Parvalbumin mRNA in raw and processed fillet of rainbow trout Oncorhynchus mykiss: Determination of copy number and stability against heat and acid

Quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) has been developed for determination of short sequences (∼120 nucleotides) of parvalbumin mRNA. The assay consisted of two steps. At first mRNA was transcribed to cDNA using primers specific for parvalbumin RNA. In the second step cDNA was quantified by real‐time PCR with the LightCycler FastStart DNA Master SYBR Green I (Roche Applied Science, Mannheim, Germany). High copy numbers of mRNA, up to 109/g wet weight, have been measured in fillets of rainbow trout. Degradation of mRNA was not observed in cases of cooked, hot‐smoked or acidified fish muscle, but storage of minced and washed raw muscle led to some reduction of copy numbers.