Developmental plasticity enables the appearance of long-term effects in offspring caused by exposure to environmental stressors during embryonic and foetal life. These long-term effects can be traced to pre- and post-implantation development, and in both cases, the effects are usually sex specific. During preimplantation development, male and female embryos exhibit an extensive transcriptional dimorphism mainly driven by incomplete X chromosome inactivation. These early developmental stages are crucial for the establishment of epigenetic marks that will be conserved throughout development, making it a particularly susceptible period for the appearance of long-term epigenetic-based phenotypes. Later in development, gonadal formation generates hormonal differences between the sexes, and male and female placentae exhibit different responses to environmental stressors. The maternal environment, including hormones and environmental insults during pregnancy, contributes to sex-specific placental development that controls genetic and epigenetic programming during foetal development, regulating sex-specific differences, including sex-specific epigenetic responses to environmental hazards, leading to long-term effects. This review summarizes several human and animal studies examining sex-specific responses to environmental stressors during both the periconception period (caused by differences in sex chromosome dosage) and placental development (caused by both sex chromosomes and hormones). The identification of relevant sex-dependent trajectories caused by sex chromosomes and/or sex hormones is essential to define diagnostic markers and prevention/intervention protocols.
Serafín Pérez-Cerezales, Priscila Ramos-Ibeas, Dimitrios Rizos, Pat Lonergan, Pablo Bermejo-Alvarez and Alfonso Gutiérrez-Adán
Lorraine Richardson, James P Hanrahan, Tharmala Tharmalingam, Stephen Carrington, Pat Lonergan, Alexander C O Evans and S. Fair
The aim of this study was to investigate the properties and to functionally characterise the cervical mucus that modulates sperm transport through the cervix by using ewe breeds with a divergent pregnancy rate (Belclare and Suffolk; high and low, respectively) following cervical insemination using frozen-thawed semen. Sperm number, as well as sialic acid and fucose content in both the channels and in the lumen of different regions of the cervix were quantified in inseminated Belclare and Suffolk ewes. Expression of glycosyltransferase and MUC genes, glycosidase activity and sialic acid speciation in follicular phase cervical tissue and mucus were assessed. More spermatozoa were found in the cervical channels in the region closest to the cervical os in Belclare than Suffolk ewes (P<0.05) and Suffolk ewes had a higher sialic acid content in the cervical channels than Belclare ewes (P<0.05) in all regions of cervix. Suffolk ewes had significantly higher expression of FUT1, ST6GAL1 and MUC5AC than Belclare ewes. There was no difference between the breeds in glycosidase activity (P>0.05). Levels of Neu5Ac were higher in Belclare than Suffolk ewes (P<0.05) and levels of Neu5Gc was higher in Suffolk than Belclare ewes (P<0.05). Competitive sperm penetration assays demonstrated that frozen-thawed sperm progression increased when cervical mucus was incubated with sialyllactose prior to a sperm penetration test (P<0.05). These results suggest that the difference between Belclare and Suffolk ewes in sperm transport with frozen-thawed semen is due to the higher concentration of sialic acid within channels, which binds to spermatozoa and reduces their ability to traverse the cervix.
Niamh Forde, Paul A McGettigan, Jai P Mehta, Lydia O'Hara, Solomon Mamo, Fuller W Bazer, Thomas E Spencer and Pat Lonergan
The aims of this study were i) to characterize the global changes in the composition of the uterine luminal fluid (ULF) from pregnant heifers during pregnancy recognition (day 16) using nano-LC MS/MS; ii) to describe quantitative changes in selected proteins in the ULF from days 10, 13, 16 and 19 by Isobaric tags for Relative and Absolute Quantification (iTRAQ) analysis; and iii) to determine whether these proteins are of endometrial or conceptus origin, by examining the expression profiles of the associated transcripts by RNA sequencing. On day 16, 1652 peptides were identified in the ULF by nano-LC MS/MS. Of the most abundant proteins present, iTRAQ analysis revealed that RPB4, TIMP2 and GC had the same expression pattern as IFNT, while the abundance of IDH1, CST6 and GDI2 decreased on either day 16 or 19. ALDOA, CO3, GSN, HSP90A1, SERPINA31 and VCN proteins decreased on day 13 compared with day 10 but subsequently increased on day 16 (P<0.05). Purine nucleoside phosphorylase (PNP) and HSPA8 decreased on day 13, increased on day 16 and decreased and increased on day 19 (P<0.05). The abundance of CATD, CO3, CST6, GDA, GELS, IDHC, PNPH and TIMP2 mRNAs was greater (P<0.001) in the endometrium than in the conceptus. By contrast, the abundance of ACTB, ALDOA, ALDR, CAP1, CATB, CATG, GD1B, HSP7C, HSP90A, RET4 and TERA was greater (P<0.05) in the conceptus than in the endometrium. In conclusion, significant changes in the protein content of the ULF occur during the pre-implantation period of pregnancy reflecting the morphological changes that occur in the conceptus.