First cytogenetic study of Cavernicola pilosa Barber, 1937 (Hemiptera, Triatominae).

Cavernicola pilosa is a triatomine species that lives in caves and feeds on bat blood. This vector has a wide geographical distribution, and is found in Brazil, Colombia, Panama, Peru, and Venezuela. Little is known about the reproductive biology of this species, because most previous studies have only characterized its morphology, morphometry, ecology, and epidemiology. Therefore, this study aimed to obtain preliminary data related to spermatogenesis in C. pilosa by conducting cytogenetic analysis. Analysis of the heterochromatic pattern of C. pilosa during the initial prophases revealed that heterochromatic blocks are only present in the sex chromosomes. Based on the analyses of the meiotic metaphase and prophases, we found that the sex determination system of C. pilosa is XY and the chromosomes are holocentric. C. pilosa spermatids are filamentous and have long flagella. It was not possible to detect corpuscle or filament heteropycnosis in spermatids of this species. The initial cytogenetic data presented in this study are important in characterizing the spermatogenesis and heterochromatic patterns of C. pilosa. Our results suggest that adaptation to troglodytism did not result in differences in spermatogenesis in this vector.

Observation of membrane fusion on the interaction of Trichomonas vaginalis with human vaginal epithelial cells.

The in vitro cytopathic effect of Trichomonas vaginalis on epithelial cells was analyzed through the interaction of two parasite strains with freshly collected human vaginal epithelial cells (HVECs) from normal women. Videomicroscopy, light and electron microscopy (scanning and transmission), freeze-fracture, the tracer lanthanum nitrate, and the periodic acid-thio-semicarbazide-silver proteinate techniques were used to analyze regions of close contact between the HVECs and T. vaginalis. After 2 h of interaction, all HVECs were dead, whereas all the trichomonads were alive. Microscopic observations demonstrated that in addition to previously described regions of adhesion and interdigitations, areas of continuity between the cytoplasm of the two interacting cells were found. They were not easy to find since they correspond to focal spots placed in different depths of the section. When these regions were depicted, the plasma membranes of the T. vaginalis and the vaginal epithelial cells seemed to be fused.