A tyrosine-free medium for the selective growth of cells expressing phenylalanine hydroxylase activity

Selection of variant hepatoma cells in liver-specific growth media: regulation at the mRNA level

“…As shown in Table 1, only rat F a 0 cells are able to survive in all three media. As reported for other derivatives of the H4IIEC3 line [2,10,21,26,40, 501, F a 0 freely grew in Tyr-and G-OA media, and gave rise to rare variants in Arg-conditions. Arg variants arose at a frequency of about By contrast, cells of clone BWTG3, a Table 1.…”

“…Indeed, the evaluation of the full set of differentiated functions a cell can express is usually achieved through modifications of the culture media, mainly with hormones and growth factors [44]. In this latter case, a differentiated cell is selected by its specific ability to synthesize an essential nutrient that has been omitted from growth medium [2,5,21,26,40,50]. In this latter case, a differentiated cell is selected by its specific ability to synthesize an essential nutrient that has been omitted from growth medium [2,5,21,26,40,50].…”

“…This type of selective nutritional media found one of its main applications in somatic cell genetics of differentiation. Arginine-free medium 26 has been used more recently with hepatoma cells [21,40,501. This property permitted an efficient screening for hepatoma cell hybrids that re-expressed the liver-specific gluconeogenic enzymes [3].…”

“…A complementary approach involves selective nutritional media based on tissue-specific enzymes or metabolic pathways. In this latter case, a differentiated cell is selected by its specific ability to synthesize an essential nutrient that has been omitted from growth medium [2,5,21,26,40,50]. Under these conditions, cells commited to the appropriate differentiated state either grow easily [2,5,261 or give rise to rare variants that would not be detectable without selective media [5,211.…”

“…In addition, sequential selection of hybrid cells in medium containing either dihydroxyacetone or oxaloacetate demonstrated that survival in glucose-free conditions requires two liver-specific enzymes, fructose bisphosphatase and either triokinase or phosphoenolpyruvate carboxykinase. Arginine-free medium 26 has been used more recently with hepatoma cells [21,40,501. It contains ornithine and selects for the two liver-specific enzymes from the urea cycle that are involved in the conversion of ornithine to arginine, i.e.…”