Effects of postmortem storage temperature on sea bass (Dicentrarchus labrax) muscle protein degradation: analysis by microfluidic capillary electrophoresis and Real-time PCR.

One of the most unique characteristics of fish as food is that it is highly perishable. Consequently, freshness is fundamental to the quality of fish, and the time that has passed after catching it and the temperature “history” of fish are very often the key factors in determining the ultimate quality characteristics of such products Delbarre-Ladrat et al. (2006). Previous studies on fish have investigated postmortem phenomena using chemical, physical, histological, and microbiological methods. Only few studies have included a molecular investigation Seear and Sweeney, (2008). Consequently, we were interested in performing a RNA stability time course study on the marine teleost sea bass (Dicentrarchus labrax). The objective of our experiment was to show that RNA degradation in postmortem samples can be measured quantitatively and might be used as an indicator of the postmortem interval. We therefore first investigated by microfluidic capillary electrophoresis the integrity of total RNA extracted from dorsal white muscle of sea bass slaughtered with three different techniques and stored for 5 days postmortem at two different temperatures (1°C and 18°C). Subsequently, the presence and integrity of two specific mRNA transcripts encoded by the sea bass μ-calpain and cathepsin L genes were determined by real-time RT-PCR analyses after isolating the respective cDNA sequences by molecular cloning and sequencing techniques.