RESUMEN
Species with a broad distribution rarely have the same genetic make-up throughout their entire range. In some cases, they may constitute a cryptic complex consisting of a few species, each with a narrow distribution, instead of a single-, widely distributed species. These differences can have profound impacts for biodiversity conservation planning. The genetic differentiation of four populations of Aegla longirostri, a freshwater crab found in two geographically isolated basins in Rio Grande do Sul State, Brazil, was investigated by analyzing pentanucleotide multi-loci microsatellites in a heteroduplex assay. Although no morphological differences were evident, we found significant genetic differentiation among the four populations, based on F(ST) values and clustering analysis. This high level of differentiation may be indicative of cryptic species in these populations. If this hypothesis is correct, then the species occurring in the Ibicuí-Mirim River, at the southern limit of the Atlantic Rain Forest, would be under threat, considering its very restricted distribution.
Asunto(s)
Anomuros/genética , Variación Genética , Repeticiones de Microsatélite , Animales , Biodiversidad , Brasil , Flujo Genético , Genética de Población , GeografíaRESUMEN
Polymerase chain reaction of a pentanucleotide microsatellite in the U1 snRNA gene complex generated a multiple band pattern due to the priming of paralogous sequences. Denaturation and slow renaturation of polymerase chain reaction products allow the formation of heteroduplex DNA that can be detected by its differential mobility in polyacrylamide gel electrophoresis. Heteroduplex analysis was used to determine if the U1 snRNA microsatellite could be a useful genetic marker in Echinococcus granulosus. A U1 snRNA microsatellite fragment from E. granulosus was isolated and characterized by Southern blot and sequencing. Four E. granulosus strains were analyzed: sheep, Tasmanian sheep, cattle, and camel strains. The former two showed polymorphism and shared three of the six patterns found for sheep strain. The cattle strain displayed two patterns, and the camel strain was monomorphic. The electrophoretic profiles were used for statistical analysis in order to determine genetic distance and the relationship among strains. Heteroduplex analysis can be helpful in genotyping E. granulosus strains and is useful in detecting polymorphism within strains.
Asunto(s)
Echinococcus granulosus/genética , Repeticiones de Microsatélite/genética , Polimorfismo Genético/genética , ARN Nuclear Pequeño/genética , Animales , Secuencia de Bases , Southern Blotting , Camelus , Bovinos , Electroforesis en Gel de Poliacrilamida , Marcadores Genéticos , Análisis Heterodúplex , Humanos , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , OvinosRESUMEN
Polymerase chain reaction of a pentanucleotide microsatellite in the U1 snRNA gene complex generated a multiple band pattern due to the priming of paralogous sequences. Denaturation and slow renaturation of polymerase chain reaction products allow the formation of heteroduplex DNA that can be detected by its differential mobility in polyacrylamide gel electrophoresis. Heteroduplex analysis was used to determine if the U1 snRNA microsatellite could be a useful genetic marker in Echinococcus granulosus. A U1 snRNA microsatellite fragment from E. granulosus was isolated and characterized by Southern blot and sequencing. Four E. granulosus strains were analyzed: sheep, Tasmanian sheep, cattle, and camel strains. The former two showed polymorphism and shared three of the six patterns found for sheep strain. The cattle strain displayed two patterns, and the camel strain was monomorphic. The electrophoretic profiles were used for statistical analysis in order to determine genetic distance and the relationship among strains. Heteroduplex analysis can be helpful in genotyping E. granulosus strains and is useful in detecting polymorphism within strains.