Effects of chronic abamectin stress on growth performance, digestive capacity, and defense systems in red swamp crayfish (Procambarus clarkii)

Abamectin is a globally used pesticide, which is one of 16-member macrocyclic lactones compound. As an environmental contaminant, pesticide residues pose a great threat to the health and survival of aquatic animals. Procambarus clarkii is one of the most important economic aquatic animals in China. It is necessary to explore the toxic mechanism of abamectin to P. clarkii. In this study, the toxic mechanism of abamectin to P. clarkii was investigated by 0, 3 and 6 μg/L abamectin stress for 28 days. The digestive-, antioxidant- and immune- related enzymes activities, genes expression levels, and histological observations were analytical indicators of growth performance, digestive capacity, and defense systems. The results in this study showed that with abamectin concentration increasing, the growth of P. clarkii was stunted significantly, and the mortality rate increased significantly. With exposure time and abamectin concentration increasing, the expression levels of related genes, the activities of digestive-, antioxidant-, and immune- related enzymes decreased ultimately. Moreover, through histological observation, it was found that with abamectin concentration increasing, the hepatopancreas, muscle, and intestine were damaged. As elucidated by the results, once abamectin exists in the environment for a long time, even low doses will threaten to healthy growth and survival of P. clarkii. This study explored the potential toxicity and the toxic mechanism of abamectin to P. clarkii, and provides a theoretical basis for further study on the toxicity of pesticides to aquatic animals.

Sub-acute toxicity of the herbicide glufosinate-ammonium exposure in adult red swamp crayfish (Procambarus clarkii)

Glufosinateammonium (GLA) is one of the most widely used agricultural herbicides. It is frequently detected in surface waters near farmland and may pose a risk to non-target aquatic species. This study aimed to explore the toxicity of subacute GLA exposure in crayfish. Adult red swamp crayfish were exposed to GLA (0, 1, 10, and 100 mg/L) for 21 days. Bioaccumulation, oxidative stress, nonspecific immunity, and the expression of genes encoding xenobiotic detoxification-related enzymes were examined. The results showed GLA accumulation and hepatopancreatic histopathological changes (dilation of hepatic tubules and vacuolation of hepatocytes) in the exposed crayfish. GLA exposure induced ROS production, inhibited glutathione expression, and catalase activity in the crayfish hepatopancreas, as well as inhibited immunoenzyme expression (acid phosphatase, alkaline phosphatase, and lysozyme) in the hemolymph. In addition, the total hemocyte number decreased, and the proportion of hemocyte subsets changed significantly. Superoxide dismutase first increased and then decreased with increasing GLA dosage. GLA promoted the expression of biotransformation enzymes (cypb5, gst) in the hepatopancreas. Our results suggest that subacute GLA exposure caused structural damage to the hepatopancreatic tissue and decreased antioxidant capacity and non-specific immunity in crayfish. These findings provide insight into the toxicity of herbicides on non-target organisms.

Effects of abamectin on nonspecific immunity, antioxidation, and apoptosis in red swamp crayfish (Procambarus clarkii)

Abamectin, a pesticide of 16-member macrocyclic lactones, is widely applied in agriculture. As an important environmental factor, pesticides pose a great threat to defense system in aquatic animals. Procambarus clarkii is one of the most important economic aquatic animals in China. It is necessary to explore the defense mechanism of P. clarkii to abamectin. In this study, P. clarkii were exposed to 0, 0.2, 0.4, 0.6 mg/L abamectin, immune- and antioxidant-related enzymes activities, genes expression levels, and histological observations were used to analyze the defense capacity of P. clarkii to abamectin. With increasing abamectin concentration, reactive oxygen species (ROS) level and malondiadehyde (MDA) content increased significantly. Meanwhiile, acid phosphate (ACP), alkaline phosphatase (AKP) activities, total haemocyte counts (THC), and Crustin expression level decreased significantly, superoxide dismutase (SOD), catalase (CAT) activities, total antioxidant capacity (T-AOC), and GPX expression level also decreased significantly. Hematoxylin & eosin (H&E) observation showed that with increasing abamectin concentration, hepatopancreas were damaged, especially membrane structure. Through TUNEL observation and apoptosis-related genes (PcCTSL, Bcl-2, Bax, BI-1, PcCytc, caspase-3) expression levels, with increasing abamectin concentration, apoptosis rate increased significantly. Results of this study indicated that abamectin caused oxidative damage to P. clarkii, resulting in damage to defense system, suppression of nonspecific immunity and antioxidation, and promotion of apoptosis. It provided theoretical basis for healthy P. clarkii culture, and for further study on defense mechanism of aquatic animals to pesticides.

Mechanistic insight into the gut microbiome and its interaction with host immunity and inflammation

The intestinal tract is a host to 100 trillion of microbes that have co-evolved with mammals over the millennia. These commensal organisms are critical to the host survival. The roles that symbiotic microorganisms play in the digestion, absorption, and metabolism of nutrients have been clearly demonstrated. Additionally, commensals are indispensable in regulating host immunity. This is evidenced by the poorly developed gut immune system of germ-free mice, which can be corrected by transplantation of specific commensal bacteria. Recent advances in our understanding of the mechanism of host–microbial interaction have provided the basis for this interaction. This paper reviews some of these key studies, with a specific focus on the effect of the microbiome on the immune organ development, nonspecific immunity, specific immunity, and inflammation.

The feeding of dietary Codonopsis pilosula polysaccharide enhances the immune responses, the expression of immune-related genes and the growth performance of red swamp crayfish (Procambarus clarkii)

Polysaccharides have many functions in aquatic animals and are widely used as immunopotentiators. However, despite the emergence of serious diseases, few studies have explored the effects of Codonopsis pilosula polysaccharide (CPP) on crustaceans. We studied the effects of CPP on the growth performance, nonspecific immunity, antioxidant activity and disease resistance of red swamp crayfish (Procambarus clarkii). Healthy crayfish (5.80 ± 0.1 g) were fed diets supplemented with 0% (control), 0.05%, 0.1%, 0.15%, 0.20%, and 0.30% CPP for 8 weeks. At the end of the 8-week feeding trial, the optimal final body weight (FBW), weight gain (WG), specific growth rate (SGR), and feed conversion ratio (FCR) were observed in the crayfish fed the diets with 0.15% and 0.20% CPP, followed by those fed the diet with 0.30% CPP and then those fed the diet with 0.10% CPP, whereas the values of these parameters were obtained with the control crayfish (P < 0.05). The crayfish fed the diets with 0.15% and 0.20% CPP exhibited a significantly higher total hemocyte count (THC) and significantly increased phenoloxidase (PO), lysozyme (LZM), hemocyte (Hc), acid phosphatase (ACP) and alkaline phosphatase (AKP) compared with those belonging to the other groups (P < 0.05). The crayfish fed the diets with 0.15% and 0.2% CPP exhibited significantly higher total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) activities, a significantly increased total antioxidant capacity (T-AOC) and a significantly lower malondialdehyde (MDA) content compared with the other groups (P < 0.05), which indicated that antioxidant capacity was significantly induced by the CPP-supplemented diets. Significantly upregulated expression of immune-related genes (anti-lipopolysaccharide factors (alf), peroxiredoxin (prx5), cathepsin B (ctsb), mitochondrial manganese superoxide dismutase (mtMnsod), cyclophilin A (cypa), glutathione peroxidase (gpx), Toll-like receptor 3 (tlr3), and heat shock protein 70 (hsp70)) was detected in the crayfish fed the diets supplemented with 0.15% and 0.20% CPP diet compared with the levels observed in the control crayfish. These results showed that dietary CPP supplementation greatly improved the growth, immunity and antioxidant capacities of crayfish, and according to the observed results, 0.15%-0.2% is the recommended optimal level of CPP dietary supplementation for crayfish.

RETRACTED: Residual papaya promoting the growth performance, antioxidant, nonspecific immunity of juvenile Tilapia mossambica

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of Editors-in-Chief and first Author. The article duplicates significant parts of a paper that had already appeared in Fish & Shellfish Immunology, Volume 93 (2019) 726-731, https://doi.org/10.1016/j.fsi.2019.06.052. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper has not been previously published and is not under consideration for publication elsewhere. As such this article represents a misuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process. The article was published without the knowledge of the co-authors.

Feasibility of cultivation of Spinibarbus sinensis with coconut oil and its effect on disease resistance (nonspecific immunity, antioxidation and mTOR and NF-kB signaling pathways)

Application of traditional bait in aquaculture caused environment pollution and disease frequent occurrence. Residual coconut could be re-utilized to culture Spinibarbus sinensis as dietary supplement. Therefore, a novel integrated system of the improvement of yield, antioxidant and nonspecific immunity of Spinibarbus sinensis by dietary residual coconut was proposed and investigated. Spinibarbus sinensis could grow well in all supplement residual coconut groups. Survival rate, yield, whole fish body composition under 15-45% groups were increased compared with control group (CK). Bioactive substances (polyphenols and vitamin) in residual coconut enhanced AKP, ACP, phagocytic, SOD, CAT activities through up-regulating AKP, ACP, SOD, CAT genes expression levels. Theoretical analysis showed bioactive substances regulated these genes expressions and enzyme activities as stimulus signal, component, active center. Moreover, residual coconut improved mTOR and NF-kB signaling pathway. Furthermore, residual coconut inhibited Aeromonas hydrophila that increased resistance to diseases. This technology completed the solid waste recovery and the Spinibarbus sinensis culture simultaneously.

Dietary chitosan oligosaccharides modulate the growth, intestine digestive enzymes, body composition and nonspecific immunity of loach Paramisgurnus dabryanus

Three test diets containing three different levels (1, 3, and 5 g kg^-1) of dietary chitosan oligosaccharides (COs) were formulated and used to test the growth performance, body composition, intestine digestive enzymes, antioxidant responses and resistance to Aeromonas hydrophila of loach Paramisgurnus dabryanus. A basal diet without any COs served as the control. After 60 days of feeding, the growth performance, intestine digestive-enzyme activities, body protein content and total polyunsaturated fatty acids, antioxidant responses, and resistance to A. hydrophila of loach P. dabryanus were higher than those of the control when the loach P. dabryanus was fed with CO-containing diets. The optimum dose of dietary COs required for the maximum growth of loach was 3 g kg^-1 of the diet. Results indicated that dietary COs can improve the growth performance, body composition, intestine digestive enzymes, antioxidant responses, and resistance to A. hydrophila of loach P. dabryanus and can thus be used as a diet supplement for them.

Effects of dietary taurine on growth, non-specific immunity, anti-oxidative properties and gut immunity in the Chinese mitten crab Eriocheir sinensis

Taurine has been widely researched as a growth-promoting additive or as an antioxidant in aquatic animals because of its multiple functions, however, few studies have explored its effects on crustacean in spite of the occurrence of serious diseases. We studied the effects of taurine supplementation on the growth, non-specific immunity, anti-oxidative properties and gut immunity of the Chinese mitten crab Eriocheir sinensis. Healthy crabs (8.0 ± 0.5 g) were fed diets supplemented with taurine at 0% (control), 0.2%, 0.4%, 0.8%, and 1.6% for 65 days. At the end of this 65 days feeding trial, the final weight, weight gain, specific growth rate, and feed conversion ratio were best in crabs fed the 0.4% taurine diet, followed by that in those fed the 0.8% taurine diet; the parameters were worst for the control group. Carapace length (CL) and carapace width (CW) were significantly increased in the crab fed the 0.4% and 0.8% taurine diet than that of the other three groups. Total haemocyte count (THC) and acid phosphatase (ACP) activity were significantly higher in the crab fed the 0.8% taurine diet than in those belonging to the other groups, the crabs fed the 0.4% taurine diet had the highest phenoloxidase (PO), lysozyme (LZM), and alkaline phosphatase (AKP) activities, however, there was no obvious change in their haemocyanin (Hc) content. According to superoxide dismutase (SOD), glutathione Peroxidase (GSH-PX), total anti-oxidant capacity (T-AOC) activities and malondialdehyde (MDA) content, the antioxidant capacity was significantly induced by taurine diet, while was higher in crabs fed 0.4 %-0.8% taurine diet than that of the other groups. Taurine supplementation significantly up-regulated the expression of gut immune genes (EsToll2, EsRelish) and antimicrobial peptides (EsALF1, EsALF2, EsCrus1, EsCrus2) in crabs gut fed the 0.2-0.8% taurine diet group compared to control. Thus, these study results indicate that dietary taurine is important for improving growth, regulating immunity, and enhancing the antioxidant capacity in crabs, with the recommended optimum dietary allowance being 0.4 %-0.8% taurine for E. sinensis.

Immune defense of emodin enriched diet in Clarias batrachus against Aeromonas hydrophila

This study investigates the effect of emodin enriched diet on growth, hematology, and immune response in walking catfish, Clarias batrachus against Aeromonas hydrophila. The basal (control) diet supplemented with emodin at 0.0, 0.1, 0.2, or 0.4 g kg^-1 was fed to the experimental groups for a period of four weeks. Feeding infected fish with 0.2 g kg^-1 and 0.4 g kg^-1 emodin enriched diets resulted in an overall weight gain, enhanced PER and FCR when compared to other diets. The survival rates were 98.3% and 96.7% in 0.1 g kg^-1 and 0.4 g kg^-1 emodin diet fed groups. Feeding with 0.2 g kg^-1 diet the RBC level significantly elevated on week 1 and with 0.4 g kg^-1 diet on weeks 2 and 4. The WBC, the percentage of globulin and neutrophils increased significantly with 0.2 g kg^-1 diet only on week 4; however with 0.4 g kg^-1 diet the increase was observed from week 1-4. The phagocytic activity increased significantly on being fed with 0.4 g kg^-1 diet on week 2 while with 0.2 g kg^-1 and 0.4 g kg^-1 diets the increase manifested only on week 4; the respiratory burst activity also significantly increased on week 4 whereas increased the complement activity on weeks 2 and 4. The superoxide dismutase (SOD) activity was high on being fed with 0.4 g kg^-1 diet on week 1; with 0.2 g kg^-1 or 0.4 g kg^-1 diets the increase was observed on weeks 2 and 4. The serum IgM level significantly increased when fed with 0.4 g kg^-1 diet whereas the lysozyme activity was enhanced with 0.2 g kg^-1 and 0.4 g kg^-1 emodin diets on weeks 2 and 4. The percentage cumulative mortality was 10% with 0.1 g kg^-1 or 0.2 g kg^-1 diets while with 0.2 g kg^-1 diet it was 15%. The results demonstrate that as a feed additive emodin acts as an immunostimulant enhancing the specific and nonspecific immune defense affording increased disease protection, enhances better growth and boosts hematology parameters in C. batrachus against A. hydrophila infection.

In vivo nonspecific immunomodulatory and antispasmodic effects of common purslane (Portulaca oleracea Linn.) leaf extracts in ICR mice

ETHNOPHARMACOLOGICAL RELEVANCE

Portulaca oleracea (common purslane) is used in traditional medicine to cure various illnesses. However, its immune-protective properties and antispasmodic effects still need more pharmacological data if the plant will be utilized in herbal and drug formulations. Therefore, the present study determined the capacity of this plant species to modulate nonspecific immune responses and to confirm its antispasmodic activity in vivo in ICR mice.

MATERIALS AND METHODS

Phagocytic activity of peritoneal macrophage, splenic lymphocyte proliferation and plasma lysozyme levels were measured in mice that were immunosuppressed using cyclophosphamide and treated with the ethyl acetate extract of Portulaca oleracea. In addition, the charcoal meal transit test was used to measure intestinal motility using ethanolic (EtOH), hexane (HEX), and ethyl acetate (EA) solvent extracts. Phytochemical analysis was undertaken and DPPH scavenging properties of the three solvent extracts were also determined.

RESULTS

The EA extract of P. oleracea exhibited immunoactivity through significant increase in phagocytosis and higher proliferative response in splenic lymphocytes. Plasma lysozyme level was also higher in EA-treated mice at high dose but this was not statistically significant. Decreased intestinal motility was also exhibited in mice treated with the three leaf solvent extracts compared to the negative control and the acetylcholine-treated group. The antispasmodic activity of the solvent extracts was comparable to that of the atropine-treated group. Phytochemical analysis showed the presence of tannins in EA extract in addition to alkaloids and steroids. The EtOH and HEX extracts contain alkaloids, steroids and terpenoids. DPPH scavenging activity was highest in the EA extract.

CONCLUSIONS

The present study showed that the EA extract of P. oleracea leaves ameliorated the immunosuppressive action of cyclophosphamide in mice. The results also indicated that the three solvent extracts of the plant decreased smooth muscle spasms in mice ileum. However, further experiments are warranted to further isolate the plant's immunoactive component. Also, the mechanisms involved in the immunoactivity and antispasmodic properties of P. oleracea deserve full elucidation.

Some immunological responses of common carp (Cyprinus carpio) fingerling to acute extremely low-frequency electromagnetic fields (50 Hz)

Increasing of anthropogenic electromagnetic fields in aquatic environments has been recently become the core of attention. In this study, the effect of extremely low-frequency electromagnetic fields (50 Hz) on immune status and metabolic markers of common carp fingerling was assessed. The fish were exposed to extremely low-frequency electromagnetic fields at four intensities of 0.1, 0.5, 1, and 2 mT only once for 2 h; then, they were reared for 60 days. Results showed that the levels of aspartate aminotransferase (AST) and alanine transaminase (ALT) and alkaline phosphatase (ALP) were increased with an increase in the electromagnetic field intensity on 15 and 60 days post exposure. A significant increase was obtained in these enzyme levels in all the tested intensities compared to the control one (p < 0.05), with a maximum value measured in 2-mT trail. Conversely, with an increasing in the electromagnetic intensity, the levels of C3, C4, and lysozyme were reduced in all the treated groups in comparison with the control group (p < 0.05). The results suggested a significant impact of electromagnetic on fish immunophysiological functions. Therefore, it is required to have serious attention in aquatic ecosystems.

Effect of stocking density on growth performance, digestive enzyme activities, and nonspecific immune parameters of Palaemonetes sinensis

Palaemonetes sinensis is a new breed of shrimp with great potential for aquaculture, which has been confirmed in our previous production tests. However, there are limited reports about this species and its biological information is scarce. This study describes the effect of stocking density on the growth, digestive enzyme activities, and nonspecific immunity of P. sinensis with an initial average body weight was 0.25 ± 0.02 g. Groups of shrimps were reared at four different initial densities (2.5, 5, 10, and 20 individuals·L^-1). After 30 days of culture, the results indicated that the final body weight, weight gain, and specific growth rate were higher in shrimps grown in groups of 10 individuals·L^-1 than other groups, but the survival rates of these shrimp were significantly lower than those reared in group of 2.5 or 5 individuals·L^-1. The trypsin, amylase, and lipase activities of shrimp significantly decreased with increase in stocking density. Nonspecific immune indicators decreased significantly with increase in density, but there were no significant differences between the 2.5 and 5 individuals·L^-1 groups in terms of the total haemocyte count (THC), phenoloxidase activity (PO), lysozyme (LZM), catalase (CAT), and superoxide dismutase (SOD). These results suggest that increasing the stocking density from 2.5 to 5 individuals·L^-1 did not affect any of the detected indicators of P. sinensis, but there are shelter in farming mode is better for culture of P. sinensis up to 10 individuals L^-1.

Effect of Agaricus bisporus enriched diet on growth, hematology, and immune protection in Clarias gariepinus against Flavobacterium columnare

The purpose of the present study was to find out the effect of dietary enriched button mushroom, Agaricus bisporus at 1%, 5%, and 10% levels on growth performance, hematology, nonspecific immune responses, and disease resistance in catfish, Clarias gariepinus against Flavobacterium columnare for a period of four weeks. The percentage weight gain and specific growth rate (SGR) were higher in the infected fish fed with 5% A. bisporus enriched diet than with 1% and 10% diets. The red blood cell (RBC), white blood cell (WBC), hematocrit (PCV), and haemoglobin (Hb) values are similar (p > .05) among the experimental groups at the end of fourth week. The phagocytic activity, complement activity, and lysozyme activity were significantly enhanced in the infected fish fed with 5% A. bisporus diet during the experimental period; however, it was significantly enhanced with 10% A. bisporus enriched diet only on weeks 2 and 4. On the other hand, the respiratory burst (RB) activity increased significantly in the infected fish fed with 5% and 10% A. bisporus enriched diets. When fed with 5% A. bisporus diet the cumulative mortality was very low (10%), followed by a high survival rate (89%) in the infected fish; nevertheless, the cumulative mortality was 25% and 20% while it was 74% and 79% when fed with 1% and 10% enriched diets. The present study recommends a dietary supplement of A. bisporus at 5% or 10% level to achieve better growth without side effect, and enhance the nonspecific immune system that prevent mortalities from F. columnare infection in C. gariepinus.

Ameliorative effect of vitamin E on hepatic oxidative stress and hypoimmunity induced by high-fat diet in turbot (Scophthalmus maximus)

This study was conducted to examine the effects of vitamin E on growth performance, oxidative stress and non-specific immunity of turbot (Scophthalmus maximus) fed with high-fat diet. Results showed that high-fat diet significantly increased hepatosomatic index, viscerosomatic index, hepatic malondialdehyde level and decreased catalase and superoxide dismutase activities, whereas final weight, specific growth rate and survival rate remained unchanged. Meanwhile, nitro blue tetrazolium positive leucocytes of head kidney, respiratory burst activity in head-kidney macrophage, phagocytic index and serum lysozyme activity were significantly reduced after feeding with high-fat diet. Furthermore, fish fed with high-fat diet promoted higher expression of heat shock protein (hsp70, hsp90), and inhibited expression of complement component 3 (c3) in the liver and tumor necrosis factor-α (tnf-α), interleukine 1β (il-1β), toll like receptor 22 (tlr-22) in the spleen and head-kidney, respectively. However, simultaneous supplementation with 480 mg kg^-1 vitamin E protected turbot against high-fat diet-induced hepatic oxidative stress, hypoimmunity through attenuating lipid peroxidation, renewing antioxidant enzymes activities and nonspecific immune responses, and modulating the expression of stress protein (hsp70, hsp90) and immune-related genes (c3, tnf-α, il-1β, tlr-22). In conclusion, the obtained results indicate the vitamin E as a wildly used functional feed additive contributes potentially to alleviate high-fat diet-induced hepatic oxidative stress and hypoimmunity, maintain the health, and improve the broodstock management for turbot.

Effect of dietary vitamin E on the growth performance and nonspecific immunity in sub-adult turbot (Scophthalmus maximus)

This study investigated the growth performance and non-specific immunity in sub-adult turbot fed with graded levels of vitamin E (0, 120, 240, 480 and 960 mg kg(-1)) for 15 weeks. Results showed that the final weight, specific growth rate, nitro blue tetrazolium positive leucocytes of head kidney, phagocytic index, serum lysozyme activity and superoxide dismutase activity significantly increased with increasing vitamin E levels. The highest values were recorded in the diet with 480 mg kg(-1) vitamin E. However, no significant differences in the hepatosomatic index, viscerosomatic index and survival rate were found among all dietary treatment. Furthermore, the expression levels of complement component 3 (C3), tumor necrosis factor-α (TNF-α) and interleukine 1β (IL-1β) were significantly upregulated in the fish feed with the vitamin E-supplemented diets. Compared with the basal diet, the diet supplemented with 480 mg kg(-1) vitamin E significantly augmented the mRNA expression of IL-1β, TNF-α in the spleen and head-kidney, C3 in the liver, respectively. In conclusion, the obtained results indicate the basal diet supplemented with moderate dietary vitamin E (480 mg kg(-1)) increased the growth, nonspecific immune responses, and expression levels of some immune-related genes in sub-adult turbot. These observations suggest that optimal dietary vitamin E can promote the growth, maintain the health and improve the broodstock management for turbot.

Role of autoimmunity in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by the presence of serum autoantibodies and chronic nonsuppurative destructive cholangitis. The pathogenesis of PBC involves environmental factors, genetic predisposition and loss of immune tolerance. In recent years, it has become univocally accepted that an inappropriately activated immune response is one of the most important factors in PBC. In this study, the role of autoimmunity in PBC is summarized and a feasible research orientation is recommended.