Expression of Bovine Trophoblast Interferon in Conceptuses Derived by in Vitro Techniques1

Abstract

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.

Differences in developmental competence and gene expression profiles between buffalo (Bubalus bubalis) preimplantation embryos cultured in three different embryo culture media

“…Studies have detected IFNT mRNA in blastocysts but not in morula (Hernandez-Ledezma et al 1992Wrenzycki et al 1999), suggestive that the beginning of IFNT production is closely correlated to blastocoel formation. In our study, hatched blastocysts produced in the defined medium lacking serum produced increased (P \ 0.05) IFNT supporting the notion that mRNA levels for this transcript are higher in good quality embryos.…”

Sexual dimorphism among bovine embryos in their ability to make the transition to expanded blastocyst and in the expression of the signaling molecule IFN-τ

“…Bovine embryos were generated from oocytes aspirated from slaughterhouse-derived ovaries and matured for 24 h. Procedures for oocyte recovery and conditions for in vitro maturation and in vitro fertilization of oocytes have been described in detail (35,36,38,39). The semen used throughout was a mixed pool from six different sires (Select Sires, Plains City, OH).…”

“…The IFN-content of the medium was measured by a cytopathic reduction assay in Madin-Darby bovine kidney (MDBK) cells challenged by vesicular stomatitis virus (35,36). The culture medium was assayed in a series of increasing 3-fold dilutions.…”

“…The primary agent responsible for maternal recognition of pregnancy in the pecoran ruminants, such as cattle, sheep, and deer, is a type I IFN, known as IFN- (32,33), which has shown some indications of dimorphic expression in red deer embryos recovered from culled hinds (29). In cattle, embryos begin to express IFN-as the blastocyst forms, although there is consid-erable variability between embryos in the amounts they produce (35)(36)(37). Here we have sought to determine whether there are gender differences in IFN-production among bovine embryos and whether culture conditions that can induce a bias in sex ratios at the EB stage simultaneously produce associated changes in IFN-expression.…”

Several fibroblast growth factors are expressed during pre-attachment bovine conceptus development and regulate interferon-tau expression from trophectoderm

“…Bovine embryo production of IFNT begins at the late morula and early blastocyst stage as the trophoblast cell lineage first develops (day 6-7 of pregnancy; Hernandez- Ledezma et al 1992, Kubisch et al 1998. In cattle, IFNT mRNA levels peak around days 14-16 of pregnancy and remain elevated until implantation occurs around days 19-21 of pregnancy (Ealy et al 2001, Robinson et al 2006.…”