Sperm Dilution Buffer for Xenopus (SDB)
75 mm KCl
250 mm sucrose (e.g., Sigma-Aldrich SX1075; dilute from a 1.5 m solution that has been filter-sterilized and stored at −20°C)
2 mm HEPES (e.g., Sigma-Aldrich H3375; dilute from a 1 m, pH 7.7 solution that has been filter-sterilized and stored at −20°C)
0.5 mm spermidine trihydrochloride (e.g., Sigma-Aldrich S2501; dilute from a 100 mm solution that has been aliquoted and stored at −20°C)
0.2 mm spermine tetrahydrochloride (e.g., Sigma-Aldrich S1141; dilute from a 100 mm solution that has been aliquoted and stored at −20°C)
Adjust pH to 7.4–7.6 with NaOH. Prepare a large volume (e.g., 50–100 mL), filter sterilize, aliquot (e.g., 0.5–1 mL), and store for a year at −20°C.
