GROUP-I INTRONS FOUND IN NUCLEAR SMALL-SUBUNIT RIBOSOMAL-RNA GENES OFTHE BALLISTOCONIDIOGENOUS ANAMORPHIC YEAST BENSINGTONIA-CILIATA AND BENSINGTONIA-YAMATOANA

Four group I introns were found in the nuclear small subunit ribosomal RNA genes (SSU rDNA) of the ballistoconidiogenous anamorphic yeast ge nus Bensingtonia. Two of them were found in B. ciliata, type species o f the genus, with the length of 335 nt and 341 nt. The remaining two w ere found in B. yamatoana with lengths of 454 nt and 457 nt, respectiv ely, The four introns were located at two different sites within the S SU rDNA. The first insertion site was the same position as group I int rons found in the SSU rDNA of Dunaliella parva-5', Dunaliella salina, Protomyces inouyei-5' and Ustilago maydis, The second insertion site w as shared among group I introns found in the SSU rDNA of Chlorella ell ipsoidea, Hildenbrandia rubra, Pneumocystis carinii and Protomyces ino uyei-3'. The putative secondary structures of the introns resembled th ose of subgroup IC1. Principal coordinate analysis of core regions of 15 group I introns found in SSU rDNA of eukaryotes showed that the seq uence of B. ciliata-5' intron resembled that of the B. yamatoana-5' in tron, and the sequence of the B. yamatoana-3' intron resembled that of the Protomyces inouyei-5' intron, Bensingtonia ciliata-3' intron had relatively different sequences compared to other group I introns exami ned. Group I introns in the nuclear SSU rDNA of red and green algae, a scomycetes and basidiomycetes, examined in this study, were scattered on the principal coordinate analysis.