Modification of culture medium for Xenopus embryonic cells : I. Effects of albumin and other proteins

Stearns medium that had originally been developed for culture of Rana pipiens embryonic cells was modified and used for Xenopus laevis embryonic cells. Modification was done either by reducing a concentration of albumin or by replacing it with other proteins, such as α-globulin, β,γ-globulin, horse serum and protamin. Comparisons were made between the original and the modified medium with regard to their ability to support not only cellular uptake of ³H-uridine, ³H-thymidine and ¹⁴C-protein hydrolysate, but also aggregate formation. From the results obtained it has been shown that the original Stearns medium containing 0.5% albumin and the modified medium, which includes 0.1% globulin in place of albumin, seem to be most suited also for Xenopus embryonic cells. A concentration of albumin can be reduced to 0.1% without lowering the rate of ³H-uridine incorporation or RNA synthesis, but with an apparent decrease in the ³H-thymidine and ¹⁴C-protein hydrolysate incorporation. In a medium containing α-globulin the cells are more active to incorporate ³H-thymidine and ¹⁴C-protein hydrolysate than in media containing β,γ-globulin and horse serum as well as albumin. No remarkable difference is found among the media tested in their ability to support aggregate formation and in the appearance of aggregates formed. In a medium with protamin there occurs neither incorporation of the precursors nor formation of aggregates.