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Effects of Small Peptides on Nonspecific Immune Responses in Sea Cucumber, Apostichopus japonicus

Authors

  • Shuxian Wang,

    1. Mariculture Institute of Shandong Province, Shandong Province Key Laboratory for Disease Control of Mariculture, Qingdao, China
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  • Haibin Ye,

    1. Mariculture Institute of Shandong Province, Shandong Province Key Laboratory for Disease Control of Mariculture, Qingdao, China
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  • Tianbao Li,

    Corresponding author
    • Mariculture Institute of Shandong Province, Shandong Province Key Laboratory for Disease Control of Mariculture, Qingdao, China
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  • Xiusheng Yang,

    1. Mariculture Institute of Shandong Province, Shandong Province Key Laboratory for Disease Control of Mariculture, Qingdao, China
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  • Ying Fan,

    1. Mariculture Institute of Shandong Province, Shandong Province Key Laboratory for Disease Control of Mariculture, Qingdao, China
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  • Xiaoqing Yu,

    1. Mariculture Institute of Shandong Province, Shandong Province Key Laboratory for Disease Control of Mariculture, Qingdao, China
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  • Yongqiang Wang

    1. Mariculture Institute of Shandong Province, Shandong Province Key Laboratory for Disease Control of Mariculture, Qingdao, China
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Corresponding authors.

Abstract

The potential immunostimulatory effects of small peptides on sea cucumber, Apostichopus japonicus, were investigated in vivo and in vitro. Small peptides were injected into sea cucumbers and a control group was injected with equal volume of sterile filtered seawater. The nonspecific humoral and cellular responses were determined, respectively, and sea cucumbers were challenged by Vibrio splendidus. The results showed that test groups significantly enhanced most of the immune parameters tested (P < 0.05). Both phagocytic capacity and respiratory burst activity were up to maximum value on the fourth day and the values were 2.3 and 1.4 times as high as the control group, respectively. However, small peptides had no significant effect on total coelomocytes counts. Among the humoral responses, the activities of acid phosphatase, alkaline phosphatase, and superoxide dismutase were up to maximum value on the fourth, fourthth and seventh day, respectively. The values were 2.3, 2.2, and 2.0 times as high as the control group, respectively. At the end of the challenge, the cumulative mortality rate of sea cucumber injected with 0.5 mg small peptides (43.3%) was significantly lower than the control group (66.7%). In conclusion, small peptides as an additive could improve the nonspecific immunity level of Apostichopus japonicus.

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