Expression of cyp110 and psbA transcripts in nitrogen-fixing and ammonia-supplemented Anabaena 7120 cultures. Anabaena 7120 control and test cultures were grown in nitrogen-free (-N) and ammonia-supplemented (+N) Chu #10 media. Test cultures were treated with 0.2 % (v/v) dodecane or hexadecane for 2 hours. Fifteen microgram samples of total Anabaena 7120 RNA from each treatment were size fractionated, transferred to a nylon membrane and probed with a cyp110 probe (panels A and C). RNA blots were stripped and reprobed with a psbA probe (panels B and D). Lanes (1) untreated control, lanes (2) dodecane treatment, lanes (3) hexadecane treatment. Bars on left side of each panel denote the approximate transcript sizes (A, and C = 8.5 kb, B and D = 1.3 kb). Quantification data is shown below each northern blot.