Table 1.

The rates of CO₂ uptake in whole filaments and O₂ exchange in whole filaments and isolated heterocysts of the WT and the flv mutant strains

Strain and inhibitors	Filaments						Heterocysts
	CO2 uptake	O2 uptake			Gross O2 evolution	Net O2 evolution	O2 uptake
		Dark	Light	Light-induced			Dark	Light	Light-induced
WT	7.0 ± 0.3	20.3 ± 1.1	69.5 ± 0.8	49.1 ± 0.8	187.5 ± 5.5	118.0 ± 5.9	3.4 ± 0.5	5.6 ± 0.5	2.2 ± 0.7
+ KCN	—	—	—	—	—	—	1.3 ± 0.4**	5.5 ± 0.8	4.2 ± 0.4**
+ KCN, SHAM	—	—	—	—	—	—	0.7 ± 0.3**	7.5 ± 0.5**	6.8 ± 0.2**
+ Antimycin A	—	—	—	—	—	—	1.4 ± 0.6**	5.7 ± 0.7	4.4 ± 0.1**
∆flv1B	7.5 ± 2.1	21.1 ± 1.6	58.5 ± 0.5**	37.4 ± 2.1**	181.5 ± 5.8	123.0 ± 5.0	4.9 ± 0.8*	6.7 ± 0.5*	1.8 ± 0.3
∆flv3B	5.2 ± 0.3**	32.4 ± 3.15*	54.3 ± 2.1**	21.8 ± 5.3**	142.8 ± 6.8**	88.5 ± 4.6*	7.4 ± 0.7**	6.5 ± 0.1*	Nd
∆flv1B/3B	5.1 ± 0.4**	30.4 ± 1.4**	55.8 ± 1.7**	25.4 ± 3.1**	145.5 ± 5.6**	89.7 ± 7.2*	6.5 ± 0.6**	6.4 ± 0.1*	Nd

Gas exchange rates are presented as micromoles per milligram of Chl a per hour. Filaments were grown in N₂-fixing conditions. Light-induced O₂ uptake was calculated by subtracting the O₂ uptake rate in darkness from the O₂ uptake rate in the light. Net O₂ evolution was deducted as a residual rate of gross O₂ evolution after subtraction of the light O₂ uptake rate. Mean ± SD, n = 3, asterisks indicate statistically significant differences with the WT (*P < 0.05; **P < 0.01). Nd, not detected.