RESUMEN
Experiments on hybridization between Fasciola hepatica and Fasciola gigantica were carried out to clarify whether a reproductive isolating mechanism appears between the two Fasciola species. Molecular evidence for hybridization was based on the DNA sequence of the internal transcribed spacer 1 (ITS1) region in nuclear ribosomal DNA, which differs between the species. The results suggested that there were not pre-mating but post-mating isolating mechanisms between the two species. However, viable adults of the hybrids F1 and F2 were produced from both parental F. hepatica and F. gigantica. The hybrids inherited phenotypic characteristics such as ratio of body length and width and infectivity to rats from parental Fasciola hepatica and F. gigantica. These findings suggest that reproductive isolation is incomplete between Fasciola hepatica and F. gigantica. Adults of the hybrids F1 and F2 were completely different in mode of reproduction from aspermic Fasciola forms that occur in Asia and seem to be offspring originated from hybridization between F. hepatica and F. gigantica and to reproduce parthenogenetically.
Asunto(s)
Quimera/genética , ADN de Helmintos/genética , Fasciola hepatica/genética , Fasciola/genética , Fascioliasis/parasitología , Hibridación Genética , Metacercarias/genética , África , Animales , Asia , ADN Espaciador Ribosómico/genética , Europa (Continente) , Fasciola/aislamiento & purificación , Fasciola/ultraestructura , Fasciola hepatica/aislamiento & purificación , Fasciola hepatica/ultraestructura , Fascioliasis/veterinaria , Cabras , Metacercarias/aislamiento & purificación , Metacercarias/ultraestructura , América del Norte , Filogeografía , Polimorfismo de Longitud del Fragmento de Restricción , Aislamiento Reproductivo , Análisis de Secuencia de ADN , Ovinos , Caracoles , América del Sur , Especificidad de la EspecieRESUMEN
Guaymi Indians, a non-intravenous drug-using population in which human T cell lymphotropic virus type II (HTLV-II) is endemic, were studied in Changuinola, Panama, to identify the prevalence and modes of transmission of HTLV-II. A population-based survey showed that 352 (9.5%) of the 3686 participants were seropositive for HTLV-II. Infection rates were the same for male and female subjects and increased significantly with age, beginning in young adulthood. HTLV-II infection status was highly concordant among spouses (P < .001) and between mother and child; of children aged 1-10 years, 36 of 219 born to seropositive mothers were seropositive compared with 3 of 997 born to seronegative mothers (P < .001). The strong associations of HTLV-II infection with age and with an infected spouse in adults and of infection in children with infection in their mothers strongly suggest sexual and mother-to-child transmission of HTLV-II in this population.