Regassa et al. BMC Genomics 2011, 12:57 http://www.biomedcentral.com/1471-2164/12/57 Page 13 of 20 Figure 19 qRT-PCR validation of the array data showing some selected transcripts that are differentially expressed between GV and MII CCs. Two bars representing the same gene and marked with star (*) between them are significantly different (P < 0.05). CCIM = immature or GV stage CCs and CCMII = cultured or metaphase II CCs. rearrangement, protein-protein interactions, protein sta- bility, cell movement, and apoptosis. These processes in turn depend on the highly regulated and opposing actions of protein kinases (PKs) and phosphatases (PPs) where the balance between the two plays an important role in the control of oocyte meiotic resumption [66]. Consistent with this notion, we found oocyte specific expression of many of the members of trans-membrane proteins (TMEM30B, TMEM163, TMEM32, TMEM 120B and TMEM52) and Rho GTPase activating pro- teins (ARHGAP10, 17, 18, 22, 24, 26, 27, 28), various members of the mitogene activated protein kinases (MAP4K2, MAPK10, MAPK8IP2), and phosphatases (PPP1R1B, PPP2R2B, PPP3R1, PPP1R3D) that may evi- dence the roles of these genes in meiotic maturation. Like wise, some of the transcripts that were highly expressed in CCs relative to oocyte include IFIT5, BMP2, FSHr, GSTA1, FST, PTGR1, hormonal receptors and hormones such as INHA, INHBA, PGR and PGRMC2. The oocyte and CC genes expression study has revealed that the receptor of BMP2, also a receptor for GDF9, is expressed only in CCs [42]. Similar studies have shown the expression of BMP2 receptor in bovine antral follicles and its potential role in the development and functioning of ovarian follicles [21]. In support of these claims, we also detected this gene only in CCs suggesting its higher activity in CCs than in oocyte. GSTA1 is highly expressed in steroidogenically active cells of bovine ovarian follicle and suggested to inter- vene in folliculogenesis and oocyte maturation [67] and steroid receptor cells are found only in CCs evidencing the involvement of CCs derived GSTA1 in oocyte maturation. On the other hand, higher expression of Figure 20 Validation of the microarray data by semi quantitative RT-PCR. A 2% agarose gel electrophoresis depicting the mRNA expression of genes that are exclusively expressed either in oocytes or CCs. Number 1 shows a negative control (dd water as a template) and 2, 3, 4 and 5 show the abundance levels of each transcript in MII CCs, MII oocytes, GV CCs and GV oocytes, respectively. 18S was used as a loading control for total RNA. FST and INHBA has been reported in cumulus oophorus that were obtained from in vivo produced COCs compared to these produced in vitro [68]. In order to validate the microarray data, specifically for those transcripts exclusively expressed in oocyte or CCs, we analyzed the expression of some selected genes using semi-quantitative PCR. A 2% agarose gel pictures showing transcripts that are specific to oocyte or CCs