Prevalence and molecular phylogenetic characterization of Trypanosoma (Megatrypanum) minasense in the peripheral blood of small neotropical primates after a quarantine period.

Neotropical primates of the Cebidae and Callitrichidae, in their natural habitats, are frequently infected with a variety of trypanosomes including Trypanosoma cruzi, which causes a serious zoonosis, Chagas' disease. The state of trypanosome infection after a 30-day quarantine period was assessed in 85 squirrel monkeys (Saimiri sciureus) and 15 red-handed tamarins (Saguinus midas), that were wild-caught and exported to Japan as companion animals or laboratory animals, for biomedical research, respectively. In addition to many microfilariae of Mansonella (Tetrapetalonema) mariae at a prevalence of 25.9%, and Dipetalonema caudispina at a prevalence of 3.5%, a few trypomastigotes of Trypanosoma (Megatrypanum) minasense were detected in Giemsa-stained thin films of blood from 20 squirrel monkeys at a prevalence of 23.5%. Although few T. minasense trypomastigotes were found in Giemsa-stained blood films from tamarins, a buffy-coat examination detected trypanosomes in 12 red-handed tamarins (80.0%), and PCR amplification of a highly variable region of the small subunit ribosomal RNA genes (SSU rDNA) for Trypanosoma spp. detected the infection in 14 of the 15 tamarins (93.3%). Nucleotide sequences of the amplicons were identical for trypanosomes from tamarins and squirrel monkeys, indicating a high prevalence but low parasitemia of T. minasense in imported Neotropical nonhuman primates. Based on the SSU rDNA and 5.8S rDNA, the molecular phylogenetic characterization of T. minasense indicated that T. minasense is closely related to trypanosomes with Trypanosoma theileri-like morphology and is distinct from Trypanosoma (Tejeraia) rangeli, as well as from T. cruzi. Using some blood samples from these monkeys, amplification and subsequent sequencing of the glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene fragments detected 4 trypanosome genotypes, including 2 types of T. cruzi clade, 1 type of T. rangeli clade, and 1 T. rangeli-related type, but failed to indicate its phylogenetic position based on the gGAPDH gene. Furthermore, species ordinarily classified in the Megatrypanum by morphological criteria do not form a clade in any molecular phylogenetic trees based on rDNA or gGAPDH genes.

Unravelling the evolution of the head lice and body lice of humans.

Recent studies of mitochondrial genes of the head and body lice of humans indicate that present-day lice comprise two lineages that diverged before the evolution of modern humans. To test if this was a locus-specific phenomenon, we studied two nuclear genes, elongation factor-1alpha (EF-1alpha) and small subunit ribosomal RNA (ssu rRNA). Our ssu rRNA phylogeny was concordant with the phylogenies from mitochondrial genes, but the EF-1alpha phylogeny was not concordant either with the mitochondrial phylogenies or with the ssu rRNA phylogeny. So both nuclear (ssu rRNA) and mitochondrial data indicate that there are two lineages of lice: one lineage with head lice only (H-only lineage) the other lineage with head and body lice (H+B lineage). Thus, body lice apparently evolved from just one of the two main lineages of lice. However, the date of divergence and geographical origins of the two lineages are controversial. Kittler et al. (Curr Biol 13:1414-1417, 2003; Curr Biol 14:2309, 2004) proposed that these two lineages diverged 0.77 mya, whereas Reed et al. (PLoS Biol 2:e340, 2004) proposed that they diverged 1.18 mya and suggested that one of the lineages, the H-only lineage, evolved in the New World on Homo erectus. We discuss this hypothesis in light of our results from ssu rRNA.