Chinese herbs (Astragalus radix and Ganoderma lucidum) enhance immune response of carp, Cyprinus carpio, and protection against Aeromonas hydrophila

Enhancing immune and antioxidant responses in Nile tilapia through dietary supplementation with Ulva fasciata extract: A study on gene expression and resistance to Aeromonas hydrophila

BACKGROUND

The study focused on the impact of Ulva fasciata extract (UFE) supplementation in the diets of Nile tilapia (Oreochromis niloticus) on blood and biochemical markers, immune and oxidative responses, and the expression of related genes, with a specific interest in their condition following exposure to Aeromonas hydrophila.

METHODS

Four different levels of UFE were tested in the diets: 0% (0 mg kg- 1) for the control group (U0), and incremental additions of 0.05% (50 mg kg-1), 0.1% (100 mg kg-1), and 0.15% (150 mg kg-1) for the experimental groups U50, U100, and U150 respectively. Groups of 45 fish weighing 3.126 ± 0.120 g were fed these diets over 90 days.

RESULTS

The study found that groups treated with UFE showed statistically significant enhancements (p < 0.05) compared to the control group. These improvements included increased red and white blood cell counts, higher haemoglobin concentrations, greater packed cell volume, and elevated enzyme activities-specifically, superoxide dismutase, catalase, alanine aminotransferase, and aspartate aminotransferase. Additionally, lysozyme and phagocytic activities were notably higher, especially in the U100 group after exposure. Before exposure to Aeromonas hydrophila, all levels of UFE supplementation led to increased expression of TNF-α and COXII genes and decreased NFκ-B expression. After the challenge, UFE intake resulted in varied expression levels of immune and antioxidant genes (TNF-α, NFκ-B, SOD, and COXII) in the liver, with the most effective responses observed in the U50, U100, and U150 groups.

CONCLUSIONS

The findings underscore the potential of dietary UFE as a natural antioxidant and immune booster for Nile tilapia.

Effects of sage (Salvia officinalis) essential oil on growth, health and antioxidant capacity of common carp (Cyprinus carpio)

In the study, effects of S. officinalis essential oil on growth performance, health and antioxidant activity in C. carpio were investigated. The fish (13 ± 0.21 g) were fed with diet containing 1 and 3 ml kg- 1 of sage oil for 60 days. At the end of study, growth performance was not affected in fish fed with sage essential oil (p > 0.05). Superoxide dismutase (SOD) activity in hepatopancreas increased with addition of 1ml kg- 1 sage oil to the diet. However, Catalase (CAT) activity and malondialdehyde (MDA) values were not significantly altered in common carp. Total protein, albumin, glucose and hepatopancreas enzymes (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP)) in blood serum were not affected by sage essential oil supplementation. At the histological examinations, no pathological findings were observed in hepatopancreas and intestine of carp. Goblet cells number and villi length in intestine increased with sage supplementation (p < 0.001). In addition, fertility, granulation and number of follicles increased in common carp fed with sage essential oil. Mortality after challenged with A. hydrophila was not observed in carp fed with 1ml kg- 1 concentration of sage essential oil. As a result, use of sage oil can be recommended in carp farming to improve gut health, provide disease resistance against A. hydrophila infection, and increase of fertility.

Role of Phytobiotics in Modulating Transcriptomic Profile in Carps: A Mini-Review

Carp is a key aquaculture species worldwide. The intensification of carp farming, aimed at meeting the high demand for protein sources for human consumption, has resulted in adverse effects such as poor water quality, increased stress, and disease outbreaks. While antibiotics have been utilized to mitigate these issues, their use poses risks to both public health and the environment. As a result, alternative and more sustainable practices have been adopted to manage the health of farmed carp, including the use of probiotics, prebiotics, phytobiotics, and vaccines to prevent disease outbreaks. Phytobiotics, being both cost-effective and abundant, have gained widespread acceptance. They offer various benefits in carp farming, such as improved growth performance, enhanced immune system, increased antioxidant capacity, stress alleviation from abiotic factors, and enhanced disease resistance. Currently, a focal point of research involves employing molecular approaches to assess the impacts of phytobiotics in aquatic animals. Gene expression, the process by which genetic information encoded is translated into function, along with transcription profiling, serves as a crucial tool for detecting changes in gene expression within cells. These changes provide valuable insights into the growth rate, immune system, and flesh quality of aquatic animals. This review delves into the positive impacts of phytobiotics on immune responses, growth, antioxidant capabilities, and flesh quality, all discerned through gene expression changes in carp species. Furthermore, this paper explores existing research gaps and outlines future prospects for the utilization of phytobiotics in aquaculture.

Effects of dietary piperine supplementation on innate immunity, growth performance, feed utilization and intestinal morphology of olive flounder (Paralichthys olivaceus)

Piperine, the main bioactive component of black pepper (Piper nigrum) or long pepper (Piper longum), has anti-inflammatory, antifungal, and antibacterial properties. This study was carried out to evaluate the supplemental effects of piperine in olive flounder (Paralichthys olivaceus) diets. Six isonitrogenous and isolipidic diets were formulated to contain different levels of piperine at 0.00, 0.25, 0.50, 0.75, 1.00, and 2.00 g/kg (Con, P25, P50, P75, P100, and P200, respectively). Diets were randomly allocated to triplicate groups of fish (initial weight 27.6 ± 0.4 g, 30 fish/tank) and fed three times daily for 8 weeks. Results showed that dietary piperine significantly improved fish growth and feed utilization efficiency. The highest growth, including the highest Igf-1 mRNA expression, was observed in the P50 group, while P50 and P75 groups showed the highest protein efficiency ratio. Compared to the Con group piperine supplemented groups had significantly higher lysozyme activity, immunoglobulin level, and phagocytosis activities. Plasma cholesterol was significantly lower in fish fed P200 diet. Dry matter and protein digestibility were higher in P25, P50, and P75 groups than in Con group. Dietary piperine increased the intestinal villi length and goblet cell counts. In the challenge test against Edwardsiella tarda, all the groups supplemented with piperine showed higher cumulative survival compared to Con group. Therefore, these findings indicate that dietary piperine supplementation can improve growth performance, innate immunity, disease resistance, diet digestibility, and intestinal morphology of olive flounder. The optimum dietary piperine level seems to be approximately 0.5 g/kg for the fish.

Immuno-physiological effects of dietary reishi mushroom powder as a source of beta-glucan on Rohu, Labeo rohita challenged with Aeromonas veronii

Beta-glucans have immense potential to stimulate immune modulation in fish by being injected intramuscularly, supplemented with feed or immersion routes of administration. We studied how supplementing Labeo rohita's diet with reishi mushroom powder containing beta-glucan influenced immunological function. A supplemented diet containing 10% reishi mushroom powder was administered for 120 days. Afterwards, analyses were conducted on different immunological parameters such as antioxidants, respiratory burst, reactive oxygen species (ROS), alternative complement activity, and serum immunoglobulin, which resulted significant increases (p < 0.05; p < 0.01) for the reishi mushroom-fed immune primed L. rohita. Additionally, analyzing various hematological parameters such as erythrocytes and leukocytes count were assessed to elucidate the immunomodulatory effects, indicating positive effects of dietary reishi mushroom powder on overall fish health. Furthermore, the bacterial challenge-test with 1.92 × 104 CFU/ml intramuscular dose of Aeromonas veronii showed enhanced disease-defending system as total serum protein and lysozyme activity levels accelerated significantly (p < 0.01). Nevertheless, reishi mushroom powder contained with beta-glucan ameliorated the stress indicating parameters like acetylcholinesterase (AChE), serum-glutamic pyruvic transaminase (SGPT) and serum-glutamic oxaloacetic transaminase (SGOT) enzyme activities results suggested the fish's physiology was unaffected. Therefore, the results indicated that adding dietary reishi mushroom as a source of beta-glucan could significantly boost the immune responses in Rohu.

Effect of Dietary Origanum onites on Growth, Non Specific Immunity and Resistance against Yersinia ruckeri of Rainbow Trout ( Oncorhynchus mykiss)

Natural substances has been identified to maintain health and improve growth performance in the aquaculture. The effect of Origanum onites on growth and immune response of rainbow trout was investigated. Experimental groups (A and B) of 70 fish were separated into 10 different treatments. A groups were fed with dietary administration of O. onites essential oil (0.5 mL kg-1 and 3.0 mL kg-1) and crude powder (1.0 g kg-1 and 10.0 g kg-1) for a period of 8 weeks. Other groups (B) were vaccinated against Yersinia ruckeri at the beginning of experiment and then fed the same diets described above. Results showed that feed conversion ratio in fish fed a combination of O. onites and vaccine was statistically better than the control. NBT-positive cells, phagocytic activity, serum lysozyme activity and immunoglobulin M level were stimulated in both non vaccinated and vaccinated fish (p<0.05). Cumulative mortality in fish fed O. onites was lower than controls following challenge with Y. ruckeri. No mortality was observed in vaccinated fish fed with 0.5 mL kg-1 of O. onites. These results indicated that dietary administration of O. onites could act as an enhanced non specific immune response, growth performance and resistance to Y. ruckeri.

Two common nanoparticles exert immunostimulatory and protective effects in Tegillarca granosa against Vibrio parahaemolyticus

There are many studies revealed that metal-based nanoparticles (NPs) possess excellent bactericidal effect on multitudinous bacteria and fungi. However, the control effect of NPs as antimicrobial agents to against Vibrio parahaemolyticus infection remain in poorly understood for blood clam, Tegillarca granosa. In order to evaluate the effect, the changes in six physiological parameters and the immune-related genes expression of clams exposed to V. parahaemolyticus alone or along with NPs (nZnO or nCuO) were investigated in present study. Results showed that both tested NPs exerted prominent redemptive or mitigative effect in an inverse dose-dependent way on physiological indexes of clam, especially in the total counts, phagocytosis and the cell viability of haemocytes, as well as the concentration and activity of lysozymes, when co-exposed with Vibrio. Gene expression analysis showed NPs at a concentration of 0.1 mg/L generally mitigated the downregulation of immune-related genes after clam exposure to V. parahaemolyticus. The combination of 0.1 mg/mL nZnO and nCuO additives has been shown to significantly enhance the humoral immunity of blood clam, suggesting its potential as a protective measure against V. parahaemolyticus infection in T. granosa.

Evaluation of immunostimulatory attributes of Asparagus racemosus and Withania somnifera supplemented diets in fish, Channa punctatus (Bloch, 1793)

With the progression of aquaculture industry, there has been a spurt in dietary supplementation with economically viable medicinal herbs having enough immunostimulatory potential. This also aids in avoidance of environmentally undesirable therapeutics that are almost inevitable to safeguard fish against an array of diseases in aquaculture practices. The study aims to determine the optimal dose of herbs that can stimulate substantial immune response in fish for reclamation of aquaculture. Immunostimulatory potential of the two medicinal herbs- Asparagus racemosus (Shatavari), Withania somnifera (Ashwagandha), individually, and in combination, with a basal diet was screened up to 60 days in Channa punctatus. 300 laboratory acclimatized healthy fish (14 ± 1 g; 11 ± 1 cm) were divided into ten groups- C, S1, S2, S3, A1, A2, A3, AS1, AS2, and AS3, based on the composition of dietary supplementation, in triplicates, with 10 specimens per group. The hematological index, total protein and lysozyme enzyme activity were performed after 30 and 60 days, while qRT-PCR analysis of lysozyme expression was done after 60 days of the feeding trial. The significant (P < 0.05) increments in hematological indices- (TEC, TLC, DLC, Hb, Hct, MCV, MCH and MCHC), total protein content and serum lysozyme activity, after 30 and 60 days; whereas upregulation of lysozyme transcript levels, both in liver and muscle tissues after 60 days of the feeding trial were recorded in groups- AS1, AS2, and AS3. The maximal increment in lysozyme expression was recorded in AS3, both in liver and muscle tissues, with 3.75 ± 0.13 and 3.21 ± 0.18-folds, respectively. However, increments were non-significant (P > 0.05) for MCV in AS2 and AS3 after 30 days; and for MCHC in AS1 for both the durations; whereas in AS2 and AS3, after 60 days of the feeding trial. A positive correlation (P < 0.05) among lysozyme expression, MCH, lymphocytes, neutrophils, total protein content, and serum lysozyme activity in AS3, after 60 days, conclusively, evinces that a 3% dietary supplementation with both A. racemosus and W. somnifera enhances immunity and health profile of the fish, C. punctatus. The study, thus finds ample scope in augmentation of aquaculture production and also paves the way for more researches for biological screenings of potential immunostimulatory medicinal herbs that can be appropriately incorporated in the fish diet.

Immune-enhancing effects of Astragalus polysaccharides and Ganoderma lucidum polysaccharides on Vibrio harveyi flgJ DNA vaccine in grouper

Astragalus polysaccharides (APS) and Ganoderma lucidum polysaccharides (GLP) have been shown to possess strong immunoregulatory properties in aquatic animals. In this study, the fragment containing Vibrio harveyi flgJ gene was ligated into pcDNA3.1(+) vector and pcDNA3.1(+)-flgJ was constructed as DNA vaccine. APS and GLP were used as DNA vaccine adjuvants to evaluate the immunoregulatory effect by intramuscular injection to pearl gentian grouper (♀Epinephelus fuscoguttatus × ♂E. lanceolatus). The results showed that pcDNA3.1(+)-flgJ combined with APS or GLP could significantly up-regulate the innate and adaptive immune response in fish, including serum-specific antibody titres, catalase and lysozyme activities. At the same time, DNA vaccine combined with APS or GLP significantly up-regulated the expression levels of CD8α, IgM, IL-1β, MHC-Iα, MyD88 and TLR3 genes in thymus, head kidney, spleen and liver of pearl gentian grouper in comparison with those of the pFlgJ group. After 42 days post-vaccination, V. harveyi was used to challenge pearl gentian grouper by intraperitoneal injection. The relative percentage of survival (RPS) of pFlgJ, pFlgJ +APS, pFlgJ +GLP and pFlgJ+APS+GLP groups were 69%, 81%, 77% and 88%, respectively. These results suggested APS and GLP were potential adjuvants for DNA vaccine against V. harveyi infection in pearl gentian grouper.

Supplementing artemisinin positively influences growth, antioxidant capacity, immune response, gut health and disease resistance against Vibrio parahaemolyticus in Litopenaeus vannamei fed cottonseed protein concentrate meal diets

Artemisinin (ART) is a kind of Chinese herbal medicine worth exploring, which obtains various physiological activities. In order to study the prebiotic effect of ART on Litopenaeus vannamei fed cottonseed protein concentrate meal diets, six groups of isonitrogenous and isolipid diets were prepared (including the fish meal control group, FM; cottonseed protein concentrate replacing 30% fishmeal protein and supplementing ART groups: ART0, ART0.3, ART0.6, ART0.9, and ART1.2). The feeding trials was lasted for 56 days. The results showed that the final body weight, weight gain and specific growth rate of the ART0.6 group were the highest, yet the feed coefficient rate of the ART0.6 group was the lowest significantly (P < 0.05). There was no significant difference in survival rate among treatments (P > 0.05). In serum, the content of malondialdehyde in ART0 group was the highest (P < 0.05); the activities of superoxide dismutase, catalase, phenol oxidase and lysozyme increased firstly and then decreased among the ARTs groups (P < 0.05). The activities of intestinal digestive enzymes (including the trypsin, lipase and amylase) showed an upward trend among the ARTs groups (P < 0.05). The histological sections showed that the intestinal muscle thickness, fold height and fold width in the FM group were significantly better than those in the ART0 group; while the mentioned above morphological indexes in the ART0 group were significantly lowest among the ARTs groups (P < 0.05). Sequencing of intestinal microbiota suggested that the microbial richness indexes firstly increased and then decreased (P < 0.05); the bacterial community structure of each treatment group was almost close; the relative abundance of pathogenic bacteria decreased significantly (P < 0.05), such as the Proteobacteria and Cyanobacteria at phylum level, besides the Vibrio and Candidatus Bacilloplasma at genus level. In intestinal tissue, the relative expression levels of TOLL1, TRAF6 and Pehaeidih3 showed up-regulated trends, while the expression of Crustin and LZM firstly up-regulated and then down-regulated (P < 0.05). The challenge experiment suggested that the cumulative mortality of FM group was significantly lower than that of ART0 group; besides the cumulative mortality firstly increased and then decreased between the ARTs groups (P < 0.05). In conclusion, the dietary supplementation of ART can improve the growth, antioxidant capacity, immune response, gut health and disease resistance of the shrimp. To be considered as a dietary immune enhancer, the recommended supplementation level of ART in shrimp's cottonseed protein concentrate meal diets is 0.43%.

Phytogenic Substances: A Promising Approach Towards Sustainable Aquaculture Industry

The aquaculture industry has shown rapid growth over the last three decades, especially with improving the farming systems. However, the rapid expansion and intensification practices in the aquaculture sector have been marred by increased stress levels and disease outbreaks, and subsequently, high fish mortality. Excessive use of veterinary drugs and antibiotics in aquaculture poses a great threat to human and aquatic animals' health, as well as to the biosystem. Furthermore, exposure to various pollutants such as industrial effluents and agricultural pesticides may cause devastating toxicological aspects of fish and adversely affect their health and growth. Besides, with a growing world population, there is a growing interest in intensifying aquaculture production to meet the global demand for nutritional security needs. Uncontrolled intensification of aquaculture production makes aquatic animals both vulnerable to, and potential sources of a wide range of hazards include pathogen transmission, disease outbreak, immunosuppression, impaired growth performance, malnutrition, foodborne illness, and high mortality. Plant-derived compounds are generally recognized as safe for fish, humans, and the environment and possess great potential as functional ingredients to be applied in aquaculture for several purposes. Phytogenic additives comprise a wide variety of medicinal plants and their bioactive compounds with multiple biological functions. The use of phytogenic compounds can open a promising approach towards enhancing the health status of aquatic animals. However, further in-vivo trials are necessary under favorable conditions with controlled amounts of identified bioactive compounds along with toxicity testing for fish safety towards a realistic evaluation of the tested substance efficacy.

Effects of Dietary Supplementation with Honeybee Pollen and Its Supercritical Fluid Extract on Immune Response and Fillet's Quality of Farmed Gilthead Seabream (Sparus aurata)

The awareness of the correlation between administered diet, fish health and products’ quality has led to the increase in the research for innovative and functional feed ingredients. Herein, a plant-derived product rich in bioactive compounds, such as honeybee pollen (HBP), was included as raw (HBP) and as Supercritical Fluid Extracted (SFE) pollen (HBP_SFE) in the diet for gilthead seabream (Sparus aurata). The experiment was carried out on 90 fish with an average body weight of 294.7 ± 12.8 g, divided into five groups, according to the administration of five diets for 30 days: control diet (CTR); two diets containing HBP at 5% (P5) and at 10% (P10) level of inclusion; two diets containing HBP_SFE, at 0.5% (E0.5) and at 1% (E1) level of inclusion. Their effects were evaluated on 60 specimens (336.2 ± 11.4 g average final body weight) considering the fish growth, the expression of some hepatic genes involved in the inflammatory response (il-1β, il-6 and il-8) through quantitative real-time PCR, and physico-chemical characterization (namely color, texture, water holding capacity, fatty acid profile and lipid peroxidation) of the fish fillets monitored at the beginning (day 0) and after 110 days of storage at −20 °C. The results obtained showed that the treatment with diet E1 determined the up-regulation of il-1β, il-6, and il-8 (p < 0.05); however, this supplementation did not significantly contribute to limiting the oxidative stress. Nevertheless, no detrimental effect on color and the other physical characteristics was observed. These results suggest that a low level of HBP_SFE could be potentially utilized in aquaculture as an immunostimulant more than an antioxidant, but further investigation is necessary.

Ganoderma Modulates Allergic Asthma Pathologic Features via Anti-inflammatory Effects

Ganoderma, a fungal genus, is a traditional medicine with immuno-modulating effects. Asthma is an inflammatory disease of airways, and the main trigger of asthma is allergic inflammation. In this study, the effects of Ganoderma (an anti-inflammatory agent) given via oral administration (G/O) or intraperitoneal injection (G/IP) on asthma was evaluated. Forty BALB/c mice were divided into four groups, including the control, OVA-challenge, OVA-challenge + G/O, and OVA-challenge + G/IP. To determine AHR, the MCh challenge test was done. The levels of IL-1β, -4, -5, -6, -8, -10, -12, -13, -17, -25, -33, -38, Cys-LT, LTB4, and hydroxyproline were measured. Finally, lung histopathology was evaluated to determine eosinophilic inflammation, goblet cell hyperplasia, and mucus hyper-secretion. Treatment with G/O and G/IP could significantly reduce the levels of IL-1β, -5, -6, -8, -17, -25, -33, and -38; the levels of IL-4 and IL-13 had no significant changes, but the levels of IL-10 and IL-12 were enhanced. The mice treated with G/O and G/IP showed decreased levels of Cys-LT, LTB4, peribronchial and perivascular inflammation, but no significant changes were observed in AHR, hydroxyproline level, goblet cell hyperplasia, and mucus hyper-secretion. Ganoderma can be applied as an immunomodulatory and anti-inflammatory agent for managing asthma.

Gut Immune System and the Implications of Oral-Administered Immunoprophylaxis in Finfish Aquaculture

The gastrointestinal immune system plays an important role in immune homeostasis regulation. It regulates the symbiotic host-microbiome interactions by training and developing the host's innate and adaptive immunity. This interaction plays a vital role in host defence mechanisms and at the same time, balancing the endogenous perturbations of the host immune homeostasis. The fish gastrointestinal immune system is armed with intricate diffused gut-associated lymphoid tissues (GALTs) that establish tolerance toward the enormous commensal gut microbiome while preserving immune responses against the intrusion of enteric pathogens. A comprehensive understanding of the intestinal immune system is a prerequisite for developing an oral vaccine and immunostimulants in aquaculture, particularly in cultured fish species. In this review, we outline the remarkable features of gut immunity and the essential components of gut-associated lymphoid tissue. The mechanistic principles underlying the antigen absorption and uptake through the intestinal epithelial, and the subsequent immune activation through a series of molecular events are reviewed. The emphasis is on the significance of gut immunity in oral administration of immunoprophylactics, and the different potential adjuvants that circumvent intestinal immune tolerance. Comprehension of the intestinal immune system is pivotal for developing effective fish vaccines that can be delivered orally, which is less labour-intensive and could improve fish health and facilitate disease management in the aquaculture industry.

Remarkable positive effects of figwort (Scrophularia striata) on improving growth performance, and immunohematological parameters of fish

This study was conducted to investigate the effect of figwort on the growth and immunohematological parameters of common carp (14.20 ± 0.53 g). Four experimental diets were developed to feed fish for eight weeks: control, Figw10 (10 g/kg figwort), Figw20 (20 g/kg figwort), and Figw30 (30 g/kg figwort). The results showed that fish fed dietary Figw10 gained more weight (38.25 g) than control (P < 0.05). Regarding immunohematological parameters, fish fed dietary Figw30 had a higher level of white blood cells (31.2 10³/mm³), hematocrit (35.82%), blood performance (14.63), total protein (1.96 g/dL), albumin (0.79 g/dL), globulin (1.17 g/dL), lymphocyte (70.53%), monocyte (3.03%), alternative hemolytic complement activity (ACH50) (147.76 u/mL), lysozyme (62.19 u/mL), and bactericidal activities (135.24) than the control group (P < 0.05). After 14 days of the challenge with Aeromonas hydrophila, the Figw30 treatment had the highest survival ratio (61.76%) compared to the control with 26.46%. Further, after the challenge, fish fed dietary Figw30 had a higher value of immunoglobulin M (42.00 μg/mL), antibody titer (19.23), complement component 3 (296.39 μg/mL), and complement component 4 (97.91 μg/mL) when compared with those fed control diet (P < 0.05). In conclusion, the optimum dosage for providing the best immune response was 30 g/kg in diet.

Growth performance, haematological assessment and chemical composition of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) fed different levels of Aloe vera extract as feed additives in a closed aquaculture system

A 105-day experimental trial was conducted to assess different levels of dietary Aleo vera extract supplementation on water quality parameters, proximate composition, growth performance and haematological parameters of fry Oreochromis niloticus. Four different percentages of dietary leaf extract powder of Aleo vera (ALE) with a basal feed, designated as, i.e., T0 (Control group; without ALE), T1 (1% ALE), T2 (2% ALE), and T3 (3% ALE). Fish fry was reared in concrete tanks (7.0 m, 1.6 m, 1.0: L, W, H; water volume 11.2 m3/tank), with an average initial weight 4.04 ± 0.03 g/ fry, and each treatment was triplicated. Fry was randomly distributed at a stocking rate of 450 individuals/ tanks. The water quality parameters revealed that temperature, pH, salinity, dissolved oxygen (DO) and nitrates were found in a promising range as given by FAO/WHO limits. However, the record values obtained for Electric Conductivity (EC), Total dissolved solids (TDS), and alkalinities were not found in all tanks' suitable range according to FAO/WHO limits. The results revealed a significant impact of different percentages of dietary ALE supplementation on fry's body composition and haematological parameters. Moreover, the final body weight, final body length, average daily weight gain (g), net weight gain (g) and specific growth rate (%) were significantly higher (p < 0.05) in T1 and T2 compared with T0 and T3 treatments. The poorest feed conversion ratio was recorded in the T2 group compared with other treatments. Thus, the current study provides information about the nutritional quality of Nile tilapia culturing in Pakistan.

Ganoderma lucidum (Reishi) an edible mushroom; a comprehensive and critical review of its nutritional, cosmeceutical, mycochemical, pharmacological, clinical, and toxicological properties

Reishi owes an exceptional value in nutritional, cosmeceutical, and medical treatments; however, none of the studies has provided its future-driven critical assessment. This study documents an up-to-date review (2015-2020, wherever applicable) and provide valuable insights (preclinical and clinical evidence-based) with comprehensive and critical assessments. Various databases 'Google scholar', 'Web of Science', 'ScienceDirect', 'PubMed', 'Springer Link', books, theses, and library resources were used. The taxonomic chaos of G. lucidum and its related species was discussed in detail with solution-oriented emphasis. Reishi contains polysaccharides (α/β-D-glucans), alkaloids, triterpenoids (ganoderic acids, ganoderenic acids, ganoderol, ganoderiol, lucidenic acids), sterols/ergosterol, proteins (LZ-8, LZ-9), nucleosides (adenosine, inosine, uridine), and nucleotides (guanine, adenine). Some active drugs are explored at an optimum level to make them potential drug candidates. The pharmacological potential was observed in diabetes, inflammation, epilepsy, neurodegeneration, cancer, anxiety, sedation, cardiac diseases, depression, hepatic diseases, and immune disorders; however, most of the studies are preclinical with a number of drawbacks. In particular, quality clinical data are intensely needed to support pharmacological activities for human use. The presence of numerous micro-, macro, and trace elements imparts an essential nutritional and cosmeceutical value to Reishi, and various marketed products are available already, but the clinical studies regarding safety and efficacy, interactions with foods/drinks, chronic use, teratogenicity, mutagenicity, and genotoxicity are missing for Reishi. Reishi possesses many valuable pharmacological activities, and the number of patents and clinical trials is increasing for Reishi. Yet, a gap in research exists for Reishi, which is discussed in detail in the forthcoming sections.

Oral delivery of pVAX-OMP and pVAX-hly DNA vaccine using chitosan-tripolyphosphate (Cs-TPP) nanoparticles in Rohu, (Labeo rohita) for protection against Aeromonas hydrophila infection

The present study examines the effectiveness of DNA vaccine against Aeromonas hydrophila through oral route using chitosan-tripolyphosphate (Cs-TPP) nanoparticles encapsulation. The virulent gene of outer membrane protein (OMP) and hemolysin (hly) related to pathogenicity of A. hydrophila was used to construct a DNA vaccine using pVAX1, and the construct was named as pVAX-OMP and pVAX-hly DNA vaccines. The pVAX-OMP and pVAX-hly DNA vaccines were encapsulated by Cs-TPP nanoparticles and size measured by field emission scanning electron microscopy (FE-SEM). The encapsulation efficiency of Cs-TPP nanoparticles was found to be 79.6% for pVAX-OMP DNA and 82.3% for pVAX-hly DNA binding with Cs-TPP nanoparticles. The stability and invitro release profile of plasmid DNA was also determined after encapsulation using DNase and chitosanase. DNA vaccines distribution in tissues was investigated in fish fed with the pVAX-OMP, pVAX-hly and pVAX-OMP+pVAX-hly encapsulated in Cs-TPP nanoparticles and confirmed by PCR and multiplex PCR. The results suggest that Cs-TPP nanoparticles encapsulated DNA vaccine delivered into fish by feeding. After oral vaccination of Labeo rohita were challenged with A. hydrophila by intraperitoneal injection. Relatively, gene expression of c- and g-type lysozyme followed by pro- and anti-inflammatory cytokines (Interlukin-10 and Tumor Growth Factor β) was up-regulated in heart and kidney for pVAX-OMP+pVAX-hly vaccinated group. Moreover, fish fed with pVAX-OMP+pVAX-hly encapsulated in Cs-TPP nanoparticles had a significantly higher survival rate (76.2%) against A. hydrophila. This study concludes that pVAX-OMP and pVAX-hly DNA vaccines can be delivered orally using Cs-TPP nanoparticles for protection against A. hydrophilainfection.

Protein-Based Vaccine Protect Against Piscirickettsia salmonis in Atlantic Salmon (Salmo salar)

An effective and economical vaccine against the Piscirickettsia salmonis pathogen is needed for sustainable salmon farming and to reduce disease-related economic losses. Consequently, the aquaculture industry urgently needs to investigate efficient prophylactic measures. Three protein-based vaccine prototypes against Piscirickettsia salmonis were prepared from a highly pathogenic Chilean isolate. Only one vaccine effectively protected Atlantic salmon (Salmo salar), in correlation with the induction of Piscirickettsia-specific IgM antibodies and a high induction of transcripts encoding pro-inflammatory cytokines (i.e., Il-1β and TNF-α). In addition, we studied the proteome fraction protein of P. salmonis strain Austral-005 using multidimensional protein identification technology. The analyzes identified 87 proteins of different subcellular origins, such as the cytoplasmic and membrane compartment, where many of them have virulence functions. The other two prototypes activated only the innate immune responses, but did not protect Salmo salar against P. salmonis. These results suggest that the knowledge of the formulation of vaccines based on P. salmonis proteins is useful as an effective therapy, this demonstrates the importance of the different research tools to improve the study of the different immune responses, resistance to diseases in the Atlantic salmon. We suggest that this vaccine can help prevent widespread infection by P. salmonis, in addition to being able to be used as a booster after a primary vaccine to maintain high levels of circulating protective antibodies, greatly helping to reduce the economic losses caused by the pathogen.

Growth performance, physiological parameters, and transcript levels of lipid metabolism-related genes in hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) fed diets containing Siberian ginseng

In high-density aquaculture, fish health can suffer because of excessive feeding, which causes fatty liver disease. Siberian ginseng (Acanthopanax senticosus) has been used as a feed additive to promote animal growth, immunity, and lipid metabolism. In this study, we explored the effects of A. senticosus on the physiology of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂). A control group and five groups fed diets containing A. senticosus (0.5, 1, 2, 4, and 8 g A. senticosus/kg feed) were established and maintained for 8 weeks. Dietary supplementation with A. senticosus at 4 g/kg promoted growth of the hybrid yellow catfish. Serum total cholesterol (TC) and triacylglycerol (TG) levels at 2 g/kg A. senticosus (TC: 1.31 mmol/L; TG: 1.08 mmol/L) were significantly lower than in the control group (TC: 1.51 mmol/L; TG: 1.41 mmol/L), and 4 g/kg A. senticosus (17.20 μmol/g tissue) reduced the liver TG level compared with the control group (21.36 μmol/g tissue) (P <0.05). Comparative transcriptomic analysis of liver tissue between the control group and the group showing optimum growth (4 g/kg A. senticosus) revealed 820 differentially expressed genes and 44 significantly enriched pathways, especially lipid metabolism pathways such as unsaturated fatty acid and fatty acid metabolism. The transcript levels of five lipid metabolism-related genes were determined by quantitative real-time PCR. The results showed that 2–4 g/kg A. senticosus supplementation reduced the FADS2, ELOVL2, CYP24a, and PLPP3 transcript levels and 4 g/kg A. senticosus increased the DIO2 transcript level (P <0.05), leading to altered synthesis of TG and thyroxine and reduced fat deposition in the liver. Our results show that dietary A. senticosus affects the regulation of fat metabolism and promotes the growth of hybrid yellow catfish. A. senticosus is a healthy feed additive, and the appropriate dietary supplementation rate is 2–4 g/kg.

Identification of Plant Soot as Novel Safe Feed Additive: Evaluation of 90-Day Oral Toxicity and Prenatal Developmental Toxicity in Rats

Plant soot, as a novel feed additive, could not only improve digestive function but also adsorb mycotoxins and inhibit bacterial infections. The subchronic toxicity and prenatal developmental effects of plant soot were studied for the first time. Our results indicated that there was no subchronic toxicity in the range of 2,000–50,000 mg/kg plant soot added in the feed, and there was no significant difference in reproductive function, embryo development, and teratogenicity between the pregnant rats exposed to 312.5, 1,250, and 5,000 mg/kg plant soot and the control group. The maximum no-observed effect level (NOEL) of supplemental dosage in feed could be set to 50,000 mg/kg, and the maximum intragastric NOEL could be set to 5,000 mg/kg, which preliminarily provided guidance on daily additive amount or clinical protocols for plant soot, as well as promoting the development and application of this harmless antibiotic substitutes.

In vitro and in vivo immunologic potentiation of herb extracts on shrimp (Litopenaeus vannamei)

In vitro and in vivo effects of Astragalus polysaccharide (APS), chlorogenic acid (CGA) and berberine (BBR) on shrimp (Litopenaeus vannamei) were studied. In vitro test showed that the combination of APS and BBR and the combination of APS and CGA have strong immune enhancement effects and no lysosomal membrane damage on hemocyte. Then, feeding experiment was proceeded to optimize the concentrations of compound herbal extracts. Four diets containing G1-G4(0.5 g kg ^-1 APS + 0.5 g kg ^-1 BBR, 1.0 g kg ^-1 APS +1.0 g kg ^-1 BBR, 0.5 g kg ^-1 APS +0.5 g kg ^-1 CGA, 1.0 g kg ^-1 APS + 1.0 g kg ^-1 CGA) associated with the control group (common diet) were compared and determined their biomolecule damage to hepatopancreas including DNA damage, lipid peroxidation and protein carbonyl. The results indicated that G3 (0.5 g kg ^-1 APS +0.5 g kg ^-1 CGA) showed higher total hemocyte counts, phagocytic activities, antibacterial activities and bacteriolytic activities during 6 days feeding, and without biomolecule damages after 6 days post-withdrawal. Therefore, the appropriate immunostimulants formula in this study was the combination of 0.5 g kg ^-1 APS and 0.5 g kg^-1 CGA, which was used for 6 days followed by 6 days post-withdrawal. Additionally, our study provides new support for screening composite immunostimulants formula by using primary shrimp hemocyte culture.

Dietary supplementation of salidroside increases immune response and disease resistance of crucian carp (Carassius auratus) against Aeromonas hydrophila

Some medicinal plants have been known as immunostimulants, and the medicinal plants extract has been used to control the outbreak of the disease in aquaculture for many years. In this study, a total of 270 crucian carp (30 ± 5 g) were randomly distributed in 9 aquaria (55 cm l × 40 cm w × 50 cm h) and divided into three feeding groups including 0 (Control), 50 mg kg^-1 (Diet A) and 100 mg kg^-1 (Diet B) of salidroside. The expression of immune-related genes (IL-1β, TNFα, MYD88, CXCL-8, TGF-β, and IL-11) in the kidney had a significant increase when the crucian carp fed with Diet B for 4 weeks (P < 0.05). Meanwhile, the expression of IL-1β, TNFα, and CXCL-8 in the spleen was significantly up-regulated when the fish fed with Diet B (P < 0.05). Higher serum alkaline phosphatase (AKP) activity, catalase (CAT) activity, superoxide dismutase (SOD) activity, and complement C3 content were found in the fish which fed with salidroside-supplemented diet. Our results also proved that fish fed with salidroside-supplemented diet for four weeks, especially at a concentration of 100 mg kg^-1 diet, improved the protection of crucian carp against A. hydrophila. The amount of A. hydrophila in the kidney and spleen was significantly decreased in salidroside-supplemented diet groups (P < 0.05). In conclusion, the present results demonstrate that the addition of salidroside for four weeks can improve the immune response of crucian carp and increase the protection against the pathogen, especially at the concentration of 100 mg kg^-1 diet. The protective effect of the salidroside to the crucian carp could be used as alternatives to antibiotics for controlling fish diseases in aquaculture.

Immunity and growth improvement of rainbow trout (Oncorhynchus mykiss) fed dietary nettle (Urtica dioica) against experimental challenge with Saprolegnia parasitica

In this study, effects of nettle (Urtica dioica) on growth, immunity, and gene expressions were examined in rainbow trout after an 8-week feeding period. A total of 264 juvenile rainbow trout (10.72 ± 0.55 g) were selected and stocked randomly in 12 aquaria. Nettle powder was added to the fish feed at three doses, 0.5,1 and 1.5% served as treatments. At the end of 8-week feeding period, the fish were exposed to Saprolegnia parasitica for 3 weeks. Results showed that all treatments fed with nettle diets exhibited significant increases in weight gain and SGR, and decreased FCR compared to the control. Feeding the fish with dietary nettle resulted in significant rises in blood indices and non-specific immunity in comparison with the control. Furthermore, fish fed 0.5% of dietary nettle showed significantly increased expressions of TNF-α, IL-1b, IL-6 and IL-8 genes following 8 weeks of feeding. A significant reduction in mortality rate was observed in the fish treated with 0.5% of nettle compared to the control following challenging with S. parasitica. Our observations indicate that the use of 0.5% nettle powder in rainbow trout diet can improve growth and immunity parameters as well as fish resistance against S. parasitica contamination.

Efficacy of Andrographis paniculata supplements induce a non-specific immune system against the pathogenicity of Aeromonas hydrophila infection in Indian major carp (Labeo rohita)

Aeromonas hydrophila, an opportunistic fish pathogen, which causes several major diseases including skin ulcer and haemorrhagic septicemia, contributes considerably to the lethality in aquaculture. Chemical and antibiotic treatment employed against A. hydrophila for disease management are expensive and consequently prompted the advent of drug resistance among the pathogens. To overcome these draw backs, alternative aquatic disease control methods using conventional plant-based medicines are focussed. Our present study aimed to augment the fish non-specific immune system with the implementation of methanolic crude extracts of Andrographis paniculata to Labeo rohita, for evaluating their efficacy against A. hydrophila. Histology of major organs of A. hydrophila-infected fish such as the gills and liver displayed severe tissue damage. A. paniculata extracts exhibited the strong antibacterial activity against A. hydrophila even at lower concentrations (50 μl). The extracts also altered the haematological profile of treated infected fishes by increasing the levels of haemoglobin and total erythrocyte-leucocyte counts, along with the phagocytic index. The extracts also had a significant impact on modifying the anatomy and swimming pattern of infected fish, post treatment with the extracts. Also, A. paniculata treated infected fishes in all the plant extract administration methods, viz. injection, oral feeding and diffusion, and reduced the cumulative mortality rate to less than 30%. Even lower concentrations of A. paniculata extracts (50 μl) resulted in maximum relative percentage survival of treated fishes. Therefore, our findings suggest that A. paniculata was effective against A. hydrophila infection in aquaculture, thereby maintaining a healthy status of these fishes in aquaculture.

Rheum officinale extract promotes the innate immunity of orange-spotted grouper (Epinephelus coioides) and exerts strong bactericidal activity against six aquatic pathogens

We investigated the antimicrobial properties and the effects of Rheum officinale extract (ROE) on nonspecific immune parameters of orange-spotted grouper (Epinephelus coioides) in vitro and in vivo. The in vitro analysis was conducted by treating grouper primary head kidney leukocytes with various concentrations of ROE. The phagocytic rate of the leukocytes was elevated in a dose-dependent manner from 0.01 to 0.1 mg/ml, but decreased with higher concentrations of ROE (0.5 and 1.0 mg/ml). The production of reactive oxygen species (ROS) was strongly enhanced in a dose-dependent manner by treatment with ROE doses of 0.1-10.0 mg/ml. However, morphological changes (e.g., rounding and shrinkage of cells, chromatin condensation, fragmentation, and appearance of apoptotic bodies) were observed in the leukocytes after incubation with higher concentrations of ROE (1.0 and 10.0 mg/ml). A 28-day feeding trial was performed to assess the impact of dietary administration of ROE on grouper innate immunity parameters. Fish were fed with feed supplemented with 0, 0.1, 1.0, or 5.0 g ROE per kg of feed. The phagocytic activity of the animals' leukocytes was significantly elevated in all ROE-fed groups on day 1 and in groups fed with ROE at 0.1 or 1.0 g/kg on day 14. Production of ROS was substantially increased on day 1 in fish fed with ROE at 1.0 and 5.0 g/kg, but decreased steadily later on. The ability to generate ROS increased steadily until day 7 in fish fed the lowest concentration of ROE (0.1 mg/ml), but decreased thereafter. ROE showed excellent antibacterial activity against six pathogens of aquatic animals: Vibrio parahaemolyticus, V. vulnificus, V. alginolyticus, V. carchariae, Aeromonas hydrophila, and Edwardsiella tarda. The minimum inhibitory and bactericidal concentrations of measured ROE-derived anthraquinones were 10.57-84.53 μg/ml and 10.57-169.05 μg/ml, respectively.

The Inclusion of a Supercritical Fluid Extract, Obtained From Honey Bee Pollen, in the Diet of Gilthead Sea Bream (Sparus aurata), Improves Fish Immune Response by Enhancing Anti-oxidant, and Anti-bacterial Activities

In the present study, the immune-stimulatory effect of two levels of honey bee pollen (5 and 10%, P5 and P10 treatment, respectively) and its supercritical fluid extract (0. 5 and 1%, E0.5 and E1, respectively) included in the diet, was tested in gilthead seabream (Sparus aurata). The in vivo trial was preceded by the evaluation of antioxidant properties of three different bee pollen extracts obtained by water, ethanol 80%, and Supercritic Fluids Extraction (SFE). The preliminary evaluation attested that the SFE showed the lowest extraction yield (10.47%) compared to ethanol 80% (48.61%) and water (45.99%). SFE extract showed good antioxidant properties with high polyphenol content (13.06 mg GAE/g), radical scavenging activity (3.12 mg/ml), reducing power (38.68 mg/mL EC50). On the contrary, the water extract showed the significantly lowest polyphenol content (2 mg GAE/g; P < 0.05). The results of in vivo trial demonstrate that the diets supplemented with SFE bee pollen extract had a stimulatory effect on fish serum immunity, respect to the inclusion of raw pollen, this latter revealing some inhibitory effects in the immune response, such a decrease of serum peroxidase and lysozyme activities, particularly in P10 group significantly different (P < 0.05) from the control group. On the contrary, serum peroxidase, protease, antiprotease, were significantly increased in fish fed the diets supplemented with supercritical fluid extract, respect to the fish fed on control and on diets supplemented with 5 and 10% of raw pollen. For what concerns the bactericidal activity against Vibrio harveyii, all the treatments containing bee pollen regardless of the type showed their serum bactericidal activity significantly increased with respect to the control groups (p < 0.05). Given its high antioxidant properties, the absence of toxic solvents and the positive action carried out on improving the humoral response in gilthead seam bream, honey bee pollen SFE extract can be taken into account in the formulation of fish feeds.

Effects of Lycium barbarum polysaccharides on immunological parameters, apoptosis, and growth performance of Nile tilapia (Oreochromis niloticus)

In this study, the effect of Lycium barbarum polysaccharides (LBP) on immunological parameters, apoptosis, and growth performance of Nile tilapia (Oreochromis niloticus) was investigated. Dietary supplementation with LBP significantly increased complement 3 (C3) activity and promoted interleukin IL-1β gene expression in spleen tissue, significantly reduced apoptosis in spleen tissue, increased the specific growth rate (SGR), relative length gain (LG), and relative weight gain (WG) of Nile tilapia. However, dietary supplementation with LBP did not have a significant effect on serum alkaline phosphatase (AKP), malondialdehyde (MDA), and superoxide dismutase (SOD), blood constituents, apoptosis, or gene expression of IL-1β in liver tissue. Overall, the results showed that dietary supplementation with LBP increased the nonspecific immunity of Nile tilapia and reduced the apoptosis rate to promote growth and development. Thus, LBP has potential for use as a new immunostimulant in aquaculture.

Optimal dietary curcumin improved growth performance, and modulated innate immunity, antioxidant capacity and related genes expression of NF-κB and Nrf2 signaling pathways in grass carp (Ctenopharyngodon idella) after infection with Aeromonas hydrophila

This study investigated the effects of dietary curcumin on growth performance, non-specific immunity, antioxidant capacity and related genes expression of NF-κB and Nrf2 signaling pathways in grass carp (Ctenopharyngodon idella). A total of 525 juvenile grass carps with mean initial body weight of (5.30 ± 0.10) g were randomly distributed into five groups with three replicates each, fed five diets containing graded levels of curcumin (0, 196.11, 393.67, 591.46 and 788.52 mg/kg diet) for 60 days. After feeding trial, fifteen fish per tank were challenged with Aeromonas hydrophila and the mortalities were recorded for 7 days. The results showed that optimal dietary curcumin (393.67 mg/kg diet) improved the weight gain (WG) and specific growth rate (SGR) of juvenile grass carp, reduced feed conversion ratio (FCR) and the mortalities after challenge (P < 0.05). Moreover, optimal dietary curcumin increased the activities of lysozyme (LYZ) and acid phosphatase (ACP), and complement 3 (C3) and C4 levels, decreased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in serum of grass carp after injection with A. hydrophila (P < 0.05). Meanwhile, optimal dietary curcumin up-regulated the mRNA levels of LYZ, C3 and antimicrobial peptides [hepcidin, liver-expressed antimicrobial peptide-2 (LEAP-2), β-defensin], and anti-inflammatory cytokines of interleukin-10 (IL-10) and transforming growth factor β1 (TGF-β1), and inhibitor of κBα (IκBα), whereas down-regulated pro-inflammatory cytokines of tumor necrosis factor-α (TNF-α), IL-1β, IL-6 and IL-8, and nuclear factor kappa B p65 (NF-κB p65), IκB kinases (IKKα, IKKβ and IKKγ) mRNA levels in the liver and blood of grass carp after injection with A. hydrophila (P < 0.05). In addition, optimal dietary curcumin increased the reduced glutathione (GSH) content and activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR), reduced reactive oxygen species (ROS) and malondialdehyde (MDA) levels in the liver of grass carp after injection with A. hydrophila (P < 0.05). Meanwhile, optimal dietary curcumin up-regulated the mRNA levels of these antioxidant enzymes and nuclear factor erythroid 2-related factor 2 (Nrf2), whereas down-regulated Kelch-like ECH-associated protein (Keap) 1a and Keap 1b mRNA levels (P < 0.05) in the liver and blood of grass carp after injection with A. hydrophila. Thus, optimal dietary curcumin supplementation could promote growth of juvenile grass carp, reduce FCR, and enhance disease resistance, innate immunity and antioxidant capacity of fish, attenuating inflammatory response. However, dietary excessive curcumin had negative effect on fish. Based on second-order regression analysis between dietary curcumin contents and weight gain, the optimum requirement of dietary curcumin in juvenile grass carp was determined to be 438.20 mg/kg diet.

In vivo and in vitro antimicrobial activity of phytol, a diterpene molecule, isolated and characterized from Adhatoda vasica Nees. (Acanthaceae), to control severe bacterial disease of ornamental fish, Carassius auratus, caused by Bacillus licheniformis PKBMS16

Bacillus licheniformis, a pathogenic new strain of bacteria is considered as the main cause of high mortalities and economic losses among the ornamental fish farms of India. The present study aimed to investigate the anti-bacterial and Immunostimulant activity of three selected Indian medicinal plants, Allium sativum, Adhatoda vasica and Centella asiatica for treating Bacillus licheniformis PKBMS₁₆ by subsequent experimental and clinical trials using different organic polar and non-polar solvents. The antimicrobial and Immunostimulant activity of methanolic crude extracts of Adhatoda vasica was fractions and active constituents was further characterized by chromatography and mass spectroscopy studies using FTIR, ¹HNMR and ^13c NMR to identify as well as to determine the nature of the pure compound which is phytol (C₂₀H₄₀O), a diterpene alcohol with a molecular weight of m/z 297. In order to study the in vivo anti-pathogenic influence of the biologically active compounds, phytol were incorporated to the artificial diets at the concentration of 2, 5 and 8 mg/kg and fed to the1.0 × 10⁵ CFU/ml of Bacillus licheniformis PKBMS₁₆ injected experimentally challenged ornamental goldfish Carassius auratus for twenty days. Phytol treated group significantly (P < 0.01 and P < 0.05) reduced the rate of fish mortality. After the termination of survivability assay the estimation of hemato-biochemical parameters have been performed and revealed the significant recovery of health condition on 20th days post treatment. Therefore, the present study concluded that the low toxicity along with high bioactivity and tolerance by lower vertebrate supports the potential of phytol as a new compound for inducing fish immunity.

Effects of dietary supplementation with apple peel powder on the growth, blood and liver parameters, and transcriptome of genetically improved farmed tilapia (GIFT, Oreochromis niloticus)

High-density aquaculture and nutritional imbalances may promote fatty liver in genetically improved farmed tilapia (GIFT, Oreochromis niloticus), thus reducing the gains achieved by breeding. In this study, apple peel powder (APP) was used as a feed additive for GIFT. A control group (fed on a diet without APP) and five groups fed on diets supplemented with APP (at 0.05%, 0.1%, 0.2%, 0.4%, or 0.8% of the diet, by weight) were established to investigate the effects of APP on GIFT growth performance and physiological parameters, and on gene expression as determined by transcriptomic analysis. Dietary supplementation with APP at 0.2% promoted GIFT growth, reduced total cholesterol and triacylglycerol levels in the serum and liver, and decreased alanine aminotransferase and aspartate aminotransferase activities in the serum. Gene expression profiles in the liver were compared among the control, 0.2% APP, and 0.8% APP groups, and differentially expressed genes among these groups were identified. Annotation analyses using tools at the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases showed that the differentially expressed genes were mainly involved in the regulation of immunity and fat metabolism. The results showed that excessive supplementation with APP in the diet significantly inhibited the expression of insulin-like growth factor 2 and liver-type fatty acid-binding protein, and stimulated the expression of fatty acid desaturase 2, heat shock protein 90 beta family member 1, and nuclear factor kappa B. This resulted in disordered lipid metabolism and increased pro-inflammatory reactions, which in turn caused liver damage. Therefore, APP has good potential as an environmentally friendly feed additive for GIFT at levels of 0.1%–0.2% in the diet, but excessive amounts can have adverse effects.

Effects of traditional Chinese medicines on immunity and culturable gut microflora to Oncorhynchus masou

The present study was conducted to evaluate the effect of dietary traditional Chinese medicines on the growth, immunity, and composition of culturable gut microflora in Oncorhynchus masou. Diets were formulated to contain no medicine (control), antitoxic decoction (A), general antiphlogistic decoction (B), or Herbae Artemisiae Capillariae decoction (C). Fish were manually fed twice daily till apparent satiation for 30 days. Compared with that in the control group, supplementation with the three kinds of Chinese herbal medicine enhanced fish growth significantly (P < 0.05). The activities of liver superoxide dismutase and glutathione peroxidase in the treatment groups were significantly higher compared with those in the control group (P < 0.05). The quantity of intestinal microflora was higher in the treatment groups compared with that in the control group. Moreover, there were some effects of dietary Chinese herbal medicine on the composition of intestinal microflora. Microflora of Pseudomonas sp., Psychrobacter sp., Microbacterium sp., Macrococcus sp., Burkholderia sp., and Arthrobacter sp. were found in the treatment groups, whereas there were none in the control group. There was a significant increase in their amounts in the treatment groups (P < 0.05). The three kinds of traditional Chinese medicines can improve the growth and immunity of Oncorhynchus masou and affect the quantity and composition of intestinal microflora.

Dietary administration of ferula (Ferula asafoetida) powder as a feed additive in diet of koi carp, Cyprinus carpio koi: effects on hemato-immunological parameters, mucosal antibacterial activity, digestive enzymes, and growth performance

This study investigated the impacts of various levels (0, 5, 10, 15, 20, and 25 g kg^-1) of dietary ferula (Ferula asafoetida) powder (FP) on the hemato-immunological indices, antibacterial properties of skin mucus, survival rate, and growth performance as well as digestive enzyme activity of Koi carp, Cyprinus carpio koi, fingerlings. Following 63 days of feeding trail, WBCs, RBCs, Hb, hematocrit, MCV, MCH, MCHC, and lymphocyte levels increased coincident with an increasing FP level in experimental diets compared with control diet (P < 0.05). Dietary FP significantly increased total protein content and the activities of total immunoglobulins, lysozyme, and alternative hemolytic complement in a concentration-dependent manner in the serum of koi fish (P < 0.05). The elevation of the FP level in experimental diets resulted in an increase in SGR value and a reduction in FCR value (P < 0.05). The survival rate also increased significantly coincident with the increasing dietary FP level (P < 0.05). The results revealed that dietary ferula powder especially at levels of 20 and 25 g kg^-1 could be used as an effective herbal dietary supplement in the enhancement of humoral innate immune responses and growth of koi carp.

Dietary chitosan-selenium nanoparticle (CTS-SeNP) enhance immunity and disease resistance in zebrafish

Selenium (Se) is an essential micronutrient for human and animals. It plays an important role in antioxidative stress, selenoenzymes regulation and immunomodulation. In this study, two common immunostimulants chitosan (CTS) and Se were used to synthesize nanoparticles (CTS-SeNP). Immunomodulation of CTS-SeNP were explored in wild-type zebrafish (Danio rerio). Dietary supplementation of CTS-SeNP enhanced lysozyme activity, phagocytic respiratory burst as well as splenocytes proliferation stimulated by LPS and ConA. CTS-SeNP showed immunomodulation effect from 5 to 20 μg/g but the best outcome was observed at 10 μg/g. Immunomodulation effect were rapidly induced after 3-9d and can sustain to 60. The zebrafish fed with 10 μg/g CTS-SeNP also showed 26.7% higher survival rate than the control after intraperitoneal injection of common bacterium Aeromonas hydrophila. Our results suggested that CTS-SeNP is an effective immunostimulant to fish and has potential application in aquaculture.

Traditional Chinese Medicine Enhances Growth, Immune Response, and Resistance to Streptococcus agalactiae in Nile Tilapia

Herbal supplements are suitable for improving fish health and combating diseases in fish culture. However, the mechanism of action of many herbal mixtures remains unclear. This study was conducted to evaluate the effects of traditional Chinese medicine (TCM; a mix of Astragalus membranaceus, Angelica sinensis, and Crataegus hupehensis at a ratio of 1:1:1 on a weight basis) on growth, immune response, and disease resistance in Nile tilapia Oreochromis niloticus. Experimental fish (mean ± SE weight = 57 ± 1 g) were divided into two groups: a control group and a TCM (10 g/kg) group. After 4 weeks of the experimental trial, a significant increase in weight gain and specific growth rate and a lower feed conversion ratio were observed in fish fed a TCM-supplemented diet compared with control fish. Similarly, the immune response of Nile Tilapia in the TCM group showed enhanced lysozyme, superoxide dismutase, catalase, and immunoglobulin levels compared with the control fish. In comparison with the control, fish fed TCM showed significant up-regulation of β-defensin, lysozyme, heat shock protein 70, superoxide dismutase, and catalase genes in the intestine and head-kidney tissues. After a Streptococcus agalactiae challenge, survival of Nile Tilapia in the TCM group was 70% compared with 35% in the control. These results indicate that the TCM mixture in this study can elevate the immune response and disease resistance of Nile Tilapia.

Enrichment of common carp (Cyprinus carpio) fingerlings diet with Psidium guajava: The effects on cutaneous mucosal and serum immune parameters and immune related genes expression

The present study aimed at evaluation of possible effects of Psidium guajava as immunostimulant on mucosal and serum immunity, as well as related genes expression in common carp (Cyprinus carpio) fingerlings. In an eight weeks feeding trial, fish were fed with experimental diets containing guava leaf powder [GLP] (0, 0.25, 0.5 and 1%). Then, skin mucus and serum immune parameters (total Ig, alkaline phosphatase activity, lysozyme activity), as well as immune related genes expression (TNF-alpha, IL1b, IL8) were measured. All levels of GLP inclusion in the diet brought about the increase in total Ig in the serum, while in the mucus only the highest level of GLP was effective. No significant differences were observed in mucus alkanine phosphatase activity, while fish fed 0.25% of GLP had noticeably higher serum lysozyme activity. The mucus total protein electrophoretic pattern revealed some differences between the control and the treated fish. Two high MW bands were present in the control group but not in the treated groups. Three bands with a low MW comprised between 35 and 17 mw were noticed in GLP fed carps and not in the control. Gene expression studies revealed no noticeable alterations in TNF-alpha gene between treated fish and control. However, the level of expression of IL-8 was strongly upregulated in fish fed 0.5 and 1% of GLP. Also, feeding on 0.5% of GLP significantly upregulated IL1b gene expression. Evaluation of growth performance revealed improved performance parameters in GLP treated groups. These results confirmed possible immunomodulatory and beneficial effects of GLP on common carp fingerlings.

Alterations of haemato-biochemical parameters pre and post-challenge with Aeromonas hydrophila and survival of Oreochromis mossambicus fed Moringa oleifera-based diets

This study investigated the extent of changes in haemato-biochemical and immunological parameters of O. mossambicus fed with M. oleifera-based diets pre and post-challenge with different concentrations of A. hydrophila. Moringa oleifera powdered leaves were added to five experimental diets at 0%, 3%, 6%, 9% and 12%, designated D1, D2, D3, D4 and D5, respectively. Each diet was randomly fed to triplicate groups of 45 fish (33.46 ± 1.57 g) for 45 days. There were no significant differences (P > 0.05) in WG, FCR and SGR between treatments. There was an increase in WBC, RBC, HGB and HCT with increasing M. oleifera levels. No significant changes (P > 0.05) were observed in AST, ALT, ALP and LDH levels between treatments. After 45 days, fish from each treatment were injected with varying concentrations (0, 1 × 10⁶ cfu, 1.5 × 10⁶ cfu, 3 × 10⁶ cfu and 4 × 10⁶ cfu ml^-1) of Aeromonas hydrophila. There was a significant decline in RBC, HGB and HCT of fish in the D1-D3 compared to the D4 and D5 groups. There was an increase in AST, ALT, ALP and LDH in the D1-D3 groups while no significant changes (P > 0.05) were observed in the D4 and D5 groups between bacterial concentrations. Survival rate was lower in the D1-D3 compared to the D4 and D5 groups, indicating that immunity was enhanced in fish fed with the highest M. oleifera inclusion levels. NBT and lysozyme activities were also lower in the D1-D3 groups compared to the D4 and D5 groups. The enhancement of immunity is attributed to the presence of biologically active compounds with immunostimulatory properties. The phytochemistry of the M. oleifera revealed high levels of total polyphenol, total phenols, total flavonoids, carotenoids, vitamins C and E.

Dietary Withania sominefera root confers protective and immunotherapeutic effects against Aeromonas hydrophila infection in Nile tilapia (Oreochromis niloticus)

In the present study, effect of dietary Withania sominefera (W. sominefera) root powder was evaluated to modulate immune and antioxidant response against Aeromonas hydrophila (A. hydrophila) infection in Nile tilapia (Oreochromis niloticus). W. sominefera root powder supplemented diets at two concentrations 2.5% (W 2.5%) and 5% (W 5%); fed for 6 weeks prior to the A. hydrophila challenge and continued the same respective diets during the post challenge period (2 weeks). Results showed that fish fed W. sominefera at 5% enhanced immune response in both pre and post-challenge period. NBT level exhibited only significant increase (P < 0.05) in the pre-challenge period compared to control. Malondialdehyde (MDA) levels in liver and muscle revealed significant decrease in both Withania supplemented groups compared to the control in post challenge period. Antioxidant enzymes activities (catalase/CAT/, glutathione S-transferase/GST/, glutathione/GSH; and superoxide dismutase/SOD) were improved in liver and muscle in post challenge period. Glutathione peroxidase (GPx) level in muscle and serum total antioxidant capacity (TAC) showed a significant increase in both Withania supplemented groups compared to the control post challenge. Withania supplementation enhanced disease resistance against A. hydrophila and reduced mortalities (20%), especially at supplemented concentration of 5%. Our findings suggest that W. sominefera root powder may have protective and immunotherapeutic roles in Nile tilapia against A. hydrophila infection which may be useful in controlling important fish bacterial diseases.

Secondary Metabolites of Antarctic Fungi Antagonistic to Aquatic Pathogenic Bacteria

Polar microbial derived antibiotics have potential as alternatives to traditional antibiotics in treating fish against pathogenic bacteria. In this paper, 23 strains of polar fungi were fermented to detect bacteriostatic products on three aquatic pathogenic bacteria, subsequently the active fungus was identified. It was indicated that secondary metabolites of 23 strains weredistinct; of these, the extract of strain B-7 (belonging to Bjerkandera according to molecular identification) demonstrated a strong antibacterial activity to Streptococcus agalactiae, Vibrio anguillarum and Aeromonas hydrophila ATCC7966 by Kirby-Bauerpaper strip method. During one fermentation cycle, the pH curve of the fermentation liquor became lowest (4.0) on the 4th day and rose back to 7.6 finally after 5 days, The residual sugar curve was decreased before stablising on the 6th day. It is presumed that a large amount of alkaline secondary metabolites might have been produced during fermentation. This study focuses on antagonism between aquatic pathogenic bacteria and fermentation metabolites from Antarctic fungi for the first time, which may provide data on research of antibiotics against aquatic pathogenic bacteria.

Leaves from banana (Musa nana) and maize (Zea mays) have no phyto-prophylactic effects on the susceptibility of grass carp (Ctenopharyngodon idella) to Aeromonas hydrophila infection

Background

The ubiquitous and opportunistic bacterial pathogen Aeromonas hydrophila has been associated with ulcerative dermatitis in fish, especially under stressful conditions. It can cause severe losses in fresh water aquaculture and is particularly prevalent in tropical and subtropical regions. Fresh leaves from maize and bananas have been used as feed supplement by fish farmers in Vietnam and it has been reported that they may have phyto-prophylactic benefits. In the present study, a feeding trial was conducted to investigate the benefits of providing maize and banana leaves as feed supplement: to determine if they were taken up and digested by grass carp (Ctenopharyngodon idella), if this uptake resulted in improved growth performance, and if leaf supplementation protected fish when challenged with A. hydrophila by intramuscular injection.

Results

All fish were fed an identical ratio of commercial pelleted feed relative to biomass. However, in 12/18 tanks, this diet was supplemented with either fresh banana leaves or fresh maize leaves; offered ad libitum. Addition of leaves increased the overall feed conversion ratio (FCR) significantly. However, if only the pellet were taken into account, then no difference was found between treatments. Changes to the isotopic composition of the fish showed leaf nutrient uptake occurred. No prophylactic effects of feeding banana or maize leaves were detected against infection with A. hydrophila, and the diet did not induce changes in the fish haematocrit. However, addition of the maize leaves was associated with significantly reduced severity of the skin lesions, which could improve the market value of the fish.

Conclusions

Addition of the leaf supplement did not result in significantly improved growth performance. Similarly, the effect of the supplement on the fish survival to infection was not significant.

Electronic supplementary material

The online version of this article (10.1186/s12917-017-1255-5) contains supplementary material, which is available to authorized users.

Ontogenetic changes in the expression of immune related genes in response to immunostimulants and resistance against white spot syndrome virus in Litopenaeus vannamei

In recent years, researchers have focused on viral and plant immunostimulants which could have beneficial effects in disease prevention and control in shrimp culture. At present, the application of the recombinant VP28 protein (r-VP28) and herbal immunostimulant has been considered as a more effective approach to prevent white spot syndrome (WSS) by enhancing the immune response in shrimp. In the present study, expression of selected immune related genes in response to r-VP28 and herbal immunostimulant mix (HIM) were separately studied qualitatively and quantitatively by RT-PCR and real time PCR, respectively during ontogenetic development from nauplius to juvenile stage in Litopenaeus vannamei. The mRNA expression level of immune related genes such as anti-lipopolysaccharides (ALF), Lysozyme, cMnSOD, Crustin, Prophenoloxidase, Tumor necrosis factor receptor-associated factor 6 (TRAF6) and Haemocyanin were found to be up-regulated significantly in different ontogenetic development stages of shrimp fed with r-VP28 and HIM formulated diets. Relative percent survival (RPS) was determined in shrimp fed with immunostimulants formulated diets after oral challenge with WSSV. The survival of WSSV challenged shrimp was found to be higher in immunostimulants treated groups when compared to untreated group. The results of PCR, ELISA and real time PCR revealed the absence of WSSV in WSSV-challenged shrimp after 20 days of treatment with immunostimulants. Among these immunostimulants, HIM was found to be more effective when compared to r-VP28. After a survey of literature, we are of the opinion that this might be the first report on the expression of immune genes during ontogenetic development of L. vannamei in response to immunostimulants.

Changes in growth, blood immune parameters and expression of immune related genes in rainbow trout (Oncorhynchus mykiss) in response to diet supplemented with Ducrosia anethifolia essential oil

An 8- week feeding trial was conducted to investigate the effects of Ducrosia anethifolia essential oil on growth, blood immune parameters and immune related genes expression in juvenile rainbow trout (Oncorhynchus mykiss). Fish were allocated into 4 groups and fed on diet containing different levels of essential oil (0, 0.001, 0.01 and 0.1%) to apparent satiation in 30 min 3 times daily. Growth and immunological parameters were measured every ten days and tissue samples were taken from kidney and spleen on days 10, 30 and 50 to study the expression of IL-1β and TNF-α. The changes of measured parameters in different treatments and over sampling time series were statistically analysis based on repeated measurement method (P < 0.05). Results showed that growth did not affected by essential oil at different treatments. The highest level of hematocrit was observed in 0.001 treatment. The mean of RBC showed no significant differences among treatments. The mean of WBC in 0.01 and 0.1 groups were higher than those in 0.001 and control groups. Total protein, albumin and globulin and serum bactericidal activity showed no significant difference in different treatments. Neither treatments nor sampling times affected serum lysozyme activity. The highest mean of respiratory burst activity was observed in 0.01 group. The highest expression of both IL-1β and TNF-α genes in kidney was observed at 0.001 dose on day 30, while in spleen, the highest expression of IL-1β and TNF-α was obtained on day 30 at doses 0.1 and 0.01%, respectively. In conclusion the results of this study showed that feeding with lower and medium level of D. anethifolia for 30 days led to immunostimulatory effects in juvenile rainbow trout.

A simple and non-invasive method for analyzing local immune responses in vivo using fish fin

Immunocompetence is an important parameter that reflects disease resistance in fish. Very few methods to examine immunocompetence in vivo have been developed, even for mammals. In the present study, we present a unique method for analyzing local immune responses using fish fin. We first demonstrated the migration of granulocytes to the site of zymosan injection in fin in a dose-dependent manner and that this could be easily observed macroscopically due to the fin membrane transparency. We also demonstrated phagocytic activity of accumulated leukocytes after zymosan administration and that almost all phagocytes were granulocytes. In addition, we succeeded to detect respiratory burst activity of granulocytes in vivo without any in vitro treatment of cells, indicating that our present method is suitable for the analysis of granulocyte phagocytic function in vivo. The method provides a unique tool applicable for fishes that possess transparent fins and may lead to better understanding of the mechanisms of local immune responses in fish.