Skip to main content
. 2014 Mar 27;9(3):e93287. doi: 10.1371/journal.pone.0093287

Figure 5. Effect of reference gene selection on expression values of non-reference target genes in immature oocytes from Holstein cattle.

Figure 5

Oocytes were retrieved from heifers (H; n = 17 and 15 oocytes, respectively), high-producing cows in peak lactation (PL; n = 16 and 18 oocytes, respectively), and repeat-breeder cows (RB; n = 17 and 17 oocytes, respectively) during winter (W) and summer (S). The amounts of HSP90AA1 (A–E) transcripts are expressed in relation to H during winter because this was considered as a reference group (see Material and methods for more information). Expression values were normalized either by YWHAZ (A), RPL15 (B), TPB (C), geometric mean of RPL15, PPIA and GUSB (D) or not normalized (E). P values for animal category, season and animal category*season are denoted in the insets above each graphic. Different letters over bars denote a significant difference among categories within season (P<0.05). *Difference between seasons within category (P<0.05).