Changes in selected stress and immune-related genes in Atlantic cod,Gadus morhua, following overcrowding

Abstract

Using Atlantic cod, Gadus morhua, as a model for the stress response in gadoid ¢sh, the changes in the expression of some stress and immune genes as well as the pro¢les of plasma cortisol were examined. Adult ¢sh were kept at a density of ca.100 kg m À 3 by lowering the water level in the rearing tank for 1h and this short-term crowding stress was repeated thrice over a 12-h interval period. Blood samples were collected before exposure and at 2, 24 and 72 h post crowding. Plasma cortisol level signi¢cantly increased at 2 h post crowding but returned to pre-crowding levels 24 h after exposure. The relative expression of the stress response genes, glucose transporter-3 and a putative heat shock protein 70 signi¢cantly increased at 2 and 24 h post crowding respectively. Signi¢cant upregulation of the pro-in£ammatory cytokines, interleukin (IL)-1b and IL-8, as well as anti-bacterial genes, g-type lysozyme and bactericidal permeability-increasing protein/lipopolysaccharide-binding protein (BPI/LBP) was also observed at 2 h and the levels were maintained until 72 h post exposure, except for BPI/LBP which had maximum up-regulation at 24 h. The present observations have implications with respect to ¢sh welfare and assessment of the health status of the farmed ¢sh.

The immune response of juvenile Atlantic cod (Gadus morhua L.) to chronic exposure to produced water

“…Further, it has been suggested in mammals that cytokines such IL-1b play an important role during the response to a variety of physiological stressors (Leon, 2006;Michel et al, 2007). This has also been documented for fish, for example, in the common carp, 24 h restraining stress significantly up-regulated the expression of IL-1b in head kidney (Metz et al, 2006), and in Atlantic cod, overcrowding resulted in elevated IL-1b and IL-8 mRNA expression (Caipang et al, 2008). Hence, it is possible that the elevated IL-1b and IL-8 mRNA expression is the result of a mild stress response caused by the exposure to PW (200 ppm) as can be seen by the non-significant increase in cortisol values; stimulatory effects of stressors on the immune system have been observed before, leading to better immune response (Caipang et al, 2008).…”

Effects of stocking density and feed ration on growth and gene expression in the Senegalese sole (Solea senegalensis): Potential effects on the immune response

“…High stocking densities increase plasma cortisol levels in most fish [3,16,57,58]. The mRNA levels of HSP70, but not of HSP90, increase after a crowding stress [57,59]. However, expression of HSPs can be transient and modulated by certain hormonal factors.…”

Antimicrobial activity in the tissues of Atlantic cod (Gadus morhua L.)

“…Both kidney and blood contain numerous lymphoid cells, cells in circulation that are responsible for phagocytosis and production of antibodies, and other immunocompetent molecules [32]. In Atlantic cod, antibacterial agents are normally present in the serum of fish and their activity was found to decrease under overcrowding [40] and increase upon immunization with heat-killed V. anguillarum [41]. Bactericidal permeabilityincreasing protein and lipopolysaccharide-binding protein (BPI/LBP) has been cloned from leukocytes and whole blood [20].…”