S U M M A R YThe taxonomic and phylogenetic relationships of Trypanosoma vivax are controversial. It is generally suggested that South American, and East and West African isolates could be classified as subspecies or species allied to T. vivax. This is the first phylogenetic study to compare South American isolates (Brazil and Venezuela) with West/East African T. vivax isolates. Phylogeny using ribosomal sequences positioned all T. vivax isolates tightly together on the periphery of the clade containing all Salivarian trypanosomes. The same branching of isolates within T. vivax clade was observed in all inferred phylogenies using different data sets of sequences (SSU, SSU plus 5.8S or whole ITS rDNA). T. vivax from Brazil, Venezuela and West Africa (Nigeria) were closely related corroborating the West African origin of South American T. vivax, whereas a large genetic distance separated these isolates from the East African isolate (Kenya) analysed. Brazilian isolates from cattle asymptomatic or showing distinct pathology were highly homogeneous. This study did not disclose significant polymorphism to separate West African and South American isolates into different species/subspecies and indicate that the complexity of T. vivax in Africa and of the whole subgenus Trypanosoma (Duttonella) might be higher than previously believed.
Trypanosoma (Megatrypanum) theileri from cattle and trypanosomes of other artiodactyls form a clade of closely related species in analyses using ribosomal sequences. Analysis of polymorphic sequences of a larger number of trypanosomes from broader geographical origins is required to evaluate the clustering of isolates as suggested by previous studies. Here, we determined the sequences of the spliced leader (SL) genes of 21 isolates from cattle and 2 from water buffalo from distant regions of Brazil. Analysis of SL gene repeats revealed that the 5S rRNA gene is inserted within the intergenic region. Phylogeographical patterns inferred using SL sequences showed at least 5 major genotypes of T. theileri distributed in 2 strongly divergent lineages. Lineage TthI comprises genotypes IA and IB from buffalo and cattle, respectively, from the Southeast and Central regions, whereas genotype IC is restricted to cattle from the Southern region. Lineage TthII includes cattle genotypes IIA, which is restricted to the North and Northeast, and IIB, found in the Centre, West, North and Northeast. PCR-RFLP of SL genes revealed valuable markers for genotyping T. theileri. The results of this study emphasize the genetic complexity and corroborate the geographical structuring of T. theileri genotypes found in cattle.
RESUMO Na região oeste do Rio Grande do Norte, diversos surtos de intoxicação em ovinos têm sido atribuídos ao consumo de Blutaparon portulacoides, conhecida como pirrixiu, bredo-de-praia e capotiraguá. No entanto, não há nenhum trabalho na literatura avaliando se realmente ocorre intoxicação por esta planta. Assim, o presente trabalho tem por objetivo determinar se o pirrixiu pode promover intoxicação nos ovinos. Foram utilizadas 3 ovelhas SRD, com aproximadamente 6 meses de idade, saudáveis pesando aproximadamente 15 kg. Elas receberam, como alimento exclusivo, fardos de pirrixiu por um período de 3 meses. A planta e a água foram ofertados ad libitum durante todo o período experimental. Os animais foram diariamente monitorados para determi nação de possíveis alterações clínicas. Após três meses da administração, as ovelhas foram abatidas, sendo coletados fragmentos de intestino grosso, intestino delgado, fígado, rins, rúmen, retículo, omaso e abomaso para análise histopatológica. Também foram coletadas partes aéreas de B. portulacoides para determinação das concentrações dos íons sódio, fósforo, potássio, cálcio, magnésio, cobre, zinco, ferro e manganês. Foi verificada que a alimentação exclusiva de ovinos com B. portulacoides é responsável por distúrbios no trato digestório, caracterizados por amole cimento das fezes e lesões no epitélio intestinal (desprendimento do epitélio das vilosidades intestinais, hiperplasia das células caliciformes, infiltrado inflamatório na submucosa e infiltrado de células mononucleares na lâmina própria). O possível mecanismo da intoxicação é o desequilíbrio osmótico no trato digestório promovido pela deficiência de sódio e excesso de magnésio, potássio e cálcio na planta.
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