Abstract
A brown alga P. littoralis is unique to that so mach as 7 group II introns are located in the mitochondrial genome. Four group IIB introns in the LSU rRNA gene and three group IIA introns in the cox1. We analyzed the arrangement of group II introns for 8 P. littoralis specimens collected at world wide habitats. The first intron located in the LSU rRNA gene of a specimen collected in France and the fourth intron of a specimen harvested in Japan had a exceptionally long evolutionary distance against the cognate introns found in P. littoralis specimens. In addition to that these introns harbored an intact or nearly intact tripartite ORF in their arm-IV loop. Based on the result of molecular phylogenetic analyses, we concluded that these introns are the result of recent reinvasion of cognate introns.
