomocyte counts, respiratory burst activity, superoxide dismutase activity, lysozyme activity, acid phosphatase activity, and phagocytic activity by coelomocytes were examined after feeding with four different diets for up to 28 days. Also the specific growth rate and survival rate were investigated after a 60-day feeding trial. Sea cucumbers were fed with 4 diets: one control, three diets supplemented with 1 × 109 cell g-1 of HS1, HS7, and HS10 for 28-60 days. Results showed that sea cucumbers fed diets containing HS1, HS7, and HS10 had led to an enhanced cellular and humoral immune response, notably higher total coelomocytes counts, respiratory burst activity, lysozyme activity, acid phosphatase activity, and phagocytic activity, as recorded during the four weeks of probiotics administration. On the other hand, the survival rate among dietary treatments ranged from 90.71 to 97.97% with significant improvement (P < 0.05) compared to that of the control; and the growth rate observed in the sea cucumbers fed HS1 and HS7 showed sharp increases after 60 days feeding. The present study confirmed the potential beneficial effects of Pseudoalteromonas elyakovii HS1, Shewanella japonica HS7, and Vibro tasmaniensis HS10 as dietary probiotics in A. japonicus.
    Fish &amp Shellfish Immunology 01/2014; · 2.96 Impact Factor
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    ABSTRACT: The effects of dietary administration of two probiotics, Shewanella colwelliana WA64 and Shewanella olleyana WA65, on the innate immunity of abalone (Haliotis discus hannai Ino), and survival of juvenile abalone challenged with Vibrio harveyi have been studied. Two groups of abalone were fed with three different diets: one control, and two diets supplemented with 10(9) cell g(-1) of probiotic WA64 (WA64 diet) and WA65 (WA65 diet) for up to four weeks. Results showed that abalone fed diets containing S. colwelliana WA64 and S. olleyana WA65 had led to an enhanced cellular and humoral immune response, notably higher haemocytes, respiratory burst activity, serum lysozyme activity and total protein levels were recorded after one week of probiotic administration. On the other hand, mortality after the challenges with V. harveyi in the group fed with control diet ranged from 77-80%, while mortality rates observed in the groups fed with diets supplemented with WA64 and WA65 ranged from 27-50% and 30-43%, respectively. The results demonstrated potential for Shewanella colwelliana WA64 and Shewanella olleyana WA65 to improve innate immunity and disease resistance in H. discus hannai.
    Fish &amp Shellfish Immunology 04/2013; · 2.96 Impact Factor
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    ABSTRACT: A bacterial strain with putative immunomodulatory properties was isolated from Xi'an hot springs in China. Comparison of 16S rRNA gene revealed a 97% similarity between the tested strain (designated XA-1) and Anoxybacillus kamchatkensis. Two compounds isolated from the secondary metabolites of XA-1 were identified by spectral data (infrared, nuclear magnetic resonance and mass spectrometry) as: (1) cyclo (Gly-L-Pro) and (2) cyclo (L-Ala-4-hydroxyl-L-Pro). Two cyclic dipeptides showed stimulatory properties towards a range of parameters when a dose of 20mg kg(-1) body weight was intraperitoneally injected in naive common carp, Cyprinus carpio. Innate immune parameters (serum SOD, lysozyme and bactericidal activity, and phagocytic activity by peripheral blood leucocytes) along with the expression of two immune-related genes (IL-1β and iNOS) in blood were examined after 7, 14, 21, and 28 days of injection. In the absence of infection, immunomodulators should ideally not affect normal physiology and immunity of the host; possible negative outcomes of activated immune responses in the naive state are discussed. Protection by two bacterial dipeptides was assessed in an intraperitoneal injection challenge trial with live Aeromonas hydrophila. Both compounds reduced mortality, with the highest survival rate observed in the group that received compound 2 (80%) followed by the group that received compound 1 (65%) while control group scored the worse (15%). Elucidation of the involved protective mechanisms in carp requires future studies.
    Fish &amp Shellfish Immunology 03/2011; 30(6):1331-8. · 2.96 Impact Factor
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    ABSTRACT: Dactylogyrus intermedius is one of the most pathogenic monogenean parasites on the gills of captive fish and can cause serious problem in aquaculture. To attempt controlling this parasite and explore novel potential antiparasitic agents, the present study was designed to investigate the anthelmintic activity of Dioscorea zingiberensis C. H. Wright against D. intermedius in goldfish under in vivo conditions. Bioactivity-guided fractionation and isolation of the compounds responsible for anthelmintic activity was carried out with the ethanolic extract yielding two bioactive compounds. Using MS, (1)H NMR, (13)C NMR spectroscopic analyses, the two compounds were identified as trillin and gracillin. The results of in vivo anthelmintic efficacy assay showed that the 48-h median effective concentrations (EC(50)) are 26.48 mg L(-1) for trillin and 0.18 mg L(-1) for gracillin. The 48-h acute toxicity tests (LD(50)) of trillin and gracillin were found to be 73.11 and 1.40 mg L(-1) for goldfish, respectively. The resulting therapeutic indices for the two active compounds are 2.76 and 7.78, respectively. These data confirmed that both trillin and gracillin are effective against D. intermedius, and the gracillin exhibits more interesting perspectives for the development of a candidate antiparasitic agent.
    Parasitology Research 11/2010; 107(6):1365-71. · 2.85 Impact Factor
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    ABSTRACT: A bacterial strain, designated DR-834 and producing immunostimulatory activities to carp (Cyprinus carpio), was isolated from Qinghai-Tibetan Plateau permafrost soil. Cultural characteristic studies suggested that this strain belongs to the genus Bacillus. The nucleotide sequence of the 16S rRNA gene of strain DR-834 exhibited close similarity (99%) with the 16S rRNA gene of Bacillus simplex. Two compounds showing potent activity were isolated from secondary metabolites of the strain through bioassay-guided isolation techniques and identified by spectral data (infrared, nuclear magnetic resonance and mass spectrometry) as: (1) 4-trans-hydroxy-l-proline and (2) cyclo-(l-Pro-Gly)(2). They were found to be significantly increased the selected innate immune function parameters, serum SOD activity, serum lysozyme activity, serum bactericidal activity, superoxide anion production and phagocytic activity by isolated blood leucocytes. The effects of two compounds on immune-related genes expression were further investigated. The outcomes of real-time quantitative polymerase chain reaction (RQ-PCR) proved that the transcribing level of interleukin 1beta (IL-1beta) and inducible nitric oxide synthase (iNOS) mRNA in the blood have been augmented by 4-trans-hydroxy-l-proline and cyclo-(l-Pro-Gly)(2). Compounds 1 and 2 administration the challenge with live Aeromonas hydrophila decreased the percentage mortality in the experimental groups with the consequence increase in relative percent survival (RPS) values. Compound 2 produced the highest protection with the RPS values of 87.50, 77.78, 55.56 and 55.56 after 1, 2, 3 and 4 weeks, respectively. The study indicates that the isolated compounds could be positively influence the immune response and protect the heath status of carp against A. hydrophila infection.
    Fish &amp Shellfish Immunology 09/2010; 29(3):378-87. · 2.96 Impact Factor