Lack of expression of alpha or omega interferons by the horse conceptus.

Horse conceptuses were collected on Days 13, 15, 20 and 25 after ovulation. Whole conceptuses (Days 13 and 15) or extra-embryonic membranes (Days 20 and 25) were homogenized and poly-adenylated RNA (poly A RNA) was isolated by binding to oligo (dT)-cellulose. Poly A RNA (1 microgram/well) was separated by size on a denaturing 1% agarose gel and blotted onto nitrocellulose filters (northern blotting). DNA probes were prepared from plasmids containing equine alpha 1, omega 1 and omega 2 interferons and human beta actin. The presence of messenger RNA (mRNA) was detected by specific hybridization of 32P-cDNA probes labelled by random priming. After hybridization at 37 degrees C, filters were washed at room temperature and 56 degrees C, and bands of 32P-cDNA:mRNA heteroduplexes were identified by autoradiography on Kodak XAR-5 radiographic film. The presence of bands on autoradiographs of Southern blots of horse DNA indicated that hybridization and probe conditions were adequate to support hybridization. The actin probe hybridized to all mRNA tested on northern blots, indicating that the mRNA was of high aquality. No hybridization was seen on northern blots using any of the interferon probes. These results indicate that poly A RNA with a high degree of homology to alpha or omega interferons does not accumulate in the horse conceptus.