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Moluscos hospedeiros intermediários de trematodes: estudo molecular de Helisoma sp. (Gastropoda: planorbidae) de diferentes áreas geográficas
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Ao longo dos tempos a caracterização das diferentes espécies da classe Gastropoda baseava-se apenas em características fenotípicas (morfologia da concha e partes moles), as quais eram insuficientes para distinguir espécies e subespécies. Assim, a caracterização genética desenvolvida nos últimos anos, tem-se mostrado uma boa
ferramenta aplicada á diferenciação molecular de espécies, permitindo uma melhor compreensão sobre moluscos com um importante papel como hospedeiros intermediários de tremátodes e qual a sua posição dentro da família Planorbidae.
Os objectivos deste trabalho foram, por um lado fazer um estudo comparativo de populações de Helisoma sp., de Portugal e Cabo Verde, baseado num estudo molecular utilizando marcadores moleculares, nomeadamente o gene COI do DNA mitocondrial (mtDNA) e o gene 16S do RNA ribossomal (rRNA) e a região interna transcrita (ITS) do DNA ribossomal, e recorrendo à técnica PCR-RFLP, direccionada para a região ITS para a identificação de possíveis polimorfismos e, por outro lado estabelecer uma relação filogenética entre as populações portuguesas e cabo verdianas de Helisoma e outros planorbideos, hospedeiros intermediários de tremátodes.
Os resultados obtidos, para os genes em análise permitiram a identificação de três regiões distintas: Cabo Verde, Madeira e Portugal Continental, esta última formada pelas amostras de Algarve e Coimbra, apesar da distante geográfica que separa cada umas destas duas áreas.
Os resultados obtidos para os genes COI e 16S e para a região ITS, mostraram uma elevada homologia com as espécies Helisoma trivolvis e H. duryi.
Over time the characterization of different species of the Class Gastropoda has solely been based on phenotypic characters (morphology of the shell and soft parts), which were insufficient to distinguish some species and subspecies. Thus, genetic characterization, developed in recent years, has proved a good tool for the molecular differentiation of species, allowing a better understanding of molluscs that have an important role as intermediate hosts of trematodes and of their position within the family Planorbidae. The aims of this research were to make a comparative study of populations of Helisoma sp, from Portugal and Cape Verde, based on a molecular study using molecular markers, including the COI gene of mitochondrial DNA (mtDNA) and 16S ribosomal RNA (rRNA) and the internal transcribed spacer (ITS) of ribosomal DNA, and using PCR-RFLP of the ITS region to identify possible polymorphisms, and on the other hand to establish the phylogenetic relation between populations of Helisoma from Portugal and Cap Verde and other Planorbidae intermediate hots for trematodes. The results for the genes under analysis allowed the identification of three distinct regions: Cape Verde, Madeira and mainland Portugal, the latter formed by the strains of Algarve and Coimbra, despite the geographical distance that separates each one of these two areas. The results obtained for the genes COI and mitochondrial 16S DNA and the ITS region showed high homology to the species Helisoma trivolvis and H. duryi.
Over time the characterization of different species of the Class Gastropoda has solely been based on phenotypic characters (morphology of the shell and soft parts), which were insufficient to distinguish some species and subspecies. Thus, genetic characterization, developed in recent years, has proved a good tool for the molecular differentiation of species, allowing a better understanding of molluscs that have an important role as intermediate hosts of trematodes and of their position within the family Planorbidae. The aims of this research were to make a comparative study of populations of Helisoma sp, from Portugal and Cape Verde, based on a molecular study using molecular markers, including the COI gene of mitochondrial DNA (mtDNA) and 16S ribosomal RNA (rRNA) and the internal transcribed spacer (ITS) of ribosomal DNA, and using PCR-RFLP of the ITS region to identify possible polymorphisms, and on the other hand to establish the phylogenetic relation between populations of Helisoma from Portugal and Cap Verde and other Planorbidae intermediate hots for trematodes. The results for the genes under analysis allowed the identification of three distinct regions: Cape Verde, Madeira and mainland Portugal, the latter formed by the strains of Algarve and Coimbra, despite the geographical distance that separates each one of these two areas. The results obtained for the genes COI and mitochondrial 16S DNA and the ITS region showed high homology to the species Helisoma trivolvis and H. duryi.
Descrição
Palavras-chave
Ciências biomédicas Biologia molecular Gastropoda Trematodes Hospedeiros Moluscos Helisoma
Contexto Educativo
Citação
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Instituto de Higiene e Medicina Tropical