Myxobolus sp. (Myxozoa) in the circulating blood of Colossoma macropomum (Osteichthyes, Characidae)

Myxosporea parasitize many organs in fresh and saltwater fish. Species of the genus Myxobolus parasitizing the gills and other organs of the tambaqui Colossoma macropomum have been described. In the present study, blood smears were made from juvenile tambaqui and were stained with May Grunwald-Giemsa-Wright in order to identify myxozoan parasites. Out of a total of 36 fish examined, one specimen (2.7%) that was reared in a cage presented spores that were identified as M. colossomatis, whereas fish kept in 250 L tanks showed prevalence of 5.5%. This is the first report of M. colossomatis in the blood of farmed tambaqui in the Amazon region. These results indicate that myxozoan parasites should also be investigated in fish blood smears. Some myxosporean species may cause diseases in fish, and these species need to be identified so that adequate preventive sanitary control can be instituted.

Mixosporídeos parasitam diversos órgãos de peixes de água doce e salgada, tendo sido descrita espécie do gênero Myxobolus parasitando brânquias e outros órgãos de tambaqui Colossoma macropomum. No presente trabalho, extensões sanguíneas de juvenis de tambaquis foram confeccionadas e coradas com May Grunwald-Giemsa-Wright para identificação de parasitos myxozoários. Do total de 36 peixes examinados, um espécime (2,7%) cultivado em tanque-rede apresentou esporos identificados como M. colossomatis, enquanto os peixes mantidos em tanques com 250 L apresentaram prevalência de 5,5%. Esse é o primeiro registro de M. colossomatis no sangue de tambaqui cultivado na Amazônia. Esses resultados indicam que parasitos Myxozoa devem ser também investigados em extensões sanguíneas. Algumas espécies de mixosporídeos podem causar doença em peixes, sendo necessária a identificação da espécie para um adequado manejo sanitário preventivo.

Hypercarbic cardiorespiratory reflexes in the facultative air-breathing fish jeju (Hoplerythrinus unitaeniatus): the role of branchial CO2 chemoreceptors.

The aim of the present study was to determine the roles that externally versus internally oriented CO(2)/H(+)-sensitive chemoreceptors might play in promoting cardiorespiratory responses to environmental hypercarbia in the air-breathing fish, Hoplerythrinus unitaeniatus (jeju). Fish were exposed to graded hypercarbia (1, 2.5, 5, 10 and 20% CO(2)) and also to graded levels of environmental acidosis (pH approximately 7.0, 6.0, 5.8, 5.6, 5.3 and 4.7) equal to the pH levels of the hypercarbic water to distinguish the relative roles of CO(2) versus H(+). We also injected boluses of CO(2)-equilibrated solutions (5, 10 and 20% CO(2)) and acid solutions equilibrated to the same pH as the CO(2) boluses into the caudal vein (internal) and buccal cavity (external) to distinguish between internal and external stimuli. The putative location of the chemoreceptors was determined by bilateral denervation of branches of cranial nerves IX (glossopharyngeal) and X (vagus) to the gills. The data indicate that the chemoreceptors eliciting bradycardia, hypertension and gill ventilatory responses (increased frequency and amplitude) to hypercarbia are exclusively branchial, externally oriented and respond specifically to changes in CO(2) and not H(+). Those involved in producing the cardiovascular responses appeared to be distributed across all gill arches while those involved in the gill ventilatory responses were located primarily on the first gill arch. Higher levels of aquatic CO(2) depressed gill ventilation and stimulated air breathing. The chemoreceptors involved in producing air breathing in response to hypercarbia also appeared to be branchial, distributed across all gill arches and responded specifically to changes in aquatic CO(2). This would suggest that chemoreceptor groups with different orientations (blood versus water) are involved in eliciting air-breathing responses to hypercarbia in jeju.

The combined effect of copper and low pH on antioxidant defenses and biochemical parameters in neotropical fish pacu, Piaractus mesopotamicus (Holmberg, 1887).

Copper sulfate is widely used in aquaculture. Exposure to this compound can be harmful to fish, resulting in oxidative metabolism alterations and gill tissue damage. Pacu, Piaractus mesopotamicus, (wt = 43.4 +/- 3.35 g) were distributed in experimental tanks (n = 10; 180 l) and exposed for 48 h to control (without copper addition), 0.4Cu (0.4 mg l(-1)), 0CupH (without copper addition, pH = 5.0) and 0.4CupH (0.4 mg l(-1), pH = 5.0). In liver and red muscle, the superoxide dismutase (SOD) was responsive to the increases in the aquatic copper. The plasmatic intermediary metabolites and hematological variables in the fish of group 0.4Cu were similar to those of the control group. Conversely, the exposure to 0.4CupH caused an increase in the plasmatic lactate, number of red blood cells (RBC) and hemoglobin (Hb). Plasmatic copper concentration [Cu(p)] increased in group 0.4Cu and 0.4CupH, which is higher in group 0.4CupH, suggests an effect of water pH on the absorbed copper. Exposure to 0.4Cu and 0.4CupH resulted in a reduction in the Na(+)/K(+)-ATPase activity and an increase in metallothionein (MT) in the gills. Exposure to 0CupH caused a decrease in glucose and pyruvate concentrations and an increase in RBC, Hb, and the branchial Na(+)/K(+)-ATPase activity. These responses suggest that the fish triggered mechanisms to revert the blood acidosis, save energy and increase the oxygen uptake. MT was an effective biomarker, responding to copper in different pHs and dissolved oxygen. Combined-factors caused more significant disturbance in the biomarkers than single-factors.

Antioxidant defenses and biochemical changes in pacu (Piaractus mesopotamicus) in response to single and combined copper and hypoxia exposure.

The effect of combined-factors (hypoxia+copper) on the biochemical parameters and antioxidant defenses were studied in the neotropical fish Piaractus mesopotamicus. Fish were exposed for 48 h to 0.4 mg Cu(2+) L(-1) (0.4Cu), hypoxia=50 mm Hg (Hpx), and 0.4 mg Cu(2) L(-1)+hypoxia=50 mm Hg (0.4CuHpx). The exposure to 0.4Cu increased the reactive oxygen species (ROS) in the liver, accompanied by increases in superoxide dismutase (SOD) and decreases in catalase (CAT) activity, showing the influence of copper in this protection. The exposure to Hpx decreased the activity of glutathione peroxidase (GSH-Px) and CAT. Exposure to a combined-factor caused an increase in the ROS production followed by an increase in SOD and a decrease in GSH-Px and CAT. At 0.4Cu, fish presented a reduction in CAT, while in Hpx decreases in SOD, CAT and GSH-Px were observed in red muscles. Single-factors were insufficient to cause ROS production. In combined-factors, increased ROS formation and decreased SOD, CAT and GSH-Px were observed. RBC increased in all groups, but only under combined-factors was there an increase in hemoglobin. Copper plasma concentration increased in groups exposed to copper. Na(+)/K(+)-ATPase activity in gills decreased in 0.4Cu and 0.4CuHpx, and increased in Hpx. Metallothionein concentration in gills increased under combined-factors. Combined-factors caused significant disturbances in the antioxidant defenses and biochemical parameters than single-factors.

Inoculação de suspensão bacteriana de Plesiomonas shigelloides em Jundiá, Rhamdia quelen (Teleostei: Pimelodidae)

As worldwide aquaculture has grown, and intensification in fish raising, the animals are subject to bacterial diseases and others. With the aim of evaluating pathogenicity of Plesiomonas shigelloides for "jundiá" (Rhamdia quelen), different bacterial concentrations (3 x 10(8) e 9 x 10(8) CFU - Colony Former Unit/ml) were inoculated via peritoneum. Eigthy four juvenile "jundiá" averaging 24.37 ± 4,28g of weight and 14.42 ± 1,62cm of length were utilized. The inoculated animals were maintained for 21 days, in asbestos water tanks, at similar temperature, pH, alkalinity and hardness conditions. The "jundiás" were slaughtered every other day for counting UFC/ml renal tissue. For daily inspections, it was observed that intraperitoneal inoculation of Plesiomonas shigelloides did not cause any change in the catfishes, regardless inoculated concentration. Bacteria counting in "jundiás" kidneys was maintained between 10(5) and 10(6) UFC/ml until the 21st day, when the experiment was ended.

Com o crescimento da aqüicultura mundial e intensificação da criação de peixes, os animais ficam sujeitos às enfermidades bacterianas e outras. Com o objetivo de avaliar a patogenicidade da Plesiomonas shigelloides para jundiás (Rhamdia quelen), diferentes concentrações bacterianas (3 x 10(8) e 9 x 10(8) UFC - Unidade Formadora de Colônia/ml) foram inoculadas por via intraperitoneal. Foram utilizados 84 jundiás juvenis com peso e comprimento médios de 24,37 ± 4,28g e 14,42 ± 1,62cm, respectivamente. Os animais inoculados foram mantidos durante 21 dias, em caixas d'agua de amianto, em condições semelhantes de temperatura, pH, alcalinidade e dureza. Os jundiás foram sacrificados a cada dois dias para contagem de UFC/ml de tecido renal. Por observações diárias, constatou-se que a inoculação intraperitoneal de Plesiomonas shigelloides não ocasionou nenhuma alteração nos jundiás, independente da concentração inoculada. As contagens das bactérias nos rins dos jundiás mantiveram-se entre 10(5) e 10(6)UFC/ml até o 21º dia, quando o experimento foi finalizado.

Alterações histológicas e comportamentais provocadas pela inoculação de suspensão bacteriana (Aeromonas hydrophila) em juvenis de jundiá (Rhamdia quelen)

The purpose of this study was to evaluate the histological and behavior alterations induced by the inoculation of different concentrations of Aeromonas hydrophila in jundiás. Eighty (80) animals were used in this study, with 16.55g of weight and 13.23cm of length. Different bacterial concentrations (3.6 x 10(7) and 7.5 x 10(6)UFC - Unity Formation of Colony/ml of saline solution) were inoculated intramuscularly. The animals were kept for 10 days in amianthus aquarium (250 liters) with similar conditions of temperature, pH, alkalinity and hardness. The jundiás were observed daily and the dying ones were used for histological cuts. It was verified that the Aeromonas hydrophila caused balance loss, apathy, exophthalmia and histological alterations like necrosis, hemorrhage and inflammatory infiltrated, reaching the epidermis layer as well as the derme and musculature.

Com objetivo de avaliar as alterações histológicas e comportamentais provocadas pela Aeromonas hydrophila em Rhamdia quelen, diferentes concentrações bacterianas (3,6 x 10(7) e 7,5 x 10(6)UFC - Unidade Formadora de Colônia/ml de solução salina) foram inoculadas por via intramuscular. Para este estudo, foram utilizados 80 juvenis de jundiá com peso e comprimento de 16,55g e 13,23cm, respectivamente. Esses peixes foram mantidos durante 10 dias, em caixas d'água de 250 litros, com condições iguais de temperatura, pH, alcalinidade e dureza. Os jundiás foram observados diariamente e, os moribundos, submetidos a cortes histológicos. Constatou-se então que a Aeromonas hydrophila causa perda de equilíbrio, apatia e exoftalmia, assim como alterações histológicas na pele do tipo necrose, hemorragia e infiltrado inflamatório, atingindo tanto a camada da epiderme como da derme e musculatura.

Alterações histológicas e comportamentais provocadas pela inoculação de suspensão bacteriana (Aeromonas hydrophila) em juvenis de jundiá (Rhamdia quelen)

The purpose of this study was to evaluate the histological and behavior alterations induced by the inoculation of different concentrations of Aeromonas hydrophila in jundiás. Eighty (80) animals were used in this study, with 16.55g of weight and 13.23cm of length. Different bacterial concentrations (3.6 x 10(7) and 7.5 x 10(6)UFC - Unity Formation of Colony/ml of saline solution) were inoculated intramuscularly. The animals were kept for 10 days in amianthus aquarium (250 liters) with similar conditions of temperature, pH, alkalinity and hardness. The jundiás were observed daily and the dying ones were used for histological cuts. It was verified that the Aeromonas hydrophila caused balance loss, apathy, exophthalmia and histological alterations like necrosis, hemorrhage and inflammatory infiltrated, reaching the epidermis layer as well as the derme and musculature.

Com objetivo de avaliar as alterações histológicas e comportamentais provocadas pela Aeromonas hydrophila em Rhamdia quelen, diferentes concentrações bacterianas (3,6 x 10(7) e 7,5 x 10(6)UFC - Unidade Formadora de Colônia/ml de solução salina) foram inoculadas por via intramuscular. Para este estudo, foram utilizados 80 juvenis de jundiá com peso e comprimento de 16,55g e 13,23cm, respectivamente. Esses peixes foram mantidos durante 10 dias, em caixas d'água de 250 litros, com condições iguais de temperatura, pH, alcalinidade e dureza. Os jundiás foram observados diariamente e, os moribundos, submetidos a cortes histológicos. Constatou-se então que a Aeromonas hydrophila causa perda de equilíbrio, apatia e exoftalmia, assim como alterações histológicas na pele do tipo necrose, hemorragia e infiltrado inflamatório, atingindo tanto a camada da epiderme como da derme e musculatura.

Inoculação bacteriana de Aeromonas hydrophila e a sobrevivência de juvenis de jundiá, Rhamdia quelen (Teleostei: Pimelodidae)

The present work studied the resistance of the "Jundiá" (Rhamdia quelen), after intramuscular inoculation with 1.3 x 10(9) and 3.5 x 10(8) UFC (Unity Formation of Colony) suspension of Aeromonas hydrophila/m img border=0 id="_x0000_i1028" src="/img/revistas/cr/v31n3/a24img01.gif"> saline solution. Thirty two fish of a total of 96 utilized fish served as control that werw inoculated with saline solution. Fish were distributed in six amianthus aquarium. After inoculation, fish submitted to bacterial suspensions showed behaviour changes and apathy at the botton of aquarium. One hundred percent of mortality was observed 24 hours after inoculation. In conclusion, 1.3 x 10(9) and 3.5 x 10(8)UFC/m img border=0 id="_x0000_i1029" src="/img/revistas/cr/v31n3/a24img01.gif"> saline solution were lethal for this species of fish.

Visando a estudar a resistência do jundiá (Rhamdia quelen), é que se inoculou, por via intramuscular, as suspensões de 1,3 x 10(9) e 3,5 x 10(8) UFC (Unidades Formadoras de Colônia) de Aeromonas hydrophila/m img border=0 id="_x0000_i1025" src="/img/revistas/cr/v31n3/a24img01.gif"> de solução salina. Dos 96 juvenis submetidos à inoculação, distribuídos em seis caixas d'água de amianto, 32 constituíram o grupo controle, em que os animais foram injetados com solução salina esterilizada. A partir do momento da inoculação de 1m img border=0 id="_x0000_i1026" src="/img/revistas/cr/v31n3/a24img01.gif"> do respectivo tratamento, foi observado que os peixes inoculados com a bactéria tiveram seu comportamento alterado, permaneceram estáticos no fundo da caixa e apresentaram 100% de mortalidade em 24 horas. Os peixes do grupo controle injetados com salina não apresentaram nenhuma anormalidade no comportamento. Sendo assim, é possível concluir que as concentrações 1,3 x 10(9) e 3,5 x 10(8)UFC/m img border=0 id="_x0000_i1027" src="/img/revistas/cr/v31n3/a24img01.gif"> de solução salina são letais para juvenis de jundiá.

Inoculação de suspensão bacteriana de Plesiomonas shigelloides em Jundiá, Rhamdia quelen (Teleostei: Pimelodidae)

As worldwide aquaculture has grown, and intensification in fish raising, the animals are subject to bacterial diseases and others. With the aim of evaluating pathogenicity of Plesiomonas shigelloides for "jundiá" (Rhamdia quelen), different bacterial concentrations (3 x 10(8) e 9 x 10(8) CFU - Colony Former Unit/ml) were inoculated via peritoneum. Eigthy four juvenile "jundiá" averaging 24.37 ± 4,28g of weight and 14.42 ± 1,62cm of length were utilized. The inoculated animals were maintained for 21 days, in asbestos water tanks, at similar temperature, pH, alkalinity and hardness conditions. The "jundiás" were slaughtered every other day for counting UFC/ml renal tissue. For daily inspections, it was observed that intraperitoneal inoculation of Plesiomonas shigelloides did not cause any change in the catfishes, regardless inoculated concentration. Bacteria counting in "jundiás" kidneys was maintained between 10(5) and 10(6) UFC/ml until the 21st day, when the experiment was ended.

Com o crescimento da aqüicultura mundial e intensificação da criação de peixes, os animais ficam sujeitos às enfermidades bacterianas e outras. Com o objetivo de avaliar a patogenicidade da Plesiomonas shigelloides para jundiás (Rhamdia quelen), diferentes concentrações bacterianas (3 x 10(8) e 9 x 10(8) UFC - Unidade Formadora de Colônia/ml) foram inoculadas por via intraperitoneal. Foram utilizados 84 jundiás juvenis com peso e comprimento médios de 24,37 ± 4,28g e 14,42 ± 1,62cm, respectivamente. Os animais inoculados foram mantidos durante 21 dias, em caixas d'agua de amianto, em condições semelhantes de temperatura, pH, alcalinidade e dureza. Os jundiás foram sacrificados a cada dois dias para contagem de UFC/ml de tecido renal. Por observações diárias, constatou-se que a inoculação intraperitoneal de Plesiomonas shigelloides não ocasionou nenhuma alteração nos jundiás, independente da concentração inoculada. As contagens das bactérias nos rins dos jundiás mantiveram-se entre 10(5) e 10(6)UFC/ml até o 21º dia, quando o experimento foi finalizado.