NUCLEOTIDE SEQUENCE HOMOLOGY OF SOME ALGAL RIBOSOMAL RNAs1

Radioactively labeled ribosomal RNA from seven species of algae was purified and hybridized to purified DNA from Chlamydomonas reinhardtii Dangeard (Chlorophyta). Delta T_m values for the heterologous RNA-DNA duplexes were obtained by thermal dissociation; values ranged from 3.9 to 10.9 C. Organisms traditionally considered to be less closely related to C. reinhardtii showed the greatest delta T_m values. Ulothrix fimbriata Bold and Klebsormidium flaccidum (Kütz.) S., M. & Bl., although similar morphologically, showed very different delta T_m values and would not appear to be closely related by these criteria.