FIG. 1.
PCR products after amplification of the tRNALeu (UAA) intron from lichen samples and three free-living strains from culture collections analyzed by agarose gel electrophoresis. Different samples from one thallus never showed size variation (subsamples 1 and 2). All samples have an intron which is larger than that of Anabaena strain PCC 7120 (A. 7120). N.a, N. arcticum; P.a, P. aphthosa, P.c, P. canina; P.m, P. membranacea; N.73102, Nostoc strain PCC 73102. Size markers (100-bp ladder) are shown to the left and to the right.