Differential expression of immune-related biomarkers in primary cultures from Atlantic salmon (Salmo salar) exposed to processed Paecilomyces variotii with or without inactivated Moritella viscosa

Paecilomyces variotii (a filamentous fungus), is a promising novel protein source in fish feeds due to its high nutritional value. Also, P. variotii has Microbial-Associated Molecular Patterns (MAMPs) such as glucans and nucleic acids that could modulate the host's immune response. To understand the potential bioactive properties of this fungus in Atlantic salmon (Salmo salar), our study was conducted to evaluate the gene expression of immune-related biomarkers (e.g., cytokines, effector molecules and receptors) on primary cultures from salmon head kidney (HKLs) and spleen leukocytes (SLs) exposed to either UV inactivated or fractions from P. variotii with or without inactivated Moritella viscosa (a skin pathogen in salmonids). Moreover, the effect of the fermentation conditions and down-stream processing on the physical ultrastructure and cell wall glucan content of P. variotii was characterized. The results showed that drying had a significant effect on the cell wall ultrastructure of the fungi and the choice of fermentation has a significant effect on the quantity of β-glucans in P. variotii. Furthermore, stimulating Atlantic salmon HKLs and SLs with P. variotii and its fractions induced gene expression related to pro-inflammatory (tnfα, il1β) and antimicrobial response (cath2) in HKLs, while response in SLs was related to both pro-inflammatory and regulatory response (tnfα, il6 and il10). Similarly, the stimulation with inactivated M. viscosa alone led to an up-regulation of genes related to pro-inflammatory (tnfα, il1β, il6) antimicrobial response (cath2), intra-cellular signalling and recognition of M. viscosa (sclra, sclrb) and a suppression of regulatory response (il10) in both HKLs and SLs. Interestingly, the co-stimulation of cells with P. variotii and M. viscosa induced immune homeostasis (il6, tgfβ) and antimicrobial response (cath2) in SLs at 48h. Thus, P. variotii induces immune activation and cellular communication in Atlantic salmon HKLs and SLs and modulates M. viscosa induced pro-inflammatory responses in SLs. Taken together, the results from physical and chemical characterization of the fungi, along with the differential gene expression of key immune biomarkers, provides a theoretical basis for designing feeding trials and optimize diets with P. variotii as a functional novel feed ingredient for Atlantic salmon.

Zika virus in India: past, present and future

Zika virus (ZIKV) is an arthropod-borne flavivirus that presents with acute febrile illness associated with rash, arthralgia and conjunctivitis. After years of sporadic reports in Africa, the three major outbreaks of this disease occurred in Yap Islands (2007), French Polynesia (2013-14) and South Americas (2015-16). Although, serological surveys suggested the presence of ZIKV in India in 1950s, cross-reactivity could not be ruled out. The first four proven cases of ZIKV from India were reported in 2017. This was followed by major outbreaks in the states of Rajasthan and Madhya Pradesh in 2018. Fortunately, the outbreaks in India were not associated with neurological complications. These outbreaks in India highlighted the spread of this disease beyond geographical barriers owing to the growing globalization, increased travel and ubiquitous presence of its vector, the Aedes mosquito. In this review, we discuss the epidemiology, clinical features and management of ZIKV in India.

Determining the efficacy of ginger Zingiber officinale as a potential nutraceutical agent for boosting growth performance and health status of Labeo rohita reared in a semi-intensive culture system

A 120-day feeding trial was conducted in a pilot field setting to study the nutraceutical properties of ginger powder (GP), focusing on the growth performance and health status of Indian major carp L. rohita reared under a semi-intensive culture system. L. rohita fingerlings (average weight: 20.5 g) were divided into five groups and fed a diet with no GP supplementation (control), or a diet supplemented with GP at 5 g (GP5), 10 g (GP10), 15 g (GP15), and 20 g (GP20) per kg of feed. The study was carried out in outdoor tanks (20 m2) following a complete randomized design with three replicates for each experimental group. Dietary supplementation of GP at 15 g·kg−1 (GP15) of feed caused a significant increase in the growth performances of the fish. Results also showed that feeding of GP15 diet led to a significant improvement in the health status of fish as indicated by a marked change in the tested haematological indices (i.e., higher RBC, WBC, Hb, and Ht values), oxidative status (increased SOD and decreased LPO levels), biochemical parameters (increased HDL, decreased cholesterol, and triglycerides levels), and activities of the liver enzymes (decreased AST and ALT). Overall results suggested that dietary supplementation of GP could positively influence the growth and health status of L. rohita fingerlings, and hence could be an important natural nutraceutical for sustainable farming of carp.

Phloroglucinol shows prophylactic and metaphylactic effects against pathogenic stressors in Macrobrachium larvae

Vibriosis caused by Vibrio campbellii and related species is amongst the major hindrance to the sustainable expansion of giant freshwater prawn Macrobrachium rosenbergii larviculture. Induction of heat shock protein Hsp70 is a natural response of stressed organisms that protect against many insults including vibriosis in aquaculture animals. Therefore, there is a great interest in searching for natural compounds that could induce Hsp70 in animals in a non-invasive manner. Previously, in a series of in vivo studies, we have shown that the phenolic compound phloroglucinol could induce Hsp70 in aquaculture organisms Macrobrachium and Artemia. This led to a significant increase in the resistance of the animals towards subsequent challenges with V. parahemolyticus. As V. parahaemolyticus belongs to the Harveyi clade similar to V. campbellii, our above findings triggered the hypothesis that phloroglucinol is a potential anti-microbial agent that could protect the freshwater prawn against V. campbellii infection. The results presented here provide evidence that the Hsp70-inducing compound phloroglucinol could induce both metaphylactic and prophylactic effects against infection stress mediated by V. campbellii. The wide-spectrum property of the compound to both prevent the occurrence and reduce the spread of V. campbellii infection in prawn larvae without affecting the larval growth makes it a potential natural agent for health management and V. campbellii-mediated disease control in freshwater prawn larvae. Overall results add new information about the functional properties of phloroglucinol and advance our knowledge of this compound as a potential antimicrobial agent for the sustainable production of giant freshwater prawns.

The Combined Use of Pediococcus pentosaceus and Fructooligosaccharide Improves Growth Performance, Immune Response, and Resistance of Whiteleg Shrimp Litopenaeus vannamei Against Vibrio parahaemolyticus

In this study, we evaluated the effect of probiotic bacteria Pediococcus pentosaceus supplemented at different inclusion levels in a control diet [basal diet containing 0.5% fructooligosaccharide (FOS)] on the growth performance, feed conversion ratio, immune response, and the disease resistance of whiteleg shrimp Litopenaeus vannamei juveniles against Vibrio parahaemolyticus. A control diet with 0.5% FOS but without P. pentosaceus supplementation (Control) was prepared. In addition, three other test diets were also formulated: control diet supplemented with P. pentosaceus at (i) 1 × 106 cfu g-1 diet (P1), (ii) 1 × 107 cfu g-1 diet (P2), or (iii) 1 × 108 cfu g-1 diet (P3). After a 60-day feeding trial, the experimental shrimps were challenged with V. parahaemolyticus. The results showed that dietary supplementation of P. pentosaceus significantly improved the growth performance and immune responses of L. vannamei juveniles. The juveniles that were fed with a P2 or P3 diet recorded the maximum increase in the final body weight, final length, weight gain, and survival rate. The total hemocyte counts, phenoloxidase, and lysozyme activity of shrimp fed with either of these two diets were significantly enhanced. The results also showed that juveniles fed with a P2 or P3 diet exhibited significantly lower mortality when challenged with V. parahaemolyticus. Overall results suggested that a combination of P. pentosaceus at the inclusion level of 1 × 107 cfu g-1 diet (P2) and 0.5% FOS could be considered as a potential synbiotic formulation for improving the growth, health, and robustness of L. vannamei.

In vitro Selection of Synbiotics and in vivo Investigation of Growth Indices, Reproduction Performance, Survival, and Ovarian Cyp19α Gene Expression in Zebrafish Danio rerio

In this study, we tested the compatibility of two extracts from the plant Jerusalem artichokes and button mushrooms with two different Lactobacillus probiotics (Lactobacillus acidophilus; La and Lactobacillus delbrueckii subsp. Bulgaricus; Lb) to develop a synbiotic formulation to improve the growth, survival, and reproductive performances of farmed fishes. Initially, we employed in vitro approach to monitor the growth of the probiotic lactobacilli in the presence of the different doses of the plant-based prebiotics, with the aim of selecting interesting combination(s) for further verification under in vivo conditions using zebrafish as a model. Results from the in vitro screening assay in the broth showed that both the probiotic species showed a preference for 50% mushroom extract as a source of prebiotic. A synbiotic formulation, developed with the selected combination of L. acidophilus, L. bulgaricus, and 50% mushroom extract, showed a positive influence on the growth and reproductive performances of the zebrafish. Our findings also imply that the improvement in the reproductive indices was associated with the upregulation of a cyp19a gene. Overall results suggest that a combination of L. acidophilus, L. bulgaricus, and mushroom extract can be considered as a potential synbiotic for the successful production of aquaculture species.

Differential modulation of oxidative stress, antioxidant defense, histomorphology, ion-regulation and growth marker gene expression in goldfish (Carassius auratus) following exposure to different dose of virgin microplastics

Goldfish (Carassius auratus) juveniles were exposed to virgin polyvinyl chloride microplastics (PVC-MPs) in triplicate at 0, 0.1 or 0.5 mg/L for four days. Afterwards, the histopathology of the gills, liver and intestines were examined, along with various antioxidant enzymes and indicators of oxidative damage (malondialdehyde (MDA) and hydrogen peroxide (H₂O₂)), in the brain, liver and gills. In addition, we also studied the expression of hepatic insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein 1 (IGFBP-1) and growth hormone (GH) receptor, while cortisol receptor (CR) and cytochrome P450 1A (CYP1A) gene expression were assayed in both the liver and gills. Histological analysis revealed PVC-MPs in the intestines at 0.1 and 0.5 mg/L, along with substantially shorter villi. The gills appeared undamaged by PVC-MPs exposure and had limited or no effect to antioxidant activity, Na⁺/K⁺-ATPase and H⁺-ATPase activity or plasma ion levels, but there was a prominent upsurge of the detoxification enzymes glutatione S-transferase (GST) activity and CYP1A expression. Livers showed inflammation and some occurrences of hemorrhaging and necrosis at 0.5 mg/L. While the brain showed some evidence of oxidative damage, the liver was the most susceptible to oxidative damage, based on increased MDA, H₂O₂ and various antioxidant enzymes. Hepatic expression of IGFBP-1 and GH receptor were significantly downregulated at 0.5 mg/L while CR was upregulated. Results indicate that exposure to environmentally relevant PVC-MP can cause oxidative damage in the brain and liver, adverse histomorphological changes to the intestine and liver and alter the gene expression in goldfish.

Beta-glucan's varying structure characteristics modulate survival and immune-related genes expression from Vibrio harveyi-infected Artemia franciscana in gnotobiotic conditions

β-Glucans have long been used as an immunostimulant in aquaculture. However, the relationship of its structure to its immunomodulatory properties are poorly understood. In this study, the particle size and chemical structure of β-glucans extracted from wild-type strain of baker's yeast (Saccharomyces cerevisiae) and its null-mutant yeasts Gas1 were characterised. Using Sigma β-glucan as a reference, the immunomodulatory properties of these polysaccharides in the germ-free Artemia franciscana model system in the presence of Vibrio harveyi bacterial challenge were investigated. The survival of the A. franciscana nauplii, upon challenge with V. harveyi, was significantly higher in all three glucan-treated groups compared to the control. The glucan Gas1 with a lower degree of branching and shorter side chain length had the most prominent V. harveyi-protective effects. The particle size did not affect the nauplii survival when challenged with V. harveyi. Results also showed that the salutary effect of the tested glucans was associated with the upregulation of innate immune genes such as lipopolysaccharide and β-1,3-glucan-binding protein (lgbp), high mobility group box protein (hmgb), and prophenoloxidase (proPO). Interestingly, the up-regulation of superoxidase dismutase (sod) and glutathione-s-transferase (gst) was only observed in Gas1 treated group, indicating that Gas1 could function to induce higher reactive oxygen species and stronger immunomodulatory function in A. franciscana, and therefore higher survival rate. The expression of heat shock protein 70 (hsp70), peroxinectin (pxn), and down syndrome cell adhesion molecule (dscam) remain unaltered in response to glucan treatment. Taken together, this study provides insights into the structure-function relationship of β-glucan and the results confirmed that β-glucan can be an effective immunostimulant in aquaculture, especially the Gas1 glucan.

Sodium Ascorbate as a Quorum-Sensing Inhibitor Leads to Decreased Virulence in Vibrio campbellii

Vibrio campbellii is one of the major bacterial pathogens for animals reared in aquaculture, affecting both vertebrates and invertebrates, and causes significant economic losses. It is now evident that the expressions of virulence factors in this pathogen are regulated by the density of the bacterial population. This type of regulation, termed quorum sensing (QS), is mediated by extracellular signal molecules called autoinducers. In this study, the impact of sodium ascorbate (NaAs) on the virulence of V. campbellii was investigated under both in vitro and in vivo conditions, to develop a natural anti-infective strategy to contain V. campbellii infection in aquacultured animals. Results showed that NaAs significantly decreased swimming motility, biofilm production, and the production of virulence enzymes, such as lipase, caseinase, phospholipase, and hemolysin in V. campbellii. Consistent with this, pretreatment of V. campbellii with NaAs before inoculation into the rearing water resulted in significantly increased survival of gnotobiotic brine shrimp larvae, when compared to larvae challenged with untreated V. campbellii. Furthermore, NaAs could interfere with QS-regulated bioluminescence in V. campbellii, suggesting the QS-inhibitory activity largely determines the protective effect of NaAs toward the brine shrimp. In essence, due to the potent anti-virulence effects observed in in vitro studies and the clinical brine shrimp-V. campbellii infection model, NaAs constitute a promising novel strategy for the control of V. campbellii infections in aquaculture.

Structure-Functional Activity Relationship of β-Glucans From the Perspective of Immunomodulation: A Mini-Review

β-Glucans are a heterogeneous group of glucose polymers with a common structure comprising a main chain of β-(1,3) and/or β-(1,4)-glucopyranosyl units, along with side chains with various branches and lengths. β-Glucans initiate immune responses via immune cells, which become activated by the binding of the polymer to specific receptors. However, β-glucans from different sources also differ in their structure, conformation, physical properties, binding affinity to receptors, and thus biological functions. The mechanisms behind this are not fully understood. This mini-review provides a comprehensive and up-to-date commentary on the relationship between β-glucans' structure and function in relation to their use for immunomodulation.

Environmental conditions steer phenotypic switching in acute hepatopancreatic necrosis disease-causing Vibrio parahaemolyticus, affecting PirAVP /PirBVP toxins production

Bacteria in nature are widely exposed to differential fluid shears which are often a trigger for phenotypic switches. The latter mediates transcriptional and translation remodelling of cellular metabolism impacting among others virulence, antimicrobial resistance and stress resistance. In this study, we evaluated the role of fluid shear on phenotypic switch in an acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio parahaemolyticus M0904 strain under both in vitro and in vivo conditions. The results showed that V. parahaemolyticus M0904 grown at lower shaking speed (110 rpm constant agitation, M0904/110), causing low fluid shear, develop cellular aggregates or floccules. These cells increased levan production (as verified by concanavalin binding) and developed differentially stained colonies on Congo red agar plates and resistance to antibiotics. In addition, the phenotypic switch causes a major shift in the protein secretome. At 120 rpm (M0904/120), PirA^VP /PirB^VP toxins are mainly produced, while at 110 rpm PirA^VP /PirB^VP toxins production is stopped and an alkaline phosphatase (ALP) PhoX becomes the dominant protein in the protein secretome. These observations are matched with a very strong reduction in virulence of M0904/110 towards two crustacean larvae, namely, Artemia and Macrobrachium. Taken together, our study provides substantial evidence for the existence of two phenotypic forms in AHPND V. parahaemolyticus strain displaying differential phenotypes. Moreover, as aerators and pumping devices are frequently used in shrimp aquaculture facilities, they can inflict fluid shear to the standing microbial agents. Hence, our study could provide a basis to understand the behaviour of AHPND-causing V. parahaemolyticus in aquaculture settings and open the possibility to monitor and control AHPND by steering phenotypes.

Adaptive Radiotherapy for Carcinoma of the Urinary Bladder: Long-term Outcomes With Dose Escalation

AIMS

To report long-term outcomes with dose-escalated, image-guided adaptive radiotherapy (ART) for bladder preservation in muscle-invasive bladder cancer (MIBC).

MATERIALS AND METHODS

All MIBC patients receiving bladder-preserving ART at our institute from 2009 to 2018 were analysed. For ART, three anisotropic planning target volumes (PTV) were concentrically grown around the simulation bladder volume. A library of intensity-modulated radiotherapy plans was created for each patient. A total dose of 64 Gy in 32 fractions to the entire bladder and 55 Gy to pelvic nodes was planned, with 68 Gy to the tumour bed (2 Gy equivalent dose = 68.7 Gy, α/β = 10) as simultaneous integrated boost for solitary tumours. The most appropriate PTV encompassing the bladder ('plan-of-the-day') was chosen daily using on-board megavoltage imaging. Neoadjuvant and concurrent chemotherapy was prescribed for medically fit patients.

RESULTS

Of a total of 106 patients, most had T2 (68%) or T3 (19%) disease. Ninety-two patients (87%) completed 64 Gy to the whole bladder. Sixty-three patients (59%) received 68 Gy as tumour bed boost. Seventy-six per cent received concurrent weekly chemotherapy. At a median follow-up of 26 months, 3-year locoregional control, disease-free survival and overall survival were 74.3, 62.9 and 67.7%, respectively. Eighty-two per cent of patients retained disease-free bladder. Radiation Therapy Oncology Group grade III/IV acute genitourinary and gastrointestinal toxicities were 7.5% and 0%, respectively, and late genitourinary/gastrointestinal toxicities were 6.5% and 3.8%, respectively. Overall survival, disease-free survival, locoregional control and grade III/IV genitourinary/gastrointestinal toxicities did not differ significantly with dose escalation.

CONCLUSION

Plan-of-the-day ART is clinically safe and effective for bladder preservation and can be implemented in routine clinical practice. A high bladder preservation rate is achievable without compromising on survival or toxicities. Dose escalation does not seem to affect outcomes.

Effect of Substituents on TICT Rate in Thioflavin T-Based Fluorescent Molecular Rotors

New fluorescent molecular rotors (FMRs) were developed by modification of the Thioflavin T (ThT) structure via introduction of methyl and methoxy groups. Effects of the substituents on fluorescence properties and twisted intramolecular charge transfer (TICT) rate in the excited state of the molecules were studied using steady-state fluorescence and time-resolved absorption spectroscopy. Quantum chemical calculations of the molecules in the ground and excited states were carried out to aid interpretation of the experimental results. Only cationic forms of ThT derivatives have FMR properties and exhibit viscosity-dependent fluorescence. The TICT rate was found to be affected by the size of the molecular fragments, which experience mutual rotation, dihedral angle [Formula: see text] between the fragments in the ground state as well as their donor/acceptor properties.

High doses of sodium ascorbate act as a prooxidant and protect gnotobiotic brine shrimp larvae (Artemia franciscana) against Vibrio harveyi infection coinciding with heat shock protein 70 activation

Ascorbate is an essential nutrient commonly regarded as an antioxidant. In this study, using axenic brine shrimp and pathogenic strain Vibrio harveyi as the host-pathogen model, we confirmed that pretreatment of sodium ascorbate (NaAs), at an optimum concentration, was a prooxidant by generation of hydrogen peroxide, inducing protective effects in the brine shrimp against V. harveyi infection. Such a protective effect could be neutralized by the addition of an antioxidant enzyme catalase. We further showed that generation of oxygen radicals is linked to the induction of heat shock protein 70 (Hsp70), which is involved in eliciting the antioxidant protection system including superoxidase dismutase (SOD) and possibly many other immune responses. Furthermore, using RNA interference technique, we found that the pretreatment of sodium ascorbate increased the survival significantly in the control knockdown groups (using green fluorescent protein, GFP) but not in Hsp70 knockdown groups and the result directly suggested that the up-regulated Hsp70 induced by sodium ascorbate pretreatment induced the protective effect. These results provide a mechanistic rationale for exploring the further use of ascorbate for antimicrobial therapy in aquaculture.

Can epigenetics translate environmental cues into phenotypes?

Living organisms are constantly exposed to wide ranges of environmental cues. They react to these cues by undergoing a battery of phenotypic responses, such as by altering their physiological and behavioral traits, in order to adapt and survive in the changed environments. The adaptive response of a species induced by environmental cues is typically thought to be associated with its genetic diversity such that higher genetic diversity provides increased adaptive potential. This originates from the general consensus that phenotypic traits have a genetic basis and are subject to Darwinian natural selection and Mendelian inheritance. There is no doubt about the validity of these principles, supported by the successful introgression of specific traits during (selective) breeding. However, a range of recent studies provided fascinating evidences suggesting that environmental effects experienced by an organism during its lifetime can have marked influences on its phenotype, and additionally the organism can pass on the acquired phenotypes to its subsequent generations through non-genetic mechanisms (also termed as epigenetic mechanism) - a notion that dates back to Lamarck and has been controversial ever since. In this review, we describe how the epigenetics has reshaped our long perception about the inheritance/development of phenotypes within organisms, contrasting with the classical gene-based view of inheritance. We particularly highlighted recent developments in our understanding of inheritance of parental environmental induced phenotypic traits in multicellular organisms under different environmental conditions, and discuss how modifications of the epigenome contribute to the determination of the adult phenotype of future generations.

The 9H-Fluoren Vinyl Ether Derivative SAM461 Inhibits Bacterial Luciferase Activity and Protects Artemia franciscana From Luminescent Vibriosis

Vibrio campbellii is a major pathogen in aquaculture. It is a causative agent of the so-called “luminescent vibriosis,” a life-threatening condition caused by bioluminescent Vibrio spp. that often involves mass mortality of farmed shrimps. The emergence of multidrug resistant Vibrio strains raises a concern and poses a challenge for the treatment of this infection in the coming years. Inhibition of bacterial cell-to-cell communication or quorum sensing (QS) has been proposed as an alternative to antibiotic therapies. Aiming to identify novel QS disruptors, the 9H-fluroen-9yl vinyl ether derivative SAM461 was found to thwart V. campbellii bioluminescence, a QS-regulated phenotype. Phenotypic and gene expression analyses revealed, however, that the mode of action of SAM461 was unrelated to QS inhibition. Further evaluation with purified Vibrio fischeri and NanoLuc luciferases revealed enzymatic inhibition at micromolar concentrations. In silico analysis by molecular docking suggested binding of SAM461 in the active site cavities of both luciferase enzymes. Subsequent in vivo testing of SAM461 with gnotobiotic Artemia franciscana nauplii demonstrated naupliar protection against V. campbellii infection at low micromolar concentrations. Taken together, these findings suggest that suppression of luciferase activity could constitute a novel paradigm in the development of alternative anti-infective chemotherapies against luminescent vibriosis, and pave the ground for the chemical synthesis and biological characterization of derivatives with promising antimicrobial prospects.

Teaching Shrimps Self-Defense to Fight Infections

A paradigm shift in our understanding of shrimp immunity offers the potential to develop novel disease-control strategies. We summarize cutting-edge findings on the phenomenon of trained immunity in shrimps and discuss how it may contribute to new avenues for controlling disease in these aquaculturally important animals.

Phloroglucinol-Mediated Hsp70 Production in Crustaceans: Protection against Vibrio parahaemolyticus in Artemia franciscana and Macrobrachium rosenbergii

The halophilic aquatic bacterium, Vibrio parahaemolyticus, is an important aquatic pathogen, also capable of causing acute hepatopancreatic necrosis disease (AHPND) in shrimp resulting in significant economic losses. Therefore, there is an urgent need to develop anti-infective strategies to control AHPND. The gnotobiotic Artemia model is used to establish whether a phenolic compound phloroglucinol is effective against the AHPND strain V. parahaemolyticus MO904. We found that pretreatment with phloroglucinol, at an optimum concentration (30 µM), protects axenic brine shrimp larvae against V. parahaemolyticus infection and induced heat shock protein 70 (Hsp70) production (twofolds or more) as compared with the control. We further demonstrated that the Vibrio-protective effect of phloroglucinol was caused by its prooxidant effect and is linked to the induction of Hsp70. In addition, RNA interference confirms that phloroglucinol-induced Hsp70 mediates the survival of brine shrimp larvae against V. parahaemolyticus infection. The study was validated in xenic Artemia model and in a Macrobrachium rosenbergii system. Pretreatment of xenic brine shrimp larvae (30 µM) and Macrobrachium larvae (5 µM) with phloroglucinol increases the survival of xenic brine shrimp and Macrobrachium larvae against subsequent V. parahaemolyticus challenge. Taken together, our study provides substantial evidence that the prooxidant activity of phloroglucinol induces Hsp70 production protecting brine shrimp, A. franciscana, and freshwater shrimp, M. rosenbergii, against the AHPND V. parahaemolyticus strain MO904. Probably, phloroglucinol treatment might become part of a holistic strategy to control AHPND in shrimp.

Enhanced resistance against Vibrio harveyi infection by carvacrol and its association with the induction of heat shock protein 72 in gnotobiotic Artemia franciscana

Induction of HSP72 is a natural response of stressed organisms that protects against many insults including bacterial diseases in farm (aquatic) animals. It would therefore be of great health benefit to search for natural compounds that are clinically safe yet able to induce HSP72 in animals. The phenolic compound carvacrol, an approved food component, had been shown in in vitro study to act as a co-inducer of HSP72, enhancing HSP72 production only in combination with a bona fide stress compared to the compound alone. However, in vitro model systems do not completely represent an in vivo physiology. Here, using the well-established gnotobiotic Artemia model system, we determined whether carvacrol could induce HSP72 in vivo, whether this putative effect could generate resistance in Artemia against biotic/abiotic stress and also unraveled the mechanism behind the possible HSP72-inducing effect of carvacrol. The gnotobiotic system is crucial for such studies because it avoids the interference of any extraneous factors on host-compound interaction. Here, carvacrol was shown to be a potent HSP72 inducer. Induction of HSP72 was associated with the generation of resistance in Artemia larvae against subsequent lethal heat stress or pathogenic Vibrio harveyi. Our results also provided new insight on the mode of HSP72 inducing action of carvacrol, in which the initial generation of reactive molecule H2O2 by the compound plays a key role. Overall results add new information about the bioactivity of carvacrol and advance our knowledge of this compound as potential prophylactic agent for controlling Vibrio infection in aquaculture animals.

Dietary protein enhances non-specific immunity, anti-oxidative capability and resistance to Aeromonas hydrophila in Labeo rohita fingerlings pre-exposed to short feed deprivation stress

Present experiment was conducted to study the effect of dietary protein levels on growth, immunity and anti-oxidative status of Labeo rohita fingerlings during feed deprivation followed by refeeding. Fish (5.44 ± 0.10 g) were deprived of feed for 3 weeks and then re-fed to satiation for 5 weeks with one of the diets containing 25 (25P), 30 (30P), 35 (35P) or 40 (40P) percent crude protein (CP) level. In addition to these groups, a control group (C) was also maintained by feeding to satiation level twice daily with a diet containing 30% CP throughout the experimental period. At the end of 8-weeks' trial, fish were challenged with Aeromonas hydrophila and survival was recorded for the next 7 days. Complete recovery of growth in terms of weight gain percentage was achieved in the fish fed 35 and 40% protein during refeeding. The body indices (condition factor and hepatosomatic index), haematological parameters and serum protein contents at the end of the experimental trial were not significantly different (P > 0.05) among different groups suggesting that the overall health of the fish was not compromised. However, respiratory burst activity and serum lysozyme activity were indicative of a better immune function in the higher protein fed groups (35P and 40P) than the lower protein groups (25P and 30P). Following challenge with Aeromonas hydrophila, survival rate, blood monocyte%, respiratory burst activity, serum lysozyme activity, serum protein and globulin were significantly higher (P < 0.05) in the 35P and 40P groups compared to the other groups. Further, fish fed lower dietary protein were not able to restore the activities of anti-oxidative enzymes (superoxide dismutase and catalase) in the liver. Conclusively, an improved disease resistance capability and immune status was observed in the fish fed a higher dietary protein (35-40%), even out-performing the daily-fed fish.

Emergence of dengue in tribal villages of Mandla district, Madhya Pradesh, India

Background & objectives:

Dengue (DEN) is a rapidly spreading arboviral disease transmitted by Aedes mosquitoes. Although it is endemic in India, dengue virus (DENV) infection has not been reported from tribal areas of Madhya Pradesh. Investigations were conducted to establish the aetiology of sudden upsurge of cases with febrile illness in June 2013 from tribal villages of Mandla district of Madhya Pradesh, India.

Methods:

The rapid response team of the National Institute for Research in Tribal Health, Jabalpur, conducted clinical investigations and field surveys to collect the samples from suspected cases. Samples were tested using molecular and serological tools. Collected mosquitoes were identified and tested for the presence of virus using semi nested reverse transcriptase-polymerase chain reaction (nRT-PCR). The sequences were analysed to identify serotype and genotype of the virus.

Results:

Of the 648 samples collected from 18 villages of Mandla, 321 (49.53%) were found to be positive for dengue. The nRT-PCR and sequencing confirmed the aetiology as dengue virus type 2. Eighteen per cent of patients needed hospitalization and five deaths were attributed to dengue. The virus was also detected from Aedes aegypti mosquito, which was incriminated as a vector. Phylogenetic analysis revealed that the dengue virus 2 detected belonged to cosmopolitan genotype of the virus.

Interpretation & conclusions:

Dengue virus serotype 2 was detected as the aetiological agent in the outbreak in tribal villages of Mandla district of Madhya Pradesh. Conducive man-made environment favouring mosquitogenic conditions and seeding of virus could be the probable reasons for this outbreak. Urgent attention is needed to control this new threat to tribal population, which is already overburdened with other vector borne diseases.

Characterization of phenotype variations of luminescent and non-luminescent variants of Vibrio harveyi wild type and quorum sensing mutants

Vibrio harveyi, a luminescent Gram-negative motile marine bacterium, is an important pathogen responsible for causing severe diseases in shrimp, finfish and molluscs leading to severe economic losses. Non-luminescent V. harveyi obtained by culturing luminescent strains under static and dark condition were reported to alter the levels of virulence factors and metalloprotease gene and luxR expression when compared to their luminescent variants. Presently, we conducted an in vitro study aiming at the characterization of virulence-related phenotypic traits of the wild-type V. harveyi BB120 strain and its isogenic quorum sensing mutants before and after switching to the non-luminescent status. We measured the production of caseinase, haemolysin and elastase and examined swimming motility and biofilm formation. Our results showed that switching from the bioluminescent to the non-luminescent state changed the phenotypic physiology or behaviour of V. harveyi resulting in alterations in caseinase and haemolytic activities, swimming motility and biofilm formation. The switching capacity was to a large extent independent from the quorum sensing status, in that quorum sensing mutants were equally capable of making the phenotypic switch.

Probing the phenomenon of trained immunity in invertebrates during a transgenerational study, using brine shrimp Artemia as a model system

The invertebrate’s innate immune system was reported to show some form of adaptive features, termed trained immunity. However, the memory characteristics of innate immune system and the mechanisms behind such phenomena remain unclear. Using the invertebrate model Artemia, we verified the possibility or impossibility of trained immunity, examining the presence or absence of enduring memory against homologous and heterologous antigens (Vibrio spp.) during a transgenerational study. We also determined the mechanisms behind such phenomenon. Our results showed the occurrence of memory and partial discrimination in Artemia’s immune system, as manifested by increased resistance, for three successive generations, of the progenies of Vibrio-exposed ancestors towards a homologous bacterial strain, rather than to a heterologous strain. This increased resistance phenotype was associated with elevated levels of hsp70 and hmgb1 signaling molecules and alteration in the expression of key innate immunity-related genes. Our results also showed stochastic pattern in the acetylation and methylation levels of H4 and H3K4me3 histones, respectively, in the progenies whose ancestors were challenged. Overall results suggest that innate immune responses in invertebrates have the capacity to be trained, and epigenetic reprogramming of (selected) innate immune effectors is likely to have central place in the mechanisms leading to trained immunity.

The gnotobiotic brine shrimp (Artemia franciscana) model system reveals that the phenolic compound pyrogallol protects against infection through its prooxidant activity

The phenolic compound pyrogallol is the functional unit of many polyphenols and currently there has been a growing interest in using this compound in human and animal health owing to its health-promoting effects. The biological actions of pyrogallol moiety (and polyphenols) in inducing health benefitting effects have been studied; however, the mechanisms of action remain unclear yet. Here, we aimed at unravelling the underlying mechanism of action behind the protective effects of pyrogallol against bacterial infection by using the gnotobiotically-cultured brine shrimp Artemia franciscana and pathogenic bacteria Vibrio harveyi as host-pathogen model system. The gnotobiotic test system represents an exceptional system for carrying out such studies because it eliminates any possible interference of microbial communities (naturally present in the experimental system) in mechanistic studies and furthermore facilitates the interpretation of the results in terms of a cause effect relationship. We provided clear evidences suggesting that pyrogallol pretreament, at an optimum concentration, induced protective effects in the brine shrimp against V. harveyi infection. By pretreating brine shrimp with pyrogallol in the presence or absence of an antioxidant enzyme mixture (catalase and superoxide dismutase), we showed that the Vibrio-protective effect of the compound was caused by its prooxidant action (e.g. generation of hydrogen peroxide, H2O2). We showed further that generation of prooxidant is linked to the induction of heat shock protein Hsp70, which is involved in eliciting the prophenoloxidase and transglutaminase immune responses. The ability of pyrogallol to induce protective immunity makes it a potential natural protective agent that might be a potential preventive modality for different host-pathogen systems.

Effect of sub-lethal concentration of endosulfan on lipid and fatty acid metabolism of spotted murrel, Channa punctatus

The spotted murrel, Channa punctatuswere exposed to sub-lethal concentration of endosulfan (8.1 microg l(-1)) for 12, 24, 48, 72 and 96 hrto elucidate the impact of pesticide on fatty acid composition of liver and muscle. After endosulfan exposure, fish from each control and experimental tanks were randomly sampled anesthetized, sacrificed and then the liver and muscle were dissected out for lipid and fatty acid (FA) profile. Results showed that total lipid, cholesterol, and triglyceride and FA in liver and muscle, and phospholipid in liver were significantly affected due to pesticide exposure. In liver and muscle tissues, 28.09 and 32.57% reduction of the total lipid, and 42.82 and 49.75% reduction in triglyceride and FAwere observed at the end of 96 hrs of exposure. Reduction of total lipid, triglyceride and FA may be due to their mobilization for energy production to combat stress. In FA, oleic (25.46 to 22.48% in liver and 25.75 to 21.87% in muscle) and linoleic acids (8.04 to 6.83% in liver and 9.88 to 8.09%) were reduced in both the tissues at the end of 96 hr of exposure. It may be concluded that exposure of fish to sub-lethal concentration of endosulfan had influenced the lipid and fatty acid metabolism of Channa punctatus.

Reactive oxygen species generated by a heat shock protein (Hsp) inducing product contributes to Hsp70 production and Hsp70-mediated protective immunity in Artemia franciscana against pathogenic vibrios

The cytoprotective role of heat shock protein (Hsp70) described in a variety of animal disease models, including vibriosis in farmed aquatic animals, suggests that new protective strategies relying upon the use of compounds that selectively turn on Hsp genes could be developed. The product Tex-OE® (hereafter referred to as Hspi), an extract from the skin of the prickly pear fruit, Opuntia ficus indica, was previously shown to trigger Hsp70 synthesis in a non-stressful situation in a variety of animals, including in a gnotobiotically (germ-free) cultured brine shrimp Artemia franciscana model system. This model system offers great potential for carrying out high-throughput, live-animal screens of compounds that have health benefit effects. By using this model system, we aimed to disclose the underlying cause behind the induction of Hsp70 by Hspi in the shrimp host, and to determine whether the product affects the shrimp in inducing resistance towards pathogenic vibrios. We provide unequivocal evidences indicating that during the pretreatment period with Hspi, there is an initial release of reactive oxygen species (hydrogen peroxide and/or superoxide anion), generated by the added product, in the rearing water and associated with the host. The reactive molecules generated are the triggering factors responsible for causing Hsp70 induction within Artemia. We have also shown that Hspi acts prophylactically at an optimum dose regimen to confer protection against pathogenic vibrios. This salutary effect was associated with upregulation of two important immune genes, prophenoloxidase and transglutaminase of the innate immune system. These findings suggest that inducers of stress protein (e.g. Hsp70) are potentially important modulator of immune responses and might be exploited to confer protection to cultured shrimp against Vibrio infection.

Bacillus sp. LT3 improves the survival of gnotobiotic brine shrimp (Artemia franciscana) larvae challenged with Vibrio campbellii by enhancing the innate immune response and by decreasing the activity of shrimp-associated vibrios

Bacteria belonging to the genus Bacillus are amongst the most intensively studied group of bacteria for use as probiotics in aquaculture. However, the exact mechanism of action of these bacteria is often not well described, and the microbiota that are naturally present in cultures of test organisms often compromise the interpretation of the results. The present study aimed to evaluate the putative probiotic effect of Bacillus sp. LT3 in a model system with gnotobiotic brine shrimp Artemia franciscana larvae. The strain significantly increased the survival of brine shrimp larvae challenged with Vibrio campbellii when administered 6h before the challenge. Under these conditions, LT3 was able to colonize the brine shrimp gastrointestinal tract and to decrease the in vivo pathogen activity as indicated by the bioluminescence of the V. campbellii associated with brine shrimp larvae. In order to investigate the effect of the Bacillus strain on the innate immune system of the brine shrimp larvae, prophenoloxidase and transglutaminase mRNA levels were monitored, while heat shock protein 70 mRNA levels were measured as an indicator of physiological stress. Interestingly, 12h after challenge, the prophenoloxidase mRNA level in the larvae pre-treated with LT3 and challenged with V. campbellii was approximately 8-fold higher than in the other treatments. Further, a decreased mRNA level of transglutaminase gene and heat shock protein 70 gene suggested that pretreatment with LT3 results in less stress and tissue damage in the brine shrimp larvae upon V. campbellii challenge. These results indicated that Bacillus sp. LT3 could improve the survival of brine shrimp larvae when challenged with pathogenic V. campbellii, both by decreasing the in vivo activity of the pathogen and by priming the innate immune response through activating the prophenoloxidase system.

Assessing effect of climate on the incidence of dengue in Tamil Nadu

Incidence of dengue is reported to be influenced by climatic factors. The objective of this study is to assess the association of local climate with dengue incidence, in two geographically distinct districts in Tamil Nadu. The study uses climate data, rainfall and mean maximum and minimum temperature to assess its association if any, with dengue incidence in two districts of Tamil Nadu, South India. According to this study while precipitation levels have an effect on dengue incidence in Tamil Nadu, non-climatic factors such as presence of breeding sites, vector control and surveillance are important issues that need to be addressed.

Feeding truncated heat shock protein 70s protect Artemia franciscana against virulent Vibrio campbellii challenge

The 70 kDa heat shock proteins (Hsp70s) are highly conserved in evolution, leading to striking similarities in structure and composition between eukaryotic Hsp70s and their homologs in prokaryotes. The eukaryotic Hsp70 like the DnaK (Escherichia coli equivalent Hsp70) protein, consist of three functionally distinct domains: an N-terminal 44-kDa ATPase portion, an 18-kDa peptide-binding domain and a C-terminal 10-kDa fragment. Previously, the amino acid sequence of eukaryotic (the brine shrimp Artemia franciscana) Hsp70 and DnaK proteins were shown to share a high degree of homology, particularly in the peptide-binding domain (59.6%, the putative innate immunity-activating portion) compared to the N-terminal ATPase (48.8%) and the C-terminal lid domains (19.4%). Next to this remarkable conservation, these proteins have been shown to generate protective immunity in Artemia against pathogenic Vibrio campbellii. This study, aimed to unravel the Vibrio-protective domain of Hsp70s in vivo, demonstrated that gnotobiotically cultured Artemia fed with recombinant C-terminal fragment (containing the conserved peptide binding domain) of Artemia Hsp70 or DnaK protein were well protected against subsequent Vibrio challenge. In addition, the prophenoloxidase (proPO) system, at both mRNA and protein activity levels, was also markedly induced by these truncated proteins, suggesting epitope(s) responsible for priming the proPO system and presumably other immune-related genes, consequently boosting Artemia survival upon challenge with V. campbellii, might be located within this conserved region of the peptide binding domain.

Influence of acclimation temperature on the induction of heat-shock protein 70 in the catfish Horabagrus brachysoma (Günther)

Every organism responds to heat stress by synthesizing a group of evolutionarily conserved proteins called the heat-shock proteins (HSPs) that, by acting as molecular chaperones, protect the cell against the aggregation of denatured proteins and play a significant role in adaptation to temperature. The present study aimed to investigate the critical thermal maxima (CTMax) and the expression of HSP70 in different tissues (gill, brain, muscle and liver) of an endemic catfish Horabagrus brachysoma acclimated at either 20 or 30°C for 30 days. To understand the HSP70 response, fish acclimated to the two temperatures were exposed to preset temperatures (26, 30, 34, 36 and 38°C for 20°C acclimated fish and 32, 34, 36, 38 and 40°C for 30°C acclimated fish) for 2 h, followed by 1 h recovery at their respective acclimation temperatures. The HSP70 levels in the gill, brain, muscle and liver tissues were determined by Western blotting of one-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. A significant (P < 0.05) increase in the CTMax values was observed for fish acclimated at 30°C (41.86 ± 0.39°C) than those acclimated at 20°C (39.13 ± 0.18°C). HSP70 was detected in all the tissues with the highest level in the liver followed by intermediate levels in muscle and brain, and lowest level in gill tissue, irrespective of the acclimation temperatures (20 or 30°C). The HSP70 levels were significantly higher (P < 0.05) in the tissues of fish acclimated at 30°C than those acclimated at 20°C. The mean induction temperature of HSP70 in all the tissues of fish acclimated at either 20 or 30°C was 30 and 34°C, respectively. The optimum temperature for HSP70 induction in all the tissues of fish acclimated at 20°C was 36°C, whereas for fish acclimated at 30°C was 36°C for gill and 38°C for brain, muscle and liver. Decreased levels of HSP70 were noted in all the tissues of fish when exposed to temperatures that exceeded the optimum temperatures for HSP70 inductions. Overall results indicated that acclimation temperature influences both temperature tolerance and induction of HSP70 in H. brachysoma.

Effect of substituting live feed with formulated feed on the reproductive performance and fry survival of Siamese fighting fish, Betta splendens (Regan, 1910)

This study aimed to elucidate the effect of partial or complete replacement of live feed (LF) (Tubifex) with formulated feed (FF) on the reproductive performance of Betta splendens. Three hundred B. splendens fry (average weight 0.19 ± 0.01 g) were equally distributed into five different groups, each with three replicates. They were fed for 105 days with following different diets: control (C)-100% LF; T1-75% LF, 25% FF; T2-50% LF, 50% FF; T3-25% LF, 75% FF, and T4-100% FF. Results showed that the average number of hatched larvae (654 ± 101) and fry survival after 2 weeks of rearing (428 ± 70), after completion of three spawning, were recorded highest in the control group, which was, however, not significantly different from the T1, T2, and T3 groups. At the end of the feeding trial, the highest hatching percentage (90.3%) was registered in the T2 group, which was not significantly different from the control and T1 groups. The T2 group also recorded highest fry survival (65.54%) after completion of three spawning, which was not significantly (P < 0.05) different from the T1 and T3 groups. Control diet contained higher saturated fatty acid (63.23%) than formulated diet (29.80%). In the whole-body tissue, highest level of EPA (0.42%) and DHA (3.13%) were found in the T4 group followed by T3 group. The DHA/EPA ration was recorded highest in the T2 group (10.96%), which did not differ significantly from the T1 and T3 groups. Significant positive correlation was observed between saturated fatty acid levels in fish whole-body tissue and number of hatched larvae (Y = 30.81 × -825.3, R(2) = 0.968) and fry survival after 2 weeks of rearing (Y = 21.38 × -580.9, R(2) = 0.967). Considering all these factors, it can be concluded that the live feed Tubifex can be replaced up to 50% without any adverse effect on the reproductive performance and fry survival of B. splendens.

Acute and chronic effects of endosulfan on the haemato-immunological and histopathological responses of a threatened freshwater fish, spotted murrel, Channa punctatus

Two experiments, one short-term and one long-term, were conducted to elucidate the acute and chronic effects, respectively, of endosulfan exposure on the haemato-immunological and histopathological responses of Channa puncatatus. In the short-term study, fish were exposed to sublethal endosulfan (8.1 μg l(-1)) for 12, 24, 36, 48, 72 and 96 h. In the long-term study, fish were fed with normal diet and simultaneously either exposed to endosulfan (1.2 μg l(-1)) for 90 days or not. Results showed that the ascorbic acid levels in both the liver and the muscle decreased significantly (P < 0.05) by acute and chronic endosulfan exposure. The haemoglobin (Hb) level reduced significantly (P < 0.05) by 15.5% within 12 h of acute endosulfan exposure, further decreased by 25.8% after 24 h of exposure, however, thereafter the values increased and at the end of 72 h returned to normal levels. Almost similar trend was observed for the erythrocyte (RBC) count. The WBC count and the nitroblue tetrazolium (NBT) value showed a general increasing trend with increase in the duration of acute endosulfan exposure. The chronic exposure of C. punctatus to endosulfan significantly (P < 0.05) lowered the Hb level, RBC and WBC counts, NBT reduction value and the plasma parameters such as plasma protein, albumin (A) and globulin (G) compared with that of the control (except for A/G ratio). Endosulfan exposure also severely altered the liver histological structure. Overall results indicated that both short-term acute and long-term chronic endosulfan exposure had a significant impact on the haemato-immunological parameters and tissue histopathology of C. punctatus.

Water soaking and exogenous enzyme treatment of plant-based diets: effect on growth performance, whole-body composition, and digestive enzyme activities of rohu, Labeo rohita (Hamilton), fingerlings

A 2 × 2 × 2 factorial experiment was conducted to delineate the main effect of water soaking of plant ingredients, phytase, cellulase, and their interactions on the growth and digestive enzyme activities of Labeo rohita fingerlings. Two basal diets were prepared using water-soaked (S) or unsoaked (US) plant-based ingredients. Feed of US ingredients was supplemented with phytase (U kg(-1)) and cellulase (%) at the level of 0, 0 (C(us)); 500, 0 (T(1)); 0, 0.2 (T(2)); 500, 0.2 (T(3)), and feed of S ingredients at 0, 0 (C(s)); 500, 0 (T(4)); 0, 0.2 (T(5)), and 500, 0.2 (T(6)), respectively. Three hundred and sixty fingerlings were randomly distributed into eight treatments, each with three replicates. Soaking of the ingredients for 24 h significantly reduced the tannin content. However, feeding of S diets did not improve the fish growth. Highest performance was recorded in the T(3) group. A significant interaction between dietary phytase and cellulase was observed for apparent net protein utilization. Tissue crude protein, ether extract, and ash content of the fingerlings were observed highest in the T(3) group. Activities of amylase, protease, and lipase were recorded highest in the T(3) group. Results suggested that soaking of plant-based ingredients reduces tannin content; however, growth and digestive enzyme activities of group fed soaked diet were not improved, possibly due to leaching of soluble nutrients. Probably, a shorter duration soaking may be effective in reducing tannin content and avoiding nutrients leaching.

Priming the prophenoloxidase system of Artemia franciscana by heat shock proteins protects against Vibrio campbellii challenge

Like other invertebrates, the brine shrimp Artemia franciscana relies solely on innate immunity, which by definition lacks adaptive characteristics, to combat against invading pathogens. One of the innate mechanisms is melanisation of bacteria mediated by the activation of the prophenoloxidase (proPO) system. The 70 kDa heat shock proteins (Hsp70) derived from either prokaryote (Escherichia coli) or eukaryote (Artemia), well conserved and immune-dominant molecules, protect Artemia against Vibrio campbellii. However, the molecular mechanisms by which these proteins protect Artemia against Vibrio campbellii infection are unknown. Here we demonstrated that feeding gnotobiotically grown Artemia with either Artemia Hsp70 or the E. coli Hsp70 equivalent DnaK, each overproduced in E. coli, followed by V. campbellii challenge enhanced the proPO system, at both mRNA and protein activity levels. Additionally, the Artemia fed with these proteins survived well in a Vibrio challenge assay. These results indicated that Hsp70s derived from either prokaryotic or eukaryotic sources generate protective immunity in the crustacean Artemia against V. campbellii infection by priming the proPO system. This is apparently the first in vivo report on priming activity of Hsp70 in an invertebrate.

Efficacy of heterologous and homologous heat shock protein 70s as protective agents to Artemia franciscana challenged with Vibrio campbellii

The Hsp70 class of heat shock proteins (Hsps) has been implicated at multiple points in the immune response of both vertebrates and invertebrates. This class of chaperones is highly conserved in both sequence and structure, from prokaryotes to higher eukaryotes. In view of their high degree of homology, it was assumed that these Hsp70 proteins derived either from the prokaryotes or eukaryotes would have similar functions, especially in relation to their protective ability in a challenge assay. To verify this, we compared two evolutionary diverse Hsp70s, Artemia Hsp70 and Escherichia coli Hsp70 equivalent DnaK (each overproduced in E.coli), for their ability to protect Artemia against Vibrio challenge. Results showed that Artemia fed with E. coli producing Artemia Hsp70 or DnaK proteins, as assessed by immune-probing in western blots, survived better in a Vibrio challenge assay. The observed effects could be due to enhancement of the Artemia immune system as phenoloxidase activity was found to be increased by these proteins. These two Hsp70 proteins exhibit a high degree of homology, particularly in the peptide-binding domain (the putative innate immunity-activating portion) with 59.6% identity, indicating that the observed protective capacity of homologous or heterologous Hsp70 proteins might reside within this peptide-binding domain.

Biochemical and histological changes in the brain tissue of spotted murrel, Channa punctatus (Bloch), exposed to endosulfan

The present experiment was conducted to establish the relationship between selected physiological parameters and histological responses of Channa punctatus brain tissue to endosulfan exposure. The fish (35.6 +/- 0.7 g) was exposed to sublethal endosulfan concentration (8.1 microg l(-1)) for a period of 12, 24, 36, 48, 72, and 96 h. Results showed that brain glucose level increased significantly after exposure, indicating a hyperglycemic state of the fish. Brain vitamin C level decreased with an increase in the exposure time. Acetylcholine esterase and adenosine triphosphatase enzyme activities also showed a significant reduction upon endosulfan exposure. Brain histopathology after 96 h endosulfan exposure showed that the apical lobe of the cerebrum (the only portion examined) had mild necrosis. Focal area of gliosis could be seen in the cerebrum, which were absent in the control fish. The results indicate that exposure of sublethal concentration of endosulfan to C. punctatus may have a direct effect on the histology of the fish's brain tissue, thereby affecting its metabolism.

Modulation of key enzymes of glycolysis, gluconeogenesis, amino acid catabolism, and TCA cycle of the tropical freshwater fish Labeo rohita fed gelatinized and non-gelatinized starch diet

A 60-day experiment was conducted to study the effect of dietary gelatinized (G) and non-gelatinized (NG) starch on the key metabolic enzymes of glycolysis (hexokinase, glucokinase, pyruvate kinase, and lactate dehydrogenase), gluconeogenesis (glucose-6 phosphatase and fructose-1,6 bisphosphatase), protein metabolism (aspartate amino transferase and alanine amino transferase), and TCA cycle (malate dehydrogenase) in Labeo rohita juveniles. In the analysis, 234 juveniles (2.53 +/- 0.04 g) were randomly distributed into six treatment groups each with three replicates. Six semi-purified diets containing NG and G cornstarch, each at six levels of inclusion (0, 20, 40, 60, 80, and 100) were prepared viz., T1 (100% NG, 0% G starch), T2 (80% NG, 20% G starch), T3 (60% NG, 40% G starch), T4 (40% NG, 60% G starch), T5 (20% NG, 80% G starch), and T6 (0% NG, 100% G starch). Dietary G:NG starch ratio had a significant (P < 0.05) effect on the glycolytic enzymes, the highest activities were observed in the T6 group and lowest in the T1 group. On the contrary, the gluconeogenic enzymes, the glucose-6-phosphatase and fructose-1,6 bisphosphatase activities in the organs, liver and kidney were recorded highest in the T1 group and lowest in the T6 group. The liver aspartate amino transferase activity showed an increasing trend with the decrease in the dietary G level. However, the muscle aspartate amino transferase activity was not significantly (P > 0.05) influenced by the type of dietary starch. The alanine amino transferase activity in both liver and muscle showed an increasing trend with the decrease in the dietary G level. The liver and muscle malate dehydrogenase activities were lowest in the T6 group and highest in the T1 group. Results suggest that NG (100%) starch diet significantly induced more the enzyme activities of amino acid metabolism, gluconeogenesis, and TCA cycle, whereas partial or total replacement of raw starch by gelatinized starch increased the glycolytic enzyme activity.