Effects of administering exogenous bovine somatotropin to beef heifers during the first trimester on conceptus development as well as steroid and eicosanoid metabolizing enzymes

ABSTRACT The aim of this study was to evaluate the effect of bovine somatotropin (bST) on fetal and placental development during the first third of gestation in beef heifers. Angus heifers (n = 97) were randomly assigned to either receive a 500 mg injection of bST (BST) biweekly on d 0, 15, 29, 43, and 57 of gestation, or not receive bST (CTL) throughout the experiment. Body weight (BW) was assessed on d -9, -3, 0, 15, 22, 29, 43, 50, 57, 64, and 77, while blood samples were collected on d 0, 22, 50, and 64. Pregnancy status was determined via transrectal ultrasonography on d 29 and 64. A subset of pregnant heifers (BST, n = 7; CTL, n = 5) were harvested on d 84 and complete gravid reproductive tracts and liver tissue were collected for analysis. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A), and uridine 5’-diphospho-glucuronosyltransferase (UGT) activities were determined. Mean change in BW and average daily gain of heifers between fixed-time artificial insemination (d 0) and d 77 did not differ between treatments (P ≥ 0.05). Mean concentrations of insulin-like growth factor 1 (IGF-1) were greater (P < 0.001) in BST (347 ± 27.7 ng/mL) compared to CTL (135 ± 32.8 ng/mL) heifers. Mean placental weight, fetal membrane weight, uterine weight, ovarian and corpus luteum (CL) weights, as well as fetal morphometric data did not differ (P ≥ 0.05) between treatments. However, BST heifers had greater (P = 0.03) quantities of combined fetal fluid compared to CTL (521.6 ± 22.9 g vs. 429.6 ± 27.14 g, respectively). Tendencies were observed for BST heifers to have reproductive tracts with fewer placentomes (P = 0.08) and fetuses with greater umbilical diameters (P = 0.09) compared to CTL. Activity of CYP1A did not differ (P ≥ 0.05) within maternal and fetal liver, caruncle, cotyledon, or CL tissue samples between treatments. Furthermore, CYP3A activity was only observed in maternal liver samples and was not different between treatments (P ≥ 0.05). Interestingly, CYP2C activity was greater (P = 0.01) in the liver of BST vs. CTL heifers, and UGT activity was greater (P = 0.02) in the CL from BST heifers compared to CTL. In conclusion, administration of bST during the first third of gestation increased plasma concentrations of IGF-1, which resulted in an increase in fetal fluid, decrease in placentome number, and greater umbilical diameter, but failed to alter fetal development.

Fetal-fluid proteome analyses in late-term healthy pregnant mares and in mares with experimentally induced ascending placentitis

Characterisation of fetal fluids in healthy and disease states of pregnant mares can help to unravel the pathophysiology and to identify putative markers of disease. Thus, this study aimed to compare the protein composition of: (1) amniotic and allantoic fluids of healthy mares obtained immediately after euthanasia and (2) allantoic fluid harvested via centesis before and after experimental induction of placentitis via transcervical inoculation of Streptococcus equi ssp zooepidemicus in healthy mares. Fetal fluids were analysed with a high-throughput proteomic technique after in-gel digestion. Statistical comparisons were performed following normalisation of peptide spectral match. Global normalisation was performed to calculate relative expression. There were 112 unique proteins present in both allantoic and amniotic fluids. There were 13 and 29 proteins defined as amniotic- or allantoic-specific respectively that were present in at least two fluid samples. Another 26 proteins were present in both amniotic and allantoic fluids. Panther DB functional classification grouped fetal-fluid proteins as transfer carriers, signalling molecules, receptors, immunity, hydrolase, enzymes, membrane traffic, cytoskeleton, cell adhesion, calcium binding and extracellular matrix. Experimentally induced placentitis resulted in 10 proteins being upregulated and 10 downregulated in allantoic fluid. Newly identified proteins and changes in the fetal-fluid proteome provide clues about the physiology of pregnancy and pathogenesis of placentitis.

Gestational Age-Dependent Fetal Fluid Dynamics in the Ovine Developmental Model: Establishment of Surrogate Markers for the Differentiation of Stem Cell Origin

The ovine developmental model represents the standard in vivo model for studies involving maternofetal physiology, amniotic fluid (AF) research, and fetal cell therapy prior to human clinical use. Although being close to the human fetal anatomy, 2 separate extraembryonic fluid compartments remain during gestation, known as the amnion and the allantois. A clear distinction between AF versus allantoic fluid (AL) is therefore indispensable for correct scientific conclusions with regard to human translation. In the presented study, the biochemical composition of AF and AL was evaluated in ovine gravid uteri postmortem (n = 31) over the entire gestation. Four parameters, consisting of Na+, Cl–, Mg2+, and total protein, have been found to allow for specific discrimination of the 2 fetal fluids at all gestational phases and therefore as potential surrogate parameters for gestational age. In addition, volumetric changes of the developing fetus and the 2 fetal fluid cavities were analyzed by contrast-enhanced computed tomography (n = 12). AF showed a significant, linear volumetric increase over gestation, whereas AL volume maintained relatively static independent of gestational age. These results serve as a basis for future studies by providing surrogate markers enabling a reliable distinction of isolated fetal fluids and contained cells in the ovine developmental model over the entire gestation.

97 MAGNITUDE AND SPECIFICITY OF EFFECTS OF MATERNAL AND PATERNAL GENOMES ON THE FETO-PLACENTAL UNIT

The placenta, a major determinant of fetal growth in eutherians, facilitates maternal-fetal cross talk and mediates programming of postnatal phenotype via genetic and epigenetic mechanisms. However, magnitude and specificity of effects of maternal and paternal genomes on placental and fetal phenotype and their relationships are unclear. Using an outbred bovine intra-species model with well-defined Bos taurus taurus and Bos taurus indicus maternal and paternal genetics, we generated purebred and reciprocal cross fetuses (Animal Ethics No. S-094-2005) to dissect and quantify effects of parental genomes, fetal sex, and nongenetic maternal effects (maternal weight and post-conception maternal weight gain) on 41 gross and histomorphological feto-placental parameters. Analysis of data from 73 fetuses recovered at midgestation (Day 153) with general linear models (Xiang et al. 2014 JBMR http://dx.doi.org/10.1002/jbmr.2263) using the GLM procedure of R version 22.14 (R Development Core Team, Vienna, Austria) revealed that maternal and paternal genome combined explained the highest proportion of variation (47.2–99.5%) in 30 investigated parameters with significant (P < 0.05–0.0001) models. Fetal sex accounted for up to 32.2% (P < 0.05–0.0001) and nongenetic maternal effects for up to 25.1% (P < 0.05–0.001) of variation in 11 and 14 parameters, respectively. Partitioning of parental (epi)genome variation showed that the maternal genome predominantly contributed to variation in gross (80.3–95.7%; P < 0.05–0.0001) and histomorphological (51.5–82.1%; P < 0.05–0.0001) placental parameters, fetal weight (54.1%; P < 0.0001), and fetal organ weights (43.7–73.1%; P < 0.05–0.0001), whereas the paternal genome predominantly contributed to fetal fluids weight (73.0%; P < 0.001), umbilical cord weight (73.9%; P < 0.05) and length (73.2%; P < 0.01), and placental (69.6%; P < 0.05) and umbilical cord (83.2%; P < 0.0001) efficiency. Our finding that the maternal genome determined placental phenotype (i.e. nutrient source) and the paternal genome determined umbilical cord and fetal fluid phenotype (i.e. nutrient flow) is in line with predicted expression patterns of genomic imprinting effects by both maternal-offspring coadaptation (Wolf and Hager 2006 PLoS Biol. 4, e380) and conflict-of-interest (Moore and Haig 1991 Trends Genet 7, 45–49) hypotheses in the feto-placental unit. Furthermore, there were 4 maternal genome determined relationships between placental weights and umbilical cord phenotype (P < 0.05–0.0001) and 28 paternal genome and/or fetal sex-determined relationships between fetus-, organ- and fetal fluid weights and umbilical cord phenotype (P < 0.05–0.0001). The finding of specific relationships between placenta and fetus merging in clusters differentiated by maternal and paternal genome effects suggests the existence of (epi)genetic-regulated morphological modules within the feto-placental unit.Funded by the JS Davies Bequest.