The methods of isolation of fish trypanosomes and the taxonomy and phylogenetic analyses were studied and discussed in the present dissertation. The main results and conclusions are summarized as follows:
1. The methods of isolation of fish trypanosomes using Percoll reagent and DEAE-cellulose column, and the recombinant aerolysin protein were discussed in this paper. The latter was first reported.
2. The trypanosomes from the blood of Ophiocephalus argus and Odontobutis obscura were used for light microscopy investigations and studied morphology using 13 morphometric characterizations. Infection with trypanosomes of Odontobutis obscura was recorded for the first time.
3. Trypanosoma siniperca was a valid species and redescribed using 13 morphometric characterizations and molecular data. The trypanosomes from the blood of Pseudobagras fulvidraco and Cyprinus carpio were compared with related species using morphological and molecular data. The results indicated the trypanosomes from Cyprinus carpio and T. siniperca probably were the same species; one form from Pseudobagras fulvidraco and Marv might be the same genotypes, the other might be tentatively identified as T. pseudobagri.
4. The fine structure of T. pseudobagri was observed with transmission electron microscopy. The pellicle of trypanosome was a unit membrane with characteristic 3-layered structure, which was covered by a well-developed glycoprotein surface coat. The structure and attachment of the flagellum and the subpellicular microtubules show the usual structural and organizational features. Kinetoplast, mitochondria, nucleus and vacuoles, which occur in trypanosomidae, were observed in electron micrographs. The significance of similarities and differences of these fine structures is uncertain in terms of the evolutionary relationship of trypanosomes.
5. Phylogenetic analysis was conducted by using 18S rRNA gene sequences, which contained 7 sequences of fish trypanosomes from China. The results indicated that all fish trypanosomes fell in a single clade, which freshwater fish trypanosomes was separate from trypanosomes of marine fish and formed sister group. Trypanosomes from China were nested within the fish clade and further subdivided into at least 2 subgroups.