Expression of the trophoblast interferon, bovine trophoblast protein-1 (bTP-1), has been studied in embryos produced by in vitro maturation-in vitro fertilization (IVM-IVF). No bTP-1 production was noted until after embryos had reached the expanded blastocyst stage and had begun to hatch (Days 8-9 post-fertilization). Single blastocysts comprising 115 +/- 22 cells released 1.0 +/- 0.1 units of interferon activity/24 h. Amplification of conceptus mRNA by reverse transcription-polymerase chain reaction procedure with bTP-1-specific oligonucleotides confirmed that bTP-1 transcripts were present in blastocysts but were not detectable at earlier stages. Although cultured blastocysts produced by IVM-IVF procedures continued to secrete bTP-1 for a few days, they failed to attach to the substratum and form outgrowths, and soon lost structural integrity. However, when Day 8 blastocysts/morulae were transferred to the uteri of synchronized cows, recovered 4 days later, and placed into individual cultures, they attached and formed outgrowths that produced large amounts of bTP-1 (greater than 2000 units/culture/24 h after 14 days). Embryos thus first expressed bTP-1 when a functional trophectoderm was first formed, and induction did not require a period of in vivo development. However, continued viability of the blastocyst and bTP-1 production were not sustained in vitro and may require some exposure to the uterine environment.

The trophoblastic interferons ovine and bovine trophoblast protein-1 (oTP-1 and bTP-1, respectively) have been implicated as mediators of maternal recognition of pregnancy in sheep and cattle. The objective of this study was to describe the onset and duration of gene expression for oTP-1 and bTP-1 in preimplantation ovine and bovine conceptuses by in situ hybridization and Northern analysis. Sections from paraffin-embedded ovine conceptuses, collected on Days 10, 11, 12, 13, and 15 of gestation (n = 1, 3, 3, 2, 2), and bovine conceptuses, collected on Days 12/13, 15/16, and 19 (n = 2, 4, 5), were hybridized to specific [35S]-labeled cDNA probes. Two different probes, one encompassing bases 442-918 and representing both coding and 3'-untranslated regions, and a second 3'-specific probe (bases 650-912) were used to detect oTP-1 mRNA. At all stages examined, oTP-1 mRNA was confined to trophectoderm of ovine conceptuses. Consistent with earlier studies, expression increased markedly at Day 13. oTP-1 mRNA was detected at low levels in seven of seven ovine conceptuses prior to Day 13 when the longer probe was employed. With the 3'-specific probe, however, oTP-1 mRNA was detected in only one of the seven ovine conceptuses prior to Day 13. Thus, although low amounts of oTP-1 mRNA may be present in ovine conceptuses prior to Day 13, massive induction of this mRNA occurs on Day 13 coincident with the initiation of maternal recognition of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

The physiological role of cumulus cells (CC) surrounding oocytes is particularly important for normal cytoplasmic maturation of oocytes. However, removal of CC from oocytes is inevitable for some embryo manipulation techniques, such as germinal vesicle (GV) transfer, somatic cell haploidization, and oocyte cryopreservation. The present study was designed to determine an optimal method to culture porcine denuded oocytes (DO). The results indicated CC from cumulus-oocyte complexes at the GV stage (GVCC) or at the metaphase II stage, and mural granulosa cells could not improve the maturation of DO. However, GVCC could enhance the development of matured porcine DO after fertilization; the percentage of blastocysts was increased from 1.1 to 17.2% (P < 0.05), and the relative value of the x-axis and y-axis of spindles was also increased (P < 0.05). Coculture with GVCC had no effect on the distribution of mitochondria and cortical granules. The results contribute to our understanding of the mechanisms by which CC promote oocyte maturation and contribute to optimization of protocols for in vitro maturation of DO.

The bovine oviductal epithelium synthesizes and secretes a class of oviduct-specific glycoproteins that is present in the luminal fluid when fertilization and early embryonic development occur. The objective of this study was to determine if these characterized glycoproteins become associated with oviductal embryos. Ovarian ova and oviductal embryos were recovered from super-ovulated cows at 72 h after onset of estrus. Eggs were fixed in 3% paraformaldehyde-1% glutaraldehyde and subsequently embedded in Lowicryl K4M. Sections (1 micron) were processed for peroxidase-antiperoxidase immunocytochemistry. Immunolabeling was not detected in any region of ovarian ova. Oviductal embryos, regardless of cleavage stage, exhibited immunoperoxidase staining localized within their zona pellucidae. Sections (100 nm) obtained from a 4- and an 8-cell embryo were also subjected to colloidal gold immunoelectron microscopy to determine conclusively the subcellular distribution of the oviduct-specific glycoproteins. Gold particles were distributed uniformly throughout the width of the zona pellucida. Also, immunoreactivity was observed associated with flocculent material in the perivitelline space and with the vitelline membrane. These results indicate that the bovine oviduct-specific secretory glycoproteins become associated with oviductal embryos. This association may be biologically important to the developing embryo.

Ovine trophoblast protein-1 (oTP-1) is an interferon (IFN) related to the IFN-omega. The objectives of this research were: (i) to attempt to induce oTP-1 mRNA in day-11 ovine conceptuses with polyinosinic-polycytidylic acid (poly(I).poly(C], and (ii) to determine if IFN-omega mRNA is also produced on day 11 of gestation. In experiment I, conceptuses were cultured in presence of 100 micrograms/ml poly(I).poly(C) (n = 5) or medium alone (control, n = 3) for up to 8 h. In situ hybridization was used to assess effects of treatment on mRNA concentrations for oTP-1 and actin (positive hybridization control). Poly(I).poly(C) increased oTP-1 mRNA concentrations approximately 2.5-fold (p less than 0.01), but had no effect on actin mRNA. In experiment II, the presence of mRNA for oTP-1 and ovine IFN-omega was determined by using reverse transcription-polymerase chain reaction (RT-PCR) analysis of conceptus total RNA coupled with Southern blot hybridization of the PCR reaction products with specific cDNA probes. oTP-1 mRNA was detectable in all poly(I).poly(C)-treated (n = 7) and control (n = 6) conceptuses, whereas IFN-omega mRNA was detected in only three of seven poly(I).poly(C)-treated conceptuses and not in any controls. Together these results demonstrate that expression of oTP-1 mRNA can be enhanced by treatment with poly(I).poly(C) and that oTP-1 is the primary but not the only type I-IFN inducible in conceptuses on day 11 of gestation.