Showing papers by "Serampore College published in 2011"

Application of phytochemicals as immunostimulant, antipathogenic and antistress agents in finfish culture

Abstract: Phytochemicals such as alkaloids, flavonoids, pigments, phenolics, terpenoids, steroids and essential oils are a large group of plant-derived compounds commonly found in diets high in fruits, vegetables, beans and cereals. Plant remedies are closely linked to the maintenance of good health in the cultural heritage of many countries. Despite the potential benefits to health and performance as noted in various terrestrial animals, the use of phytochemicals in fish farming has rarely been investigated. Fish culture is under pressure to decrease the use of synthetic antibiotics and chemotherapeutics because of the risk caused to humans by chemical residues in food and by antibiotic resistance being passed on to human pathogens. Consequently, efforts are being made to exploit plants, plant extracts or natural plant compounds as potential alternatives to synthetic chemicals for the stimulation of immune responses and disease resistance in fish. The phytochemicals contained in herbs may enhance the innate immune system and possess antimicrobial capabilities that may be of immense use in fish culture without causing any environmental and/or hazardous problems. Most phytochemicals are redox active molecules that have anti-oxidant characteristics that may improve the general physiological condition of fish. This review discusses the results emanating from different studies related to the in vivo application of plants and/or phytochemicals in fish in relation to immunostimulation, antipathogenic and antistress activities. Special emphasis is given to the use of Chinese and Indian herbs as immunostimulants in different finfish species during culture and as antibacterial agents against Aeromonas hydrophila.

Heat stress-induced hepatotoxicity and its prevention by resveratrol in rats.

Abstract: The high ambient temperature beyond the range of comfort zone or thermoneutral zone causes environmental heat stress (HST). It causes serious physiological dysfunction that may result in heat-related diseases and even death. The underlying mechanism in the pathogenesis of hepatic dysfunction following hyperthermic challenge and the possible involvement of oxidative stress to induce oxidative deterioration of liver functions in adult rats are investigated in this study. Cellular damage was assessed in terms of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and histology of liver. The effect of hyperthermia in altering the oxidative stress was evaluated on the basis of its influence on hepatic lipid peroxidation and antioxidant status-superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activity. The current study demonstrated that HST is associated with a complex set of integrated alterations in liver, time-dependent rise in oxidative stress followed by distinct pattern of liver injury in animals. Heat-induced hepatotoxicity was assessed by increased lipid peroxidation, depletion of antioxidant enzyme activities such as SOD, CAT, GPx and tissue damages revealed by hepatic vacuolization, and widespread necrosis. The study also revealed that pretreatment with resveratrol resulted in normalizing these parameters appreciably, emphasizing the therapeutic potentials of this polyphenol. Taken together, the results suggest that an increase in free radical formation relative to loss of the antioxidant defense system during heat stress may render liver more susceptible to oxidative damage, leading to their functional inactivation. However, resveratrol supplementation can be an effective antidote in the treatment of HST-induced malfunction.

Dielectric and impedance spectroscopy study of Ba 0.8 Bi 2.133 Nb 1.6 Ta 0.4 O 9 ferroelectric ceramics, prepared by chemical route

Abstract: Nanocrystalline ceramic powder of Ba0.8Bi2.133Nb1.6Ta0.4O9 was synthesized by chemical precursor decomposition method. The single-phase formation of the compound was confirmed using an X-ray diffraction technique and was found to be a tetragonal phase at room temperature. Average crystallite size and particle size were found to be 41 and 48.5 nm, which were analyzed through XRD and TEM respectively. The dielectric constant and tangent loss were measured in the frequency range 1 kHz–1 MHz after sintering the sample at 900 °C for 4 h. The polarization behavior was studied at an applied voltage of 6.2 kV/cm. Electrical properties of the material were investigated using complex impedance spectroscopy (CIS) technique, which revealed the presence of both grain and grain-boundary effects in the materials, which is also evidenced from the scanning electron microscope image. Grain conductivity indicated Arrhenius-type thermally activated process. AC conductivity spectrum obeys Jonscher’s universal power law. The electric modulus analysis suggests the possibility of hopping mechanism for electrical processes in the system with a non-debye type relaxation, which is supported by the impedance data.

Self assembled tetranuclear Cu4(II), Ni4(II) [2 × 2] square grids and a dicopper(II) complex of heterocycle based polytopic ligands - Magnetic studies

Abstract: The ditopic ligand PyPzOAP (N-[(Z)-amino(pyridin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid) and the polytopic ligand 2-PzCAP (N′3,N′5-bis[(1E)-1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3,5-dicarbohydrazide) were synthesized in situ by condensation of methyl imino picolinate with 5-methyl-1-(2-pyridyl) pyrazole-3-carbohydrazide and 2-acetyl pyridine with pyrazole-3,5-dicarbohydrazide respectively. The ligands PyPzOAP and PzOAP (reported earlier, Dalton Trans., 2007, 1229) self-assemble to form homoleptic [2 × 2] tetranuclear M4 (M = Cu(II) and Ni(II)) square grids structures [Cu4(PyPzOAP)4](NO3)4 (1), [Cu4(PzOAP)4](ClO4)4 (2) and [Ni4(PyPzOAP)4](NO3)4·8H2O·2CH3CN (3). While the ligand 2-PzCAP forms a dicopper(II) complex [Cu2(2-PzCAP)(OH)(NO3)(H2O)](NO3)·2H2O (4). The complex 1 is a perfect square grid (a = 4.201 A), whereas, 2 and 3 are almost square grids. All these compounds have been characterized by X-ray structural analyses and variable temperature magnetic susceptibility measurements. EPR studies have also been carried out for complexes 1, 2 and 4. In the Cu4 grid (1), all the Cu(II) centers are in a distorted octahedral environment with N4O2 chromophore, while, in complex 2, all four Cu(II) centers have a square pyramidal environment with N3O2 chromophore. In complex 3, all four Ni(II) centers have distorted octahedral geometry with N4O2 chromophore. In compound 4, the Cu(II) centers are in square pyramidal environment with N3O2 chromophore. The magnetic properties of compounds 1 and 2 show the presence of intramolecular ferromagnetic exchange interaction (J = 5.88 cm−1 for 1 and 4.78 cm−1 for 2). The complex 3 shows weak intramolecular antiferromagnetic interaction (J = −4.02 cm−1). While, complex 4, shows strong antiferromagnetic behavior (J = −443 cm−1).

Increased androgen receptor expression in muscle tissue contributing to growth increase in androgen-treated Nile tilapia

Abstract: The aim of this study was to investigate the molecular mechanism behind androgen-induced sex reversal and growth increase in Nile tilapia. Three-day-old mixed-sex tilapia juveniles were treated with differential dose (0, 5, 10, 20, 30 mg/kg diet) and duration (0, 15, 30, 45, 60 days) regimes of 17α-methyltestosterone. Treatment regimes 10, 20, 30 mg/kg-30, 45, 60 days showed ~95% males, while 0 mg/kg-0 days (control) showed ~50% males (P < 0.01). Next, tilapia was cultured for 6 months in cistern and pond culture systems with 17α-methyltestosterone-treated diet (10 mg/kg) for three different durations: 0 days (control), 30 days (30-day-treated), and 180 days (throughout-treated). Fish in pond culture showed significantly higher (P < 0.05) final weight compared with tilapia in cistern culture (235.76, 156.82 g, respectively). Both 30-day-treated and throughout-treated fish showed significantly higher (P < 0.05) final weight, length, daily weight gain, specific growth rate, and muscle protein content compared with control fish. The androgen receptor β mRNA and protein expression levels in both 30-day-treated and throughout-treated fish were significantly higher (~twofolds, P < 0.05) compared with hormone-untreated control males. However, there was not much difference for all these parameters among the two hormone-treated groups. This higher growth probably results from an androgen-induced increased ‘androgen-androgen receptor’ mediated anabolic pathway. Serum testosterone concentration of 30-day-treated fish after 6 months was similar to that of control males (0.9 ng/ml). Moreover, culture of 17α-methyltestosterone-treated monosex tilapia was found beneficial than hormone-untreated mixed-sex tilapia culture for maintenance of natural fish diversity in indigenous water bodies.

A novel synthesis of FeNbO 4 nanorod by hydrothermal process

Abstract: This study reports a facile, gram-scale synthesis of FeNbO4 nanorods via hydrothermal route, using iron nitrate [Fe(NO3)3] and niobium tartarate (Nb tartarate) in presence of potassium peroxosulfate. The formation of single phase, polycrystalline orthorhombic structure of FeNbO4 was confirmed by the careful analysis of the X-ray diffraction (XRD) pattern. The average crystallite size, calculated using a few XRD peaks, was found to be 12.8 nm. As indicated by transmission electron microscopy (TEM) and field emission scanning electron microscopy, the average length and diameter of the rods were found to be only 25 × 7 nm and 47 × 14 nm, respectively. The selected area electron diffraction and high-resolution transmission electron microscopy (HRTEM) data of the single rod implied that FeNbO4 nanorods were polycrystalline in nature and grew up along the c-axis. HRTEM also revealed that the fringes are equidistant with a lattice separation of 0.91 Ǻ, which corresponded to the (111) plane of the FeNbO4 crystal. Elemental composition of the nanorods was confirmed using electron dispersive X-ray spectroscopy analysis while binding state of the surface was intervened through X-ray photoelectron spectroscopy. Mechanistic investigations suggested that potassium peroxosulfate played a crucial role in the unidirectional growth of particles. The synthetic method is simple, amenable to scale up and contributes a new tool box for the development of FeNbO4-based one-dimensional (1D) structures that appears to be more promising for a myriad of applications, compared to their 3D counterparts.

Influence of substitution on dielectric diffuseness in Ba(1-x)Bi(2+2x/3)Nb2O9 ceramics prepared by chemical precursor decomposition method

Abstract: Barium bismuth niobate, Ba(1-x)Bi(2+2x/3)Nb2O9 (BBN with x = 0.0, 0.1, 0.2, 0.3, 0.4) ceramic powders in the nanometer range were prepared by chemical precursor decomposition method (CPD). The single phase layered perovskite was prepared throughout the composition range studied. No intermediate phase was found during heat treatment at and above 600°C. The crystallite size and the particle size, obtained from XRD and TEM respectively, were in the range of 15–30 nm. The addition of Bi2O3 substantially improved the sinterability associated with high density (96%) which was otherwise difficult in the case of pure BaBi2Nb2O9 (BBN x = 0.0). The sintering was done at 900°C for 4 h. The relative permittivity of BBN ceramics at both room temperature and in the vicinity of the temperature of maximum permittivity (Tm) has increased significantly with increase in bismuth content and loss is also decreased to a certain level of bismuth doping. Tm increased with increase in Bi2O3. The diffuseness (γ) in the phase transition was found to increase from 1.54 to 1.98 with the increase in Ba2+ substitution level from x = 0.0 to x = 0.3.

Association of major earthquakes (magnitude ≥ 6 richter scale) with geomagnetic activity index kp during the period 2001-2007

Abstract: A critical study of variation of geomagnetic activity index Kp for the period 2001-2007 have been made and its close association with major earthquakes (magnitude >= 6 Richter scale) is presented. From statistical analysis it is confirmed that when Kp touches 0 or 0+ values, major earthquakes take place within 48 hours. This is also explained considering the motion of the molten metal inside the outer core of earth.