Sexually dimorphic gene expression in bovine conceptuses at the initiation of implantation is not reflected in the changes in the endometrial transcriptome.

ABSTRACT: In cattle, maternal recognition of pregnancy occurs on Day 16 via secretion of interferon tau (IFNT) by the conceptus. The endometrium can distinguish between embryos with different developmental competencies. In eutherian mammals, X-chromosome inactivation (XCI) is required to ensure an equal transcriptional level of most X-linked genes for both male and female embryos in adult tissues, but this process is markedly different in cattle than mice. We examined how sexual dimorphism affected conceptus gene expression and amino acid composition as well as the endometrial transcriptome during the peri-implantation period of pregnancy. Of the 5132 genes were differently expressed on Day 19 in male compared to female conceptuses, 2.7% were located on the X-chromosome. Concentrations of specific amino acids were higher in the uterine luminal fluid with male compared to female conceptuses, while female conceptuses had higher expression of specific amino acid transporters (SLC6A19 and SLC1A35). Of note, the endometrial transcriptome was not different in cattle gestating a male or a female conceptus. These data support the hypothesis that, far from being a blastocyst specific phenomenon, XCI is incomplete before and during implantation in cattle. Despite differences in gene expression and amino acid utilization in male versus female conceptuses, the sex of the conceptus itself does not elicit a different response in the endometrium. Following a synchronized estrous cycle, all heifers observed in standing estrus (=Day 0, n=30) were inseminated with semen from a proven sire. All samples were recovered at slaughter on Day 19 following estrus corresponding to the initiation of implantation in cattle, flushed with 10 ml of PBS and the presence of a conceptus was observed under a stereo-microscope (n=24). Each conceptus was dissected into 4 pieces, 3 containing only trophectoderm cells and one containing the embryonic disc along with associated trophectoderm cells, and immediately snap-frozen in liquid nitrogen along with the corresponding intercaruncular endometrium from the uterine horn ipsilateral to the corpus luteum. DNA was extracted from each conceptus with phenol/chloroform treatment and finally re-suspended in 200 μL of milliQ water. Two microliters of each sample were used to perform embryo sexing by PCR amplification of sex-specific polymorphic fragments in the amelogenin gene. N=5 samples of intercaruncular endometirum and the corresponding trophectoderm only sample were anaylsed for gene expression.

ORGANISM(S): Bos taurus

SUBMITTER: Peadar O'Gaora 

PROVIDER: E-GEOD-75754 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress