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Animals (Basel) ; 10(12)2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-33265935


Long-term exposure to hyperosmotic environments can induce severe immune damage and increase risk in tilapia breeding. As an effective immunoregulator, ß-glucan has attracted extensive attention in nutritional research and given rise to high expectations of improving health status and alleviating organismal damage in tilapia, Oreochromis niloticus, in brackish water. In this study, an 8-week cultivation experiment was conducted on tilapia fed a basal diet or diets with ß-glucan supplementation in freshwater (control) and brackish water. Growth performance, hematological aspects, immune cytokine expression, and the intestinal microbiota of tilapia were analyzed. The results indicated that supplementation with ß-glucan significantly reduced the enlarged spleen of tilapia resulting from hypersaline stress. Tilapia fed ß-glucan showed significantly-greater decreases in the red blood cell count, hematocrit, red cell distribution width, platelet count, and plateletcrit than those fed the basal diet. ß-glucan significantly decreased the high expression of immune-related genes in the spleen induced by hyperosmotic stress. In the intestine, the high migration inhibitory factor-2 (MIF-2) and IL-1ß gene expression induced by hypersaline stress was significantly reduced. ß-glucan supplementation also significantly increased the abundance of beneficial microbiota such as Lactobacillus, Phycicoccus, and Rikenellaceae. Therefore, dietary ß-glucan supplementation can significantly reduce spleen enlargement and improve immune function in tilapia in brackish water. ß-glucan intake can also optimize the intestinal microbiota of tilapia in brackish water and improve fish health.

Fish Shellfish Immunol ; 76: 48-57, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29486352


Hyperosmotic stress can adversely affect fish immunity, but little is known about the histological and transcriptomic responses of immune organs in fish in a hyperosmotic environment. This study evaluated the effects of long-term hypersaline conditions (16‰) on the growth, histology and transcriptomics of the two main immune organs, the spleen and head kidney, in Nile tilapia Oreochromis niloticus relative to those reared in freshwater for eight weeks. No differences in weight gain and specific growth rate were found between fish reared under these two salinities. Hyperosmotic stress induced a congestive or enlarged spleen. Platelet- and coagulation-related gene expression was significantly decreased in tilapia at 16‰. The red cell distribution width and value of the mean corpuscular hemoglobin were significantly greater in fish at 16‰ salinity than in control fish in freshwater. A large volume of melano-macrophages in the spleen and pigment deposition in both the spleen and head kidney were observed in the histological sections in fish at 16‰ salinity. Transmission electron microscopic results showed abnormal macrophages with deposition granules in the spleen and head kidney and more neutrophils in the head kidney of fish at 16‰ than in control fish. In total, 772 and 502 genes were annotated for significantly different expression in the spleen and head kidney, respectively, and corresponded to five and one significantly changed immune system pathways, respectively. The complement pathway in the spleen was significantly down-regulated at 16‰. This study indicates that long-term exposure of Nile tilapia to a hyperosmotic environment can induce splenomegaly, reduce coagulation function, enhance phagocytic activity and down-regulate the complement pathway in the spleen. The spleen is a more sensitive organ for immune responses to chronic ambient salinity stress than the head kidney in Nile tilapia.

Ciclídeos/imunologia , Rim Cefálico/imunologia , Salinidade , Baço/imunologia , Transcriptoma/imunologia , Animais , Ciclídeos/sangue , Ciclídeos/genética , Masculino , Distribuição Aleatória , Estresse Fisiológico/imunologia
Fish Shellfish Immunol ; 63: 87-96, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28192256


Sulfide is a natural and widely distributed toxicant. It can be commonly found on the interface between water and sediment in the aquatic environment. The Pacific white shrimp Litopenaeus vannamei starts life in the benthic zone soon after the mysis stage, an early stage of post larvae. Therefore, L. vannamei is inevitably affected by exposure to sulfide released from pond sediment. This study explored the toxicant effect of different concentrations of sulfide on the intestinal health and microbiota of Pacific white shrimp by monitoring the change of expression of inflammatory, immune related cytokines, and the structure of the intestinal microbiota. The gut histology, expressions of inflammatory and immune related cytokines (tumor necrosis factor-alpha, C-type lectin 3, myostatin and heat shock transcription factor 1), and the microbiota were determined in L. vannamei after exposure to 0 (control), 425.5 (1/10 LC 50-96 h), and 851 µg/L (1/5 LC 50-96 h) of sulfide for 21 days. With the increase of sulfide concentration, intestinal injury was aggravated and the inflammatory and immune related cytokines generated a range of reactions. The expression of myostatin (MSTN) was significantly down-regulated by the concentration of sulfide exposure. No difference in the expression of heat shock transcription factor 1 (HSF1) was found between the control and shrimp exposed to 425.5 µg/L, but significantly higher HSF1 expression was found in shrimp exposed to 851 µg/L of sulfide. Significantly higher values of tumor necrosis factor-alpha (TNF-α) and C-type lectin 3 (CTL3) were found in the shrimp exposed to 425.5 µg/L of sulfide compared to the control, but a lower value was found in the shrimp exposed to 851 µg/L (P < 0.05). Sulfide also changed the intestinal microbial communities. The abundance of pathogenic bacteria, such as Cyanobacteria, Vibrio and Photobacterium, increased significantly with exposure to the increasing concentration of sulfide. The abundance of some anti-stress bacteria, such as Chlorobi and Fusobacterium, increased. Nitrospirae which can alleviate nitrite toxicity decreased. Microbacterium, Parachlamydia, and Shewanella were all commonly found and down-regulated in both sulfide groups, which is associated with an adaptation to sulfide stimulation. This study indicates that chronic exposure to sub-lethal levels of sulfide could lead to damage of the gut structure, stimulate the response of the inflammatory and immune systems, and shape the structure of the gut microbiota in L. vannamei.

Microbioma Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/efeitos dos fármacos , Imunidade Inata/efeitos dos fármacos , Penaeidae/efeitos dos fármacos , Sulfetos/toxicidade , Poluentes Químicos da Água/toxicidade , Androstenóis , Animais , Proteínas de Artrópodes/genética , Proteínas de Artrópodes/metabolismo , Trato Gastrointestinal/anatomia & histologia , Trato Gastrointestinal/metabolismo , Expressão Gênica/efeitos dos fármacos , Penaeidae/genética , Penaeidae/imunologia
Aquat Toxicol ; 183: 28-37, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27988416


The toxicity and poisoning mechanisms of sulfide were studied in Litopenaeus vannamei from the perspective of energy metabolism and metabolomics. The lethal concentrations of sulfide in L. vannamei (LC50) at 24h, 48h, 72h, and 96h were determined. Sulfide at a concentration of 0, 1/10 (425.5µg/L), and 1/5 (851µg/L) of the LC50 at 96h was used to test the metabolic responses of L. vannamei for 21days. The chronic exposure of shrimp to a higher sulfide concentration of 851µg/L decreased shrimp survival but did not affect weight gain or the hepatopancreas index. The glycogen content in the hepatopancreas and muscle and the activity of hepatopancreas cytochrome C oxidase of the shrimp exposed to all sulfide concentrations were significantly lower, and the serum glucose and lactic acid levels and lactic acid dehydrogenase activity were significantly lower than those in the control. Metabolomics assays showed that shrimp exposed to sulfide had lower amounts of serum pyruvic acid, succinic acid, glycine, alanine, and proline in the 425.5µg/L group and phosphate, succinic acid, beta-alanine, serine, and l-histidine in the 851µg/L group than in the control. Chronic sulfide exposure could disturb protein synthesis in shrimp but enhance gluconeogenesis and substrate absorption for ATP synthesis and tricarboxylic acid cycles to provide extra energy to cope with sulfide stress. Chronic sulfide exposure could adversely affect the health status of L. vannamei, as indicated by the high amounts of serum n-ethylmaleamic acid, pyroglutamic acid, aspartic acid and phenylalanine relative to the control. This study indicates that chronic exposure of shrimp to sulfide can decrease health and lower survival through functional changes in gluconeogenesis, protein synthesis and energy metabolism.

Penaeidae/efeitos dos fármacos , Sulfetos/toxicidade , Poluentes Químicos da Água/toxicidade , Aminoácidos/metabolismo , Animais , Glicemia/análise , Ácidos Carboxílicos/sangue , Metabolismo Energético/efeitos dos fármacos , Glicogênio/metabolismo , Hepatopâncreas/efeitos dos fármacos , Hepatopâncreas/metabolismo , L-Lactato Desidrogenase/sangue , Metabolômica , Músculos/efeitos dos fármacos , Músculos/metabolismo , Penaeidae/metabolismo