Karyotype of Trichomonas vaginalis

At present, information on ploidy, number and morphology of chromosomes in protozoa is scarce. Thus, we investigated the karyotype of the parasitic protozoon, Trichomonns vaginalis. The metaphase chromosomes from colchicin-treated cells were obtained by a spreading technique using Carnoy fixative and Giemsa staining. The karyotype of T. vaginalis is haploid and consists of six different monocentric chromosomes ranging from 2.40 to 1.00 mu m. A typical karyotype consists of 1 metacentric, 1 metacentric/submetacentric, 1 submetacentric/subtelocentric, 1 subtelocentric/acrocentric and 2 acrocentric chromosomes. The nature of the chromosome constrictions, the probable occurrence of meiosis and the reciprocal relationship between diploid/haploid phases are discussed. Comparison of our results with previous data indicates only a small variation in chromosome numbers during the karyotype evolution of the subfamily Trichomonadinae. Morphology of the centromeric area in T. vaginalis seems to be different from those described earlier in the class Hypermastigotea and in a devescovinid trichomonad, Caduceia theobromae.