2.2. Experimental design and treatments
The cultures of Anabaena PCC 7120 were harvested at their
exponential phase by centrifugation at 4,000g for 10 min and gently
washed thrice with distilled water. After this, cells were resuspended
in BG-11 medium (pH 7.5) having different combinations of treatments
viz., Ni (NiCl2; 1.5 μM), salicylic acid (SA; 40 μM),
calcium (CaCl2; 800 μM), sodium nitroprusside (SNP; 10
μM), ethyleneglycol-bis (β- aminoethyl)- N,N,N,N- tetraacetic
acid (EGTA; 1mM) and 2-4-carboxyphenyl-
4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO; 20 μM). The
following combinations were made: control (only BG-11 medium), Ni,
Ni+SA, Ni+Ca, Ni+NO, Ni+SA+Ca+c-PTIO, Ni+SA+NO+EGTA and
Ni+SA+c-PTIO+EGTA. After 72 h of treatment, cultures were harvested and
various parameters were analyzed.