Partial and total replacement of fish meal by marine microalga Spirulina platensis in the diet of Pacific white shrimp Litopenaeus vannamei: Growth,digestive enzyme activities,fatty acid composition and responses to ammonia and hypoxia stress

In the this study, we evaluated the effect of replacement of fish meal by a marine microalgae Spirulina platensis on growth, digestive enzyme activities, fatty acid composition and responses to ammonia and hypoxia stress in Pacific white shrimp Litopenaeus vannamei (2.6 ± 0.2 g). Experimental diets contained S. platensis at 0%, 25%, 50%, 75% and 100% replacement levels. After 8 weeks of feeding trial, growth parameters and proximate body composition were not significantly different among treatments (p > .05). Amylase and lipase activities did not show any significant differences between control group and other experimental diets (p > .05), while activities of trypsin and chymotrypsin were significantly higher in shrimp fed diet with 50% substitution of microalgae compared to control group. Fatty acid contents, particularly polyunsaturated fatty acids (PUFAs) including arachidonic acid (ARA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), were significantly higher in control diet compared to other experimental diets. On the contrary, the majority of fatty acids including the contents of PUFAs in the whole body of L. vannamei fed with different levels of S. platensis were significantly higher compared to those of control group. After 48‐h exposure to ammonia, survival per cent was not statistically different between all groups (p > .05), but in hypoxia challenge, the survival per cent of control group was significantly less than that of treatments fed diets contained S. platensis (p < .05). Altogether, o ur results demonstrated the effectiveness of S. platensis as a reliable protein source for substitution of fish meal in shrimp aquaculture.     

Effect of catecholamine stress hormones (dopamine and norepinephrine) on growth,swimming motility,biofilm formation and virulence factors of Yersinia ruckeri in vitro and an in vivo evaluation in rainbow trout

In this study, we evaluated the impact of the catecholamines on growth, swimming motility, biofilm formation and some virulence factors activities of pathogenic Yersinia ruckeri. Norepinephrine and dopamine (at 100 µM) significantly increased the growth of Y. ruckeri in culture media containing serum. An increase in swimming motility of the pathogen was found following the exposure to the hormones; however, no effect was seen on caseinase, phospholipase and haemolysin productions. Further, antagonists for the catecholamine receptors were observed to block some of the influences of the catecholamines. Indeed, the effects of catecholamines were inhibited by chlorpromazine (the dopaminergic receptor antagonist) for dopamine, labetalol (α‐and β‐adrenergic receptor antagonist) and phenoxybenzamine (the α‐adrenergic receptor antagonist) for norepinephrine, but propranolol (the β‐adrenergic receptor antagonist) showed no effect. Pretreatment of Y. ruckeri with the catecholamines resulted in a significant enhancement of its virulence towards rainbow trout and the antagonists could neutralize the effect of the stress hormones in vivo. In summary, our results show that the catecholamines increase the virulence of Y. ruckeri which is pathogenic to trout through increasing the motility, biofilm formation and growth.     

Dual-mode adsorption of cochineal natural dye on wool fibers: Kinetic,equilibrium, and thermodynamic studies

The dual-mode adsorption model was used to investigate the adsorption behavior of cochineal natural dye on wool fibers. Kinetic, thermodynamic, and equilibrium characteristics were investigated in terms of the adsorption isotherm, affinity, enthalpy and entropy changes, dyeing rate, diffusion coefficient, and activation energy of dye diffusion. The results revealed the prominent role of dyeing pH in determination of dyeing mechanism and dye adsorption isotherm type. At pH 4, dual Langmuir-Nernst model with the highest correlation coefficient was found as the most appropriate isotherm model to describe the adsorption behavior of cochineal onto wool fibers while at pH 6, the adsorption isotherm was the Nernst type. Cochineal adsorption onto wool was exothermic which resulted in progressive fall in affinity and equilibrium dye up-take values with increasing temperature. Moreover, dyeing rate steadily increased with temperature. At pH 4, affinity, dyeing rate, and diffusion coefficient demonstrated higher values compared to pH 6 whereas enthalpy and entropy changes, and activation energy showed lower values. Additionally, negative value for activation energy was obtained at pH 6. The results are deliberated based on the different possible interactions between cochineal dye and wool fiber.     

Helicobacter pylori SabA adhesin in persistent infection and chronic inflammation

Helicobacter pylori adherence in the human gastric mucosa involves specific bacterial adhesins and cognate host receptors. Here, we identify sialyl-dimeric-Lewis x glycosphingolipid as a receptor for H. pylori and show that H. pylori infection induced formation of sialyl-Lewis x antigens in gastric epithelium in humans and in a Rhesus monkey. The corresponding sialic acid-binding adhesin (SabA) was isolated with the "retagging" method, and the underlying sabA gene (JHP662/HP0725) was identified. The ability of many H. pylori strains to adhere to sialylated glycoconjugates expressed during chronic inflammation might thus contribute to virulence and the extraordinary chronicity of H. pylori infection.     

Dietary fat content and feed supply influence growth and body composition in juvenile beluga sturgeon (Huso huso)

This study is to evaluate the impacts of two levels of fat on the fish growth, feed intake, and compositions of muscle, liver, and viscera on the juvenile Huso huso. There were four treatments: two experimental diets (high-fat: 30% and low-fat: 15%) and two feeding levels (100 or 60% of satiation). The treatments were assigned to 16 tanks each with 15 fish, with four replicates for each treatment. Beluga sturgeon juveniles with an initial weight of 61.3?±?4.4?g were reared for 3?months. Increasing fat content of the diets resulted in an increased final weight (621.8 vs. 467.5?g for high-fat and low-fat diets, respectively, at 100% feeding level; p?<?0.01), but had no impact on feed conversion rate (FCR; p?>?0.05). Total feed intake was increased by the use of high-fat diet (487.8 vs. 365.0?g for high-fat and low-fat diets, respectively, at 100% feeding level; p?<?0.01). Results also showed no interactions between fat level of the diets and feeding level in final weight and FCR. Beluga sturgeon muscle and liver fed high-fat diets contained higher fat than those fed low-fat diets (186.5 and 329.6 vs. 144.1 and 261.9?g?kg^?1 for high-fat and low-fat diets, respectively, at 100% feeding level; p?<?0.01), and feeding levels did not change protein content of the examined organs. In conclusion, beluga sturgeon shows an enhanced growth on high-fat diet, and feed intake does not reduce by the use of high-fat diets.     

Effect of natural neosporosis on bull sperm quality

Neospora is one of the protozoans that can infect the male and female’s reproduction system. Despite the existence of N. caninum in the genitalia, its effect on sperm characteristics was not studied yet. Therefore, the aim of this study was to investigate the influence of natural neosporosis on the sperm parameters of bulls. Using 30 bulls with neosporosis diagnosed by modified agglutination test and enzyme-linked immunosorbent assay (ELISA) and 15 healthy bulls, some sperm parameters such as sperm concentration, viability, motility, and morphology were studied and compared. Also, the activity of super oxide dismutase (SOD), glutathione peroxidase (GPX), and malondialdehyde (MDA) level as the biomarker of lipid peroxidation was investigated. Results showed that sperm concentration, viability, and motility were significantly lower in bulls with neosporosis in the present study. There were no significant differences in activities of SOD and MDA level but GPX activity was significantly increased in infected bulls.     

Bipolar membrane electroacidification of demineralized skim milk.

The aim of this study was to evaluate the effect of decreasing the mineral content of skim milk by electrodialysis (ED) prior to electroacidification with bipolar membrane (BMEA) on the performance of the process, the chemical composition, and the physicochemical and functional properties of the isolates produced. ED used to demineralize the skim milk solution was very efficient. However, the electroacidification parameters were influenced by the demineralization level of the skim milk solution: the energy efficiency was decreased with an increase in demineralization, but it was still possible to perform BMEA at a very low conductivity level. Moreover, the isolates produced by BMEA after electrodialysis demineralization at different rates showed similar chemical composition, except on potassium and lactose contents for 75% demineralized isolate. These isolates, except on protein load for 75% demineralization rate, showed similar physicochemical and functional properties, whatever the demineralization rate.     

Crystallization of PVDF in graphene-filled electrospun PVDF/PMMA nanofibers processed at three different conditions

In this study, the morphology and crystal polymorphism of electrospun blend nanocomposite of graphene filled-polyvinylidene fluoride (PVDF)/poly(methyl methacrylate) (PMMA) nanofibers were investigated. The preparation of the nanofibers was carried out by synthesis of PMMA/graphene as a masterbatch through in-situ polymerization, and then followed by compounding with PVDF solution in the different ratios. The process of electrospinning was done at three selective conditions of temperature, moist and ordinary environment. Crystallinity, morphology and thermal properties of nanofibers were characterized by X-ray diffraction spectroscopy (XRD), differential scanning calorimetric (DSC), Transmittance Electron Microscopy (TEM), Thermogravimetric Analyses (TGA), and Field Emission Scanning Electron Microscopic (FE-SEM). The enhancement of β crystal formation in the electrospun graphene-filled blend nanofibers was confirmed by XRD and DSC results. This can be ascribed by the benefits of solution casting, mechanical stretching, high electric field, PMMA interactions and graphene restrictions, altogether in one simple process. Also, presence of water molecules during the electrospinning causes the orientation of fluorine atoms in PVDF due to polar-polar interactions which enhance the polar conformation even in the pure PVDF nanofibers.     

Relationship among vegetative growth and nutrient elements in the scion of different Persian lime accessions and its effect on WBDL phytoplasma

Journal of Plant Diseases and Protection - Nutrient elements have a significant role in plant physiology and metabolism, and the concentration of nutrients in the plant depends on plants genetic...