Figure 6.

A, Schematic drawings of the chimeric constructs. The CAH1 5′-upstream region between −651 and −109 was divided into two fragments at position −293 and each fragment was fused to the ARS reporter gene driven by the β₂-tubulin minimal promoter. The chimeric construct pCT37 contains the 385-bp region from −651 to −294, and pCT44 contains the 185-bp region from −293 to −109, respectively. B, Quantification of arylsulfatase activity in individual transformants. The arylsulfatase activity under high- (H) and low-CO₂ conditions (L) was quantified in transformants containing pCT37 (CT37-1) or pCT44 (CT44-1 and CT44-2). Results for two representative CT44 strains among four tested are shown. Bars above the graph indicate the sd for the average of three determinations. C, Northern-blot analysis of β₂-TUB/ARS chimeric transcripts in transformants CT37, CT44-1, and CT44-2. Ten micrograms of total RNA from cells exposed to high- (H) or low-CO₂ conditions (L) for 4 h was electrophoresed in each lane. Radiolabeled ARS cDNA (upper autoradiographs) or p-CA1-5′ (lower autoradiographs) were used as probes. Values of the relative amount of mRNA represent the percentage of the amount of the chimeric transcripts in CT37 and CT44 over the average amount in three independent T strains.