Transcriptome Analysis of the Spleen Provides Insight into the Immune Regulation of GCRV Resistance in Grass Carp (Ctenopharyngodon idella).

Grass carp (Ctenopharyngodon idella) is one of the most economically important fish in China, and its production is commonly lost due to GCRV infection. To understand the molecular mechanism of GCRV resistance in grass carp, we compared the spleen transcriptome of the GCRV-resistant and susceptible individuals under GCRV infection (Res-Sus) and the GCRV-resistant individuals under different conditions of injection with GCRV and PBS (Res-Ctl). A total of 87.56 GB of clean data were obtained from 12 transcriptomic libraries of spleen tissues. A total of 379 DEGs (156 upregulated genes and 223 downregulated genes) were identified in the comparison group Res-Ctl. A total of 1207 DEGs (633 upregulated genes and 574 downregulated genes) were identified in the comparison group Res-Sus. And 54 DEGs were shared including immune-related genes of stc2 (stanniocalcin 2), plxna1 (plexin A1), ifnα (interferon alpha), cxcl 11 (C-X-C motif chemokine ligand 11), ngfr (nerve growth factor receptor), mx (MX dynamin-like GTPase), crim1 (cysteine-rich transmembrane BMP regulator 1), plxnb2 (plexin B2), and slit2 (slit guidance ligand 2). KEGG pathway analysis revealed significant differences in the expression of genes mainly involved in immune system and signal transduction, including antigen processing and presentation, Toll-like receptor signaling pathway, natural killer cell-mediated cytotoxicity, and Hippo signaling pathway. This study investigates the immune mechanism of the resistance to GCRV infection in grass carp and provides useful information for the development of methods to control the spread of the GCRV infection.

Anti-inflammatory and antioxidant properties of rice bran oil extract in copper sulfate-induced inflammation in zebrafish (Danio rerio).

Tocotrienols have strong antioxidant properties; however, tocotrienol has not been investigated in detail in aquatic products. In this study, the anti-inflammatory and antioxidant activities of the tocotrienol-rich fraction from rice bran oil and its potential mechanism were verified in a zebrafish CuSO4 inflammation model. The in vitro antioxidant activity was evaluated using the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) stable radical method. The copper chelating activity was determined using the pyrocatechol violet method. Intracellular reactive oxygen species in zebrafish were detected using a fluorescent ROS probe. Transgenic Tg (lyz: DsRed2) zebrafish were used for neutrophil transmigration assays. The mRNA expression levels of antioxidant and pro-inflammatory factor genes were measured using quantitative real-time reverse transcription PCR. In the concentration range tested, 100 µg/mL TRF had the highest copper chelating activity (10%). TRF showed DPPH-free radical scavenging ability, which was 53% at 100 µg/mL TRF. TRF effectively repressed ROS generation and inhibited neutrophil migration to the inflamed site. Moreover, TRF upregulated the expression of antioxidant genes sod and gpx4b, inhibited the expression of pro-inflammatory factors tnfa and il8, and suppressed CuSO4-induced inflammation. In conclusion, TRF has significant anti-inflammatory and antioxidant properties, which supports the use of TRF as an aquatic feed additive to improve the anti-inflammatory and antioxidant capacity of aquatic products.

Sequence and functional analysis of intestinal alkaline phosphatase from Lateolabrax maculatus.

Alkaline phosphatases (Alps) belong to a class of phosphate transferases that dephosphorylate lipopolysaccharide (LPS), adenosine triphosphate, and nucleotides. In this study, a 1874-base pair (bp) intestinal alp cDNA sequence was cloned from Lateolabrax maculatus and designated as Lm-alpi. It contained a 1611 bp open reading frame which encoded a protein with 537 amino acids. Protein sequence alignment showed that Lm-AlpI shared 29.8-79.8% identity with its homologs. Lm-AlpI catalytic sites contained three metal ion sites (two Zn2+ and one Mg2+), referring to D73, H184, D348, H349, H352, H464, D389, and H390 residues, which are essential for enzymatic activity and conservation in different organisms. Two predicted disulfide bonds in Lm-AlpI were composed of four cysteines (C152-C214 and C499-C506), which were homologous to those of mammals. Immunohistochemical staining revealed that Lm-AlpI was mainly expressed on the mucosal surface of the gastrointestinal tract, including stomach, intestine, and gastric cecum. Lm-AlpI was mainly located on the plasma membrane of transiently transfected HeLa cells. The mRNA of Lm-alpi was mainly expressed in the intestine, and its expression levels gradually increased after LPS treatment and further increased by 1.81-fold after 48 h. After desalting culture, the relative mRNA expression level of Lm-alpi decreased at 30 and 50 days after hatching (DAH) and then returned to normal levels at 70 DAH. Further experiments demonstrated that the enzyme activity of Lm-AlpI exhibited an expression pattern similar to that of the mRNA expression of Lm-alpi after LPS treatment and desalting culture. This study provided valuable information on the Lm-AlpI functions associated with the mucosal immunity and salinity adaptation of L. maculatus.