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Camu camu, Myrciaria dubia, is an Amazon plant that presents high levels of vitamin C in its composition. Several studies in animals and humans have demonstrated their efficiency in the prevention and treatment of various diseases. However, there are no reports of its properties in fish. The aim of this study was to evaluate the effect of the oral administration of the extract of this plant in the immune parameters in Nile tilapia, Oreochromis niloticus. 400 Nile tilapia (80 ± 5 g) were randomly distributed into 20 tanks with 1500 L capacity each (20 fish/tank). After a week of adaptation to environmental conditions, it was provided a diet for 5 weeks, using different levels of inclusion of camu camu extract: 0, 50, 100, 250, and 500 mg/kg of feed. Each treatment consisted of four replicates. It was obtained 40.5 mg of vitamin C/g of camu camu pulp powder by high-performance liquid chromatography. At the end of the trial period, fish were inoculated with Aeromonas hydrophila in the swim bladder. Samples were taken after 6; 24 and 48 h of the challenge. Results revealed that fish supplemented with this herb showed significant increase (P < 0.05) in white blood cells counts in blood and exudate, burst respiratory activity, lysozyme activity, serum bactericidal activity, direct agglutination, and melanomacrophage centers count. Red blood cells count, hemoglobin, hematocrit, and biochemical profile of fish supplemented with the herb presented no statistical differences compared to control group (P > 0.05). No histopathological lesions were observed in intestine, kidney, spleen, and gills. It can be concluded that the addition of Myrciaria dubia in tilapia feed improves the immune response and the growth after 5 weeks, especially, at a dose of 500 mg/kg.

Understanding the functional mechanisms of the humoral and cellular immune responses among teleost broadens the possibilities for intervention and improvement of vaccination methods. The aim of this study was to evaluate the dynamics of the humoral immune response, hematological biochemical changes, and electrophoretic profile of proteins in Oreochromis niloticus, when submitted to antigen stimulation using sheep erythrocytes in a single dose and with booster doses. Seventy O. niloticus were distributed in two groups (n=35): one received a single dose and the other received two doses of antigen. Evaluations were made at the following predetermined times: zero (pre-immune, i.e., before inoculation with the first injection of sheep erythrocytes, negative control) and on 7th, 14th, 21st, and 28th days after the first immunization to evaluate the hemogram, biochemistry, and electrophoresis of proteins and direct hemagglutination. Twenty-eight days after antigen inoculation, it was observed that there had been an increase in the serum antibody titer and fractions gamma globulins after second antigen stimulation. The results suggest that teleost fish have the capacity to produce antibodies from a single stimulation, and a second antibody production wave after second stimulation.

Environmental changes affect fish homeostasis, turning them more susceptible to diseases. In Brazil, outbreaks of Streptococcus agalactiae infection have been reported in Nile tilapia when they are outside of their thermal comfort zone. This investigation evaluated mortality rate and which were the most infected organs at temperatures that naturally occurred in southern of Brazil. Forty Nile tilapia (Oreochromis niloticus) were infected with S. agalactiae and distributed in four groups (n=10) and each group was exposed to a different temperature: G1: 24°C, G2: 26°C, G3: 28°C, and G4: 32°C. Fish were monitored for 10 days. In this period, fish that presented irreversible clinical signs were sacrificed and samples of brain, liver, and kidney were collected for bacteriological and molecular analysis. Signs compatible with a streptococcal infection were observed in all groups. Highest mortality rates occurred at 24°C and 32°C. The brain was the most affected organ with the highest percentage of isolation of S. agalactiae by both methods of diagnosis. The results suggest that, as in mammals, temperatures that are further away from the comfort zone influence fish homeostasis, increasing susceptibility to bacterial infections. Keywords:Homeostasis. Oreochromis niloticus. Teleost. Thermal stress. ResumoMudanças ambientais afetam a homeostase dos peixes, tornando-os mais suscetíveis a doenças. No Brasil, têm sido relatados surtos de infecção por Streptococcus agalactiae em tilápia do Nilo, principalmente quando se encontram fora da zona de conforto térmico. No presente trabalho, foi avaliada a taxa de mortalidade e determinado quais foram os órgãos mais afetados por essa bactéria em temperaturas que ocorrem naturalmente no Sul do Brasil. Quarenta tilápias-do-nilo (Oreochromis niloticus) foram infectadas por Streptococcus agalactiae e distribuídas em quatro grupos (n = 10), cada um deles submetidos a diferentes temperaturas: G1: 24°C, G2: 26°C, G3: 28°C e G4: 32°C. Os peixes foram monitorados durante 10 dias. Os peixes com sinais clínicos irreversíveis foram sacrificados e coletadas amostras de cérebro, fígado e rins para análise bacteriológica e molecular. Foram observados sinais compatíveis com infecção estreptocócica em todos os grupos. A taxa de mortalidade mais elevada ocorreu nos grupos mantidos nas temperaturas de 24°C e 32°C. O cérebro foi o órgão mais afetado, com a maior percentagem de isolamento de S. agalactiae pelos dois métodos de diagnóstico. Os resultados sugerem que, tal como nos mamíferos, temperaturas que estão mais afastadas da zona de conforto afetam significativamente a homeostase dos peixes, aumentando a sua susceptibilidade para infecções bacterianas. Palavras-chave:Homeostase. Oreochromis niloticus. Teleósteo. Estresse por temperatura.

Uncaria tomentosa is a medicinal plant used in folk medicine by Amazon tribes. In this study the constituents of aqueous extract of U. tomentosa bark were quantified by chromatographic technique and its lethal concentration 50 (48 h) in Hyphessobrycon eques was determined. The chromatography showed high levels of oxindole alkaloids, quinovic acid glycosides, and low molecular weight polyphenols. The CL50 48 h was 1816 mg/L. Fish showed behavior changes at concentrations above 2000 mg/L, accompanied by a significant decrease of dissolved oxygen. At the highest concentration 100% mortality was observed attributed to oxygen reduction by the amount of oxindole alkaloids, polyphenols accumulation of the extract in the gills, and the interaction of these compounds with dopamine. In conclusion, the aqueous extract of U. tomentosa did not alter the chemical components and it was shown that U. tomentosa has low toxicity to H. eques; therefore, it can be used safely in this species.

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Resumo -O objetivo deste trabalho foi avaliar a inter-relação entre a suplementação alimentar com parede celular de Saccharomyces cerevisae e a vacinação contra Streptococcus agalactiae e seu efeito sobre o desempenho produtivo e as variáveis hematológicas de tilápia-do-nilo (Oreochromis niloticus). Oitenta e quatro tilápias-do-nilo foram distribuídas em 12 caixas de fibra (n=7), em arranjo fatorial 2x2x3, correspondente a dois níveis de suplementação com parede celular de levedura, dois tipos de inoculação e três tempos de avaliação. Os peixes foram alimentados durante 77 dias. A vacinação dos peixes foi realizada 60 dias após o início da alimentação. Quinze dias após a vacinação, todos os peixes foram submetidos ao desafio com cepa viva de S. agalactiae, e 6, 24 e 48 horas após o desafio, o sangue foi colhido da veia caudal para avaliações. Peixes alimentados com ração suplementada apresentam maior ganho de peso e taxa de crescimento específico, e a interação entre os efeitos da dieta e da vacinação resulta em maiores taxas de hematócrito, hemoglobina e leucócitos.Termos para indexação: Oreochromis niloticus, inflamação, probiótico, sangue, teleósteos, vacinação. Performance and hematological profile of Nile tilapia fed with Saccharomyces cerevisiae and vaccinated against Streptococcus agalactiaeAbstract -The objective of this work was to evaluate the inter-relationship between dietary supplementation with Saccharomyces cerevisiae cell wall and vaccination against Streptococcus agalactiae, and its effect on the productive performance and hematological variables of Nile tilapia (Oreochromis niloticus). Eighty-four Nile tilapia were distributed in 12 fiber boxes (n=7), in a 2x2x3 factorial arrangement, corresponding to two levels of supplementation with yeast cell wall, two types of inoculation, and three evaluation times. Fish were fed during 77 days. Vaccination of fish was done 60 days after feeding started. Fifteen days after vaccination, all fish were subjected to challenge with live strain of S. agalactiae, and 6, 24, and 48 hours after the challenge, blood was collected from the caudal vein for evaluations. Fish fed with supplemented diets show greater weight gain and specific growth rate, and the interaction between the diet and vaccination effects results in higher hematocrit, hemoglobin, and leukocyte rates.