Marcela Videira

Infection of the heart of Pimelodus ornatus (Teleostei, Pimelodidae), by Myxobolus sp. (Myxozoa, Myxobolidae)

The phylum Myxozoa Grassé, 1970, consists of a heterogenous group of around 50 genera that are worldwide disseminated in a wide variety of aquatic media. In the present study, 43 specimens of Pimelodus ornatus were collected from an adjacent area to the Cachoeira do Arari municipality on Marajó Island, in the Brazilian state of Pará, in 2013. Macroscopic analysis showed the presence of whitened plasmodia located in the cardiac muscle and also in the region between the bulbus arteriosus and atrium cordis. Microscopic analysis on the parasitized tissues revealed spores that were typically piriform, with the anterior portion slightly narrower than the posterior end. The spore valves were symmetrical. The present species is placed in the genus Myxobolus Butschli, 1882, because of the presence of a pair of equal polar capsules in each spore. The prevalence of parasitism observed was 13.9% (6/43). This research note reports the first occurrence of Myxobolus as a parasite of the heart in the teleostean fish P. ornatus in the Amazon region and confirms the occurrence of secondary myocarditis in this fish, caused by parasitism by Myxobolus sp. The rarity of this parasitic species of Myxobolus at this tissue site, associated with other spore morphology characteristics in the fish, suggests that it is an undescribed species.

Fine structure of the Plasmodia and Myxospore of Ellipsomyxa gobioides n. sp. (Myxozoa) found in the gallbladder of Gobioides broussonnetii (Teleostei: Gobiidae) from the lower Amazon river.

A fish infecting myxosporean Ellipsomyxa gobioides n. sp. is described in the gallbladder of the Amazonian dragon fish Gobioides broussonnetii. Irregular disporous plasmodia (up to ~30 μm in diameter) with long branched and anastomosed pseudopodia were found attached to the gallbladder wall. Mature ellipsoid myxospores occurring floating in the bile measured 6.8 (6.5–7.0) μm (n = 30) long, 7.2 (6.9–7.5) μm (n = 15) wide, and 13.1 (12.8–13.5) (n = 25) thick. They had smooth thin valves elongated in the direction perpendicular to the plane of the straight central transverse sutural line. The two ellipsoidal polar capsules (PC) opened some distance from the sutural line on opposite sides, each measuring 4.6 (4.3–4.8) μm (n = 15) long and 2.5 (2.1–2.7) μm (n = 20) wide. Distance between PC 3.5 (3.1–3.8) μm (n = 15) in apical view. The polar filament was isofilar and consisted of a single coil with five or six turns. The objective of this study was to characterize this new species based on its morphological differences from the three previously described species. This is the first reported species of genus Ellipsomyxa from among the South American fauna.

Gobioides broussonnetii (Gobiidae): a new host for Pterobothrium crassicolle (Trypanorhyncha) on Marajó Island, northern Brazil.

In the present study, the cestoid Pterobothrium crassicolle Diesing, 1850 (Trypanorhyncha), was observed parasitizing specimens of the violet goby (Gobioides broussonnetii Lacepède, 1800) collected from the estuary of the Paracauarí River on Marajó Island in the north of the Brazilian state of Pará, between January 2009 and December 2010. Tissue samples were analyzed, which led to identification of blastocysts containing plerocercoid larvae. These larvae were processed for scanning electron microscopy. Sixty G. broussonnetii specimens were dissected, and P. crassicolle was found in 48 (80%) of them. The violet goby, G. broussonnetii, is a new host for P. crassicolle.

Infection by Henneguya sp. (Myxozoa) in the bone tissue of the gill filaments of the Amazonian catfish Hypophthalmus marginatus (Siluriformes)

This study describes aspects of the infection caused by the myxosporean genus Henneguya, which forms cysts in the bony portion of the gill filaments of Hypophthalmusmarginatus. Specimens of this catfish were acquired dead from artisanal fishermen near the town of Cametá, state of Pará, northern Brazil, between July 2011 and May 2012. They were transported in refrigerated containers to the Carlos Azevedo Research Laboratory at the Federal Rural University of Amazonia, in Belém, where analyses were performed. After confirmation of parasitism by the genus Henneguya, observation were made using optical and differential interference contrast (DIC) microscopy. The histological technique of embedment in paraffin was used. Ziehl-Neelsen staining was applied to the histological sections. Necropsy analyses on specimens of H. marginatus showed that 80% of them (40/50) had cysts of whitish coloration inside the bony portion of the gill filaments, filled with Henneguya spores. The present study found inflammatory infiltrate in the vicinity of the cysts. Furthermore, the special Ziehl-Neelsen staining technique made it possible to mark the Henneguya sp. cysts in the bone tissue and in spore isolates in the gill tissue structure. The descriptions of these histopathological findings show that this parasite is very invasive and causes damage to its host tissues.

Spontaneous multi-cystic peripheral ameloblastoma in the freshwater angelfish, from the Brazilian state of Pará

Este trabalho registra a ocorrencia espontânea de ameloblastoma em P. scalare. O tumor foi obtido a partir de um exemplar de Acara Bandeira, sendo fixado, seccionado, e os fragmentos processados para microscopia de luz e microscopia eletronica de varredura (MEV). O exame macroscopico evidenciou uma massa tumoral que se estendia do rebordo alveolar do maxilar superior a face externa labial. A MEV, a neoplasia apresentou uma serie de espiculas. Microscopicamente, percebia-se um processo neoplasico constituido por tecido conjuntivo de caracteristica mixoide, ricamente vascularizado, onde eram observados fragmentos de tecido osteoide. A amostra revelou proliferacao neoplasica do epitelio odontogenico, onde as celulas neoplasicas se organizavam na forma de palicada. Alteracoes histopatologicas em peixes tem sido uteis biomarcadores do efeito a exposicao a substâncias toxicas, sendo as neoplasias lesoes especificas, comumente encontradas em peixes de areas poluidas, revelando uma associacao entre as lesoes e a exposicao a irritantes.

Hepatic steatosis associated with microsporidiosis in teleost fishes from Marajó Island, Brazil

A total of 40 specimens of the teleost fish Gobioides grahamae Palmer & Wheeler, 1955 were obtained from the municipality of Salvaterra on Marajó Island in the Brazilian state of Pará. Their livers were removed and processed for light microscopy. Overall, 90% of the specimens presented some degree of steatosis of the liver, which was invariably associated with the presence of Microsporidium sp. The present study confirms the occurrence of steatosis in G. grahamae associated with parasitic infections by Microsporidium. The findings indicate that the condition of otherwise healthy fishes in their natural environment may be affected negatively by parasites.

Anatomopathological study of parrot pufferfish Colomesus psittacus parasitized by the aspidogastrean Rohdella sp.

Aspidogastrea are globally-distributed parasites of the class Trematoda, which have been described as pathogens of a range of aquatic organisms, in marine and freshwater environments. The principal morphological characteristic of the group is an adhesive ventral disc, which is responsible for fixing the parasite to the host organism. In this study, 112 specimens of Colomesus psittacus from the municipality of Cametá, in the state of Pará (Brazil), were necropsied. Platyhelminthes of the genus Rohdella attached to the mucous membrane of the fishs intestine by the adhesive disc were observed. Fragments of parasitized tissue were fixed in Davidson solution and then processed and stained with hematoxylin-eosin. Other fragments were fixed in glutaraldehyde, processed and observed under a scanning electron microscope. The prevalence of the parasite was 76.4%, mean intensity of infection was 8.0 and mean abundance was 6.2. The parasitism provoked chronic enteritis with diffused inflammatory infiltration. The adherence of the parasite to the mucous membrane of the intestine resulted in strangulation and hyperplasia of the region, as well as causing hypertrophy of the muscle of the mucous membrane. The present study describes the anatomopathological and ultrastructural aspects of the parasitism of the intestine of C. psittacus by Rohdella sp.

Anatomopathological study of parrot pufferfishColomesus psittacus parasitized by the aspidogastreanRohdella sp.

Aspidogastrea are globally-distributed parasites of the class Trematoda, which have been described as pathogens of a range of aquatic organisms, in marine and freshwater environments. The principal morphological characteristic of the group is an adhesive ventral disc, which is responsible for fixing the parasite to the host organism. In this study, 112 specimens of Colomesus psittacus from the municipality of Cametá, in the state of Pará (Brazil), were necropsied. Platyhelminthes of the genus Rohdella attached to the mucous membrane of the fishs intestine by the adhesive disc were observed. Fragments of parasitized tissue were fixed in Davidson solution and then processed and stained with hematoxylin-eosin. Other fragments were fixed in glutaraldehyde, processed and observed under a scanning electron microscope. The prevalence of the parasite was 76.4%, mean intensity of infection was 8.0 and mean abundance was 6.2. The parasitism provoked chronic enteritis with diffused inflammatory infiltration. The adherence of the parasite to the mucous membrane of the intestine resulted in strangulation and hyperplasia of the region, as well as causing hypertrophy of the muscle of the mucous membrane. The present study describes the anatomopathological and ultrastructural aspects of the parasitism of the intestine of C. psittacus by Rohdella sp.

Estudo anatomopatológico do peixe baiacu papagaioColomesus psittacus parasitado pelo aspidogastreaRohdella sp.

Aspidogastrea are globally-distributed parasites of the class Trematoda, which have been described as pathogens of a range of aquatic organisms, in marine and freshwater environments. The principal morphological characteristic of the group is an adhesive ventral disc, which is responsible for fixing the parasite to the host organism. In this study, 112 specimens of Colomesus psittacus from the municipality of Cametá, in the state of Pará (Brazil), were necropsied. Platyhelminthes of the genus Rohdella attached to the mucous membrane of the fishs intestine by the adhesive disc were observed. Fragments of parasitized tissue were fixed in Davidson solution and then processed and stained with hematoxylin-eosin. Other fragments were fixed in glutaraldehyde, processed and observed under a scanning electron microscope. The prevalence of the parasite was 76.4%, mean intensity of infection was 8.0 and mean abundance was 6.2. The parasitism provoked chronic enteritis with diffused inflammatory infiltration. The adherence of the parasite to the mucous membrane of the intestine resulted in strangulation and hyperplasia of the region, as well as causing hypertrophy of the muscle of the mucous membrane. The present study describes the anatomopathological and ultrastructural aspects of the parasitism of the intestine of C. psittacus by Rohdella sp.

An anatomopathological study of hepatic coccidiosis (Calyptospora sp.) in the Acará-pixuna, Aequidens plagiozonatus Kullander, 1984 from the Brazilian state of Pará

The present study focuses on the anatomopathological alterations provoked by parasitism by Calyptospora sp. in 40 specimens of Aequidens plagiozonatus collected in Para, Brazil. Examinations of the fresh material by compression of the hepatopancreas and histological sections showed immature forms and oocysts characteristic of the genus Calyptospora, in addition to a large quantity of melanomacrophagic centers spread throughout the organ. No significant inflammation of the hepatic tissue was observed. The melanomacrophagic centers and the compression of the hepatocytes are part of the response of the host to the parasite. This study represents the first record of parasitism by Calyptospora in A. plagiozonatus.