Short communication: profiling the expression of Let-7d-5p microRNA in circulating blood of pregnant and nonpregnant cows.

MicroRNAs are critical molecules in cell homeostasis and can bind their target in the cellular cytoplasm by miRNA recognition of the 3ʹUTR sequence in the messenger RNA (mRNA) or other RNAs and inhibiting the mRNA translation. This molecular mechanism is called gene silencing. These miRNAs are stable in blood and can be useful as biomarkers of early pregnancy in the bovine. We demonstrated a decrease in the miRNAs, Let-7d-5p, at day 21 post embryo transfer for nonpregnant samples contrasted with pregnant blood samples (P < 0.05). This research opens new methodologies to study and understand miRNAs circulating in blood of pregnant vs. nonpregnant cows at early stages.