ABSTRACT
BACKGROUND Didelphis spp. are a South American marsupial species that are among the most ancient hosts for the Trypanosoma spp. OBJECTIVES We characterise a new species (Trypanosoma janseni n. sp.) isolated from the spleen and liver tissues of Didelphis aurita in the Atlantic Rainforest of Rio de Janeiro, Brazil. METHODS The parasites were isolated and a growth curve was performed in NNN and Schneider's media containing 10% foetal bovine serum. Parasite morphology was evaluated via light microscopy on Giemsa-stained culture smears, as well as scanning and transmission electron microscopy. Molecular taxonomy was based on a partial region (737-bp) of the small subunit (18S) ribosomal RNA gene and 708 bp of the nuclear marker, glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) genes. Maximum likelihood and Bayesian inference methods were used to perform a species coalescent analysis and to generate individual and concatenated gene trees. Divergence times among species that belong to the T. cruzi clade were also inferred. FINDINGS In vitro growth curves demonstrated a very short log phase, achieving a maximum growth rate at day 3 followed by a sharp decline. Only epimastigote forms were observed under light and scanning microscopy. Transmission electron microscopy analysis showed structures typical to Trypanosoma spp., except one structure that presented as single-membraned, usually grouped in stacks of three or four. Phylogeography analyses confirmed the distinct species status of T. janseni n. sp. within the T. cruzi clade. Trypanosoma janseni n. sp. clusters with T. wauwau in a well-supported clade, which is exclusive and monophyletic. The separation of the South American T. wauwau + T. janseni coincides with the separation of the Southern Super Continent. CONCLUSIONS This clade is a sister group of the trypanosomes found in Australian marsupials and its discovery sheds light on the initial diversification process based on what we currently know about the T. cruzi clade.
Subject(s)
Humans , Trypanosoma , Trypanosomatina , Didelphis/classification , Phylogeography , BrazilABSTRACT
O objetivo deste estudo foi avaliar o efeito da estimulação elétrica transcutânea de alta freqüência nas alterações morfológicas do músculo tríceps sural depois da lesão nervosa periférica do nervo ciático em ratos. Quarenta ratos foram divididos em 4 grupos: controle negativo (sem lesão), controle positivo (com lesão), lesados e tratados com 4 mA e lesados e tratados com 6 mA. Entre o grupo controle positivo (5,7 ± 2,4) e controle negativo (36,3 ± 6,15) observamos uma diminuição significativa na densidade relativa de tecido muscular e conjuntivo, demonstrando a efetividade do modelo experimental. Entre os grupos tratados não houve diferença estatística, entretanto, ocorreu um aumento significativo na densidade relativa entre os grupos tratados com 4 mA (16,35 ± 0,46) e 6 mA (14,4 ± 2,63) em relação ao grupo controle positivo (5,7 ± 2,4), indicando a diminuição da proliferação de tecido conjuntivo nas amostras analisadas. Nossos resultados indicam que a estimulação elétrica transcutânea de alta freqüência, dentro desses parâmetros, foi efetiva na diminuição da proliferação de tecido conjuntivo no grupo muscular tríceps sural de ratos após lesão nervosa periférica por esmagamento do nervo ciático.
The aim of this study was to evaluate the effect of the transcutaneous electric stimulation of high frequency in the morphological alterations of the triceps surae muscle after peripheral nervous injury of the sciatic nerve in rats. Forty rats were divided into 4 groups: negative control (without injury), positive control (with injury), injured and treated with 4 mA and injured and treated with 6 mA. Between the positive control group (5.7 ± 2.4) and negative control group (36.3 ± 6.15) it was observed a significant decrease in relative density of muscular tissue and conjunctive tissue, showing the effectiveness of the experimental model. We did not observe difference between the treated groups. However, a significant increase in the relative density occurred between the treated groups with 4 mA (16.35 ± 0.46) and 6 mA (14.4 ± 2.63) in relation to the positive control group (5.7 ± 2.4), indicating the reduction of the conjunctive tissue proliferation in the analyzed samples. Our results indicate that the transcutaneous electric stimulation of high frequency, within these parameters, was effective in reducing conjunctive tissue proliferation in triceps surae muscle of rats after peripheral nervous injury for crushing of the sciatic nerve.