Onset of paternal gene activation in early mouse embryos fertilized with transgenic mouse sperm

Abstract

We investigated the onset of paternal gene expression in the early mouse embryo. We obtained transgenic mouse embryos by fertilizing BD (C57BL/6N x DBA) F1 hybrid female oocytes in vitro, with sperm from homozygous transgenic males carrying integrated chicken beta-actin promoter-driven firefly luciferase cDNA. We then examined the RNA and protein synthesis of the luciferase gene in embryos from the 1- to 2-cell stage. RNA transcripts of the luciferase gene were first detected in the 1-cell stage embryos as early as 13 hr postinsemination, just prior to elongation. By photon-count imaging, functional luciferase was identified at the 2-cell stage 23 hr postinsemination. These findings indicate that the paternal endogenous gene is already transcribed in the late 1-cell embryos, although paternally derived protein is not synthesized until the 2-cell stage. Therefore, these results suggest that the embryonic gene is activated as early as the late 1-cell stage.

A single, mild, transient scrotal heat stress causes DNA damage, subfertility and impairs formation of blastocysts in mice

“…In mice, reactivation of the paternal genome is thought to occur during early cleavage beginning around the one-cell stage (Matsumoto et al 1994) and therefore any mutations/deletions of DNA in the male genome could result in the disruption of regulatory networks in early embryos. The fact that the embryos resulting from heated males were able to undergo the first two cleavages as normal but fail after this point further suggests that the paternal genome is not involved in these cleavages but becomes more active after the 4-cell stage.…”

A rapid and non‐invasive selection of transgenic embryos before implantation using green fluorescent protein (GFP)

“…Reddy et al introduced the LacZ gene into embryonic stem cells and separated the transgenic cells by fluorescence-activated cell sorting [17]. Matsumoto et al used a firefly luciferase and detected enzyme activity at the 2-cell stage of mouse embryo without killing cells [18]. However, these methods need the step of loading the substrate inside the cells and the toxicity of the substrates is well known.…”

Expression and Subcellular Localization of GSE Protein in Germ Cells and Preimplantation Embryos

“…The procedures for in vitro fertilization were essentially those reported by Matsumoto et al [17]. In brief, spermatozoa were collected from the cauda epididymis of a male mouse as described above and incubated in 0.4 ml drops of TYH medium (Mitsubishi Kagaku Iatron, Tokyo, Japan) under liquid paraffin.…”