M. Reith et J. Munholland, THE RIBOSOMAL-RNA REPEATS ARE NONIDENTICAL AND DIRECTLY ORIENTED IN THE CHLOROPLAST GENOME OF THE RED ALGA PORPHYRA-PURPUREA, Current genetics, 24(5), 1993, pp. 443-450
A detailed restriction map of the chloroplast genome of the red alga P
orphyra purpurea has been constructed. Southern hybridization experime
nts with cloned or gel-purified restriction fragments and PCR products
indicate that the P. purpurea chloroplast genome is approximately 188
kb in size. This circular molecule contains two rRNA-encoding repeats
(approximately 4.9 kb) that separate the genome into single-copy regi
ons of 34 kb and 144 kb. Interestingly, these repeats are arranged in
a direct orientation. In addition, DNA sequencing of the ends of both
repeats revealed that the two-rRNA repeats are not identical. No intra
molecular recombination between the repeats can be detected. We discus
s the possibility that the chloroplast genome of P. purpurea is organi
zed like that of the ancestral chloroplast.