Thermal degradation of RNA-RNA hybrids during hybridization in solution.

Degradation of single-stranded RNA molecules at high temperatures was examined in relation to the kinetics of RNA-RNA hybridization in solution. Eleven species (ranging from 670 bases to 3300 bases) of single-stranded RNAs transcribed from rotavirus genomic RNAs degraded significantly after 16 h of incubation at 65 degrees C. The hybridization of these 11 RNA molecules to the corresponding genomic RNAs, however, was completed within 30 min of incubation. Partially homologous hybrids that were once formed at an early time of incubation gradually degraded in proportion to the length of incubation at 65 degrees C. Thus, the length of hybridization has a critical effect on the final hybridization results. Furthermore, thermal hydrolysis of single-stranded RNA molecules provides a plausible explanation why the percent of nucleotide sequence mismatch allowed to form a stable hybrid in the RNA-RNA hybridization assays for rotavirus genes is much less than that predicted by calculation.