... differentiation is stimulated by DIF-1 and inhibited by cAMP. (3) Half-maximal effects are produced by 10-70 nM DIF-1, which is in the physiological range. (4) Ammonia and adenosine, which can affect cell differentiation in other circumstances, have no significant pathway-specific effect in our conditions...

... the ratio of NH 3 :NH4 + secreted into the medium by developing cells. High ammonia levels and high pH stimulated precocious accumulation of intra cellular cAMP in both sporogenous and wild-type cells. In both treatments, peak cAMP levels equaled or exceeded control levels and were maintained for longer...

... organism. It was found that in migrating or submerged slugs DIF cannot induce stalk cell differentiation, which is most likely due to the presence of a DIF antagonist. Cyclic AMP and ammonia were earlier reported to act as DIF antagonists in vitro . We show here that ammonia, but not cAMP, acts...

... tractable system in which to identify and characterize cellular morphogens. Cyclic AMP and ammonia stimulate prespore cell differentiation and ammonia plays an additional role in repressing terminal cellular differentiation. Differentiation Inducing Factor (DIF) acts to direct prestalk cell differentiation...

.... In this report, we analysed in more detail the effects of an ammonium salt and trimethylamine on rRNA synthesis in Xenopus embryonic cells cultured under several different conditions. Results obtained showed that ammonia and trimethylamine inhibit formation of 40S pre-rRNA, without inducing breakdown (wastage...