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Abstract
The rate of DNA synthesis in Allomyces arbuscula during differentiation of zoosporangia depends on the stage of development. The first stage of cytoplasmic reorganization in the hyphal apex is accompanied by a rapid decrease in DNA synthesis. The appearance of septa and the development of young zoosporangia are paralleled by a renewal of DNA synthesis which then declines as the zoosporangia mature. The transfer of an actively growing mycelium to the induction medium results in a transient accumulation (up to 1 h post-transfer) of ATP in the cell, which then starts to diminish. Analysis of the pulse-labelled native DNA by neutral CsCl equilibrium density gradient centrifugation indicates that in these early stages, all the DNA is being synthesized at a uniform rate. The amount of rRNA cistrons varies with the developmental stage and, on reorganization of the hyphal apex, the synthesis of such genes is inhibited and subsequently stimulated as zoosporangia mature.
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