Qingsong Liu

Oxidative stress response of the black tiger shrimp Penaeus monodon to Vibrio parahaemolyticus challenge

Vibrio parahaemolyticus is a virulent pathogen that affects shrimp aquaculture. Reactive oxygen species are produced by the immune system that defends the host against foreign microorganisms. In the present study, the oxidative stress response in hepatopancreas and gills of Penaeus monodon to V. parahaemolyticus challenge were studied, such as respiratory burst, ROS production (·O2(-) and ·OH), activities of antioxidant enzymes (CAT, GPx, SOD, POD and GST) and oxidative damage to lipid and protein (indexed by contents of MDA). Compared with the control group, after V. parahaemolyticus challenge, respiratory burst and ROS production were up-regulated significantly. GPx and POD activity increased significantly in hepatopancreas and gills of the shrimps at 12 h, but CAT activity decreased markedly at 12 h and 24 h. SOD and GST activity in hepatopancreas of the shrimps increased significantly at 1.5 h, but decreased markedly at 12 h-48 h. MDA content increased significantly after 6 h-24 h challenge. HE staining showed that V. parahaemolyticus challenge induced damage symptoms in hepatopancreas of P. monodon. Our study revealed that V. parahaemolyticus influenced the antioxidative status and caused oxidative stress and tissue damage via confusion of antioxidant enzymes in P. monodon.

Effect of dietary poly-β-hydroxybutyrate (PHB) on growth performance, intestinal health status and body composition of Pacific white shrimp Litopenaeus vannamei (Boone, 1931).

ABSTRACT In the present study, the effect of dietary supplementation of poly‐&bgr;‐hydroxybutyrate (PHB) on the growth performance, intestinal digestive and immune function, intestinal short‐chain fatty acids (SCFA) content and body composition of Pacific white shrimp Litopenaeus vannamei (Boone, 1931) was evaluated. The shrimp was fed for 35 days with four different diets: 0%, 1%, 3% and 5% PHB supplemented feed. The results indicated that supplementation of PHB significantly increased the growth performance of the shrimp, and the feed conversion rate (FCR) in 3%PHB treatment group was significantly lower than the control (P < 0.05). The intestinal amylase, lipase and trypsin activity in the three PHB treatment groups were all significantly higher than that of the control (P < 0.05), but the pepsin activity were only significantly affected by 3%PHB treatment (P > 0.05). The activities of intestinal immune enzymes such as total antioxidant capacity (T‐AOC) and inducible nitric oxide synthase (iNOS) was significantly induced by 3%PHB treatment (P < 0.05), while lysozyme (LSZ) activity was significantly affected by 5%PHB treatment and nitric oxide (NO) content was significantly induced in three PHB treatments. Meanwhile, PHB induced significantly the expression level of intestinal heat shock protein 70 (HSP70), Toll and immune deficiency (Imd) gene. HE staining showed that PHB induced the intestinal health status of L. vannamei. Intestinal SCFA content analysis revealed that the content of propionic and butyric acid of 3%PHB treatment were significantly higher than that of the control (P < 0.05). Body composition analysis showed that the crude protein in 3% and 5%PHB treatments, and the crude lipid in 1% and 5%PHB treatments were all significantly higher than the control (P < 0.05). These results revealed that PHB could improve the growth performance, modulated intestinal digestive and immune function, increased intestinal SCFA content and body composition in L. vannamei, and the optimum dietary PHB requirement by L. vannamei was estimated at 3% (w/w) diet. HIGHLIGHTSThe effect of dietary poly‐&bgr;‐hydroxybutyrate (PHB) supplementation in Litopenaeus vannamei was studied.PHB improved the growth performance and feed utilization of L. vannamei.PHB increased the intestinal digestive and immune function of L. vannamei.PHB influenced the intestinal structure and SCFA content of L. vannamei.PHB changed the body composition of L. vannamei.

Intestine oxidative stress and immune response to sulfide stress in Pacific white shrimp Litopenaeus vannamei.

Abstract The effects of sulfide stress on oxidative stress and immune response in intestine of Pacific white shrimp Litopenaeus vannamei were evaluated in the present study. Oxidative stress parameters, immune enzymes activity and immune gene mRNA expression level were detected in intestine of L. vannamei after the exposure of 5.0 mg/L sulfide stress 72 h. The duration of sulfide stress influenced the shrimp survival, and the cumulative mortality rate was 30.0% and 33.3% at 48 h and 72 h respectively. HE staining showed that sulfide stress caused the intestine tissue damage symptoms. Compared with the control group, after exposed to sulfide stress, the content of lipid peroxidation (LPO), malondialdehyde (MDA) and ROS production (·O2− generation capacity) increased. Total antioxidant capacity (T‐AOC) activity increased at 6 h and decreased at 48 h. Superoxide dismutase (SOD) activity increased in the entire experiment. Inducible nitric oxide synthase (iNOS) activity and nitric oxide (NO) content increased to the highest at 6 h and 12 h respectively, and both decreased at 48 h. The relative mRNA expression level of heat shock protein 70 (HSP70) gene decreased at 6 h and increased to the highest at 48 h. The relative mRNA expression level of hypoxia inducible factor 1&agr; (HIF‐1&agr;) gene increased at 12 h and decreased to a lower level at 72 h. The relative mRNA expression level of Toll and immune deficiency (Imd) gene increased to the highest at 12 h and 24 h respectively, and both decreased at 48 h. These results revealed that sulfide stress could induce oxidative stress and immune response via confusion of immune enzymes activity and gene expression level in intestine of L. vannamei. HighlightsEffect of sulfide stress on oxidative stress and immune response in intestine of Litopenaeus vannamei was studied.Sulfide stress caused the oxidative stress and tissue damage in intestine of L. vannamei.Sulfide stress influenced the immune enzymes activity in intestine of L. vannamei.Sulfide stress induced the expression of immune genes in intestine of L. vannamei.

Impairment of the intestine barrier function in Litopenaeus vannamei exposed to ammonia and nitrite stress

ABSTRACT Intestine barrier serves as the front‐line of shrimp defense, which rely on its structural integrity, microbial composition, and mucus immune compounds. Mucins are the major organic components of the intestine mucus layer that contribute to the immunity of intestine mucus. In this study, we examined the histological structure, microbial composition, and mucin genes expression in the intestines of Litopenaeus vanmei under three different conditions: control, ammonia stress, and nitrite stress for 72h. H&E stain showed that ammonia and nitrite stress exposure both damaged the intestine mucosal tissue. High‐throughput 16S rDNA sequencing revealed that two stresses exposure decreased the bacterial diversity, and altered the composition of intestine microbial. Specifically, the dominant bacterial phyla Bacteroidetes abundance was increased, while Proteobacteria and Planctomycetes were decreased; at the genus level, Formosa abundance was increased and Photobacterium was decreased, opportunistic pathogens including Nautella and Pseudoalteromonas was also increased. Intestine mucus immune genes including mucin‐2 and mucin‐19 were up‐regulated, while mucin‐1, mucin‐5AC, and mucin‐5B were down‐regulated in two stress exposure groups. These results revealed that ammonia and nitrite stress harmed the intestine barrier function of L. vannamei by damaging the mucosal tissue, disrupting the composition of intestine microbial, and suppressing the immune function. HIGHLIGHTSImpairment of the intestine barrier function in Litopenaeus vannamei exposed to ammonia and nitrite stress was studied.Ammonia and nitrite stress damaged the intestine mucosal tissue.Ammonia and nitrite stress decreased the intestine bacterial diversity.Ammonia and nitrite stress disrupted the composition of intestine microbial.Ammonia and nitrite stress influenced the intestine mucin genes expression.

Morphologic, digestive enzymes and immunological responses of intestine from Litopenaeus vannamei after lipopolysaccharide injection

The shrimp intestine barrier serves as the first line of the host defense against pathogen infection. Lipopolysaccharide (LPS) is the cell wall component of gram-negative bacteria, which known as endotoxin and induce the intestine inflammation. In this study, the acute toxicity effects of LPS injection on the morphology, digestive enzymes and immunological responses of intestine from Litopenaeus vannamei was investigated. HE stain showed that LPS injection damaged the intestine connective and epithelium tissue. Specifically, a decrease in the activities of digestive enzymes including of amylase, lipase, trypsin and pepsin was observed. Moreover, LPS injection increased the content of oxidative stress parameters (O2- generation capacity, LPO, MDA and PC), and the expression of HIF-1α gene. Alternatively, the antibacterial activities (PO and T-NOS), and the expression of the antibacterial genes (proPO, ALF, Toll and Imd) and pathogen pattern recognition genes (LGBP and Lec) increased at first and then decreased. Significant variations in anitioxidant enzyme activity of T-AOC, and the expression of the anitioxidant-related genes (SOD, HSP70 and Trx). These results revealed that LPS injection harmed the intestine barrier of L. vannamei by damaging intestine mucosal structure, increasing oxidative stress, and suppressing the digestive and immune status.

Plasticization of Poly (lactic) acid Film as a Potential Coating Material

PLA-based composite films with different plasticizers, such as polyethylene glycol (PEG) and Tributyl citrate (TBC), were prepared using a solvent casting method and their machanical, water absorbency and NO3 --N permeability properties were tested. Tensile strength, elongation at break, water absorbency and NO3 --N permeability of neat PLA film were 1.99 ± 0.04 MPa, 2.7 ± 0.46%, 29.33 ± 0.3% and 216.03 ± 19.92 mgL-1m-2h-1, respectively. After the addition of plasticizers the tensile strength were decreased, tensile strength of flims added 40wt% TBC and PEG decreased by 59.3% and 52.26%. While the elongation at break of the PLA film gradually increased. The elongation at break reached the value of 23.96±0.48% and 38.55±1.66% for the films added PEG and TBC respectively at the concentration of 40wt%. Water absorbency decreased as the increase of plasticizers. The NO3 --N permeability attained a maximum of 300.05±10.47 and 270.97±14.54 mgL-1m-2h-1 for films added PEG and TBC at the concentration of 10 wt % respectively. Considered the NO3 --N permeability, PEG at 10wt% seemed the better plasticizer for PLA used in control release of fertilizer.

Changes in the Intestine Microbial, Digestive, and Immune-Related Genes of Litopenaeus vannamei in Response to Dietary Probiotic Clostridium butyricum Supplementation

The intestine barrier serves as the front-line defense in shrimp. Clostridium butyricum (CB) can produce butyric acid that provides energy for the intestine epithelial cells of the host. However, the effects of dietary CB on the intestine microbiome and the digestion and immunity of the host is not clear. In this study, we therefore investigated the composition and metabolic activity of the intestine microbiome, and digestive and immune-related gene expression in Litopenaeus vannamei fed with diets containing different levels of CB: basal diet (control), 2.5 × 109 CFU kg−1 diet (CB1), 5.0 × 109 CFU kg−1 diet (CB2), and 1.0 × 1010 CFU kg−1 diet (CB3) for 56 days. Dietary CB altered the composition of the intestine microbiome. Specifically, the dominant bacterial phylum Proteobacteria was enriched in the CB3 group and weakened in the CB1 and CB2 groups. The Bacteroidetes was enriched in the CB1 and CB2 groups and weakened in the CB3 group. The Firmicutes was enriched in all three CB groups. At the genus level, the potential pathogen (Desulfovibrio and Desulfobulbus) were weakened, and beneficial bacteria (Bacillus, Clostridium, Lachmoclostridium, Lachnospiraceae, and Lactobacillus) were enriched in response to dietary CB; these might contribute to the expression of the host digestive genes (α-amylase, lipase, trypsin, fatty acid-binding protein, and fatty acid synthase) and immune-related genes (prophenoloxidase, lipopolysaccharide and β-1,3-glucan binding protein, lysozyme, crustin, and superoxide dismutase). Additionally, CB enhanced the bacterial metabolism, especially that of carbohydrates, polymers, amino acids, carboxylic acids, and amines. These results revealed that dietary CB had a beneficial effect on the intestine health of L. vannamei by modulating the composition of the intestine microbiome, enhancing the microbial metabolism activity, and promoting the digestion and immunity of the host. The optimal dietary supplementation dosage was found to be 5.0 × 109 CFU kg−1 in the diet.

Physiological and immune response in the gills of Litopenaeus vannamei exposed to acute sulfide stress

&NA; Sulfide is a harmful environmental pollutant that affects the survival and immunity of shrimps. The gill is important for shrimp respiratory and osmotic adjustment, the physiological and immune homeostasis of the organ can be influenced by sulfide. In this study, we investigated the acute toxicity of sulfide (5 mg/L) on the morphology, physiological and immune response in the gills of Litopenaeus vannamei. H&E stain showed that sulfide stress damaged the gills histological structure. Specifically, osmoregulation capacity including of Na+/K+‐ATPase and Ca2+/Mg2+‐ATPase activity was both increased at 6 h and 12 h, and decreased at 72 h; the contents of free amino acid including of Gly, Pro, Ser, Thr and Ala were decreased at 72 h. Respiratory metabolic enzymes, such as cytochrome c oxidase and succcinate dehydrogenase activity was decreased at 12 h‐72 h, while fumarate reductase and lactate dehydrogenase activity kept a higher level at 12 h‐72 h. Significant variations in the activities of immune enzymes (acid phosphatase, alkaline phosphatase, total antioxidant capacity and lysozyme). The expression of immune‐related genes (heat shock protein 70, thioredoxin and caspase‐3) was increased at first and then decreased, while hypoxia inducible factor 1&agr; kept a higher level at 6 h‐72 h. These results revealed that sulfide stress influenced the L. vannamei gills physiological and immune function by damaging histological structure, and confusing osmoregulation, respiratory metabolic and immune capacity. HighlightsSulfide stress induced physiological and immune responses in the gills of Litopenaeus vannamei.Sulfide stress caused gills histological structure damage.Sulfide stress confused respiratory metabolic enzymes and ATPase activity.Sulfide stress influenced the immune enzymes activity and genes expression.Sulfide stress deduced the content of free amino acid (FAA).

A green porous solid carbon source supports denitrification in low C/N salinity wastewater

A green porous composite was prepared using two kinds of natural polysaccharides, konjac glucomannan (KGM) and semen litchi (SL) in aqueous medium under mild conditions. The effect of mass ratios of KGM : SL on structures and denitrification was systematically investigated. The intermolecular hydrogen bonds and other synergistic interactions between KGM and SL gave the composite an amorphous phase and honeycomb network structure with a wide range of macropores. Its high porosity and biocompatibility meant the composite had short acclimation time. Nitrate removal rate could reach up to 98.8% on the first day and denitrification rate could reach up to 320.2 ± 5.82 mg N (L−1 d−1). In particular, the KGM : SL = 3 : 3 composite exhibited better mechanical property and much longer lifetime during the denitrification reaction. The porous composite can be used as an economical and effective carbon source for denitrification in low C/N wastewater.