Cholinesterase activities and oxidative stress in cattle experimentally exposed to nitrate/nitrite in cultivated pasture with different fertilization schemes

Background: Nitrate and nitrite poisoning is associated with pasture intake that has high nitrate levels and leads to acute methemoglobinemia. Pasture may accumulate nitrate under certain conditions, such as excessively fertilized soil or environmental conditions that enhance the N absorption (rain preceded by a period of drought). After ingestion of plants, this substrate reaches the rumen and, in physiological conditions, is reduced to nitrite and afterward to ammonia. The aim of this study was to evaluate changes in cholinesterase activities and oxidative stress caused by subclinical poisoning for nitrate and nitrite in cattle fed with Pennisetum glaucum in three different fertilization schemes.Materials, Methods & Results: In order to perform the experimental poisoning, the pasture was cultivated in three different paddocks: with nitrogen topdressing (urea; group 1), organic fertilizer (group 2) or without fertilizer (group 3; control). Nitrate accumulation in forage was evaluated by the diphenylamine test. After food fasting of 12 h, nine bovine were randomly allocated to one of the experimental groups and fed with fresh forage (ad libitum) from respective paddock. In different time points from beginning of pasture intake (0, 2, 4, 6 and 9 h) heart rate and respiratory frequency were assessed, as well as mucous membrane color and behavioral changes. Blood samples from jugular vein into vials with and without anticoagulant were collected. From blood samples, serum nitrite levels, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzyme activity were evaluated, as well as oxidative stress through the following parameters: levels of nitrate/nitrite (NOx ), thiobarbituric acid reactive substances (TBARS) and reactive oxygen species (ROS), beyond the antioxidant system by enzyme activity measurement of catalase (CAT) and superoxide dismutase (SOD).[...]

Cholinesterase activities and oxidative stress in cattle experimentally exposed to nitrate/nitrite in cultivated pasture with different fertilization schemes

Background: Nitrate and nitrite poisoning is associated with pasture intake that has high nitrate levels and leads to acute methemoglobinemia. Pasture may accumulate nitrate under certain conditions, such as excessively fertilized soil or environmental conditions that enhance the N absorption (rain preceded by a period of drought). After ingestion of plants, this substrate reaches the rumen and, in physiological conditions, is reduced to nitrite and afterward to ammonia. The aim of this study was to evaluate changes in cholinesterase activities and oxidative stress caused by subclinical poisoning for nitrate and nitrite in cattle fed with Pennisetum glaucum in three different fertilization schemes.Materials, Methods & Results: In order to perform the experimental poisoning, the pasture was cultivated in three different paddocks: with nitrogen topdressing (urea; group 1), organic fertilizer (group 2) or without fertilizer (group 3; control). Nitrate accumulation in forage was evaluated by the diphenylamine test. After food fasting of 12 h, nine bovine were randomly allocated to one of the experimental groups and fed with fresh forage (ad libitum) from respective paddock. In different time points from beginning of pasture intake (0, 2, 4, 6 and 9 h) heart rate and respiratory frequency were assessed, as well as mucous membrane color and behavioral changes. Blood samples from jugular vein into vials with and without anticoagulant were collected. From blood samples, serum nitrite levels, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzyme activity were evaluated, as well as oxidative stress through the following parameters: levels of nitrate/nitrite (NOx ), thiobarbituric acid reactive substances (TBARS) and reactive oxygen species (ROS), beyond the antioxidant system by enzyme activity measurement of catalase (CAT) and superoxide dismutase (SOD).[...](AU)

Benefits of a prepartum anionic diet on the health of dairy cows in the transition period: prevented subclinical hypocalcemia and minimizing oxidative stress

Background: There are many metabolic diseases that affect dairy cows during the transition period, among them, the postparturient hypocalcemia, also known as milk fever, puerperal paresis syndrome, or fallen cow. This disease may affect animals 72 h after calving due to a nutritional imbalance in the calcium metabolism, which occurs after a sudden demand of this mineral at the beginning of lactation. This problem is more common in animals with high milk production, and usually after the second lactation. Therefore, this study evaluated whether the anionic diet on the prepartum phase would be beneficial for dairy cows in the transition period. Materials, Methods & Results: Eight Holstein cows on their second and third pregnancy with body condition score between 3.5 and 4 were used. During the experiment, the animals remained in paddock with grazing Tifton 85 (Cynodon spp.) and water ad libitum. Two groups of four animals each were used: the group A (control) received a dietary cation-anion difference (DCAD) diet of 2.57 mEq kg-1, and the second group, called the group B (treatment), received a DCAD diet of -112.2 mEq kg-1. To evaluate animal health, we performed gynecological examinations, in addition to blood samplings on days 20, 10 and 5 prepartum and 3, 7, 12 and 20 postpartum to assess seric levels of calcium (Ca), total protein, albumin, globulin, cholesterol, triglyceride, urea, and hepatic function (AST, ALT and GGT). It was also measured the production of free radicals (ROS) and lipid peroxidation (TBARS) in the transition period of the cows. No statistical differences were observed between groups regarding body condition score, uterine tone, dominant follicle diameter, size and presence of the corpus luteum and the presence of genital discharge up to 30 days postpartum. However, the anionic diet prevented a dramatic reduction in calcium levels, unlike what occurred in the control cows (the group A) where a subclinical hypocalcemia was observed.[...]

Benefits of a prepartum anionic diet on the health of dairy cows in the transition period: prevented subclinical hypocalcemia and minimizing oxidative stress

Background: There are many metabolic diseases that affect dairy cows during the transition period, among them, the postparturient hypocalcemia, also known as milk fever, puerperal paresis syndrome, or fallen cow. This disease may affect animals 72 h after calving due to a nutritional imbalance in the calcium metabolism, which occurs after a sudden demand of this mineral at the beginning of lactation. This problem is more common in animals with high milk production, and usually after the second lactation. Therefore, this study evaluated whether the anionic diet on the prepartum phase would be beneficial for dairy cows in the transition period. Materials, Methods & Results: Eight Holstein cows on their second and third pregnancy with body condition score between 3.5 and 4 were used. During the experiment, the animals remained in paddock with grazing Tifton 85 (Cynodon spp.) and water ad libitum. Two groups of four animals each were used: the group A (control) received a dietary cation-anion difference (DCAD) diet of 2.57 mEq kg-1, and the second group, called the group B (treatment), received a DCAD diet of -112.2 mEq kg-1. To evaluate animal health, we performed gynecological examinations, in addition to blood samplings on days 20, 10 and 5 prepartum and 3, 7, 12 and 20 postpartum to assess seric levels of calcium (Ca), total protein, albumin, globulin, cholesterol, triglyceride, urea, and hepatic function (AST, ALT and GGT). It was also measured the production of free radicals (ROS) and lipid peroxidation (TBARS) in the transition period of the cows. No statistical differences were observed between groups regarding body condition score, uterine tone, dominant follicle diameter, size and presence of the corpus luteum and the presence of genital discharge up to 30 days postpartum. However, the anionic diet prevented a dramatic reduction in calcium levels, unlike what occurred in the control cows (the group A) where a subclinical hypocalcemia was observed.[...](AU)

Oxidative stress and changes on the adenosinergic system of cats infected by feline leukemia virus (FeLV)

Background: The feline leukemia virus (FeLV) is clinically important retroviruses that infect domestic and wild feline worldwide, affecting more than 3 million cats representing a great risk for premature death. Some studies have demonstrated that oxidative stress, as well as the adenosinergic system, exert an important role in the pathogenesis of viral diseases. Oxidative stress is considered a disturbance in the antioxidant/oxidant status in favor of the excessive generation or lower removal of free radicals. Therefore, the aim of this study was to evaluate whether changes on the adenosinergic system and oxidative stress occurred in cats positives for feline leukemia virus (FeLV). Materials, Methods & Results: Forty-nine serum samples of cats (between 4 months and 13 years of age) seen at the Veterinary Hospital of the University of Santa Catarina State (UDESC - Lages, SC, Brazil) were used. Blood samples were collected from the jugular vein and stored in tubes without anticoagulant to obtain serum. An aliquot was used to detect both viral infections using the kit SNAP FIV/FeLV, that detects the p27 protein from FeLV and antibodies against the p24 protein from FIV. The test was performed according the manufacture’s recommendations. Based on this result, this study involved 20 FeLV negative cats, 20 FeLV positive symptomatic cats, and 9 FeLV positives asymptomatic cats. Serum samples were used to determine the activities of adenosine deaminase (ADA) and glutathione-S-transferase (GST), as well as thiobarbituric acid reactive substances (TBARS) and reactive oxygen levels (ROS). Seric ADA and GST activities, as well as TBARS (lipid peroxidation) and ROS (free radical) levels were determined spectrophotometrically according to the specific method. Seric ADA activity was increased in symptomatic animals compared to negatives and also to asymptomatic positive animals, and the same was observed for seric TBARS levels.[...]

The protective effects of an adsorbent against oxidative stress in quails fed aflatoxin-contaminated diet

Background: Contamination of crops with aflatoxin is considered a serious global threat to food safety, since potent carcinogenic, teratogenic, mutagenic and immunosuppressive effects of aflatoxins are well recognized. Recently, the use of adsorbents has been linked with protective effects against oxidative stress in several diseases. Thus, the aim of this study was to assess the occurrence of oxidative stress in quails (Coturnix coturnix) fed with aflatoxin-contaminated diet, as well as the protective effect of an adsorbent.Materials, Methods & Results: Twenty-eight quails were divided into four groups (n = 7): diet without additives (control; the group A), diet and adsorbent containing aluminosilicates (the group B), aflatoxin-contaminated diet (200 ppb) (the group C), and aflatoxin-contaminated diet (200 ppb) and adsorbent containing aluminosilicates (the group D). The composition of the adsorbent containing aluminosilicates was 0.3% based on yeast cell wall, silymarin, and bentonite. The animals received feed and water ad libitum during 20 days. At the end of the experimental period, total blood was collected by cardiac puncture in tubes without anticoagulant to obtain serum (centrifuged at 3500 g during 10 min) for later determination of biochemical parameters. The liver was placed in a solution of Tris–HCl 10 mM, pH 7.4 for TBARS (Thiobarbituric acid reactive substances), ROS (Reactive oxygen species), SOD (Superoxide dismutase) and CAT (Catalase) analysis. The hepatic tissue was gently homogenized in a glass potter in specific buffer, homogenated, and centrifuged at 10.000 g at 4ºC for 10 min to yield a supernatant (S1) used for analyses. Homogenate aliquots were stored at -80°C until utilization. Fragments of liver and intestine (5 cm) were collected for histopathological analyses. Between days 15 to 20 of the experiment, group C quails showed clinical signs, such as apathy, creepy feathers and reduced feed intake.[...]

The protective effects of an adsorbent against oxidative stress in quails fed aflatoxin-contaminated diet

Background: Contamination of crops with aflatoxin is considered a serious global threat to food safety, since potent carcinogenic, teratogenic, mutagenic and immunosuppressive effects of aflatoxins are well recognized. Recently, the use of adsorbents has been linked with protective effects against oxidative stress in several diseases. Thus, the aim of this study was to assess the occurrence of oxidative stress in quails (Coturnix coturnix) fed with aflatoxin-contaminated diet, as well as the protective effect of an adsorbent.Materials, Methods & Results: Twenty-eight quails were divided into four groups (n = 7): diet without additives (control; the group A), diet and adsorbent containing aluminosilicates (the group B), aflatoxin-contaminated diet (200 ppb) (the group C), and aflatoxin-contaminated diet (200 ppb) and adsorbent containing aluminosilicates (the group D). The composition of the adsorbent containing aluminosilicates was 0.3% based on yeast cell wall, silymarin, and bentonite. The animals received feed and water ad libitum during 20 days. At the end of the experimental period, total blood was collected by cardiac puncture in tubes without anticoagulant to obtain serum (centrifuged at 3500 g during 10 min) for later determination of biochemical parameters. The liver was placed in a solution of Tris–HCl 10 mM, pH 7.4 for TBARS (Thiobarbituric acid reactive substances), ROS (Reactive oxygen species), SOD (Superoxide dismutase) and CAT (Catalase) analysis. The hepatic tissue was gently homogenized in a glass potter in specific buffer, homogenated, and centrifuged at 10.000 g at 4ºC for 10 min to yield a supernatant (S1) used for analyses. Homogenate aliquots were stored at -80°C until utilization. Fragments of liver and intestine (5 cm) were collected for histopathological analyses. Between days 15 to 20 of the experiment, group C quails showed clinical signs, such as apathy, creepy feathers and reduced feed intake.[...](AU)

Oxidative stress and changes on the adenosinergic system of cats infected by feline leukemia virus (FeLV)

Background: The feline leukemia virus (FeLV) is clinically important retroviruses that infect domestic and wild feline worldwide, affecting more than 3 million cats representing a great risk for premature death. Some studies have demonstrated that oxidative stress, as well as the adenosinergic system, exert an important role in the pathogenesis of viral diseases. Oxidative stress is considered a disturbance in the antioxidant/oxidant status in favor of the excessive generation or lower removal of free radicals. Therefore, the aim of this study was to evaluate whether changes on the adenosinergic system and oxidative stress occurred in cats positives for feline leukemia virus (FeLV). Materials, Methods & Results: Forty-nine serum samples of cats (between 4 months and 13 years of age) seen at the Veterinary Hospital of the University of Santa Catarina State (UDESC - Lages, SC, Brazil) were used. Blood samples were collected from the jugular vein and stored in tubes without anticoagulant to obtain serum. An aliquot was used to detect both viral infections using the kit SNAP FIV/FeLV, that detects the p27 protein from FeLV and antibodies against the p24 protein from FIV. The test was performed according the manufactures recommendations. Based on this result, this study involved 20 FeLV negative cats, 20 FeLV positive symptomatic cats, and 9 FeLV positives asymptomatic cats. Serum samples were used to determine the activities of adenosine deaminase (ADA) and glutathione-S-transferase (GST), as well as thiobarbituric acid reactive substances (TBARS) and reactive oxygen levels (ROS). Seric ADA and GST activities, as well as TBARS (lipid peroxidation) and ROS (free radical) levels were determined spectrophotometrically according to the specific method. Seric ADA activity was increased in symptomatic animals compared to negatives and also to asymptomatic positive animals, and the same was observed for seric TBARS levels.[...](AU)

Glyphosate-based herbicide affects biochemical parameters in Rhamdia quelen (Quoy & Gaimard, 1824 and) Leporinus obtusidens (Valenciennes, 1837)

Rhamdia quelen (silver catfish) and Leporinus obtusidens (piava) were exposed to a commercial formulation Roundup(r), a glyphosate-based herbicide at concentrations of 0.2 or 0.4 mg/L for 96 h. The effects of the herbicide were analyzed on the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and glucose in plasma, glucose and protein in the mucus layer, nucleotide hydrolysis in the brain, and protein carbonyl in the liver. The parameters were chosen, owing to a lack of information concerning integrated analysis, considering oxidative damage parameters, liver damage, and effects on the mucus layer composition and triphosphate diphosphohydrolase (NTPDase) activities. Plasmatic glucose levels were reduced in both species, whereas the transaminase activities (ALT and AST) increased after exposure to the herbicide. Herbicide exposure increased protein and glucose levels in the mucus layer in both species. There was a reduction in both NTPDase and ecto-5'-nucleotidase activity in the brain of piava, and increased enzyme activity in silver catfish at both concentrations tested. The species showed an increase in protein carbonyl in the liver after exposure to both concentrations of the glyphosate. Our results demonstrated that exposure to Roundup(r) caused liver damage, as evidenced by increased plasma transaminases and liver protein carbonyl in both of the fish species studied. The mucus composition changed and hypoglycemia was detected after Roundup(r) exposure in both species. Brain nucleotide hydrolysis showed a different response for each fish species studied. These parameters indicated some important and potential indicators of glyphosate contamination in aquatic ecosystems.(AU)

Rhamdia quelen (jundiá) e Leporinus obtusidens (piava) foram expostos a formulação comercial Roundup(r), um herbicida a base de glifosato nas concentrações de 0,2 e 0,4 mg/L por 96h. Os efeitos do herbicida foram analisados na atividade da alanina aminotransferase (ALT), aspartato aminotransferase (AST) e glicose no plasma, glicose e proteína na camada de muco, hidrólise de nucleotídeos no cérebro e a proteína carbonil no fígado. Os parâmetros foram escolhidos devido à falta de informação com relação a análises integradas, considerando parâmetros oxidativo, danos no fígado, efeitos na composição da camada do muco e atividade da trifosfato difosfoidrolase (NTPDase). Níveis de glicose plasmática foram reduzidos em ambas às espécies, enquanto a atividade das transaminases (ALT e AST) aumentou após exposição ao herbicida. A exposição ao herbicida aumentou a proteína e níveis de glicose na camada de muco em ambas as espécies. Houve uma redução em ambas atividades de NTPDase e ecto-5'-nucleotidase no cérebro de piava, e um aumentou a atividade destas enzimas em jundiás em ambas as concentrações testadas. As espécies mostraram um aumento na proteína carbonil no fígado após exposição a ambas as concentrações de glifosato. Nossos resultados demonstraram que a exposição ao Roundup(r) causou danos no fígado, como evidenciado pelo aumento das transaminases plasmáticas e proteína carbonil no fígado em ambas as espécies de peixes estudadas. A composição do muco alterou e uma hipoglicemia foi detectada após a exposição ao Roundup(r) em ambas espécies. A hidrólise de nucleotídeos em cérebro mostrou diferente resposta para cada espécie estudada. Esses parâmetros indicam alguns importantes e indicadores potenciais da contaminação do glifosato no ecossistema aquático.(AU)

Cholinesterase activity in serum, whole blood and lymphocytes of dogs experimentally infected with Rangelia vitalii

Background: The cholinergic system is involved in many biological functions in mammals and is associated with pathogenesis of infectious diseases, as has participation in transmission of nerve impulses in cholinergic synapses, haematopoiesis, regulation of inflammatory markers, production and coordination of movement, and memory. Rangelia vitalii is a parasite endemic to south of Brazil. This parasite multiplies in the blood and can be visualized in plasma in its free form and/or within leukocytes and erythrocytes, causing various pathologies. Therefore, the purpose of this study was to investigate the activity of cholinergic system enzymes in dogs experimentally infected with R. vitalii. Materials, Methods & Results: Twelve dogs were used, divided into two groups: control group (n = 5), consisting of healthy animals, and infected group with R. vitalii (n = 7). Fresh blood samples of these infected animals were inoculated in seven dogs (2 mL/dog through the jugular vein). Blood samples were collected on days 0, 10 and 20 post-infection (PI). Butyrylcholinesterase (BChE) activity was measured in serum and acetylcholinesterase (AChE) in lymphocytes and whole blood. Boold samples were diluted 1:50 (v/v) in lysis solution (0.1 mmol/L potassium/sodium phosphate buffer containing 0.03% Triton X-100) and frozen (-20 ºC by 7 days) to determine AChE activity in whole blood. Lymphocytes were also obtained from whole blood with EDTA by gradient separation using Ficoll-Histopaque™ plus to AChE activity this cell. After analysis of the samples, was observed that the dogs infected with R. vitalii presented a signifi cant (P < 0.01) increase in AChE activity in whole blood on days 10 and 20 PI. However, the infected group showed a reduced activity in AChE in lymphocytes (P < 0.01) and BChE in serum (P < 0.05) on day 20 PI. Discussion: According to the literature, infected dogs R. vitalii develop regenerative anemia evidenced by an increase in the erytroid precursors in bone marrow associated with alterations of leucogram as leukopenia, neutropenia, eosinopenia, lymphocytosis and monocytosis. Furthermore, it was observed severe thrombocytopenia, with alteration in platelet aggregation and activity of enzymes involved in the control of ATP, ADP and adenosine levels on platelets, thereby influencing hemostasis and contributing to the typical bleeding disease. AChE activity in whole blood was increased in dogs parasitized by R. vitalii observed in this study. This increase may be a compensatory effect to severe anemia caused by the parasite infection, because this enzyme is involved in the maturation of erythrocytes and in the regulation of hematopoiesis. In the present study, we found that the reduction in AChE activity in lymphocytes is associated to lymphocytosis; and it is known that ACh is produced within lymphocytes and has the ability to negatively modulate the immune response, acting directly on the inhibition of inflammatory mediators. Therefore, the decrease of AChE activity may have an anti-inflammatory action in order to have more free ACh to bind lymphocytes and inhibit inflammation. The enzyme BChE can also act as an inflammatory marker in various diseases, similar to AChE, because the enzyme can hydrolyze acetylcholine when AChE is inhibited. In conclusion, our results indicate that canine rangeliosis alters the activity of cholinesterase's, which may be involved in the pathogenesis of the disease, as well as various pathological conditions.

NTPDase and acetylcholinesterase activities in silver catfish, Rhamdia quelen (Quoy & Gaimard, 1824) (Heptapteridae) exposed to interaction of oxygen and ammonia levels

The effects of various levels of oxygen saturation and ammonia concentration on NTPDase (ecto-nucleoside triphosphate diphosphohydrolase, E.C. 3.6.1.5) and acetylcholinesterase (AChE, E.C. 3.1.1.7) activities in whole brain of teleost fish (Rhamdia quelen) were investigated. The fish were exposed to one of two different dissolved oxygen levels, including high oxygen (6.5 mg.L-1) or low oxygen (3.5 mg.L-1), and one of two different ammonia levels, including high ammonia (0.1 mg.L-1) or low ammonia (0.03 mg.L-1) levels. The four experimental groups included the following (A) control, or high dissolved oxygen plus low NH3; (B) low dissolved oxygen plus low NH3; (C) high dissolved oxygen plus high NH3; (D) low dissolved oxygen plus high NH3. We found that enzyme activities were altered after 24 h exposure in groups C and D. ATP and ADP hydrolysis in whole brain of fish was enhanced in group D after 24 h exposure by 100 percent and 119 percent, respectively, compared to the control group. After 24 h exposure, AChE activity presented an increase of 34 percent and 39 percent in groups C and D, respectively, when compared to the control group. These results are consistent with the hypothesis that low oxygen levels increase ammonia toxicity. Moreover, the hypoxic events may increase blood flow by hypoxia increasing NTPDase activity, thus producing adenosine, a potent vasodilator.(AU)

No presente estudo, avaliou-se o efeito de diferentes níveis de saturação de oxigênio e amônia sobre a atividade das enzimas NTPDase (ecto-nucleosídeo trifosfato difosfohidrolase, E.C. 3.6.1.5) e acetilcolinesterase (AChE, E.C. 3.1.1.7) em encéfalo total de jundiás (Rhamdia quelen). Os peixes foram expostos a diferentes níveis de oxigênio dissolvido e amônia, níveis altos de oxigênio (6,5 mg/L) ou baixos de oxigênio (3,5 mg/L), e níveis altos de amônia (0,1 mg/L) ou baixos de amônia (0,03 mg/L). Os peixes foram divididos em quatro diferentes grupos: (A) controle ou alto nível de oxigênio dissolvido mais baixo nível de NH3; (B) baixo nível de oxigênio dissolvido mais baixo nível de NH3; (C) alto nível de oxigênio dissolvido mais alto nível de amônia; (D) baixo nível de oxigênio dissolvido mais alto nível de NH-3. As atividades de ambas as enzimas nos grupos C e D somente foram alteradas após 24 horas de exposição. A hidrólise do ATP e ADP em encéfalo total de jundiás foi aumentada após 24h de exposição para 104 por cento e 155 por cento no grupo D quando comparado ao grupo controle, respectivamente. A atividade da AChE apresentou após 24h de exposição um aumento de 37 por cento no grupo C e 27 por cento no grupo D, ambos comparados ao grupo controle. Os resultados obtidos corroboram com a hipótese que baixos níveis de saturação de oxigênio aumentam a toxicidade da amônia. Além disso, os eventos de hipóxia podem aumentar o fluxo sanguíneo, e este evento aumenta a atividade da NTPDase produzindo adenosina, um potente vasodilatador(AU)

NTPDase and acetylcholinesterase activities in silver catfish, Rhamdia quelen (Quoy & Gaimard, 1824) (Heptapteridae) exposed to interaction of oxygen and ammonia levels

The effects of various levels of oxygen saturation and ammonia concentration on NTPDase (ecto-nucleoside triphosphate diphosphohydrolase, E.C. 3.6.1.5) and acetylcholinesterase (AChE, E.C. 3.1.1.7) activities in whole brain of teleost fish (Rhamdia quelen) were investigated. The fish were exposed to one of two different dissolved oxygen levels, including high oxygen (6.5 mg.L-1) or low oxygen (3.5 mg.L-1), and one of two different ammonia levels, including high ammonia (0.1 mg.L-1) or low ammonia (0.03 mg.L-1) levels. The four experimental groups included the following (A) control, or high dissolved oxygen plus low NH3; (B) low dissolved oxygen plus low NH3; (C) high dissolved oxygen plus high NH3; (D) low dissolved oxygen plus high NH3. We found that enzyme activities were altered after 24 h exposure in groups C and D. ATP and ADP hydrolysis in whole brain of fish was enhanced in group D after 24 h exposure by 100 percent and 119 percent, respectively, compared to the control group. After 24 h exposure, AChE activity presented an increase of 34 percent and 39 percent in groups C and D, respectively, when compared to the control group. These results are consistent with the hypothesis that low oxygen levels increase ammonia toxicity. Moreover, the hypoxic events may increase blood flow by hypoxia increasing NTPDase activity, thus producing adenosine, a potent vasodilator.(AU)

No presente estudo, avaliou-se o efeito de diferentes níveis de saturação de oxigênio e amônia sobre a atividade das enzimas NTPDase (ecto-nucleosídeo trifosfato difosfohidrolase, E.C. 3.6.1.5) e acetilcolinesterase (AChE, E.C. 3.1.1.7) em encéfalo total de jundiás (Rhamdia quelen). Os peixes foram expostos a diferentes níveis de oxigênio dissolvido e amônia, níveis altos de oxigênio (6,5 mg/L) ou baixos de oxigênio (3,5 mg/L), e níveis altos de amônia (0,1 mg/L) ou baixos de amônia (0,03 mg/L). Os peixes foram divididos em quatro diferentes grupos: (A) controle ou alto nível de oxigênio dissolvido mais baixo nível de NH3; (B) baixo nível de oxigênio dissolvido mais baixo nível de NH3; (C) alto nível de oxigênio dissolvido mais alto nível de amônia; (D) baixo nível de oxigênio dissolvido mais alto nível de NH-3. As atividades de ambas as enzimas nos grupos C e D somente foram alteradas após 24 horas de exposição. A hidrólise do ATP e ADP em encéfalo total de jundiás foi aumentada após 24h de exposição para 104 por cento e 155 por cento no grupo D quando comparado ao grupo controle, respectivamente. A atividade da AChE apresentou após 24h de exposição um aumento de 37 por cento no grupo C e 27 por cento no grupo D, ambos comparados ao grupo controle. Os resultados obtidos corroboram com a hipótese que baixos níveis de saturação de oxigênio aumentam a toxicidade da amônia. Além disso, os eventos de hipóxia podem aumentar o fluxo sanguíneo, e este evento aumenta a atividade da NTPDase produzindo adenosina, um potente vasodilatador(AU)

Presence of multiple acid phosphatases activity in seedlings of cucumber, radish and rocket salad / Presença de atividade de múltiplas fosfatases ácidas em plântulas de pepino, rabanete e rúcula

Acid phosphatases (3.1.3.2) are a group of enzymes widely distributed in nature, which catalyze the hydrolysis of a variety of phosphate esters in the pH range of 4-6. We confirmed the presence of acid phosphatases in seedlings of cucumber (Cucumis sativus), radish (Raphanus sativus) and rocket salad (Eruca vesicaria) under different assay conditions using a rapid and simple preparation. The results showed that the optimum pH and temperature used for all species were close to 5.5 and 35ºC, respectively. The enzyme was inhibited by molybdate, fluoride, azide, levamisole, orthovanadate, Zn2+ and Cu2+. Suramin had no effect on enzyme activity. The acid phosphatase from cucumber, radish and rocket salad hydrolyzed a wide variety of phosphate esters and the highest activity was observed with PPi, ATP and GTP. These results demonstrate that the enzyme investigated in this study is different from well known ester phosphate cleaving plant enzymes (apyrase and inorganic pyrophosphatases) and this preparation could be a useful tool to future toxicological studies and to study initially all isoforms of acid phosphatase.(AU)

As fosfatases ácidas (3.1.3.2) são um grupo de enzimas amplamente distribuídas na natureza, as quais catalisam a hidrólise de uma variedade de ésteres de fosfato com uma variação de pH entre quatro e seis. Foi confirmada a presença de fosfatases ácidas em plântulas de pepino (Cucumis sativus), rabanete (Raphanus sativus) e rúcula (Eruca vesicaria) sob diferentes condições de ensaio usando uma preparação rápida e simples. Os resultados mostraram que o pH e a temperatura ótimos para todas as espécies foram 5,5 e 35ºC, respectivamente. A enzima foi inibida por molibdato, fluoreto, azida, levamisole, ortovanadato, Zn2+ e Cu2+. O inibidor suramim não afetou a atividade enzimática. As fosfatases ácidas de pepino, rabanete e rúcula hidrolisaram uma ampla variedade de ésteres de fosfato e a maior atividade foi observada com PPi, ATP e GTP para pepino e rabanete e PPi, frutose-6-fosfato e GTP para rúcula. Esses resultados demonstraram que a enzima investigada neste estudo é diferente das conhecidas enzimas de plantas que clivam ésteres de fosfato (apirase e pirofosfatases inorgânicas). Desse modo, esta preparação pode ser uma ferramenta útil para futuros estudos toxicológicos e para se estudar inicialmente todas as isoformas das fosfatases ácidas.(AU)