Aquatic organisms are increasingly exposed to lowering of environmental pH due to anthropogenic pressure (e.g. acid rain, acid mine drainages). Such acute variations trigger imbalance of fish-associated microbiota, which in turn favour opportunistic diseases. We used the tambaqui (Colossoma macropomum), an Amazonian fish tolerant to significant pH variation in its natural environment, to assess the response of fish endogenous microbiota to acute short-term acid stress. We exposed 36 specimens of tambaquis to acidic water (pH 4.0) over 2 consecutive weeks and sampled cutaneous mucus, feces and water at 0, 7 & 14 days. The 16S RNA hypervariable region V4 was sequenced on Illumina MiSeq. After two weeks of acidic exposure, fecal and skin microbiota taxonomic structures exhibited different patterns: skin microbiota was still exhibiting a significantly disturbed composition whereas fecal microbiota recovered a similar composition to control group, thus suggesting a stronger resilience capacity of the intestinal microbiota than cutaneous microbiota.

/pdf/ph-drop-impacts-differentially-skin-and-gut-microbiota-of-27sesm4z8k.pdf

pH drop impacts differentially skin and gut microbiota of the Amazonian fish tambaqui (Colossoma macropomum)

Formation of self-assembled polyelectrolyte complex hydrogel derived from salecan and chitosan for sustained release of Vitamin C.

Hematological methods in fish – Not only for beginners

Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

Tambaqui Colossoma macropomum (Cuvier) is a fish of primary importance in Amazon aquaculture. It has been described as an acid-resistant species that moves seasonally between white (muddy) water and black water rivers and enters the extremely dilute acidic areas of flooded jungle to feed during the rainy season. To analyse the pH tolerance of this species, tambaqui were exposed to three water pH levels for 40 days (pH 4.0, 6.0 and 8.0). The water was acidified slowly over 3 h, allowing the fish to acclimate. A similar protocol was used to adjust water pH to 8.0. No mortality was observed during the exposure period. Several haematological parameters were significantly changed in alkaline-exposed animals, with significant decreases in haematocrit (20%), haemoglobin concentration (8%) and red blood cells (12%). Tambaqui showed severe blood variations when exposed to alkaline pH. Fish final weight, condition factor and specific growth rate (SGR) was inversely proportional to a pH increase, and SGR were higher for fish reared in acidic water. The relative insensitivity of tambaqui to low pH confirms its acid tolerance and is in accordance with its natural occurrence in black water habitats.

Tolerance response of tambaqui Colossoma macropomum (Cuvier) to water pH

Tambaqui, Colossoma macropomum, were fed with three vitamin C levels and two iron levels for 21 d: Diet 1 without vitamin C and with 30 mg of iron/kg; Diet 2 with 100 mg of vitamin C and 30 mg of iron/kg; and Diet 3 with 100 mg of vitamin C and 300 mg of iron/kg. Mortality was not observed during the feeding experiment. There were no changes in hematological parameters in fish that were fed the different diets. Iron contents in liver, muscle, and plasma were significantly different in fish fed with different iron content in the diets; when associated with vitamin C, changes were observed only for plasma iron. Therefore, tambaqui exhibits varied iron absorption in response to different levels of iron with and without vitamin C, a conclusion consistent with findings for other species of fish.

Ascorbic Acid (Vitamin C) and Iron Concentration in Tambaqui, Colossoma macropomum, Iron Absorption

The use of different photoperiods (light) were investigated during tambaqui (Colossoma macropomum) juvenile growth under captivity. Light intensity tested was: continuous dark (24hrs without light), natural photoperiod simulation (10hrs of light and 14hrs without light) and continuous light (24 with light). No mortality was recorded among treatments. Significant differences was observed after 50 days of experiment among mean fish weight, fish kept under a continuous darkness showed a better specific growth rate (6.02%) when compared to control fish (natural photo period, 3.67%). Fish exposed to continuous light presented the lowest mean specific growth rate (2.04%). It is possible to improve tambaqui juvenile weight gain performance when kept under continuous darkness.

/pdf/tambaqui-growth-and-survival-when-exposed-to-different-1ylig7090h.pdf

Tambaqui growth and survival when exposed to different photoperiods

In this work the authors evaluated the expression of cat, glu, cypP450, hsp70 and 18S RNA in Colossoma macropomum following exposure to copper and cadmium by semi-quantitative RT-PCR and quantitative qRT-PCR. In RT-PCR and qRT-PCR hsp70 expression was highest after exposure to copper for 3 hours (h). glu expression increased after exposure to cadmium, regardless of time. cat expression increased after the first hour of exposure to both metals, and decreased after 3 hs. cyp450 expression was higher when compared to controls in exposed fish regardless of metal and exposure time. cyp450 expression after exposure to copper for 3 h was twice that recorded after 1 h. In the presence of cadmium, cyp450 expression was higher in the animals exposed for 1 h and lower at 3 h. Therefore, toxicology tests and biomonitoring based on molecular markers should focus on a set of molecular and/or environmental parameters, rather than isolated markers.

effects of copper and cadmium exposure on mRnA expression of catalase, Glutamine synthetase, cytochrome p450 and Heat shock protein 70 in Tambaqui Fish (Colossoma Macropomum)

Este estudo avaliou a eficacia de tres anticoagulantes em parâmetros sanguineos de arraias cururu Potamotrygon sp. O sangue de dez animais foi coletado e diluido nos anticoagulantes: EDTA 5% e 10%, heparina 2.500 e 5.000 UI e citrato de sodio 3,2%, outra parte do sangue tambem foi analisada sem anticoagulante.  O sangue de 20% e 30% das amostras de sangue que nao continha anticoagulante e citrato de sodio (3,2%), respectivamente, coagularam.  Grumos de celulas foram observados durante a contagem de eritrocitos em 30% das amostras com EDTA 10%, 40% das amostras com heparina 2.500 UI e 60% das amostras com heparina 5.000 UI. Nao foram observadas alteracoes no eritrograma da arraia cururu com diferentes anticoagulantes, os valores da glicose plasmatica foram semelhantes em todos os grupos, enquanto os niveis de proteinas totais foram menores nas amostras coletadas com EDTA 5% e 10%. Em arraias Potamotrygon sp., para a conservacao de amostras de sangue nao e recomendado o uso de citrato de sodio 3.2%, porem, para a determinacao da glicose plasmatica e do eritrograma os anticoagulantes usados nao influenciaram os parâmetros analisados. Portanto, esses resultados indicam que para evitar qualquer sinal de coagulacao do sangue deve ser coletadas amostras diretamente com qualquer uma dessas concentracoes de anticoagulantes. Palavras-chave: potamotrigonideos, anticoagulantes, sangue, hematologia.

https://periodicos.unifap.br/index.php/biota/article/download/1506/v5n3p55-58.pdf

COMPARAÇÃO DOS EFEITOS DE ANTICOAGULANTES USADOS NA COLHEITA SANGUÍNEA PARA A DETERMINAÇÃO DOS PARÂMETROS DO SANGUE EM ARRAIAS DE VIDA LIVRE DO GÊNERO Potamotrygon (ELASMOBRANCHII: POTAMOTRYGONIDAE)

Paulo Henrique Rocha Aride

Papers

Tolerance response of tambaqui Colossoma macropomum (Cuvier) to water pH

Ascorbic Acid (Vitamin C) and Iron Concentration in Tambaqui, Colossoma macropomum, Iron Absorption

Tambaqui growth and survival when exposed to different photoperiods

effects of copper and cadmium exposure on mRnA expression of catalase, Glutamine synthetase, cytochrome p450 and Heat shock protein 70 in Tambaqui Fish (Colossoma Macropomum)

COMPARAÇÃO DOS EFEITOS DE ANTICOAGULANTES USADOS NA COLHEITA SANGUÍNEA PARA A DETERMINAÇÃO DOS PARÂMETROS DO SANGUE EM ARRAIAS DE VIDA LIVRE DO GÊNERO Potamotrygon (ELASMOBRANCHII: POTAMOTRYGONIDAE)