Analysis of prion protein mRNA by in situ hybridization in brain and placenta of sheep

In this study, prion protein (PrP) mRNA was focally detected in brain and p lacenta of pregnant sheep by Northern blot analysis. In addition, host-enco ded cellular prion protein (PrPc) was observed in brain and placenta of the ruminant by Western blot analysis as well. Localization of PrP mRNA in pre gnant sheep tissues was rendered possible with in situ hybridization. In sh eep brain, PrP mRNA was predominantly localized within large neocortical ne urons in the cerebrum, Purkinje cells and neurons of the molecular and gran ule cell layers in the cerebellum, In the placenta, signals were observed i n the myometrium, including stratum longitudinale tunicae muscles and circu lar layers of muscular tunics. In the caruncle and placentome, signals were stronger by in situ hybridization. Since accumulation of the scrapie isofo rm PrP (PrPSc) is required to PrPc, these results suggest that brain and pl acenta of sheep may be important organs and sites for the conversion of PrP c to PrPSc. (C) 2000 Academic Press.