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The present study aimed to evaluate the cumulative mortality, reactive oxygen species production (ROS) and total hemocyte counts (THC) of the marine shrimp Litopenaeus vannamei infected with Vibrio alginolyticus at different oxygen saturations. A total of 240 shrimp (10 ± 1.5g) were distributed into 16 tanks (60L), divided into two groups, infected and uninfected, which were subjected to 30 or 100% of saturation (in quadruplicate). During 72 hours after infection, daily hemolymph samples were collected for THC and ROS evaluation, and dead animals were removed and computed to assess cumulative mortality rates. Mortality was observed only in infected group, and was higher under 30% of saturation (97.2%) than 100% (77.8%), however, no significant differences were observed between THC and ROS production of infected and uninfected animals, under both saturations. Therefore, the results of this study suggested that hypoxia increases the susceptibility of the shrimps to vibrio infection, which may be not related to the modulation of THC and ROS production. Resumo: O objetivo deste trabalho foi avaliar a mortalidade acumulativa, a contagem total de hemócitos (CTH) e a produção de espécies reativas de oxigênio (EROs) de camarões Litopenaeus vannamei infectados com Vibrio alginolyticus e submetidos a diferentes saturações de oxigênio dissolvido. Para tanto, 240 camarões (10 ± 1,5g) foram distribuídos em 16 caixas plásticas (60L), divididos em quatro grupos, infectados e não infectados, submetidos a 30% ou 100% de saturação (em quadruplicata). Foram coletadas amostras de hemolinfa para avaliação da CTH e das EROs antes (0h) e depois (24h, 48h e 72h) da infecção, e estimada a mortalidade nesse período. Foi observada mortalidade apenas nos tratamentos com infecção, sendo maior com 30% de saturação (97,2%) do que 100% (77,8%), porém não foram constatadas diferenças significativas na CTH e nas EROs dos animais infectados e não infectados em ambas as saturações. Dessa forma, pode-se concluir que a hipóxia aumenta a susceptibilidade dos camarões à infecção bacteriana, porém, aparentemente, sem relação com a modulação da quantidade de hemócitos circulantes e do burst respiratório.

The present study evaluated the acute inflammatory response induced by carrageenin (500 µg) injected in the swim bladder of Nile tilapia, after fed or not probiotic supplemented diet. Fifty four fish were distributed in six treatments and three replicates: Group A: Fish fed unsupplemented diet: 0.5 mL saline-injected fish; fish injected with 500 µg carrageenin diluted in 0.5 mL saline; Non-injected. Group B: Fish fed probiotic supplemented diet: saline-injected fish; carrageenin-injected fish; Non-injected. Fifteen days after feeding the fish were injected with carrageenin or saline. After six hours, inflammatory exudate was collected, as well as the blood for hematocrit, red blood cell (RBC) and white blood cell (WBC) counts, differential count of leucocytes and phagocytic activity in the blood. Supplementation with probiotic did not influence the RBC, hematocrit and the numbers of lymphocytes and basophils in the blood. The number of neutrophils was significantly higher in supplemented fish injected with carrageenin. Glucose concentration in supplemented and non-injected fish was higher than that observed in the saline injected ones. Probiotic potentialized the migration of cells to the inflammatory focus in the animals injected with the carrageenin irritant. In fish injected with saline and carrageenin occurred the greatest phagocytic activity in the blood in relation to those treatments. The present study evaluated the acute inflammatory response induced by carrageenin (500 µg) injected in the swim bladder of Nile tilapia, after fed or not probiotic supplemented diet. Fifty four fish were distributed in six treatments and three replicates: Group A: Fish fed unsupplemented diet: 0.5 mL saline-injected fish; fish injected with 500 µg carrageenin diluted in 0.5 mL saline; Non-injected. Group B: Fish fed probiotic supplemented diet: saline-injected fish; carrageenin-injected fish; Non-injected. Fifteen days after feeding the fish were injected with carrageenin or saline. After six hours, inflammatory exudate was collected, as well as the blood for hematocrit, red blood cell (RBC) and white blood cell (WBC) counts, differential count of leucocytes and phagocytic activity in the blood. Supplementation with probiotic did not influence the RBC, hematocrit and the numbers of lymphocytes and basophils in the blood. The number of neutrophils was significantly higher in supplemented fish injected with carrageenin. Glucose concentration in supplemented and non-injected fish was higher than that observed in the saline injected ones. Probiotic potentialized the migration of cells to the inflammatory focus in the animals injected with the carrageenin irritant. In fish injected with saline and carrageenin occurred the greatest phagocytic activity in the blood in relation to those treatments.

Este estudo teve como objetivo comparar o efeito de diferentes densidades celulares da microalga Thalassiosira weissflogii na alimentação de larvas de Litopenaeus vannamei, e avaliar sua utilização em escala comercial. Para avaliar a densidade algal adequada foram utilizados três tratamentos, 0,5; 1,0 e 2,0 x 104 células/mL. Na avaliação em escala comercial comparou-se a utilização de T. weissflogii com Chaetoceros muelleri, quanto à metamorfose, sobrevivência e peso final. Os resultados mostraram que a densidade de 2,0 x 104 cels/mL apresentaram menor sobrevivência e a água do cultivo maiores concentrações de nutrientes e contagem de bactérias totais em comparação com os tratamentos de 0,5 e 1,0 x 104 células/mL (p < 0,05), que não apresentaram diferenças estatísticas entre si (p > 0,05) para os parâmetros analisados. Não foram observadas diferenças significativas nos parâmetros analisados entre as duas espécies de microalgas utilizadas na larvicultura comercial (p > 0,05). Os resultados mostraram que a densidade de 2,0 x 104 cels/mL de T. weissflogii pode causar prejuízos para a larvicultura de camarões, devido à degradação da qualidade da água causada pela introdução de maiores volumes de inóculos de microalgas, gerando acúmulo de nutrientes e o aumento da carga bacteriana. O uso de T. weissflogii em larviculturas comerciais apresentou resultados satisfatórios para a produção de larvas de L. vannamei. The objective of this work was to establish the effects of the microalgae Thalassiosira weissflogii in different densities added to experimental L. vannamei larval rearing, as well as assess its use in commercial-scale production. To evaluate the algal densities, were tested three treatments (0.5, 1 and 2 x 104 cells/mL) in experimental conditions. In the commercial-scale larval rearing was compared the use of T. eissflogii with Chaetoceros muelleri as regard to shrimp metamorphosis, final survival and final weight. The results showed that larvae fed with 2 x 104 cells/mL presented low survival and the culture water became highly concentrated with nutrients and total bacteria counts when compared to treatments 0.5, 1 x 104 cells/mL (p < 0.05), which no statistically significant differences were observed in both treatments (p > 0.05) for analyzed parameters. No significant differences were observed in the parameters tested between microalgae species in the commercial-scale larval rearing (p > 0.05). Results demonstrate that T. weissflogii at a density of 2 x 104 cells/mL can be detrimental to shrimp larval rearing due to decay in water quality caused by the introduction of high microalga inoculum, which generates accumulation of nutrients and increase of total bacteria. The use of T. weissflogii showed good results and can be adopted in commercial-scale of the L. vannamei larval rearing.

O objetivo deste trabalho foi isolar bactérias ácido-lácticas do intestino de tilápias-do-nilo, e avaliar seu potencial probiótico. Foram isoladas cepas de bactérias ácido-lácticas, e foi avaliada a inibição aos patógenos in vitro. As cepas com os melhores resultados foram identificadas e utilizadas no experimento de colonização do trato intestinal de tilápias-do-nilo, via suplementação na dieta, em delineamento inteiramente ao acaso, com três tratamentos e quatro repetições. Foram avaliados: o total de bactérias, as bactérias ácido-lácticas, Vibrio ssp. e Pseudomonas ssp. A cepa com melhor resultado foi utilizada na infecção experimental, em delineamento inteiramente ao acaso, em esquema fatorial 2x3: dieta suplementada com a cepa e dieta-controle; e os peixes não submetidos à injeção, peixes submetidos à injeção de solução salina e à injeção de Enterococcus durans, com três repetições. Foram avaliados os parâmetros hematológicos. As duas cepas identificadas foram: Lactobacillus plantarum e Lactobacillus brevis, que colonizaram o trato intestinal de tilápias, contudo L. plantarum teve menor número total de bactérias e de Pseudomonas ssp. Foi observado maior número total de eritrócitos, trombócitos, leucócitos, linfócitos, neutrófilos e monócitos, em peixes alimentados com L. plantarum e submetidos à injeção de E. durans. O L. plantarum tem efeito probiótico e melhora o sistema imune das tilápias. The objective of this work was to isolate lactic-acid bacteria from the intestines of Nile tilapia, and to assess their potential as probiotic. Strains of lactic-acid bacteria were isolated, and inhibition against pathogens was evaluated in vitro. Strains with best results were identified and used in tilapia intestinal tract colonization experiment through supplementation in the diet, in a completely randomized design, with three treatments and four replicates. Total number bacteria, lactic-acid bacteria, Vibrio ssp. and Pseudomonas ssp. were evaluated. The strain with best result was used for experimental infection, in a completely randomized design, in factorial arrangement 2x3: diet supplemented with strain and control diet; and fish not submitted to injection, fish submitted to injection of saline solution, and fish submitted to injection of Enterococcus durans, with three replicates. Hematological parameters were evaluated. Two strains were identified as Lactobacillus plantarum and Lactobacillus brevis, which colonized fishes' intestinal tract. However, L. plantarum had the lowest number of total bacteria and of Pseudomonas ssp. Greater number of red blood cells, thrombocytes, leukocytes, lymphocytes, neutrophils and monocytes were observed in fish fed with L. plantarum and submitted to injection of E. durans. L. plantarum has probiotic effect on Nile tilapias and improve their immune system.