Figure 4.

Metaphase II (MII) Mdr1 mutant and wild-type oocytes present different Ca²⁺ oscillations upon strontium, ionomycin (IO), thapsigargin (TG) and PLCZ1 treatment. (A) When 10 µM TG was used, no differences were observed between wild-type and Mdr1 mutant cells. (B) After oocyte treatment with 2.5 µM IO, wild-type oocytes were characterized by a quick Ca²⁺ depletion; on the other hand, Mdr1 mutant oocytes presented a broader Ca²⁺ transient (t-test, ***P < 0.001). No difference was observed in the peak amplitude. (C) Treatment with 10 mM strontium chloride (SrCl²⁺) induces Ca²⁺ oscillations with a lower number of rises in the mutant oocytes and a delay in the oscillations (t-test, ***P < 0.001). (D) In mutant oocytes, 0.01 µg/µL PLCZ mRNA induced Ca²⁺ oscillations characterized by a lower frequency in comparison to the wild type (t-test, ***P < 0.001). A schematic representation of the procedure is reported. n  =  3 wild-type and 3 Mdr1 mutant mice. The number of oocytes is reported under each graph per individual treatment.