ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
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 daughterstrand 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.
Additional Material:
14 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1040860304
