Modified Barth's Saline (MBS) for Oocytes

• 1. Prepare a 0.1 m CaCl₂ solution by dissolving 1.11 g of CaCl₂ in deionized H₂O for a final volume of 100 mL.

• 2. Prepare a 10× MBS salt solution by dissolving the following reagents in deionized H₂O for a final volume of 1 L. Adjust the pH to 7.8 with 10 m NaOH, and sterilize by autoclaving. Store indefinitely at room temperature.

  HEPES	11.92 g
  NaCl	51.43 g
  KCl	0.75 g
  NaHCO3	2.10 g
  MgSO4 · 7H2O	2.46 g

• 3. To prepare 1× MBS, combine 100 mL of 10× MBS salt solution and 7 mL of 0.1 m CaCl₂ with 893 mL of autoclaved deionized H₂O. Add antibiotics. Store for up to 1–2 mo at 16°C–18°C (the same temperature used for oocyte incubation). Check before use.

  • The final reagent concentrations in 1× MBS are 0.7 mm CaCl₂, 5 mm HEPES, 88 mm NaCl, 1 mm KCl, 2.5 mm NaHCO₃, and 1 mm MgSO₄.

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