Shrimp lectin–conjugated copper sulfide nanoparticles enhance immune response and gene expression in Etroplus suratensis infected with Aeromonas hydrophila

Aquaculture International - Lectins are hemagglutinating glycoproteins which act as pathogen recognition receptors that can bind to the pathogen-associated molecular patterns. Shrimp lectin...     

Antimicrobial activity of bioactive compounds and leaf extracts in Jatropha tanjorensis

Objectives

Jatropha tanjorensis was investigated scientifically to generate evidence for the efficacies reported in traditional systems and the results are given here.

Methods

Different concentrations of the solvent extracts of leaves and four isolated compounds were tested against human pathogenic microorganisms such as gram-positive bacteria of Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermis, gram-negative bacteria of Aeromonas hydrophila, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Proteus vulgaris, Salmonella paratyphi, Salmonella paratyphi A, Vibrio alcaligenes, Vibrio cholerae and fungi of Aspergillus fumigatus, Candida albicans, Microsporum gypseum and Trichophyton rubrum by agar-well diffusion and disk diffusion methods.

Results

In agar-well diffusion method, maximum activity was recorded in a concentration-dependent manner. The extracts recorded activity against bacteria such as 17–26, 15–25 and 13–24 mm to methanol extract and 15–24, 14–23 and 12–22 mm to chloroform extract at 50, 25 and 12.5 mg/ml respectively and fungi such as 9–15 mm to A. fumigatus and 5–16 mm to T. rubrum. Maximum activity was 30–46, 27–43 and 17–40 mm to friedelin and 23–46, 28–44 and 18–41 mm to R (+) 4-hydroxy-2-pyrrolidinone against bacteria and 12–37, 8–34 and 31–33 mm to friedelin and 12–40, 11–35 and 10–33 mm to R (+) 4-hydroxy-2-pyrrolidinone against fungi at 10, 5 and 2.5 mg respectively.

Conclusions

The present study concludes that friedelin, β-amyrin, stigmasterol and R (+) 4-hydroxy-2-pyrrolidinone present in the methanol extract could be responsible for the broad spectrum of antimicrobial activity and provide scientific evidence.     

Quantifying dietary phosphorus requirement of fish – a meta‐analytic approach

A meta‐analysis of available data on dose response to dietary phosphorus (P) in fish from over 70 feeding trials reported in 64 published studies covering over 40 species of fish was performed. Broken‐line regression was used to model the data sets. The meta‐analysis showed that estimated minimal dietary P level varies with the response criterion and that estimates should preferably be expressed in terms of available P than in terms of total P. Estimates based on whole‐body P concentration (4.7 g available P kg^?1 dry matter, DM) or vertebral P (5.2 g available P kg^?1 DM) were greater than that for maximizing somatic weight gain (WG) (3.5 g available P kg^?1 DM) or plasma P concentration (2.8 g available P kg^?1 DM). P content of fish varies linearly with body mass (3.6 g kg^?1 live weight). Use of ingredients rich in P or of diets with high basal P content or high levels of water P concentration can affect the estimations. Among the different response criteria tested, WG was found to be the most reliable and whole‐body P concentration to be the most stringent criterion to estimate P requirement of a given fish species. Expressing available P requirement as g P per unit DM or digestible energy (DE) in the diet was equally effective, but expressing in terms of g P intake per kg BW^0.8 per day would be more precise.     

Optimum selenium levels in diets high in plant‐based feedstuffs for gilthead sea bream (Sparus aurata) fingerlings

Substitution of marine ingredients (FM‐FO) by plant protein and oil sources can modify selenium (Se) levels in feeds. Se plays an important role in the antioxidative defence by forming part of selenoproteins. Se requirements of gilthead sea bream are not accurately determined; therefore, this study was conducted to define Se supplementation levels in low FM‐FO practical diets for sea bream fingerlings. A plant‐based diet containing 0.45 mg Se/kg diet was used as the basal diet. Four other diets were supplemented to contain 0.68, 0.86, 1.00 or 1.70 mg Se/kg diet, supplied as sodium selenite. Sea bream, weighing 12.6 ± 1.4 g, were distributed in triplicate groups per diet and fed for 42 days. Se supplementation up to 1.00 mg Se/kg significantly improved the growth of sea bream, whereas further increase up to 1.70 mg Se/kg diet reduced growth. The results of this study suggest that the optimum dietary levels of sodium selenite in diets with low FM‐FO with basal levels of 0.45 mg Se/kg are around 0.94 mg Se/kg to promote growth of gilthead sea bream juveniles. On the contrary, dietary levels of 1.70 mg Se/kg were found to be excessive and caused growth reduction, increased catalase expression and hydropic degeneration in the liver.     

A novel murrel Channa striatus mitochondrial manganese superoxide dismutase: gene silencing,SOD activity,superoxide anion production and expression

We have reported the molecular characterization including gene silencing, superoxide activity, superoxide anion production, gene expression and molecular characterization of a mitochondrial manganese superoxide dismutase (mMnSOD) from striped murrel Channa striatus (named as CsmMnSOD). The CsmMnSOD polypeptide contains 225 amino acids with a molecular weight of 25 kDa and a theoretical isoelectric point of 8.3. In the N-terminal region, CsmMnSOD carries a mitochondrial targeting sequence and a superoxide dismutases (SOD) Fe domain (28–109), and in C-terminal region, it carries another SOD Fe domain (114–220). The CsmMnSOD protein sequence shared significant similarity with its homolog of MnSOD from rock bream Oplegnathus fasciatus (96 %). The phylogenetic analysis showed that the CsmMnSOD fell in the clade of fish mMnSOD group. The monomeric structure of CsmMnSOD possesses 9 α-helices (52.4 %), 3 β-sheets (8.8 %) and 38.8 % random coils. The highest gene expression was noticed in liver, and its expression was inducted with fungal (Aphanomyces invadans) and bacterial (Aeromonas hydrophila) infections. The gene silencing results show that the fish that received dsRNA exhibited significant (P < 0.05) changes in expression when compared to their non-injected and fish physiological saline-injected controls. The SOD activity shows that the activity increases with the spread of infection and decreases once the molecule controls the pathogen. The capacity of superoxide anion production was determined by calculating the granular blood cell count during infection in murrel. It shows that the infection influenced the superoxide radical production which plays a major role in killing the pathogens. Overall, this study indicated the defense potentiality of CsmMnSOD; however, further research is necessary to explore its capability at protein level.     

Evaluating dietary supply of microminerals as a premix in a complete plant ingredient‐based diet to juvenile rainbow trout (Oncorhynchus mykiss)

Two basal diets M0 and V0 were formulated with marine and plant based ingredient composition. Seven experimental diets were prepared from the two basal diets namely M0, M100, V0, V30, V60, V100 and V150 by incorporating different levels of a micromineral premix (Cu, Fe, Mn, Se and Zn). Triplicate groups of rainbow trout (initial weight: 20 g) reared at 17°C were fed one of each diet to apparent visual satiation over 12 weeks. Among the V diet fed fish, growth and feed intake exhibited maximal response at V60 level of premix inclusion; Apparent availability coefficient of Fe, Cu and Zn decreased linearly with increasing level of premix whereas apparent availability coefficient of Mn and Se was unaffected. The available dietary concentration in basal V0 diet was for Fe, 20.6; Cu, 2.8; Mn, 6.5; Zn, 17.3 and Se, 0.195 (in mg/kg DM) and in the M0 diet for Fe, 63.3; Cu, 5.2; Mn, 2.9; Zn, 35.2 and Se, 0.87 (in mg/kg DM). In reference to NRC (Nutrient requirements of fish and shrimp. Washington, DC: National Research Council, The National Academies Press, 2011) recommendations, the V0 basal diet accounted for 34.3%, 92.9%, 53.9%, 115% and 130.2% and the contribution from M0 diet for 105.5%, 173.3%, 24.2%, 234.7% and 580% of the minimal dietary inclusion levels of Fe, Cu, Mn, Zn and Se to rainbow trout, respectively. However, data on whole body mineral contents showed that normal levels were maintained only for Cu and Mn through supply from basal V0 diet. For Zn and Se, available supply even from the highest supplemented diet (V150) was not sufficient to maintain normal body mineral levels of rainbow trout in the present study. On the whole, optimal dietary inclusion levels of microminerals are altered while using fishmeal‐free diets for rainbow trout.     

Anti-oxidative and immuno-hematological status of Tilapia (Oreochromis mossambicus) during acute toxicity test of endosulfan

Endosulfan is an organochlorine pesticide widely used in agriculture and hence finds its way into natural water bodies, thus affecting aquatic life. The purpose of this study was to determine LC₅₀ of endosulfan (99%; α:β ratio of 7:3) in Tilapia, Oreochromis mossambicus and study its effect on anti-oxidative enzymes (superoxide dismutase, glutathione-S-transferase and catalase), immuno-hematological profile (RBC, WBC, Hb, serum protein, albumin-A, globulin-G, A/G ratio, phygocytic activity as indicated by nitroblue tetrazolium reduction, serum cortisol and serum lipid peroxidation) and neurotransmitter acetylcholine esterase enzyme activity. The LC₅₀ value at 96 h and 95% confidence limit for tilapia (46.78 g) was estimated as 3.6 μg/L. Activities of anti-oxidative enzymes, immuno-hematological profile, blood glucose and neurotransmitter activity was significantly influenced (P < 0.01) in dose dependent manner. This was reflected in the behavior of fish that was altered from normal during acute toxicity.