Research Paper Volume 9, Issue 4 pp 1186—1201

Expression profiles and function analysis of microRNAs in postovulatory aging mouse oocytes

Figure 5. Activation rates and calcium stores in oocytes microinjected with miR-98 mimic (upper row) or inhibitor (lower row). Freshly ovulated oocytes recovered at 13 h post hCG were injected with miR-98 mimic (MM) or miRNA mimic negative control (MC), or with miR-98 inhibitor (IN) or inhibitor negative control (IC), before aging culture in CZB medium. To observe activation, oocytes were treated with ethanol and 6-DMAP at 36 h (mimic) or 30 h (inhibitor) of aging culture, and activation was checked 6 h later. Each treatment was repeated 3 to 4 times and each replicate contained 35-40 oocytes. For calcium measurement, at 3 h and 36 h (mimic) or 30 h (inhibitor) of aging culture, oocytes were loaded with Fura-2 AM and the loaded oocytes were measured for calcium stores (ΔF340/380) using a Ca2+ imaging system. Oocytes were monitored for 5 min to record baseline F340/380 ratio before ionomycin stimulation to release Ca2+ into cytoplasm. Following ionomycin addition, oocytes were monitored for 20 min to record peak F340/380 ratio. The difference between peak and baseline F340/380 ratios represents the calcium stores (ΔF340/380) of an oocyte. Each treatment was repeated 3 to 4 times and each replicate contained 35-40 oocytes. a-c: Values with a different letter above bars differ significantly (P < 0.05).