The plastid ribosomal RNA-operon of the unicellular red alga Cyanidium caldarium GEITLER, strain 14—1-1 isolated by Alien (1), strain 107.79 from the collection of algae maintained by the Institute of Plant Physiology, University of Gottingen was located about 4.5 kb upstream of the psbA gene (2). The nucleotide sequence of the 16S rRNA gene is presented. The 3'and 5'-ends of the coding region were identified tentatively by sequence comparisons with the corresponding regions from the chloroplasts of Chlamydomonas reinhardtii (3), Chlorella ellipsoidea (4) and Euglena gracilis (5). ACKNOWLEDGEMENTS