Pararosaniline-induced Akinetoplastic Trypanosoma evansi : Formation and Characterization

抄録

A kinetoplastic strain of Trypanosoma evansi was induced to become akinetoplastic by pararosaniline. Loss of kDNA minicircles was analyzed by DAPI fluorescence and Southern blot analysis probed with cloned kDNA fragments. Qualitative changes in the kinetoplast prior to akinetoplastidy include various fragmented fluorescence patterns and formation of inter-mediate fluorescence intensity. Thus, kDNA loss induced by pararosaniline is preceded by a gradual decrease in its size. We show that trypanosomes with intermediate amount of kDNA are unstable tending to become akinetoplastic. We further demonstrate that the difference in population doubling time between kinetoplastic and akinetoplastic forms is 4.7 and 5.5 hrs, respectively. Our results indicate that although the mutants have maintained their ability to multiply, their slower doubling rate limits them to dominate in a given population. Moreover, this feature may be one of the possible factors responsible for their inferiority to those with kDNA and for their selective disadvantage in nature.