INTRON REVEALED BY NUCLEOTIDE SEQUENCE OF LARGE SUBUNIT OF RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE/OXYGENASE FROM CODIUM FRAGILE (CHLOROPHYTA): PHYLOGENETIC ANALYSIS1

The coding sequence for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) from Codium fragile (Suringar) Hariot chloroplast DNA is 1428 bp in length and contains a 1813-bp group II intron. The only other organisms in which introns have been found in the rbcL gene are Euglena and Astasia. The Codium intron likely had a separate origin from the Euglena and Astasia introns, based on comparisons of intron sizes and sequences. Phylogenetic analyses of rbcL nucleotide and amino acid sequences place Codium between Chlorella and two Chlamydomonas spp., indicating that the Chlorophyceae may be polyphyletic.