Effect of guava leaves on growth and the non-specific immune response of Penaeus monodon

Effects of dietary soluble β-1,3-glucan on the growth performance, antioxidant status, and immune response of the river prawn (Macrobrachium nipponense)

The effects of dietary β-1,3-glucan on the growth performance, body composition, hepatopancreas tissue structure, antioxidant activities, and immune response of the river prawn (Macrobrachium nipponense) were investigated. In total, 900 juvenile prawns were fed one of five diets with different contents of β-1,3-glucan (0%, 0.1%, 0.2%, and 1.0%) or 0.2% curdlan for 6 weeks. The growth rate, weight gain rate, specific growth rate, specific weight gain rate, condition factor, and hepatosomatic index of juvenile prawns fed 0.2% β-1,3-glucan were significantly higher than those fed 0% β-1,3-glucan and 0.2% curdlan (p < 0.05). The whole-body crude lipid content of prawns supplemented with curdlan and β-1,3-glucan was significantly higher than that of the control group (p < 0.05). The antioxidant and immune enzyme activities of superoxide dismutase (SOD), total antioxidant capacity (T-AOC), catalase (CAT), lysozyme (LZM), phenoloxidase (PO), acid phosphatase (ACP), and alkaline phosphatase (AKP) in the hepatopancreas of juvenile prawns fed 0.2% β-1,3-glucan were significantly higher than those of the control and 0.2% curdlan groups (p < 0.05), and tended to increase and then decrease with increasing dietary β-1,3-glucan. The highest malondialdehyde (MDA) content was observed in juvenile prawns without β-1,3-glucan supplementation. The results of real-time quantitative PCR indicated that dietary β-1,3-glucan promoted expression of antioxidant and immune-related genes. Binomial fit analysis of weight gain rate and specific weight gain rate showed that the optimum β-1,3-glucan requirement of juvenile prawns was 0.550%-0.553%. We found that suitable dietary β-1,3-glucan improved juvenile prawns growth performance, antioxidant capacity, and non-specific immunity, which provide reference for shrimp healthy culture.

Andrographis paniculata improves growth and non-specific immunity of shrimp Litopenaeus vannamei, and protects it from Vibrio alginolyticus by reducing oxidative stress and apoptosis

Andrographis paniculata (AP) is a traditional medicinal plant with many pharmacological activities, including anti-inflammatory, antimicrobial, immunity stimulation and so on. Several studies have reported that AP plays a strong role in promoting the immune system of aquatic animals to resist several pathogens. In the present study, we investigate the effects of a diet containing AP on the immune responses, growth, and the resistance to Vibrio alginolyticus (V. alginolyticus) in Litopenaeus vannamei (L. vannamei). Four diets were formulated by adding AP at the dosage of 0% (Control), 0.25%, 0.5%, and 1% in the basal diet, respectively. Each diet was randomly fed to one group with three replicates of shrimps in a 28-day feeding trial. The results showed that dietary AP improved the growth performance and non-specific immune function of shrimps. To investigate the effect of AP on disease resistance of L. vannamei, shrimps fed with diet containing AP were challenged with V. alginolyticus. Compared with the control group, the shrimps fed diet containing AP showed significantly higher survival. Furthermore, the hepatopancreas injury in the shrimp fed with AP was less than control group at 6 h after V. alginolyticus infection. However, no difference was observed in the degree of hepatopancreas injury between AP groups and control group at 12 h and 24 h after V. alginolyticus infection. Based on this result, the samples at 6 h after V. alginolyticus infection was selected for subsequent detection. Reactive oxygen species (ROS) accumulation in hemocytes and O₂^- production in hepatopancreas caused by V. alginolyticus infection was significantly reduced after feeding a diet containing 0.25% and 0.5% AP (p < 0.05). In addition, we found that feeding AP significantly up-regulated the expression of pro-apoptotic genes (Bax, Caspase 3, p53) and down-regulated the expression of anti-apoptotic genes (Bcl-2) in hepatopancreas after V. alginolyticus infection. In conclusion, AP promote the growth and immunity of L. vannamei, and protects shrimps against V. alginolyticus by regulating the oxidative damage and apoptosis. These results provide useful information regarding the effects of AP extracts as a shrimp feed additive for sustainable shrimp culture.

Cytotoxicity profiling of decabromodiphenyl ethane to earthworm (Eisenia fetida): Abnormity-recovery-dysregulation physiological pattern reflects the coping mechanism

Response of terrestrial invertebrates to decabromodiphenyl ethane (DBDPE) is an emerging field of research nowadays, while cytotoxicity of DBDPE and self-defense strategies of invertebrates are poorly understood. In this study, earthworms (Eisenia fetida) were incubated in the DBDPE-spiked soil system (10, 30, 50, 70, and 100 mg kg^-1 dw) for 28-d uptake. The bioaccumulation and distribution of DBDPE, a series of biomarkers associated with lysosomes/mitochondria, and the apoptosis rate of coelomocytes have been evaluated on the 7th, 14th, 21th, and 28th day. At experimental endpoint, the autophagy/apoptosis phenomena have been observed under transmission electron microscopy and the expression levels of six target genes have been explored. Findings in this paper revealed that: bioaccumulation factors decreased with the incremental DBDPE concentrations in the soil. Intestinal ingestion, but not epidermal contact predominated the absorption of DBDPE. The fluctuations of biomarkers and the apoptosis rate were described as the "abnormity-recovery-dysregulation" pattern. Intense oxidative stress, energy demands, membrane-system damage, pathological organelles, and apoptosis were observed in the treated groups. Conclusively, the cytotoxicity of DBDPE initiated the mitochondrial apoptosis pathway which affected the physiological status of lysosomes, autophagy, and the expression of genes. The coping mechanisms of Eisenia fetida to DBDPE included activating mitochondrial electron transport processes, reorganizing actin cytoskeleton, and initiating autophagy. Earthworms resisted the cytotoxicity of DBDPE to a certain extent, while long-term exposure still resulted in apoptosis of coelomocytes. This study works as a laboratory simulation for the environmental safety evaluation of DBDPE and the detoxification mechanisms for earthworm.

Effect of infection with Aeromonas hydrophila on antioxidant capacity, inflammation response, and apoptosis proteins in Chinese mitten crab (Eriocheir sinensis)

Aeromonas hydrophila (A. hydrophila) as a serious bacterial disease endangering aquaculture and the Chinese mitten crabs (Eriocheir sinensis) industry. The present study was conducted to investigate the effects of A. hydrophila on the antioxidant, inflammation, immunity and apoptosis of the E. sinensis. The E. sinensis (female: 150 crabs and male: 150 crabs; 67.11 ± 0.76 g) were randomly divided into the control group (Foot injection with 200 μl PBS) and infection group (Foot injection with 200 μl A. hydrophila of 10⁶ cfu/mL). The hepatopancreas and serum was collected to detect the related indicators after injection 24 h. The results showed that A. hydrophila significantly reduced the malondialdehyde (MDA) level and gamma-glutamyl-cysteine synthetase (γ-GCS) activity in the hepatopancreas of male and female crabs (P < 0.05). A.hydrophila also significantly decreased the total-superoxide dismutase (T-SOD) activity while the levels of total antioxidant capacity (T-AOC) and total glutathione (T-GSH) were significantly increased in the hepatopancreas and serum of male crabs (P < 0.05). At the transcriptional level, the expression of catalase (CAT) and glutathione peroxidases (GPx), Glutathione S-transferase (GST) in the hepatopancreas of male and female crabs was significantly reduced compared to the control group (P < 0.05). However, A. hydrophila could not significantly change the Kelch-like ECH-associated protein 1 (Keap1) gene expression level in both of male and female carbs. A. hydrophila injection for 24 h, the lysozyme (LZM) and phenoloxidase (PO) activity was significantly increased in the hepatopancreas and serum of the male and female crabs (P < 0.05). Simultaneous increase of immune-related enzyme activity (acid phosphatase and alkaline phosphatase) was found in the serum of male and female crabs (P < 0.05). However, the acid phosphatase (ACP) and alkaline phosphatase (ALP) activity was significantly decreased in the hepatopancreas of male and female crabs (P < 0.05). Meanwhile, the LZM mRNA level was significantly decreased in the hepatopancreas of E. sinensis (P < 0.05). Furthermore, A. hydrophila significantly inhibited the mRNA expression of immune regulated factors (Interleukin enhancer binding factor 2: ILF2, interleukin-16: IL-16, Toll-like receptor: TLR) in the male and female crabs. The levels of inflammatory cytokines (interleukin-1β: IL-1β, interleukin-6: IL-6, interleukin-8: IL-8, interleukin-10: IL-10) were significantly increased in the hepatopancreas of male and female crabs. Moreover, A.hydrophila increased the mRNA expression of apoptosis - related genes in male crabs (p38 mitogen-activated protein kinase: p38, adamalysin 17: ADAM17, Cysteine-aspartic acid protease 3: Caspase 3, and Bcl-2-associated X: BAX), but reduced the expression of p38, ADAM17, Caspase 3 and BAX genes in female crabs. In conclusion, A. hydrophila could induce oxidative stress and the response of inflammation and immunity, and also trigger the mRNA expression changes of apoptosis related-genes in E. sinensis. This study provides a theoretical basis for the study of E. sinensis diseases.

Guava (Psidium guajava) leaf extract enhances immunity, growth, and resistance against Vibrio parahaemolyticus in white shrimp Penaeus vannamei

This study investigated the effects of guava leaf extract (GLE) on immune responses, growth performance, and resistance to Vibrio parahaemolyticus in white shrimp (Penaeus vannamei). To examine the effect of GLE on the immune response of white shrimps, they were treated with various concentrations of GLE on hemocyte (in vitro) and were orally administered (in vivo) feed containing various concentrations of 0, 1, 5, and 10 g kg^-1 GLE (control, GLE1, GLE5, and GLE10, respectively) for 28 days. Furthermore, their growth performance was evaluated for 56 days. In a separate experiment, the shrimps were challenged with V. parahaemolyticus injection after 7 days of culture. In vitro experiments indicated that GLE is nontoxic and can activate immune response. In vivo experiments revealed that the GLE5 led to the highest total hemocyte count, phenoloxidase activity, phagocytic activity, and superoxide anion production and the highest upregulation of lipopolysaccharide, β-1,3-glucan-binding protein, peroxinectin, lysozyme, crustin, penaeidin 2, penaeidin 3, clotting protein, superoxide dismutase, and glutathione peroxidase. Moreover, better growth performance was observed in the GLE groups, with GLE5 exhibiting the highest specific growth rate, weight gain, and feed conversion rate. In addition, GLE5 enhanced resistance to V. parahaemolyticus, with a survival rate of 72.27%. In conclusion, GLE was found to be effective in enhancing nonspecific immune response and growth performance and in reducing V. parahaemolyticus infection in white shrimp.

Transcriptome analysis reveals the molecular mechanism of long-term exposure of Eriocheir sinensis to low concentration of trichlorfon

Trichlorphon, a common organophosphorus pesticide (OPs), is widely used in aquaculture to prevent aquatic insects from infecting cultured objects as well as to control the excessive proliferation of plankton in water bodies. However, its repeated use time can contaminate water bodies and impart direct/indirect toxicity to beneficial aquatic species. However, the underlying mechanism regarding toxicity and cellular metabolism remains unclear. Understanding the mechanism would enable the standardized use and management of OPs and their use in the aquatic environment. Here, low concentration of trichlorphon (5 × 10^-5 g/L) was used to construct a hepatopancreatic transcriptional library 30 d, 60 d and 90 d after exposure using RNA-Seq. We detected 649, 148, and 2949 DEGs in the hepatopancreas of E. sinensis for the Tri01 vs. Ctr01, Tri02 vs. Ctr02 and Tri03 vs. Ctr03 library, respectively. The results of KEGG pathway enrichment analysis showed that DEGs were mainly enriched in signal transduction, carbohydrate metabolism, transport and catabolism, endocrine system, and digestive system. Also, under trichlorfon stress, DEGs of E. sinensis were enriched in thyroid hormone signaling pathways, protein digestion and absorption, cancer pathways, etc. The significant DEGs were mainly related to metabolism and the apoptosis and autophagy pathways. This study lays a foundation for further revealing the effects of long-term trichlorfon stress on E. sinensis as well as the potential physiological toxicity. The relevant transcriptome data could provide a reference for the molecular toxicological evaluation of trichlorfon in aquaculture.

Anti-vibrio and immune-enhancing activity of medicinal plants in shrimp: A comprehensive review

Disease epidemics in shrimp aquaculture increase apace with the development of aquaculture systems throughout the world. The disease caused by Vibrio spp. (vibriosis) is considered the most devastating, which has made it the most feared bacterial disease in the shrimp sector. In aquaculture, several strategies have already been applied to control Vibrio strains, including chemicals, probiotics, antibiotics, natural products from plants, including plant oils; hence, there has been considerable attention for using plants in shrimp aquaculture to provide sustainable, eco-friendly and safe compounds, such as alkaloids, saponins, terpenoids and flavonoids for replacing chemical compounds and antibiotics in current aquaculture. Medicinal plants may also have immunostimulating activity, increase growth and resistance in shrimps. The present paper aims to review the inhibition of Vibrio spp. in shrimp by medicinal plants, using both in vitro or/and in vivo techniques. Several medicinal plants appear capable of inhibiting growth of Vibrio pathogens outside living shrimp or in the body of shrimp, through enhancing growth and immune capacity when shrimps are fed or injected with them. In the current review Gracilaria spp. (Gracilariaceae family) and Sargassum spp. (family Sargassaceae) have been used most for in vitro and in vivo experiments. Among the terrestrial plants, Eucalyptus camaldulensis, Psidium guajava, Rhodomyrtus tomentosa, and Syzygium cumini (Myrtaceae family) had significant activity against Vibrio.

Effects of Phyllanthus amarus extract on nonspecific immune responses, growth, and resistance to Vibrio alginolyticus in white shrimp Litopenaeus vannamei

This study investigates the effects of Phyllanthus amarus extract (PAE) on immune responses, growth, and resistance to Vibrio alginolyticus in white shrimp (Litopenaeus vannamei). In vitro PAE treatment did not alter the cell viability of haemocytes and significantly enhanced immune parameters such as phenoloxidase (PO) activity, phagocytic activity, and superoxide anion (O₂^-) production. We conducted two feeding trials to examine the effects of PAE on the growth, disease resistance, and innate immune parameters of white shrimp. In the first in vivo trial, shrimps (4.01 ± 0.03 g) were fed a diet containing 0 g (control), 10 g (PAE10), 20 g (PAE20), or 40 g (PAE40) of PAE per kilogram of feed for 56 days. After the feeding period, the PAE20 group showed a significantly higher weight gain and specific growth rate than shrimp fed the control diet. Furthermore, after challenge with V. alginolyticus, shrimp fed a diet containing PAE showed significantly higher survival than those fed the control diet. The second in vivo trial (28 days) was performed to identify the mechanisms of enhanced immunity in PAE-fed shrimp. Shrimp fed the PAE20 diet generally had the highest total haemocyte count, PO activity, phagocytic activity, and O₂^- production, followed by the PAE40 and PAE10 groups. Thus, our results suggest that administration of 20 g of PAE per kilogram of feed can enhance immunity, growth, and resistance to V. alginolyticus in white shrimp.

Bactericidal effect on skin mucosa of dietary guava (Psidium guajava L.) leaves in hybrid tilapia (Oreochromis niloticus × O. mossambicus)

ETHNOPHARMACOLOGICAL RELEVANCE

Due to the intensification practices in global aquaculture, fish are often confined in small volumes, which can results in outbreak diseases. In this context, the use of antibiotics is very usual. Thus, looking for natural substance able to reduce the use of the antibiotics is imperative. Among them, there is a great interest at present in the study of medicinal plants such as guava (Psidium guajava L.). These plants could help to develop a more sustainable aquaculture all over the world. The application of guava in traditional medicine dates for centuries and it is widely used in tropical countries for the treatment of diseases in human and animals.

AIM OF THE STUDY

The purpose of this work was to study the effects of the dietary administration of dried leaves of Psidium guajava on the skin mucosal immunity of hybrid tilapia (Oreochromis niloticus × O. mossambicus). Furthermore, the ability of this plant to inhibit the bacterial load in different tissues after an experimental infection with Vibrio harveyi was studied.

MATERIALS AND METHODS

P. guajava leaves collection and the experimentation was carried out in Dominican Republic. Fish were fed with a commercial diet supplemented with guava leaf at different concentrations (0%, 1.5% and 3%) for 21 days before being intraperitoneally injected with V. harveyi (1 × 10⁴ cells mL^-1). Thereafter, several immune activities were measured in fish skin mucus and after 48 h of injection, the skin, spleen and liver were collected to analyse the bactericidal activity of guava leaf and the gene expression of some immune related genes.

RESULTS

The administration of P. guajava leaves significantly modulated some immune-related enzymes (protease, antiprotease and peroxidase) in the skin mucus of hybrid tilapia. In addition, the bacterial load after V. harveyi infection in skin, spleen and liver significantly reduced in fish supplemented with guava leaves. Finally, the expression profile of hepcidin gene in skin and liver was modulated in fish feed with control diet after V. harveyi infection.

CONCLUSION

These results demonstrate that the dietary intake of guava leaves increases the skin mucosal barrier defences of hybrid tilapia and confers protection against V. harveyi colonization.

Shift in phagocytosis, lysosomal stability, lysozyme activity, apoptosis and cell cycle profile in the coelomocytes of earthworm of polluted soil near a tannery field of India

Calcutta Leather Complex of the state of West Bengal, India has been designated as an industrially active zone with around 400 active tannery units. This area spanning 4.5 km² is surrounded by human habitation. The soil of this region is contaminated with metal pollutants and exhibited an alteration in selected physicochemical parameters, namely cation exchange capacity, moisture content, pH, total nitrogen, total organic carbon and water holding capacity. Metaphire posthuma, a common variety of endogeic earthworm inhabiting this region is thus continuously exposed to these toxic metals. Coelomocytes, the chief immune effector cells of earthworm presented a shift in phagocytosis, lysosomal membrane stability, lysozyme and phosphatase activity, physiological apoptosis and cell cycle profile of M. posthuma sampled from the soil of tannery industry. Presence of high concentration of toxic metals and change in the physicochemical characteristics of soil led to a state of cellular stress and immunocompromisation in M. posthuma, a common inhabitant of soil of this region. Experimental endpoints bear ecotoxicological significance as biomarkers of physiological stress in earthworm for monitoring the health of soil around this tannery industrial zone.

Single or Combined Dietary Supply of Psidium guajava and Phyllanthus amarus Extracts Differentially Modulate Immune Responses and Liver Proteome in Striped Catfish (Pangasianodon hyphophthalmus)

Guava Psidium guajava L (Pg) and bhumi amla Phyllanthus amarus Schum. et Thonn (Pa) are well-known plants in traditional medicine. However, the capacity of these plants for improving the immune system of aquatic species has received less attention so far. This study aimed to investigate the effects of single supply or mixture of Pg and Pa extracts on immune responses, disease resistance and liver proteome profiles in striped catfish Pangasianodon hypophthalmus. Fish were fed diets including basal diet 0% or one of three doses of each plant extract, either alone or in mixture, 0.08, 0.2, or 0.5% Pg, Pa or mixture (Pg:Pa, v/v) for 6 weeks. The immune parameters (respiratory burst activity (RBA); nitric oxide synthase (NOS), total immunoglobulin, lysozyme, and complement activities) were examined at W3, W6 post-feeding, and after challenge test. The growth parameters and the challenge test with Edwardsiella ictaluri were done at W6. The liver proteome profiles were analyzed in W6 at 0.08 and 0.5% of each extract. The results showed that extract-based diets significantly improved growth parameters in the Pg0.2 group compared to control. The cellular immune responses in spleen and the humoral immune responses in plasma were significantly improved in a dose and time-dependent manner. Diets supplemented with single Pg and Pa extracts, and to lesser extent to combined extracts, could significantly decrease the mortality of striped catfish following bacterial infection compared to control. The proteomic results indicated that some pathways related to immune responses, antioxidant and lipid metabolism were enriched in liver at W6. Several proteins (i.e., CD8B, HSP90AA1, HSP90AB1, PDIA3, CASP8, TUBA1C, CCKAR, GNAS, GRIN2D, PLCG1, PRKCA, SLC25A5, VDAC2, ACTN4, GNAI2, LCK, CARD9, NLRP12, and NLRP3) were synergistically upregulated in mixture of Pg and Pa-based diets compared to control and single dietary treatments. Taken together, the results revealed that single Pg and Pa extracts at 0.2 and 0.5% and their mixture at 0.08 and 0.5% have the potential to modulate the immune mechanisms and disease resistance of striped catfish. Moreover, the combination of Pg and Pa in diets suggested positive synergistic effects liver proteome profile related to immune system processes.

Dietary reduced glutathione supplementation can improve growth, antioxidant capacity, and immunity on Chinese mitten crab, Eriocheir sinensis

Eriocheir sinensis is an important aquaculture species in China, and its yield and quality are threatened by oxidative stress caused by deteriorating water conditions. Reduced glutathione (GSH) is an endogenous antioxidant, but whether dietary GSH can increase the resistance of E. sinensis to environmental stress remains unclear. Therefore, in this study, crabs were fed with dietary GSH (0, 300, 600, 900, and 1200 mg/kg diet weight) for up to 10 weeks to determine the effects of different dietary GSH concentrations on growth, antioxidant capacity, and immunity of E. sinensis. The results showed that the weight gain rate and survival rate increased significantly as dietary GSH levels increased from 0 to 900 mg/kg, but decreased at 1200 mg/kg. Compared with the control group, the diet supplemented with 900 mg/kg GSH not only increased the concentration of GSH in the haemolymph and hepatopancreas, but also enhanced the activity of glutathione peroxidase (GSH-Px) (p < 0.05). Diets supplemented with 600 or 900 mg/kg GSH significantly increased the enzymes activities of superoxide dismutase (SOD), lysozyme (LZM), alkaline phosphatase, and acid phosphatase, and significantly decreased the content of malondialdehyde. To understand the changes in the activity of these enzymes further, the expression of related genes was detected. Diets supplemented with 600 or 900 mg/kg GSH significantly upregulated the genes expressions of cytosolic manganese SOD, mitochondrial manganese SOD, copper, zinc-SOD, GSH-Px, LZM, and prophenoloxidase activating factor, and significantly down regulated the expression of Toll-like receptor 1, Toll-like receptor 2, Dorsal, and the myeloid differentiation factor 88. However, a diet supplemented with 1200 mg/kg GSH decreased those positive indicators. Overall, our results demonstrated that an appropriate diet supplemented with 600 or 900 mg/kg GSH enhances antioxidant capacity and immunity, which will enhance the general health of E. sinensis.

Survival and immune response of white shrimp Litopenaeus vannamei following single and concurrent infections with WSSV and Vibrio parahaemolyticus

The survival and immune responses of Litopenaeus vannamei were evaluated during white spot syndrome virus (WSSV) or Vibrio parahaemolyticus single and concurrent infections. The mortality, WSSV load, activities of 4 immune enzymes: acid phosphatase (ACP), alkaline phosphatase (AKP), peroxidase (POD) and superoxide dismutase (SOD), and the transcription of Evolutionarily Conserved Signaling Intermediate in Toll pathways of L.vannamei (LvECSIT) were quantified at 0, 3, 6, 12, 24, 48, 72 and 96 h post-infection (pi). The results showed: (i) the cumulative mortality of the co-infection group (WSSV and V. Parahaemolyticus 83%) was significantly lower than the WSSV infection group (97%) (P < 0.05) at 96 hpi; (ii) copies of WSSV in the co-infection group were significantly lower than that of the single infection group from 24 to 96 hpi (P < 0.05); (iii) ACP, AKP,POD and SOD activity in the gills of the co-infection group was higher than that of the WSSV group at12, 48 and 96 hpi (P < 0.05).The expression of LvECSIT mRNA in the co-infection group was significantly higher than in the WSSV infection group from 12 to 72 hpi (P < 0.05).The results indicate that proliferation of WSSV is inhibited by V.parahaemolyticus infection. In addition, infection with WSSV alone causes a significant reduction in some immune responses of shrimp than co-infection with WSSV and V.parahaemolyticus occurs at 26 °C. Third, LvECSIT, an essential member of TLR signaling pathway might play a crucial role in shrimp defense against WSSV - Vibrio co-infection.

Spatio-temporal variability of biomarker responses and lipid composition of Marphysa sanguinea, Montagu (1813) in the anthropic impacted lagoon of Tunis

In this study the Polychaeta Marphysa sanguinea, was tested to investigate the impact of metal pollution on the environmental state of a coastal Mediterranean lagoon, Tunis Lagoon (Tunisia). A multi-biomarker approach comprising glutathione-stransferase, cyclooxygenase, lysozyme activity, and lipid class composition of the Polychaeta was employed on a seasonal basis in the present investigation. The multivariate statistical approach (principal component analysis and Pearson correlation) clearly demonstrated different spatial patterns in biomarker values and lipid class concentrations. The phospholipids were the dominant lipid class in M. sanguinea, with the highest value found at the control station. The impact of pollution was most clearly observed on the main storage lipid class, triacylglycerol, which was lowest in the most impacted sites. Our work suggests that M. sanguinea can be used in warmer Mediterranean costal habitats as a sentinel species of contaminated ecosystems.

Gene identification and antimicrobial activity analysis of a novel lysozyme from razor clam Sinonovacula constricta

Lysozymes are important immune effectors present in phylogenetically diverse organisms. They play vital roles in bacterial elimination during early immune responses. In the present study, a second invertebrate-type (i-type) lysozyme gene from razor clam Sinonovacula constricta (denoted as ScLYZ-2) was cloned by RACE and nested PCR methods. The full-length cDNA sequences of ScLYZ-2 were 1558 bp, including a 5' untranslated region (UTR) of 375 bp, an open reading frame of 426 bp, and a 3'-UTR of 757 bp with polyadenylation signal sequence (AATAAA) located upstream of the poly(A) tail. SMART analysis showed that ScLYZ-2 contains a signal peptide in the first 16 amino acid (AA) sequences and a destabilase domain located from 24 to 134 AA sequences. The deduced AA sequences of ScLYZ-2 were highly similar (42%-58%) to other known lysozyme genes of bivalve species. Multiple alignments of AA sequences showed that ScLYZ-2 possesses the classical i-type lysozyme family signature of two motifs ["MDVGSLSCGP(Y/F)QIK" and "CL(E/L/R/H)C(I/M)C"] and two catalytic residues (Glu³⁵ and Asp⁴⁶). Moreover, phylogenetic analysis showed that ScLYZ-2 is a new member of the i-type lysozyme family. In healthy razor clams, ScLYZ-2 was highly expressed in the hepatopancreas, followed by the gills, water pipes, and abdominal foot. Lysozyme activity and ScLYZ-2 expression levels were significantly upregulated in the hepatopancreas and gills after being infected with V. splendidus, V. harveyi, V. parahaemolyticus and S. aureus and M. luteus. Moreover, the recombinant ScLYZ-2 had strong antimicrobial activities against V. splendidus, V. harveyi, and V. parahaemolyticus. Furthermore, the minimal inhibitory concentration of the recombinant ScLYZ-2 against V. parahaemolyticus was 7.2 μmol/mL. Taken together, our results show that ScLYZ-2 plays an important role in the immune defense of razor clam by eliminating pathogenic microorganisms.

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.

α-Phellandrene enhances the immune response and resistance against Vibrio alginolyticus in white shrimp (Litopenaeus vannamei)

Innate immunity and resistance against Vibrio alginolyticus in white shrimp, Litopenaeus vannamei, that received α-phellandrene were examined. The results indicated that the percent survival of shrimp receiving 4, 8, and 12 μg g^-1 α-phellandrene was significantly higher than that of control shrimp after 72 h (p < 0.05). In a separate experiment, the phenoloxidase (PO), respiratory bursts, superoxide dismutase (SOD), and phagocytic and lysozyme activity of L. vannamei receiving 8 and 12 μg g^-1 α-phellandrene were significantly higher than those of the other groups upon challenge with V. alginolyticus at 24-60, 36-60, 12-60, 12-72 and 48-72 h, respectively. However, no significant differences in the total haemocyte counts (THC) of L. vannamei receiving any dose of α-phellandrene and of control shrimp were observed at 12-72 h. The expression (mRNA transcripts) of the immune genes prophenoloxidase (proPO), LPS- and β-1,3-glucan-binding protein (LGBP) and peroxinectin (PE) of shrimp receiving α-phellandrene at 8 and 12 μg g^-1 significantly increased after challenge with V. alginolyticus for 72 h (p < 0.05). We conclude that the immune ability and resistance against V. alginolyticus infection increased in L. vannamei receiving >4 μg g^-1 α-phellandrene. These results indicated that α-phellandrene plays an important role in the innate immunity of white shrimp.

Recombinant phosphoglucomutase and CAMP factor as potential subunit vaccine antigens induced high protection against Streptococcus iniae infection in flounder (Paralichthys olivaceus)

AIMS

The aim of this study was to screen vaccine candidates from virulence factors of Streptococcus iniae in flounder model.

METHODS AND RESULTS

The immunogenicity of recombinant phosphoglucomutase (rPGM) and rCAMP factor was confirmed by Western blot. The percentage of surface membrane immunoglobulin-positive (sIg⁺ ) lymphocytes in peripheral blood leucocytes, the specific and total serum IgM and the activity of acid phosphatase (ACP) and peroxidase (POD) in flounder were determined with flow cytometry, ELISA and commercial enzyme activity kits, respectively, after intraperitoneal immunization with rPGM and rCAMP factor. The results showed that rPGM and rCAMP factor could induce significant rise in sIg⁺ lymphocytes, specific serum IgM and activities of ACP and POD. Additionally, the relative percent survival rate of the vaccinated flounder was 64 and 54% in challenge experiment using S. iniae, respectively. These results indicated that rPGM and rCAMP factor could evoke humoural and innate immune response in flounder and provide high-efficiency immunoprotection against S. iniae infection.

CONCLUSIONS

Phosphoglucomutase (PGM) and CAMP factor were promising vaccine candidates against S. iniae in flounder.

SIGNIFICANCE AND IMPACT OF THE STUDY

Phosphoglucomutase and CAMP factor have the potential to be vaccine candidates, which provide important information for us to develop the effective subunit vaccines, especially the multivaccine, against S .iniae in aquaculture.

Health Effects of Psidium guajava L. Leaves: An Overview of the Last Decade

Today, there is increasing interest in discovering new bioactive compounds derived from ethnomedicine. Preparations of guava (Psidium guajava L.) leaves have traditionally been used to manage several diseases. The pharmacological research in vitro as well as in vivo has been widely used to demonstrate the potential of the extracts from the leaves for the co-treatment of different ailments with high prevalence worldwide, upholding the traditional medicine in cases such as diabetes mellitus, cardiovascular diseases, cancer, and parasitic infections. Moreover, the biological activity has been attributed to the bioactive composition of the leaves, to some specific phytochemical subclasses, or even to individual compounds. Phenolic compounds in guava leaves have been credited with regulating blood-glucose levels. Thus, the aim of the present review was to compile results from in vitro and in vivo studies carried out with guava leaves over the last decade, relating the effects to their clinical applications in order to focus further research for finding individual bioactive compounds. Some food applications (guava tea and supplementary feed for aquaculture) and some clinical, in vitro, and in vivo outcomes are also included.

Shift in aggregation, ROS generation, antioxidative defense, lysozyme and acetylcholinesterase activities in the cells of an Indian freshwater sponge exposed to washing soda (sodium carbonate)

Washing soda, chemically identified as anhydrous sodium carbonate, is a popular cleaning agent among the rural and urban populations of India which often contaminates the freshwater ponds and lakes, the natural habitat of sponge Eunapius carteri. Present investigation deals with estimation of cellular aggregation, generation of ROS and activities of antioxidant enzymes, lysozyme and acetylcholinesterase in the cells of E. carteri under the environmentally realistic concentrations of washing soda. Prolonged treatment of washing soda inhibited the degree of cellular aggregation. Experimental exposure of 8 and 16mg/l of sodium carbonate for 48h elevated the physiological level of reactive oxygen species (ROS) generation in the agranulocytes, semigranulocytes and granulocytes of E. carteri, whereas, treatment of 192h inhibited the ROS generation in three cellular morphotypes. Activities of superoxide dismutase, catalase and glutathione-S-transferase were recorded to be inhibited under prolonged exposure of washing soda. Washing soda mediated inhibition of ROS generation and depletion in the activities of antioxidant enzymes were indicative to an undesirable shift in cytotoxic status and antioxidative defense in E. carteri. Inhibition in the activity of lysozyme under the treatment of sodium carbonate was suggestive to a severe impairment of the innate immunological efficiency of E. carteri distributed in the washing soda contaminated habitat. Washing soda mediated inhibition in the activity of acetylcholinesterase indicated its neurotoxicity in E. carteri. Washing soda, a reported environmental contaminant, affected adversely the immunophysiological status of E. carteri with reference to cellular aggregation, oxidative stress, antioxidative defense, lysozyme and acetylcholinesterase activity.

Dietary choline regulates antibacterial activity, inflammatory response and barrier function in the gills of grass carp (Ctenopharyngodon idella)

An 8-week feeding trial was conducted to determine the effects of graded levels of choline (197-1795 mg/kg) on antibacterial properties, inflammatory status and barrier function in the gills of grass carp. The results showed that optimal dietary choline supplementation significantly improved lysozyme and acid phosphatase activities, complement component 3 (C3) content, and the liver expressed antimicrobial peptide 2 and Hepcidin mRNA levels in the gills of fish (P < 0.05). In addition, appropriate dietary choline significantly decreased the oxidative damage, which might be partly due to increase copper, zinc superoxide dismutase (Cu/Zn-SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) activities and increased glutathione content in the gills of fish (P < 0.05). Moreover, appropriate dietary choline significantly up-regulated the mRNA levels of interleukin 10 and transforming growth factor β1, Zonula occludens 1, Occludin, Claudin-b, c, 3 and 12, inhibitor of κBα, target of rapamycin, Cu/Zn-SOD, CAT, GR, GPx, GST and NF-E2-related factor 2 in the gills of fish (P < 0.05). Conversely, appropriate dietary choline significantly down-regulated the mRNA levels of pro-inflammatory cytokines, tumor necrosis factor α, interleukin 8, interferon γ, interleukin 1β, and related signaling factors, nuclear factor kappa B p65, IκB kinase β, IκB kinase γ, myosin light chain kinase and Kelch-like-ECH-associated protein 1a (Keap1a) in the gills of fish (P < 0.05). However, choline did not have a significant effect on the mRNA levels of IκB kinase α, Claudin-15 and Keap1b in the gills of fish. Collectively, appropriate dietary choline levels improved gill antibacterial properties and relative gene expression levels of tight junction proteins, and decreased inflammatory status, as well as up-regulated the mRNA levels of related signaling molecules in the gills of fish. Based on gill C3 content and AHR activity, the dietary choline requirements for young grass carp (266.5-787.1 g) were estimated to be 1191.0 and 1555.0 mg/kg diet, respectively.

Morphological alteration, lysosomal membrane fragility and apoptosis of the cells of Indian freshwater sponge exposed to washing soda (sodium carbonate)

Washing soda is chemically known as sodium carbonate and is a component of laundry detergent. Domestic effluent, drain water and various anthropogenic activities have been identified as major routes of sodium carbonate contamination of the freshwater ecosystem. The freshwater sponge, Eunapius carteri, bears ecological and evolutionary significance and is considered as a bioresource in aquatic ecosystems. The present study involves estimation of morphological damage, lysosomal membrane integrity, activity of phosphatases and apoptosis in the cells of E. carteri under the environmentally realistic concentrations of washing soda. Exposure to washing soda resulted in severe morphological alterations and damages in cells of E. carteri. Fragility and destabilization of lysosomal membranes of E. carteri under the sublethal exposure was indicative to toxin induced physiological stress in sponge. Prolonged exposure to sodium carbonate resulted a reduction in the activity of acid and alkaline phosphatases in the cells of E. carteri. Experimental concentration of 8 mg/l of washing soda for 192 h yielded an increase in the physiological level of cellular apoptosis among the semigranulocytes and granulocytes of E. carteri, which was suggestive to possible shift in apoptosis mediated immunoprotection. The results were indicative of an undesirable shift in the immune status of sponge. Contamination of the freshwater aquifers by washing soda thus poses an alarming ecotoxicological threat to sponges.

Flavonoid fraction of guava leaf extract attenuates lipopolysaccharide-induced inflammatory response via blocking of NF-κB signalling pathway in Labeo rohita macrophages

Psidium guajava L. is a well-known traditional medicinal plant widely used in folk medicine. To explore the anti-inflammatory activity of the flavonoid fraction of guava leaf extract (FGLE), we investigated its ability to suppress the levels of inflammatory mediators elevated by lipopolysaccharide (LPS) in Labeo rohita head-kidney (HK) macrophages. HK macrophages of L. rohita were treated with LPS in the presence or absence of the FGLE. We examined the inhibitory effect of FGLE on LPS-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production. The inhibitory effect of FGLE on nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were investigated by RT-PCR and western blot. The effect of FGLE on proinflammatory cytokines tumour necrosis factor alpha (TNF-α) or interleukin-1β (IL-1β) was also investigated by ELISA and RT-PCR. The phosphorylation of three mitogen activated protein kinases (MAPK) molecules ERK, JNK and p38 was analysed by western blot analysis. FGLE inhibited LPS-induced NO and PGE2 production. It also effectively inhibited TNF-α, IL-1β, IL-10, iNOS, and COX-2 production in a concentration-dependent manner. In addition, FGLE suppressed the mRNA expression levels of TNF-α and IL-1β in LPS-stimulated HK macrophages. RT-PCR and western blot analysis showed that FGLE decreased both the mRNA and protein expression levels of LPS-induced iNOS and COX-2 in HK macrophages. FGLE suppresses the phosphorylation of MAPK molecules in LPS-stimulated HK macrophages. FGLE also significantly inhibited LPS-induced NF-κB transcriptional activity. The molecular mechanism by which FGLE suppresses the expression of inflammatory mediators appears to involve the inhibition of NF-κB activation, through the suppression of LPS-induced IκB-α degradation. Together these results suggest that FGLE contains potential therapeutic agent(s), which regulate NF-κB activation, for the treatment of inflammatory conditions in L. rohita macrophages.