Disease related tissue damage and subsequent changes in fillet structure

Fish meat quality is influenced by many biological and physical factors like e.g. rearing, feeding, slaughtering, processing and storage. Observations from practical fish farming indicate that infections in e.g. salmon caused by Moritella viscosus or Pancreas Disease (PD) results in downgrading of the fish and subsequent a reduction in price.

Despite this, the impact of infectious diseases on the meat quality and the mechanisms behind are poorly investigated. Wound repair is a dynamic, interactive response to tissue injury that involves a complex interaction and cross talk of various cell types, extracellular matrix molecules, soluble mediators and cytokines.

In order to describe the molecular mechanisms and processes of wound repair, a panel of genes covering immunological factors and tissue regeneration were used to measure changes at the mRNA level following mechanical tissue damage in rainbow trout (Oncorhynchus mykiss). Needle disrupted muscle tissue was sampled at different time points and subject to real-time RT-PCR for measuring the expression of the genes IL-1β, IL-8, IL-10, TGF-β, Myostatin-1ab, MMP-2, CTGF, Collagen-1α, VEGF, iNOS, Arg-2 and FGF.

The results showed an initial phase with up-regulation of immune-related genes followed by a regenerative phase with regulation of genes coding for muscle growth and synthesis of connective tissue.