Culture media modulates the regime of Ca2+ signaling, miRNA expression at fertilization and the post-natal growth in the mice

Several reports have shown that incubation media used for in-vitro fertilization impacts adult phenotype. However, it is still difficult to identify the critical composition of the culture media that modulates the development. Here we develop a new method that makes it possible to establish functional linkage between the composition of the medium, the regime of Ca2+ signaling and mitochondrial activity during fertilization, the miRNA expression and the post- natal growth. Mouse eggs were fertilized by ICSI, incubated 4h in M16 or KSOM and transferred to recipients. With a specific algorithm, we used Ca2+ signaling following ICSI as a detector of changes of egg functioning. Pools of 30 eggs incubated in each condition were used to screen the miRNA expression 4h after ICSI. The results show that the females issued from egg cultured for 4 hours in KSOM are significantly smaller at the 8th week (-15%, p<0,05) than those cultured in M16. In KSOM, eggs displayed an average of 15 (+/- 5) Ca2+ impulses versus 9 (+/-2) in M16. Differential miRNA expression (Cp<37) were found between eggs incubated in M16 (26 miR) and KSOM (18 miR). Among the predicted gene targets by the more expressed miRNA we found: MAPK signaling, PI3K-Akt,metabolic pathway, calcium signaling, Jak-STAT and dorsoventral axis regulation. Therefore, since the M16 and KSOM formula are known, it becomes possible to establish a precise functional linkage between the parameters of the culture media, the modulation of egg metabolism, mRNA regulation and the post-natal consequences.