Analysis of ZP1 gene reveals differences in zona pellucida composition in carnivores.

The zona pellucida (ZP) is an extracellular envelope that surrounds mammalian oocytes. This coat participates in the interaction between gametes, induction of the acrosome reaction, block of polyspermy and protection of the oviductal embryo. Previous studies suggested that carnivore ZP was formed by three glycoproteins (ZP2, ZP3 and ZP4), with ZP1 being a pseudogene. However, a recent study in the cat found that all four proteins were expressed. In the present study, in silico and molecular analyses were performed in several carnivores to clarify the ZP composition in this order of mammals. The in silico analysis demonstrated the presence of the ZP1 gene in five carnivores: cheetah, panda, polar bear, tiger and walrus, whereas in the Antarctic fur seal and the Weddell seal there was evidence of pseudogenisation. Molecular analysis showed the presence of four ZP transcripts in ferret ovaries (ZP1, ZP2, ZP3 and ZP4) and three in fox ovaries (ZP2, ZP3 and ZP4). Analysis of the fox ZP1 gene showed the presence of a stop codon. The results strongly suggest that all four ZP genes are expressed in most carnivores, whereas ZP1 pseudogenisation seems to have independently affected three families (Canidae, Otariidae and Phocidae) of the carnivore tree.

Differential gene expression in porcine oviduct during the oestrous cycle.

The oviduct undergoes changes under the influence of steroid hormones during the oestrous cycle. However, the molecular mechanisms underlying oviductal regulation are not fully understood. The aim of the present study was to identify the gene expression profile of the porcine oviduct in different stages of the cycle using microarray technology. A systematic study was performed on animals at four different stage: prepubertal gilts, and sows in the preovulatory, postovulatory and luteal phase of the oestrous cycle. The porcine oviduct expressed a total of 4929 genes. Moreover, significant differences in the expression of several genes were detected as the oestrous cycle progressed. Analysis of the differentially expressed genes indicated that a total of 86, 89 and 15 genes were upregulated in prepubertal gilts, preovulatory and luteal sows respectively compared with levels observed in postovulatory sows. Moreover, 80, 51 and 64 genes were downregulated in prepubertal, preovulatory and luteal animals respectively compared with the postovulatory sows. The concentrations of 10 selected transcripts were quantified by real-time reverse transcription-polymerase chain reaction to validate the cDNA array hybridisation data. Conversely, for some genes, localisation of corresponding protein expression in the oviduct was analysed by immunohistochemistry (i.e. cholecystokinin, glutathione peroxidase 2, mucin 1, phosphatidylethanolamine binding protein 4 and tachykinin 3) and mass spectrometry analysis of oviductal fluid allowed identification of peptides from all five proteins. The results of the present study demonstrate that gene expression in the porcine oviduct is clearly regulated during the oestrous cycle, with some oviductal proteins that could be related to several reproductive processes described here for the first time.

Expression of the vascular endothelial growth factor system (VEGF) in the porcine oviduct during the estrous cycle.

The expression and localization of VEGFA and its main receptors Flt-1 and KDR is characterized in the oviduct throughout the porcine estrous cycle. Oviducts were sampled from sows at early follicular, late follicular, early luteal and late luteal stages of the estrous cycle and a segment from the mid portion of the ampulla and isthmus studied by real time RT-PCR and quantitative immunohistochemistry. The expression of the three components of the VEGF system was continuous, although differences were observed depending on the oviduct portion, the stage of the estrous cycle and the histological layer. VEGFA and KDR mRNA expressions were higher in ampulla, while Flt-1 mRNA was higher in isthmus. VEGFA protein was also higher in ampulla but Flt-1 and KDR did not show regional differences between ampulla and isthmus. While the mRNA expression of VEGFA, Flt-1 and KDR increased progressively during the luteal period, the amount of VEGFA and Flt-1 protein decreased in the same period (in isthmus only). Contrastinly, KDR protein peaked in ampulla and isthmus just before ovulation. The VEGF system was majorly located in both the secretory and ciliated cells of the oviduct epithelium, but also in the endothelium and fibroblasts of the lamina propia and the muscle fibres and vessels of the tunica muscularis. Our results are consistent with a participation of VEFG in the regulation of the dynamics of oviductal fluid secretion and the oviduct contractibility.