ON SMALL GENOMES IN EUKARYOTIC ORGANISMS - MOLECULAR KARYOTYPES OF 2 MICROSPORIDIAN SPECIES (PROTOZOA) PARASITES OF VERTEBRATES

Pulsed field gel electrophoresis (PFGE) was used to separate chromosom e-sized DNA from two species of microsporidia of fishes. The molecular karyotype of Glugea atherinae exhibits 16 DNA bands from 420 to 2,700 kb, and that of Spraguea lophii 12 bands from 230 to 980 kb. Until no w they represent respectively the largest and the smallest genomes vis ualized for microsporidia : 19.5 Mb for G. atherinae and 6.2 Mb for S. lophii (the smallest nuclear genome in eukaryotic organism). We have analysed separately five strains of G. atherinae (individual cysts), w ith this technique. The electrophoretic spectra are the same for these strains, except for the absence of the 2,380-kb band in one case. The refore, the karyotype seems to be rather well conserved for this speci es.