title: DNA replication in homogenates of Physarum polycephalum.
abstract: Homogenates of Physarum polycephalum incorporate [3H]dATP into nuclear DNA at an initial rate of approximately 15% of the in vivo rate. To attain this level of synthesis, cultures, are homogenized in a medium containing Mg++, EGTA, glucose and spermine. Incorporation is strongly stimulated by the addition of ATP and all four deoxyribonucleoside triphosphates to homogenates prior to incubation. Various inorganic cations other than Mg++ either do not affect synthesis or are inhibitory. Incorporation is inhibited by a nonionic detergent, Triton X-100. DNA synthesis in this cell-free nuclear system is similar in several respects to that which occurs in vivo: (1) The rate of DNA synthesis in the intact organism at a given time in the mitotic cycle is reflected by the level of synthesis in homogenates prepared from cultures at that time of the cycle; (2) DNA strands labeled in vitro exhibit alkaline sucrose density gradient sedimentation properties similar to those of daughter-strand DNA pulse-labeled in vivo; and (3) Homogenates of cultures which were pre-treated with cycloheximide incorporate [3H]dATP at about 60% of the level observed in homogenates of untreated controls.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002474:Cell-Free System; D003513:Cycloheximide / Q000494:pharmacology; D004261:DNA Replication / Q000187:drug effects; D003854:Deoxyribonucleotides / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D005656:Fungal Proteins / Q000096:biosynthesis; D005947:Glucose / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009235:Myxomycetes / Q000378:metabolism*; D010804:Physarum / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000494:pharmacology; D013096:Spermine / Q000494:pharmacology; D013696:Temperature
chemical_list: D003854:Deoxyribonucleotides; D005656:Fungal Proteins; D013096:Spermine; D011092:Polyethylene Glycols; D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D003513:Cycloheximide; D008274:Magnesium; D005947:Glucose; D002118:Calcium