An evaluation of potential reference genes for stability of expression in two salmonid cell lines after infection with either Piscirickettsia salmonis or IPNV

Peña, Andrea A; Bols, Niels C; Marshall, Sergio H

In order to show how transcription profile of the least stable genes can be affected during each experimental setting, their relative transcription levels were determined using the normalization factor calculated from the geometric mean of the three most stable housekeeping genes ( Figure 5 ). In agreement with several other studies on teleosts, GAPDH was one of the least stable genes in our panel [13, 15, 28] . In mammals GAPDH was shown to be influenced by a large number of Figure 5 Normalized GAPDH, TUBA and EF1A gene expression. Relative mRNA levels for GAPDH (grey bars), TUBA (dark grey bars) and EF1A (white bars) at times after the addition of either P. salmonis (A) or IPNV (B). Gene expression was normalized by the geometric mean of the three most stable housekeeping genes determined by geNorm in each assay. The 2d and the 6 h controls were used as calibrators (value = 1) in the (A) P. salmonis and in the (B) IPNV assays, respectively. Bars represent the mean values (± SE) for samples from three biological replicates. The asterisk (*) denotes significant differences from calibrators (P < 0.05; Mann-Whitney test).