Effect of 7-azatryptophan on heterocyst differentiation inAnabaena doliolum Bharadwaja

The effect of DL-7-azatryptophan, an analogue of tryptophan, has been studied on the heterocyst spacing pattern and the probability of proheterocyst regression inAnabaena doliolum. 7-azatryptophan suppressed growth and induced heterocyst differentiation in nitrogen-free medium. In ammonium (1 mM), nitrite (2 mM) and nitrate (2 mM) supplemented media, it caused proheterocyst regression with a frequency of 100%, 35% and 10% respectively. The role of azatryptophan in nitrogen metabolism has been discussed in relation to ammonia-uptake study.