Maternal blood transcriptome as a sensor of foetal organ maturation at the end of organogenesis in cattle

Abstract

Harnessing information from the maternal blood to predict foetal growth is attractive yet scarcely explored in livestock. The objectives were to determine the transcriptomic modifications in maternal blood and foetal liver, gonads, and heart according to foetal weight and to model a molecular signature based on the foetal organs allowing the prediction of foetal weight from the maternal blood transcriptome in cattle. In addition to a contemporaneous maternal blood sample, organ samples were collected from 10 male foetuses at 42 days of gestation for RNA-sequencing. Foetal weight ranged from 1.25 to 1.69 gr (mean 1.44 ± 0.15 gr). Clustering data analysis revealed clusters of co-expressed genes positively correlated with foetal weight and enriching ontological terms biologically relevant for the organ. For the heart, the 1346 co-expressed genes were involved in energy generation and protein synthesis. For the gonads, the 1042 co-expressed genes enriched seminiferous tubule development. The 459 co-expressed genes identified in the liver were associated with lipid synthesis and metabolism. Finally, the cluster of 571 co-expressed genes determined in maternal blood enriched oxidative phosphorylation and thermogenesis. Next, data from the foetal organs were used to train a regression model of foetal weight, which was predicted with the maternal blood data. The best prediction was achieved when the model was trained with 35 co-expressed genes overlapping between heart and maternal blood (root mean square error = 0.04, R-square = 0.93). In conclusion, linking transcriptomic information from maternal blood with that from the foetal heart unveiled maternal blood as a predictor of foetal development.