title: Biomphalaria tenagophila: dynamics of populations of resistant and susceptible strains to Schistosoma mansoni, with or without pressure of the parasite.
abstract: Resistant (Taim, RS) and susceptible albino (Joinville, SC) Biomphalaria tenagophila populations were kept together, at different proportions, throughout a 18-month-period. Some of the snail groups were submitted to Schistosoma mansoni infection. The targets of this study were (a) to analyze the populational dynamics among resistant and susceptible individuals to S. mansoni; (b) to study the resistance phenotype in descendants of cross-breeding; (c) to observe whether the parasite could exert any kind of selection in those snail populations. Throughout the experiment it could be observed that the susceptible B. tenagophila strain (Joinville) underwent a selective pressure of the parasite that was negative, since the individuals showed a high mortality rate. Although B. tenagophila (Taim) population presented a higher mortality rate without pressure of the parasite, this event was compensated by a reproductive capacity. B. tenagophila Taim was more fecund than B. tenagophila Joinville and was able to transmit the resistance character to their descendants. F1 generation obtained by cross-breeding between resistant and susceptible lineages was completely resistant to S. mansoni infection, irrespective of the Taim proportion. Moreover, less than 5% of F2 progeny were susceptible to S. mansoni infection.
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-901 Belo Horzonte, MG, Brazil.
authors.forename: Florence Mara
authors.initials: FM
authors.lastname: Rosa
authors.forename: Ana Lúcia Brunialti
authors.initials: AL
authors.lastname: Godard
authors.forename: Deborah
authors.initials: D
authors.lastname: Negrão-Correa
authors.forename: Horácio Antonio
authors.initials: HA
authors.lastname: Rodrigues
authors.forename: Omar Dos Santos
authors.initials: Odos S
authors.lastname: Carvalho
authors.forename: Roberta Lima
authors.initials: RL
authors.lastname: Caldeira
authors.forename: Horácio Manoel Santana
authors.initials: HM
authors.lastname: Teles
authors.forename: Engels
authors.initials: E
authors.lastname: Maciel
authors.forename: Liana Konovaloff
authors.initials: LK
authors.lastname: Jannotti-Passos
authors.forename: Paulo Marcos Zech
authors.initials: PM
authors.lastname: Coelho
mesh_terms: D000818:Animals; D001700:Biomphalaria / Q000235:genetics* / Q000469:parasitology; D001947:Breeding / Q000379:methods*; D003433:Crosses, Genetic; D004199:Disease Vectors; D005799:Genes, Dominant / Q000235:genetics*; D006790:Host-Parasite Interactions / Q000235:genetics; D011157:Population Dynamics; D012550:Schistosoma mansoni / Q000502:physiology*