RESUMO
A myxosporean parasite in the gill lamellae of the freshwater teleost fish, Sciades herzbergii (Ariidae) (Block, 1794), from the Poti River (Northeast of Brazil) was described by light and electron microscopy studies. Polysporic histozoic cyst-like plasmodia containing several life-cycle stages, including mature spores, were observed. The spores were pyriform and uninucleate, measuring 9.15 +/- 0.39 microm (n = 50) long, 4.36 +/- 0.23 microm (n = 25) wide and 2.61 +/- 0.31 microm (n = 25) thick. Elongated pyriform polar capsules (PC) were of equal size (4.44 +/- 0.41 microm long and 1.41 +/- 0.42 microm in diameter) and each contained a polar filament with 9-10 coils obliquely arranged in relation to the axis of PC. The PC wall was composed of two layers of different electron densities. Histological analysis revealed the close contact of the cyst-like plasmodia with the basal portion of the epithelial gill layer, which exhibited some alterations in the capillary vessels. Based on the morphological and ultrastructural differences, the similarity of the spore features to those of the genus Myxobolus and the specificity of this host to previously described species, we describe a new species named Myxobolus sciades n. sp. in this study.
Assuntos
Doenças dos Peixes/parasitologia , Peixes/parasitologia , Myxobolus/ultraestrutura , Doenças Parasitárias em Animais/parasitologia , Animais , Brasil , Feminino , Brânquias/parasitologia , Estágios do Ciclo de Vida , Masculino , Microscopia Eletrônica de Transmissão , Myxobolus/classificação , Myxobolus/fisiologia , RiosRESUMO
A myxosporean parasite in the gill lamellae of the freshwater teleost fish, Sciades herzbergii (Ariidae) (Block, 1794), from the Poti River (Northeast of Brazil) was described by light and electron microscopy studies. Polysporic histozoic cyst-like plasmodia containing several life-cycle stages, including mature spores, were observed. The spores were pyriform and uninucleate, measuring 9.15 ± 0.39 ìm (n = 50) long, 4.36 ± 0.23 ìm (n = 25) wide and 2.61 ± 0.31 ìm (n = 25) thick. Elongated pyriform polar capsules (PC) were of equal size (4.44 ± 0.41 ìm long and 1.41 ± 0.42 ìm in diameter) and each contained a polar filament with 9-10 coils obliquely arranged in relation to the axis of PC. The PC wall was composed of two layers of different electron densities. Histological analysis revealed the close contact of the cyst-like plasmodia with the basal portion of the epithelial gill layer, which exhibited some alterations in the capillary vessels. Based on the morphological and ultrastructural differences, the similarity of the spore features to those of the genus Myxobolus and the specificity of this host to previously described species, we describe a new species named Myxobolus sciades n. sp. in this study.
Assuntos
Animais , Feminino , Masculino , Doenças dos Peixes/parasitologia , Peixes/parasitologia , Myxobolus/ultraestrutura , Doenças Parasitárias em Animais/parasitologia , Brasil , Brânquias/parasitologia , Estágios do Ciclo de Vida , Microscopia Eletrônica de Transmissão , Myxobolus/classificação , Myxobolus/fisiologia , RiosRESUMO
A myxosporean parasitizing the gill filaments of the freshwater teleost fish Centromochlus heckelii collected in the Tocantins River (Lower Amazonian Region, Brazil) is described using light and electron microscopy. This parasite produces spherical to ellipsoidal cyst-like plasmodia up to 250 mum in diameter, with a thick wall strengthened by several stratified juxtaposed crossed collagen layers, whose thickness varies according to the number of the layers. Several compressed fibroblasts are observed among the collagen fibrils. Deposits of spherical dense material are scattered at the internal periphery of the cysts. Plasmodia and different developmental stages, including immature and mature spores, filled the central region of the cysts. The spore body is ellipsoidal in valvar view and biconvex in sutural view. It is formed by two equal-sized and symmetric valves measuring 12.7 microm long (12.2-13.1) (n=50), 6.6 microm wide (6.3-6.9) (n=25), and 4.0 microm (3.7-4.4) (n=20) thick. A thin layer formed by fine and anastomosed microfibrils is observed at the spore surface. Two equal, elongated pyriform polar capsules measure 2.9 microm (2.7-3.3) x 1.7 microm (1.4-2.0) (n=25), each containing four or five oblique polar filament coils. The binucleated sporoplasm contains numerous spherical sporoplasmosomes, glycogen particles, and a large vacuole with fine granular matrix. Based on the morphological and ultrastructural differences and specificity of the host, we describe this isolate as a new myxosporidian, Myxobolus heckelii n. sp. (Myxozoa, Myxosporea).
Assuntos
Peixes-Gato/parasitologia , Doenças dos Peixes/parasitologia , Myxobolus/ultraestrutura , Esporos de Protozoários/ultraestrutura , Animais , Brasil , Colágenos Fibrilares/ultraestrutura , Fibroblastos/ultraestrutura , Água Doce/parasitologia , Interações Hospedeiro-Parasita , Microscopia Eletrônica de Transmissão , Myxobolus/classificação , Myxobolus/fisiologia , Especificidade da EspécieRESUMO
In this report, we describe the morphology and histopathology of Myxobolus salminus n. sp., a parasite of the gill filaments of wild Salminus brasiliensis (dourado) from the Brazilian Pantanal. The small polysporic plasmodia were approximately 100 microm in diameter and the development was asynchronous. The mature spores were oval to pear shaped and had a smooth wall. The spore measurements were (mean+/-S.D., with range in parentheses): length 10.1+/-0.4 microm (9.6-10.5), width 6.1+/-0.4 microm (5.8-6.6) and thickness 5.0+/-0.6 microm (4.7-5.3). The polar capsules were elongated and of equal size: length 4.6+/-0.2 microm (4.3-4.8) and width 1.7+/-0.1 microm (1.5-1.9). The histological analysis revealed numerous plasmodia in the blood vessels of the gill filaments. The site of parasite development was the wall of the large-caliber blood vessel of the gill filament, with progressive growth towards the lumen, resulting in the obstruction of blood flow, congestion and perivascular edema. The ultrastructural study revealed that the plasmodial wall was composed of two membranes, had numerous pinocytic canals and was in direct contact with the basement membrane of the vessel. The development of the parasite was asynchronous, with mature spores, immature spores and young developmental stages randomly distributed throughout the plasmodium. The prevalence of the parasite was 4.4%, with male and female fish being infected.