RESUMO
Developmental curves for the sister species Chrysomya chloropyga (Wiedemann, 1818) and Chrysomya putoria (Wiedemann, 1830) (Diptera: Calliphoridae) were established at eight and 10 different constant temperatures, respectively, using developmental landmarks and body length as measures of age. The thermal summation constants (K) and developmental threshold (D(0)) were calculated for five developmental landmarks using a previously described method. Isomorphen and isomegalen diagrams were also constructed for the purpose of estimating postmortem intervals (PMIs). Chrysomya chloropyga had an average developmental threshold value (D(0)) of 10.91 degrees C (standard error [SE] = 0.94 degrees C, n = 5), significantly lower than that of C. putoria (13.42 degrees C, SE = 0.45 degrees C, n = 5) (paired t-test: t = - 4.63, d.f. = 8, P < 0.00). Similarly, K values for C. chloropyga were larger than those for C. putoria for all developmental events except onset of the wandering phase. These are the first data that can be used to calculate minimum PMIs and predict population growth of C. chloropyga and C. putoria in Africa; the data indicate that developmental data for one of these species cannot be used as surrogate data for the sister species.
Assuntos
Dípteros/classificação , Dípteros/crescimento & desenvolvimento , África , Animais , Ciências Forenses , Temperatura Alta , Larva/crescimento & desenvolvimento , América do Sul , Fatores de TempoRESUMO
Development of Schistosoma mansoni in the intermediate host Biomphalaria glabrata is influenced by a number of parasite and snail genes. Understanding the genetics involved in this complex host/ parasite relationship may lead to an often discussed approach of introducing resistant B. glabrata into the field as a means of biological control for the parasite. For the snail, juvenile susceptibility to the parasite is controlled by at least four genes, whereas one gene seems to be responsible for adult nonsusceptibility. Obtaining DNA from F2 progeny snails from crosses between parasite-resistant and -susceptible snails, we have searched for molecular markers that show linkage to either the resistant or susceptible phenotype. Both restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) approaches have been used. To date, using a variety of snail and heterologous species probes, no RFLP marker has been found that segregates with either the resistant or susceptible phenotype in F2 progeny snails. More promising results however have been found with the RAPD approach, where a 1.3 kb marker appears in nearly all resistant progeny, and a 1.1 kb marker appears in all susceptible progeny.
Assuntos
Biomphalaria/crescimento & desenvolvimento , Biomphalaria/genética , Biomphalaria/parasitologia , Esquistossomose mansoni/parasitologia , Animais , Interações Hospedeiro-Parasita , Polimorfismo de Fragmento de Restrição , Técnica de Amplificação ao Acaso de DNA Polimórfico , Schistosoma mansoni/crescimento & desenvolvimento , Schistosoma mansoni/isolamento & purificação , Schistosoma mansoni/fisiologiaRESUMO
Interactions between different Biomphalaria glabrata stocks and Schistosoma mansoni strains were studied. A series of inbred stocks of B. glabrata were characterized as to genetic variations in susceptibility at different ages to a series of different S. mansoni strains. A series of inbred strains of S. mansoni were characterized as to genetic variations in infectivity for B. glabrata stocks at different ages. Also described is a process of selection for substrains from a single S. mansoni isolate that differ genetically in snail infectivity.
Assuntos
Biomphalaria/parasitologia , Variação Genética , Schistosoma mansoni/genética , Animais , Biomphalaria/genética , Brasil , República Democrática do Congo , República Dominicana , Egito , Interações Hospedeiro-Parasita , Porto Rico , Schistosoma mansoni/patogenicidade , Schistosoma mansoni/fisiologia , Índias OcidentaisRESUMO
Genetic differences in infectivity for intermediate snail hosts in two strains of S. mansoni from the same geographical area and within a single isolated parasite population are reported. The importance of recognizing the potential for such genetic variation is stressed.
Assuntos
Biomphalaria/parasitologia , Schistosoma mansoni , Animais , Porto RicoRESUMO
Biomphalaria glabrata selected for genetic differences in susceptibility to infection with a Puerto Rican strain of Schistosoma mansoni were exposed to miracidia of a strain of S. mansoni from St Lucia. The St Lucian strain was less infective than the Puerto Rican. Results suggested that in snails susceptible to the Puerto Rican S. mansoni differences in susceptibility to the St Lucian straing were determined by a single gene, with insusceptibility dominant.