The serial dilutions were used to determine PCR efficiencies, and any reaction with efficiency above 85% was
used for further analysis. Relative abundance of mRNA (cDNA) was determined at the exponential phase as the difference between the threshold cycle values measured between 14- and 4-d storage durations. Each gene was normalized using the average threshold cycle values of 3 housekeeping genes (hypoxanthine-guanine phosphoribosyltransferase, β-actin, and ubiquitin).