title: Programmed synthesis of tubulin for the flagella that develop during cell differentiation in Naegleria gruberi.
abstract: Amebae of Naegleria gruberi differentiate into flagellates when transferred from growth medium to nonnutrient buffer. Experiments were performed to determine whether the tubulin that forms the flagellar microtubules pre-exists in amebae or is synthesized during differentiation. Amebae prelabeled uniformly with [(35)S]methionine were allowed to differentiate in the presence and in the absence of exogenous unlabeled methionine. In the presence of unlabeled methionine the flagellar tubulin contained only 30% as much [(35)S]methionine as in its absence. Thus at least 70% of the tubulin was synthesized de novo. Isotope dilution and pulse experiments showed that flagellar tubulin synthesis began one-third of the way through differentiation, before any morphological change had occurred. Flagellar tubulin antigen, as measured using a specific antiserum, also began to increase one-third of the way through differentiation and increased 35- to 55-fold during the course of differentiation. These experiments demonstrate that most if not all of the flagellar tubulin is synthesized de novo during differentiation.
mesh_terms: D000656:Amoeba / Q000378:metabolism*; D000941:Antigens / Q000032:analysis; D002454:Cell Differentiation; D004591:Electrophoresis, Polyacrylamide Gel; D005407:Flagella / Q000378:metabolism*; D007106:Immune Sera; D008715:Methionine / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D011863:Radioimmunoassay; D011865:Radioisotope Dilution Technique; D012967:Sodium Dodecyl Sulfate; D013462:Sulfur Radioisotopes; D013997:Time Factors
chemical_list: D000941:Antigens; D007106:Immune Sera; D009419:Nerve Tissue Proteins; D013462:Sulfur Radioisotopes; D012967:Sodium Dodecyl Sulfate; D008715:Methionine