Spirulina elicits the activation of innate immunity and increases resistance against Vibrio alginolyticus in shrimp.

The effect of Spirulina dried powder (SDP) on the immune response of white shrimp Litopenaeus vannamei was studied in vitro and in vivo. Incubating shrimp haemocytes in 0.5 mg ml(-1) SDP caused the degranulation of haemocytes and a reduction in the percentage of large cells within 30 min. Shrimp haemocytes incubated in 1 mg ml(-1) SDP significantly increased their phenoloxidase (PO) activity, serine proteinase activity, and respiratory burst activity (RB, release of superoxide anion). A recombinant protein of lipopolysaccharide and ß-1,3-glucan binding protein (LGBP) of the white shrimp was produced, named rLvLGBP, and examined for its binding with SDP. An ELISA binding assay showed that rLvLGBP binds to SDP with a dissociation constant of 0.0507 µM. In another experiment, shrimp fed diets containing SDP at 0 (control), 30, and 60 g kg(-1) after four weeks were examined for LGBP transcript level and lysozyme activity, as well as phagocytic activity, clearance efficiency, and resistance to Vibrio alginolyticus. These parameters were significantly higher in shrimp receiving diets containing SDP at 60 g kg(-1) or 30 g kg(-1) than in controls. In conclusion, shrimp haemocytes receiving SDP provoked the activation of innate immunity as evidenced by the recognition and binding of LGBP, degranulation of haemocytes, reduction in the percentage of large cells, increases in PO activity, serine proteinase activity, superoxide anion levels, and up-regulated LGBP transcript levels. Shrimp receiving diets containing SDP had increased lysozyme activity and resistance against V. alginolyticus infection. This study showed the mechanism underlying the immunostimulatory action of Spirulina and its immune response in shrimp.

The complete mitochondrial genome of Holland's spinibarbel Spinibarbus hollandi Oshima (Cypriniformes, Cyprinidae).

In this study, the complete mitogenome sequence of cyprinid fish, Holland's spinibarbel Spinibarbus hollandi Oshima (1919) (Cypriniformes, Cyprinidae, Barbinae) has been amplified and sequenced by employing long polymerase chain reaction method. The mitogenome, consisting of 16,523 base pairs (bp), had the typical vertebrate mitochondrial gene arrangement, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs genes, and a non-coding control region (CR). CR of 867 bp length is located between tRNA(Pro) and tRNA(Phe). The overall base composition of S. hollandi is 31.87% for A, 26.56% for C, 25.89% for T, and 15.68% for G, with a slight AT bias of 57.76%. The complete mitogenome may provide rather essential and important DNA molecular data for further phylogenetic analysis for not only congeneric species but also higher different taxa of Cyprinid fishes.

Endogenous molecules induced by a pathogen-associated molecular pattern (PAMP) elicit innate immunity in shrimp.

Invertebrates rely on an innate immune system to combat invading pathogens. The system is initiated in the presence of cell wall components from microbes like lipopolysaccharide (LPS), ß-1,3-glucan (ßG) and peptidoglycan (PG), altogether known as pathogen-associated molecular patterns (PAMPs), via a recognition of pattern recognition protein (PRP) or receptor (PRR) through complicated reactions. We show herein that shrimp hemocytes incubated with LPS, ßG, and PG caused necrosis and released endogenous molecules (EMs), namely EM-L, EM-ß, and EM-P, and found that shrimp hemocytes incubated with EM-L, EM-ß, and EM-P caused changes in cell viability, degranulation and necrosis of hemocytes, and increased phenoloxidase (PO) activity and respiratory burst (RB) indicating activation of immunity in vitro. We found that shrimp receiving EM-L, EM-ß, and EM-P had increases in hemocyte count and other immune parameters as well as higher phagocytic activity toward a Vibrio pathogen, and found that shrimp receiving EM-L had increases in proliferation cell ratio and mitotic index of hematopoietic tissues (HPTs). We identified proteins of EMs deduced from SDS-PAGE and LC-ESI-MS/MS analyses. EM-L and EM-P contained damage-associated molecular patterns (DAMPs) including HMGBa, HMGBb, histone 2A (H2A), H2B, and H4, and other proteins including proPO, Rab 7 GPTase, and Rab 11 GPTase, which were not observed in controls (EM-C, hemocytes incubated in shrimp salt solution). We concluded that EMs induced by PAMPs contain DAMPs and other immune molecules, and they could elicit innate immunity in shrimp. Further research is needed to identify which individual molecule or combined molecules of EMs cause the results, and determine the mechanism of action in innate immunity.