Theronts of the ciliate Ichthyophthirius multifiliis (Fouquet) with up to 4 micronuclei were recorded in populations from two different parasite isolates, maintained as primary infections in juvenile carp through 2 and 10 cycles, respectively. The largest number of multimicronucleate forms occurred within the older isolate (10 cycles) following cyst incubation at 20"C. Tro-phonts were induced to emerge from the host epidermis following incubation of the fish in Eagles MEM for 10-15 min at 20"C. This provided for the first time a technique to recover trophonts in all stages of development; observations were made on the transition from theront to trophont, with respect to nuclear events, the organelle of Lieberklihn, and phagocytosis of host cells. On re-exposure of carp already carrying a two-day primary infection, recently entered trophonts were found in various stages of fusion with established parasites. Results are discussed with respect to conjugation, anisogamy and senescence.
he surface proteins of trophic (vacuolar and ameboid forms) and cyst forms of two axcnic Blastocystis hominis Brumpt, 1912 isolates were studied. The surface proteins of both forms were biotin-labeled and the soluble proteins from unlabeied and biolin-labcled cells were clcctrophoresed in 10% SDS-polyacrylamide gels under reducing conditions. The clcctrophoresed proteins from biolinylated cells were transferred to nitrocellulose membranes and the avidin-peroxidase-labeled complex was used to identify the surface proteins. In trophic forms, 26 of the 38 soluble proteins, with MW ranging between 30 and >200 kDa, were identified as surface proteins. In cyst forms, 15 of Ihe 29 soluble proteins, with MW ranging between 30 and 193 kDa, were considered as located on the surface of cysts. The comparative analysis of surface protein profiles of both forms showed the presence of a common pattern, composed of 13 bands, and the characteristic proteins of trophic (36, 44, 46, 51, 70, 74, 76, 92, 98, 101, 166, 176 and >200 kDa) and cyst forms (42 and 193 kDa).