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The changes in cortisol and expression of immune genes of GIFT tilapia Oreochromis niloticus (L.) at different rearing densities under Streptococcus iniae infection.
- Source :
-
Aquaculture International . Oct2016, Vol. 24 Issue 5, p1365-1378. 14p. - Publication Year :
- 2016
-
Abstract
- The present study was conducted to investigate the effects of stocking density on serum cortisol (COR) levels and expression of immune genes in the head kidney of juvenile GIFT tilapia ( Oreochromis niloticus) after Streptococcus iniae ( S. iniae) infection. Juveniles (2700) were distributed into 30 tanks at five stocking densities (150, 300, 450, 600 and 750 g/m), and each treatment had six replicates. After a 45-day feeding trial, a S. iniae challenge study was conducted for 96 h. Differences in mortality, serum COR and gene expression of C-type lysozyme, heat-shock protein 70 (HSP70), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) were analyzed. The levels of serum COR at all infected treatments were significantly higher compared with the levels of pre-infection ( P < 0.05). At 96 h post-infection, serum COR levels of high stocking densities (600 and 750 g/m) were significantly higher than those of low-density groups ( P < 0.05); the mRNA levels of C-type lysozyme, HSP70, IL-1β, TNF-α and IFN-γ were significantly lower in tilapia reared at 600 g/m group than in those reared at 300 g/m group ( P < 0.05). Fish reared in high-density treatments (600 and 750 g/m) exhibited significantly higher post-challenge mortality (43.3 and 40.0 %) at 96 h following S. iniae infection, and it was significantly higher than other groups ( P < 0.05). The data suggest that when living in high stocking density, GIFT tilapia showed decrease in immune capability, together with increased serum COR and susceptibility to S. iniae. [ABSTRACT FROM AUTHOR]
- Subjects :
- *TILAPIA
*FISH stocking
*GENE expression
*MESSENGER RNA
*FISH mortality
Subjects
Details
- Language :
- English
- ISSN :
- 09676120
- Volume :
- 24
- Issue :
- 5
- Database :
- Academic Search Index
- Journal :
- Aquaculture International
- Publication Type :
- Academic Journal
- Accession number :
- 117760721
- Full Text :
- https://doi.org/10.1007/s10499-016-9995-y