β-Defensin in Nile tilapia (Oreochromis niloticus): Sequence, tissue expression, and anti-bacterial activity of synthetic peptides

Influence of traditional Chinese medicine and Bacillus species (TCMBS) on growth, immune response and disease resistance in Nile tilapia, Oreochromis niloticus

“…It has been documented that β‐defensins act as the first barrier of defence against viral and bacterial infections (Dong et al., ) while lysozyme expression shows evidence of innate immune action acting against bacterial infection (Qiang et al., ). A previous study in Gift tilapia, Oreochromis niloticus (Qiang et al., ) and in grouper Epinephelus coioides (Sun, Yang, Ma, & Lin, ) reported significant up‐regulation of β‐defensins and lysozyme genes in intestines after probiotic administration.…”

“…In the present study, increased expressions of HSP 70 observed in TCMBS1 and TCMBS3 groups in relation with CT group in MINT most likely lead to increased tolerance to stressful conditions (Figure ). Antioxidants, for examples, expression of SOD and CAT genes are vital to protecting the host from free radicals and effects of reactive oxygen species (ROS) resulting from oxidation reaction in the host (Dong et al., ). As shown in Figure in this study after 2 and 4 weeks, significant up‐regulation of expression of SOD gene was observed in all treated groups, with the highest expression in TCMBS3 compared with the CT after 4 weeks.…”

Antimicrobial Peptides as Mediators of Innate Immunity in Teleosts

“…In adult fish, the expression pattern and levels of β-defensins varies greatly depending on the fish species and the defensin gene [ 12 ]. However, the primary expression of β-defensin appears to be in the immune and mucosal tissues including the intestine, gill, kidney, spleen, skin, and liver [ 6 , 13 , 14 , 18 , 19 , 20 ], with expression also detected in the muscle, stomach, eye, gonad, heart, blood, monocytes and lymphocytes [ 5 , 6 , 11 , 15 , 16 , 20 , 21 ]. In some fish species, β-defensin transcripts were also detected in the pituitary, testis [ 7 ], swim bladder and peritoneum (with low levels in the skin and kidney) [ 8 ].…”

“…One study noted the translocation of β-defensin peptides from the cytoplasm to the nucleus where viral replication was occurring in infected cells [ 18 ], demonstrating that β-defensins are actively mobilized to sites of pathogen replication within a cell. Recombinant or synthetic fish defensins have demonstrated antimicrobial activity towards Gram-negative bacteria [ 6 , 11 , 17 , 19 , 20 ], Gram-positive bacteria, [ 19 , 20 ] and viruses [ 8 , 15 , 18 ], although the antimicrobial activity was dependent on the fish species and the defensin gene. A complete list of MICs for fish β-defensins and the pathogens they have been tested against can be found in [ 4 ].…”

Transgenic rice expressing a novel phytase-lactoferricin fusion gene to improve phosphorus availability and antibacterial activity

“…The hydrolysate products were transferred into ultrafiltration tubes of molecular weight cutoff 10 kD, centrifuged at 12 000 r min -1 for 10 min; after that, filtrates below the ultrafiltration membrane were transferred into ultrafiltration tubes of molecular weight cutoff 3 kD, centrifuged at 12 000 r min -1 for 10 min; liquids above the ultrafiltration membrane containing bovine lactoferricin (LfcinB) were collected. Antibacterial activity analysis was based on the standard method (Dong et al 2015), but was slightly modified: 1 mL broth containing 0.1% E. coli DH5α at the logarithmic growth phase was mixed with 30 μL filtrates containing LfcinB or un-hydrolyzed control; after shaking 200 r min -1 at 37°C for 16 h, the mixtures were evaluated in term of OD 600 .…”