Novel pathways for implantation and establishment and maintenance of pregnancy in mammals

Abstract

Uterine receptivity to implantation varies among species, and involves changes in expression of genes that are coordinate with attachment of trophectoderm to uterine lumenal and superficial glandular epithelia, modification of phenotype of uterine stromal cells, silencing of receptors for progesterone and estrogen, suppression of genes for immune recognition, alterations in membrane permeability to enhance conceptus-maternal exchange of factors, angiogenesis and vasculogenesis, increased vascularity of the endometrium, activation of genes for transport of nutrients into the uterine lumen, and enhanced signaling for pregnancy recognition. Differential expression of genes by uterine epithelial and stromal cells in response to progesterone, glucocorticoids, prostaglandins and interferons may influence uterine receptivity to implantation in mammals. Uterine receptivity to implantation is progesterone-dependent; however, implantation is preceded by loss of expression of receptors for progesterone (PGR) so that progesterone most likely acts via PGR-positive stromal cells throughout pregnancy. Endogenous retroviruses expressed by the uterus and/or blastocyst also affect implantation and placentation in various species. Understanding the roles of the variety of hormones, growth factors and endogenous retroviral proteins in uterine receptivity for implantation is essential to enhancing reproductive health and fertility in humans and domestic animals.

Dimethylated H3K27 Is a Repressive Epigenetic Histone Mark in the Protist Entamoeba histolytica and Is Significantly Enriched in Genes Silenced via the RNAi Pathway

“…blocked antibody), 1 g of unblocked antibody, or preimmune serum with the peptides blotted on the membranes overnight then proceeded with the Western blot protocol. To test antibody specificity against E. histolytica histone H3, as in the peptide competition assays described above, we blocked the antibody with different peptide amounts (2,4,10,20,50, and 100 g). Blocked or unblocked antibodies or preimmune serum were used to probe increasing amounts of whole cell lysates (10,20,40, and 80 g).…”

Evaluation of treatments with hCG and carprofen at embryo transfer in a demi-embryo and recipient virgin heifer model

“…Embryonic survival is dependent on the timely elongation and secretion of interferon tau by the blastocyst, in order to inhibit the luteolytic signal, features that are regulated by maternal concentrations of P 4 (Garrett et al, 1988;Kerbler et al, 1997; -E-mail: lcosta@fmv.utl.pt 1317 Mann and Lamming, 2001). This regulation by P 4 is apparently indirect (Clemente et al, 2009) through the modulation of the luteolytic signal (Mann et al, 1998) and the composition of the histotroph (Lonergan, 2011) and, probably by other embryo-maternal signaling pathways yet poorly understood or unknown (Bazer et al, 2010).…”

Effects of Equine Chorionic Gonadotropin on Follicular, Luteal and Conceptus Development of Non-LactatingBos IndicusBeef Cows Subjected to a Progesterone Plus Estradiol-Based Timed Artificial Insemination Protocol

“…In high-producing dairy cows, the major part of these gestation losses occurs before D16 of the conception (43% of the total mortality) (Diskin et al, 2012;Dune et al, 2000). It is well recognised that P4 has a pivotal function in establishing gestation and adequate embryonic development (Mann and Lamming, 2001;Spencer, 2004;Bazer et al, 2009). Several studies have described the positive effect of exogenous P4 supplementation on embryo growth, survival and pregnancy establishment (Larson et al, 2007;Lonergan et al, 2007;Carter et al, 2008;Beltman et al, 2009;Lonergan, 2011).…”