Homologies between higher plant and algal 25S cytoplasmic ribosomal RNA

Using heat and urea treatment, the degradation products of denatured 25S cytoplasmic ribosomal RNA from jack bean (a higher plant) and $\text{Chlamydomonas reinhardi}$ (an alga) were compared. Several specific modes of 25S RNA breakdown are postulated. The results suggest that (1) both higher plant algal 25S RNA may contain homologous endonuclease susceptible regions as judged by the stoichiometry of degradation and (2) that similar secondary structural properties of 25S cytoplasmic RNA have been conserved by evolution in the plant kingdom.