Figure 3.

Effects of long-term growth at elevated CO₂ on the relative abundance of rbcS gene members. Ten micrograms of total RNA per lane was used for northern-blot analysis. Gene-specific probes were labeled to similar specific activities (approximately 5 × 10⁷ dpm pmol⁻¹), and equal amounts of radioactivity of each probe were used. Blots were exposed for the same length of time. The relative amounts of individual rbcS mRNA were expressed as a percentage of the sum of hybridizing signals from each of the rbcS members. Relative changes attributable to CO₂ treatments were expressed using the ambient values of each rbcS gene as 100%. One of the blots was stripped and hybridized to an internal control gene (α-tubulin [Tub]). Numbers represent means ± sd from two filters each, with RNA samples extracted from two replicate experiments. Leaves were collected at midday.