AXENIC CULTURE OF REPTILIAN BLASTOCYSTIS ISOLATES IN MONOPHASIC MEDIUM AND SPECIATION BY KARYOTYPIC TYPING

The growth of axenic reptilian isolates of Blastocystis in Iscove's mo dified Dulbecco's medium (IMDM) was studied and the morphology of the parasite was examined by phase-contrast microscopy. The chromosomal pa tterns of these reptilian isolates of Blastocystis were examined by pu lsed-field gel electrophoresis (PFGE) and compared with those of B. ho minis and B. lapemi, a sea snake Blastocystis. IMDM with 10% horse ser um supported excellent growth of the reptilian Blastocystis isolates. The parasites from all the isolates were predominantly vacuolar, but m ultivacuolar and amoeboid forms were also seen. Amoeboid forms with ra ther elongate pseudopodia were also observed. There were some differen ces in size, morphology, and growth characteristics in the different r eptilian isolates. The karyotypic patterns of the Blastocystis isolate s from tortoise, iguana, and python were distinctly different from one another and from those obtained with B. hominis and B. lapemi. On the basis of the above-mentioned differences in chromosomal patterns, the tortoise, iguana, and python isolates are described as new species, v iz., B. geocheloni sp. nov. from Geochelone carbonaria (red-footed tor toise), B. cycluri sp, nov. from Cyclura cornuta (rhino iguana), and B . pythoni sp. nov. from Python reticulatus (reticulated python).