FIG. 5.

Analysis of the expression of glutaredoxin genes in response to arsenate. (A) Northern blot analysis of the expression of the grxA, grxB, and grxC genes. Total RNA was isolated from mid-log-phase Synechocystis cells grown in BG11C medium and was exposed to 100 mM sodium arsenate for 0.5, 1, and 2 h. Control cells were not exposed. Fifteen micrograms of total RNA was denatured, separated by electrophoresis on a 1% agarose gel, blotted, and hybridized with probes for the grxA, grxB, and grxC genes. The filters were stripped and rehybridized with an rnpB gene probe as the control (see Materials and Methods). (B and C) Northern blot analysis of the expression of grxB in strain SGRXA (B) and of grxA in strain SGRXB (C) after arsenate exposure as described for panel A.