[Effect of inhibitors of DNA-, RNA-, and protein synthesis on growth and antheridium formation in Anemia phyllitidis].

A number of inhibitors of DNA-, RNA-, and protein synthesis were applied to prothallia of Anemia phyllitidis, and their effects were investigated with regard to cell division and inhibition of antheridium formation (after induction by gibberellin A3). All compounds tested cause a significant inhibition of growth accompanied by teratologies typical for each inhibitor. Only 5-bromouracil proved to be inactive, even at a concentration of 8×10(-4)m.None of the inhibitors blocked the induction of the biplanar growth form in continuous light.With the exception of 5-bromodeoxyuridine and 5-iododeoxyuridine all the antimetabolites investigated cause a significant lag in antheridium formation. The result of an analysis of this inhibition on the basis of the "critical cell number" (SCHRAUDOLF, 1966a) demonstrates that this time lag is clearly a direct consequence of the retardation of cell division caused by the inhibitors. There is no inhibition of the induction process proper. So therefore it appears highly improbable that antheridium induction in Anemia by gibberellins is based on a specific gene activation in the sense of JACOB and MONOD.The results presented in this paper demonstrate that the production of a time lag in the realisation of a process of differentiation or morphogenesis is not sufficient evidence to permit definite conclusions to be drawn about the basic mechanism of induction; the effect of inhibition of cell division caused by the inhibitors must be excluded or at least taken in to account.The possible function of gibberellins as "realisators" of already present but inactive m-RNA is discussed.5-Bromo- and 5-iododeoxyuridine do not cause a time lag in antheridium formation; both inhibitors, however, cause a deformation of the cell pattern of the antheridia. The degree of this deformation depends on inhibitor concentration as well as on exposure time. Probably a competition exists between these halogensubstituted pyrimidines and thymidine for incorporation into DNA.