The thermodynamic stability hypothesis RNA results

As for RNA stability, abundant evidence indieates that high GC stabilizes RNA by the formation of stem-and-loop structures (Hasegawa et al., 1979 Wada and Suyama, 1986). As an example, the GC level of ribosomal RNA of bacteria is well correlated with their optimum growth temperature (Galtier and Lobry, 1997). 

These results are similar to the in vivo data on the effect of growth temperature on the structure and function of ori sequences in the mitochondrial genome of yeast (Goursot et al., 1988 see Part 2). In this case too, increasing temperature from 28°C to 33°C led to the melting of AT stems in the ori sequence of some petite mutants and to the consequent decrease of replicative ability. These results demonstrate direct (reversible) temperature effects on the secondary (and tertiary) structures of DNA and RNA. 

---