The long-term objectives of this study are to define the roles of polypeptides secreted by the conceptus in embryo-maternal communication during the perimplantation period of pregnancy and to understand the underlying basis of the high rates of embryonic loss that occur around this time. The current proposal will focus largely on the involvement of embryo-derived interferons (IFN's) and other cytokines in triggering maternal responses to early sheep, cattle, pig and mouse embryos. The specific objectives are i) To determine the number of functional genes for the embryonic IFN'S, ovine trophoblast protein-1 (oTP-1) and the related bovine protein, bTP-1, by Southern blotting procedures with CDNA probes that will distinguish these IFN's from related IFN-alphas; ii) To map and sequence some of these genes and to define those regulatory regions that may be in common with other IFN-alphas Is and those that are uniquely associated with this embryonic class of IFN. A longer-term objective is to characterize transacting factors binding to these cis- control elements that are associated with oTP-1 and bTP-1 activation and repression in embryonic trophectoderm. iii) To produce large amounts of pure recombinant bTP-1 and oTP-1 in E. coli or cultured mammalian cells by recombinant DNA procedures. iv.) To test the physical, biochemical and biological properties of the recombinant proteins and, in particular, to assess their effects on a number of reproductive parameters, such as estrous cycle length, in sheep and cattle. v) To study how early bTP-1 or oTP-1 are inducible by double-stranded RNA in embryos and whether there are factors in uterine secretion that are responsible for the "natural" induction of these IFN's around the time of maternal recognition of pregnancy. Induction will be studied by in situ hybridization procedures, and the relatively large numbers of bovine embryos necessary for these studies will be prepared by in vitro procedures from slaughterhouse-derived ovaries. vi) To characterize the secretory proteins responsible for IFN-like activity in pig and mouse embryos. It is hypothesized that production of IFN's by early embryos is a widespread phenomenon of broad significance to mammalian fertility. vii) A final long-term objective is to screen existing ovine libraries for cDNA's representing other proteins secreted by embryos around Day 15 of development, to sequence these cDNA's and to infer the likely functions of the proteins they represent. It is anticipated that the proteins comprise additional bioactive components involved in conceptus-maternal signalling during early pregnancy.