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JM Garbayo1 , JA Green1 , JF Beckers2 *, RM Roberts1 *
Dept of Animal Sciences, Univ of Missouri, Columbia, Missouri 1
Dept of Animal Reproduction, Faculty of Veterinary, Univ of Liege, Liege, Belgium 2
PAGs are related to aspartic proteinases and belong to a rapidly evolving gene family expressed in the placenta of Artiodactyla. In cattle and sheep there may be over 100 genes, many of them expressed. The aim of this study was to clone different PAGs from the goat, study their expression over gestation and determine their phylogenetic relationship to PAG from related species. A general PAG 5' primer and PAG-specific 3' primers were used to generate cDNA by RT-PCR from placental RNA at d45, 65 and 87 of pregnancy. Those cDNA that differed by at least 5% from other PAGs were fully sequenced. Eleven clearly distinct caPAGs were identified (caPAG1 to caPAG11). They can be classified into three groups in terms of sequence identity and phylogenetic distance. Nine of the cDNAs (caPAG1, caPAG3-7, caPAG9-11) had greater than 80% nucleotide and 70% aminoacid (aa) identity with bovine (bo) PAG1. Some of them have conserved sequences around the active site, whereas others possess mutations that probably inactivate them. Two other PAG groups were also apparent. CaPAG2 and caPAG8 each possess only 60% aa identity with each other and with other PAG members. Both may be active proteinases. Northern blotting of placental RNA from days 18, 19, 24, 25, 30, 45, 65, 87 and 115 with probes specific for different transcripts showed that caPAG8 was expressed uniformly throughout pregnancy, while caPAG2 was only detectable at days 18 and 19. In contrast, the members of the boPAG1 group were only expressed strongly from d45 onwards. Transcript concentrations remained constant or declined as pregnancy progressed. These data confirm that many different PAG genes are expressed in goat placenta and their expression varies considerably during placental development. Supported by USDA grant 960-1842.
This abstract is being presented on Tuesday, August 3 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.