Showing papers by "Annamalai University published in 2009"

Antioxidant defense responses: physiological plasticity in higher plants under abiotic constraints

Abstract: Environmental stresses (salinity, drought, heat/cold, light and other hostile conditions) may trigger in plants oxidative stress, generating the formation of reactive oxygen species (ROS). These species are partially reduced or activated derivatives of oxygen, comprising both free radical $$ ( {\text{O}}_{2}^{\cdot - } ,{\text{OH}} \cdot , {\text{OH}}_{ 2} \cdot ) $$ and non-radical (H2O2) forms, leading to cellular damage, metabolic disorders and senescence processes. In order to overcome oxidative stress, plants have developed two main antioxidants defense mechanisms that can be classified as non-enzymatic and enzymatic systems. The first class (non-enzymatic) consists of small molecules such as vitamin (A, C and E), glutathione, carotenoids and phenolics that can react directly with the ROS by scavenging them. Second class is represented by enzymes among them superoxide dismutase, peroxidase and catalase which have the capacity to eliminate superoxide and hydrogen peroxide. In this review, we have tried to explore the related works, which have revealed the changes in the basic antioxidant metabolism of plants under various abiotic constraints.

Understanding water deficit stress-induced changes in the basic metabolism of higher plants – biotechnologically and sustainably improving agriculture and the ecoenvironment in arid regions of the globe

Abstract: Water is vital for plant growth, development and productivity. Permanent or temporary water deficit stress limits the growth and distribution of natural and artificial vegetation and the performance of cultivated plants (crops) more than any other environmental factor. Productive and sustainable agriculture necessitates growing plants (crops) in arid and semiarid regions with less input of precious resources such as fresh water. For a better understanding and rapid improvement of soil-water stress tolerance in these regions, especially in the water-wind eroded crossing region, it is very important to link physiological and biochemical studies to molecular work in genetically tractable model plants and important native plants, and further extending them to practical ecological restoration and efficient crop production. Although basic studies and practices aimed at improving soil water stress resistance and plant water use efficiency have been carried out for many years, the mechanisms involved at different scales are still not clear. Further understanding and manipulating soil-plant water relationships and soil-water stress tolerance at the scales of ecology, physiology and molecular biology can significantly improve plant productivity and environmental quality. Currently, post-genomics and metabolomics are very important in exploring anti-drought gene resources in various life forms, but modern agriculturally sustainable development must be combined with plant physiological measures in the field, on the basis of which post-genomics and metabolomics have further practical prospects. In this review, we discuss physiological and molecular insights and effects in basic plant metabolism, drought tolerance strategies under drought conditions in higher plants for sustainable agriculture and ecoenvironments in arid and semiarid areas of the world. We conclude that biological measures are the bases for the solutions to the issues relating to the different types of sustainable development.

Effect of welding processes on tensile properties of AA6061 aluminium alloy joints

Abstract: The present investigation is aimed at to study the effect of welding processes such as GTAW, GMAW and FSW on mechanical properties of AA6061 aluminium alloy. The preferred welding processes of these alloys are frequently gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) due to their comparatively easier applicability and better economy. In this alloy, the weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often causes inferior weld mechanical properties and poor resistance to hot cracking. Friction stir welding (FSW) is a solid phase welding technique developed primarily for welding metals and alloys that heretofore had been difficult to weld using more traditional fusion techniques. Rolled plates of 6 mm thickness have been used as the base material for preparing single pass butt welded joints. The filler metal used for joining the plates is AA4043 (Al-5Si (wt%)) grade aluminium alloy. In the present work, tensile properties, micro hardness, microstructure and fracture surface morphology of the GMAW, GTAW and FSW joints have been evaluated, and the results are compared. From this investigation, it is found that FSW joints of AA6061 aluminium alloy showed superior mechanical properties compared with GTAW and GMAW joints, and this is mainly due to the formation of very fine, equiaxed microstructure in the weld zone.

Classification of audio signals using SVM and RBFNN

Abstract: In the age of digital information, audio data has become an important part in many modern computer applications Audio classification has been becoming a focus in the research of audio processing and pattern recognition Automatic audio classification is very useful to audio indexing, content-based audio retrieval and on-line audio distribution, but it is a challenge to extract the most common and salient themes from unstructured raw audio data In this paper, we propose effective algorithms to automatically classify audio clips into one of six classes: music, news, sports, advertisement, cartoon and movie For these categories a number of acoustic features that include linear predictive coefficients, linear predictive cepstral coefficients and mel-frequency cepstral coefficients are extracted to characterize the audio content Support vector machines are applied to classify audio into their respective classes by learning from training data Then the proposed method extends the application of neural network (RBFNN) for the classification of audio RBFNN enables nonlinear transformation followed by linear transformation to achieve a higher dimension in the hidden space The experiments on different genres of the various categories illustrate the results of classification are significant and effective

Bioaccumulation and depuration of chromium in the selected organs and whole body tissues of freshwater fish Cirrhinus mrigala individually and in binary solutions with nickel.

Abstract: Contamination of aquatic ecosystems with heavy metals has been receiving increased worldwide attention due to their harmful effects on human health and other organisms in the environment. Most of the studies dealing with toxic effects of metals deal with single metal species, while the aquatic organisms are typically exposed to mixtures of metals. Hence, in order to provide data supporting the usefulness of freshwater fish as indicators of heavy metal pollution, it has been proposed in the present study to investigate the bioaccumulation and depuration of chromium in the selected organs of freshwater fingerlings Cirrhinus mrigala, individually and in binary solutions with nickel. The results show that the kidney is a target organ for chromium accumulation, which implies that it is also the "critical" organ for toxic symptoms. The results further show that accumulation of nickel in all the tissues of C. mrigala is higher than that of chromium. In addition, the metal accumulations of the binary mixtures of chromium and nickel are substantially higher than those of the individual metals, indicating synergistic interactions between the two metals. Theoretically the simplest explanation for an additive joint action of toxicants in a mixture is that they act in a qualitatively similar way. The observed data suggest that C. mrigala could be suitable monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats.

Lipase catalyzed ester synthesis for food processing industries

Abstract: Lipases are one of the most important industrial biocatalyst which catalyzes the hydrolysis of lipids. It can also reverse the reaction at minimum water activity. Because of this pliable nature, it is widely exploited to catalyze the diverse bioconversion reactions, such as hydrolysis, esterification, interesterification, alcoholysis, acidolysis and aminolysis. The property to synthesize the esters from the fatty acids and glycerol promotes its use in various ester synthesis. The esters synthesized by lipase finds applications in numerous fields such as biodiesel production, resolution of the recemic drugs, fat and lipid modification, flavour synthesis, synthesis of enantiopure pharmaceuticals and nutraceuticals. It plays a crucial role in the food processing industries since the process is unaffected by the unwanted side products. Lipase modifications such as the surfactant coating, molecular imprinting to suit for the non-aqueous ester synthesis have also been reported. This review deals with lipase catalyzed ester synthesis, esterification strategies, optimum conditions and their applications in food processing industries. Key words: Lipase, food applications, ester, esterification, synthesis

Larvicidal and oviposition activity of Cassia obtusifolia Linn (Family: Leguminosae) leaf extract against malarial vector, Anopheles stephensi Liston (Diptera: Culicidae)

Abstract: The ethanolic leaf extract of Cassia obtusifolia was investigated for their larvicidal and oviposition deterrence effects against Anopheles stephensi. Concentrations ranging from 25 to 125 mg/l were assessed at 24 h post-treatment against late third instar larvae. The leaf extract had significant larvicidal effect with LC50 and LC90 values were 52.2 and 108.7 mg/l, respectively. In oviposition behaviour study, four different concentrations ranging from 100 to 400 mg/l were studied against gravid female mosquitoes. The results of oviposition study indicated that the leaf extract showed concentration dependent oviposition deterrent activity. At higher concentration (400 mg/l) showed 92.5% effective repellency against oviposition, followed by 300, 200 and 100 mg/l showed 87.2%, 83.0% and 75.5%, respectively. The larvicidal and oviposition deterrent effect of C. obtusifolia against A. stephensi make this plant product promising as an alternative to synthetic insecticide in mosquito control programs.

Breast mass classification based on cytological patterns using RBFNN and SVM

Abstract: Correct diagnosis is one of the major problems in medical field. This includes the limitation of human expertise in diagnosing the disease manually. From the literature it has been found that pattern classification techniques such as support vector machines (SVM) and radial basis function neural network (RBFNN) can help them to improve in this domain. RBFNN and SVM with their remarkable ability to derive meaning from complicated or imprecise data, can be used to extract patterns and detect trends that are too complex to be noticed by either humans or other computer techniques. This paper compares the use of polynomial kernel of SVM and RBFNN in ascertaining the diagnostic accuracy of cytological data obtained from the Wisconsin breast cancer database. The data set includes nine different attributes and two categories of tumors namely benign and malignant. Known sets of cytologically proven tumor data was used to train the models to categorize cancer patients according to their diagnosis. Performance measures such as accuracy, specificity, sensitivity, F-score and other metrics used in medical diagnosis such as Youden's index and discriminant power were evaluated to convey and compare the qualities of the classifiers. This research has demonstrated that RBFNN outperformed the polynomial kernel of SVM for correctly classifying the tumors.

Seasonal variations of plankton diversity in the Kaduviyar estuary, Nagapattinam, southeast coast of India

Abstract: The results of an investigation carried out during October 2005 to September 2006 on hydrography composition and community structure of phytoplankton and zooplankton including chlorophyll 'a' (Chl-a) content and primary productivity (PP) at the Kaduviyar estuary (Southeast coast of India) are reported. Air and surface water temperatures (degrees C) varied from 23 to 29 and from 24 to 31 respectively while the light extinction coefficient values (LEC) ranged between 0.15 and 0.59. Salinity values (per thousand) varied from 4 to 34 and the pH ranged between 7.8 and 8.3. Variation in dissolved oxygen content was from 3.06 to 5.63 mg l(-1). The ranges of inorganic nutrients (microM) viz., nitrate, nitrite, phosphate, silicate and ammonia were: 0.36-12.65; 0.06-1.86; 0.06-4.57; 17.96-235.06 and 0.001-0.75 respectively. The ranges of Chlorophyll 'a' (mg m(-3)) and the primary productivity (mg Cm(-3) hr(-1)) values were: 3.4-12.8 and 55-119 respectively. Presently, 85 phytoplankton species representing different classes viz: Bacillariophyceae (58); Dinophyceae (16); Cyanophyceae (7); Chlorophyceae (3) and Chrysophyceae (1) were recorded. The phytoplankton density varied from 14,135 to 74,697 cells l(-1), with peak diversity (3.46 bits ind.(-1)) during premonsoon season. The maximum density was found during summer season coinciding with the stable hydrographical conditions. Totally 92 species of zooplankton besides 18 larvae were recorded and the copepods formed the dominant group. The occurrence of most of the zooplankton species showed a distinct seasonal pattern, which was closely associated with the species-specific environmental conditions. That way the environmental factors exert major influence on the species composition, abundance and diversity of zooplankton. The zooplankton density (org. l(-1)) ranged between 4342 and 14,002 and between 4867 and 15,816 at stations 1 and 2 respectively. Kaduviyar estuarine waters were very rich in zooplankton diversity (bits ind.(-1)) viz: 5.29 at Station 2 which was slightly higher than 5.27 at Station 1. Higher values of zooplankton density and species diversity were found during premonsoon and summer seasons and which showed positive correlation with salinity. The seasonal distribution and abundance of plankton are discussed in relation to hydrographical parameters.

Synthesis and Characterization of Rare Earth Orthovanadate (RVO4; R = La, Ce, Nd, Sm, Eu & Gd) Nanorods/Nanocrystals/Nanospindles by a Facile Sonochemical Method and Their Catalytic Properties

Abstract: We report herein on an efficient sonochemical method for the synthesis of rare earth orthovanadate nanorods/nanoparticles/nanospindles, (general formula RVO4; R = La, Ce, Nd, Sm, Eu and Gd). TGA, XRD, FTIR, Raman, UV–Vis, and TEM studies are employed for their characterization and for understanding their morphologies. In order to vary the textural properties of the rare earth vanadates, two surfactants, polyethylene glycol (PEG) and amphiphilic triblock copolymer Pluronic P123, are chosen in the preparation. While the sonochemical synthesis in the presence of PEG results in the formation of nearly spherical nanoparticles of LaVO4, CeVO4, SmVO4 and EuVO4, the same technique yields nanorods and nanospindles of NdVO4 and GdVO4, respectively. When P123 is used as the surfactant, the morphologies of RVO4 are strikingly different, and in most cases nanorods and nanospindles are formed. The photocatalytic activities of the rare earth orthovanadate have been evaluated by studying the degradation of methylene blue, and CeVO4 seems to be the best catalyst in the heterogeneous photolysis. The electrocatalytic activity of the vanadates has been examined by studying the hydrogen evolution reaction using a linear sweep voltammogram technique in 1 M of a H2SO4 solution. GdVO4 seems to be the best electrocatalyst.

Effect of vermicompost on soil fertility and crop productivity - beans (Phaseolus vulgaris).

Abstract: Field experiments were conducted at Sivapuri, Chidambaram, Tamil Nadu to evaluate the efficacy of vermicompost, in comparison to inorganic fertilizers-NPK, on the physio-chemical and biological characteristics of the soils--clay loam soil (CLS) and sandy loam soil (SLS) and on the growth, yield and nutrient content of beans--Phaseolus vulgaris. Results showed that the application of vermicompost @ 5 tonnes ha(-1) had enhanced significantly the pore space (1.09 and 1.02 times), water holding capacity (1.1 and 1.3 times), cation exchange capacity (1.2 and 1.2 times). It reduced particles (1.2 and 1.2 times), and bulk density (1.2 and 1.2 times), pH (1 and 1.02 times) and electrical conductivity (1.4 and 1.2 times) and increased organic carbon (37 and 47 times), micro (Ca 3.07 and 1.9 times, Mg 1.6 and 1.6 times, Na 2.4 and 3.8 times, Fe 7 and 7.6 times, Mn 8.2 and 10.6 times, Zn 50 and 52 times and Cu 14 and 22 times) and macro (N 1.6 and 1.7 times, P 1.5 and 1.7 times, K 1.5 and 1.4 times) nutrients and microbial activity (1.4 and 1.5 times) in both soil types, particularly more in CLS. The growth, yield (1.6 times) and quality (protein (1.05 times) and sugar (1.01 times) content in seed) of bean were enhanced in CLS than SLS. On the other hand, the application of inorganic fertilizers @ 20:80:40 kg ha(-1) has resulted in reduced porosity (1.03 and 1.01 times), organic carbon (1.04 and 9.5 times) and microbial activity (1.02 and 1.03 times) in both soil types.

Nimbolide a limonoid from Azadirachta indica inhibits proliferation and induces apoptosis of human choriocarcinoma (BeWo) cells

Abstract: We investigated the cytotoxic effects of nimbolide, a limonoid present in leaves and flowers of the neem tree (Azadirachta indica) on human choriocarcinoma (BeWo) cells. Treatment with nimbolide resulted in dose- and time-dependent inhibition of growth of BeWo cells with IC50 values of 2.01 and 1.19 μM for 7 and 24 h respectively, accompanied by downregulation of proliferating cell nuclear antigen. Examination of nuclear morphology revealed fragmentation and condensation indicating apoptosis. Increase in the generation of reactive oxygen species (ROS) that was reversed by addition of reduced glutathione suggested ROS involvement in the cytotoxicity of nimbolide. A decrease in Bcl-2/Bax ratio with increased expression of Apaf-1 and caspase-3, and cleavage of poly(ADP-ribose) polymerase provide compelling evidence that nimbolide-induced apoptosis is mediated by the mitochondrial pathway. The results of the present study suggest that nimbolide has immense potential in cancer prevention and therapy based on its antiproliferative and apoptosis inducing effects.

Study of electrochemical machining characteristics of Al/SiCp composites

Abstract: Non-conventional machining is increasing in importance due to some of the specific advantages which can be exploited during machining operation. Electrochemical machining (ECM) appears to be a promising technique, since in many areas of application, it offers several special advantages including higher machining rate, better precision and control, and a wider range of materials that can be machined. The present work is, therefore, initiated to investigate the influence of some predominant electrochemical process parameters such as applied voltage, electrolyte concentration, electrolyte flow rate and tool feed rate on the metal removal rate (MRR), and surface roughness (Ra) to fulfill the effective utilization of electrochemical machining of LM25 Al/10%SiC composites produced through stir casting. The contour plots are generated to study the effect of process parameters as well as their interactions. The process parameters are optimized based on Response Surface Methodology (RSM).

Bioefficacy of Cassia fistula Linn. (Leguminosae) leaf extract against chikungunya vector, Aedes aegypti (Diptera: Culicidae).

Abstract: The leaf extract of Cassia fistula with different solvens viz, methanol, benzene and acetone were studied for the larvicidal, ovicidal and repellent activity against Aedes aegypti. The extract exhibited dose dependent activity and produced significant mortality. The 24 h LC50 concentration of the extract against Aedes aegypti were observed at 10.69, 18.27 and 23.95 mg/l respectively. Mean percent hatchability of the ovicidal activity was ob- served 120.00 h after treatment. The percent hatchability was inversely proportional to the concentration of extract and directly propor- tional to the eggs. The crude extract of Cassia fistula shows significant repellency against Aedes aegypti. These results clearly reveal that the crude extract of Cassia fistula served as a potential larvicidal, ovicidal and repellent agent against chikungunya vector mosquito, Aedes aegypti.

Genistein improves liver function and attenuates non-alcoholic fatty liver disease in a rat model of insulin resistance.

Abstract: Background: The high fructose-fed rat is widely used as a model of insulin resistance. Genistein, a soy isoflavone, has been shown to improve insulin sensitivity in this model. The present study investigated whether genistein could prevent fatty liver disease in this model. Methods: Male Wistar rats were fed a diet containing starch (control) or 60% fructose (insulin-resistant model). Fifteen days later, rats in each dietary group were divided into two groups and were treated with either genistein (1 mg/kg per day) in dimethylsulfoxide (DMSO) or 30% DMSO alone. After 60 days, markers of liver injury, oxidative stress, interleukin (IL)-6, tumor necrosis factor (TNF)-α, lipids, lipoprotein profile, nitrite, and nitrosothiol in the plasma and liver were quantified. Liver sections were examined for 3-nitrotyrosine (3-NT) expression and pathological lesions. Results: Fructose-fed rats displayed hyperlipidemia, significant changes in plasma lipoprotein profile, and increases in IL-6 and TNF-α levels compared with control. In addition, the accumulation of lipids, liver injury, a decline in liver function, inactivation of the glyoxalase system, depletion of antioxidants, and increased 3-NT expression were observed in the fructose-fed group. Administration of genistein to fructose-fed rats significantly reduced these biochemical and histological abnormalities. Conclusions: Genistein activates the antioxidant profile, decreases IL-6 and TNF-α concentrations, prevents oxidative damage, and ameliorates fatty liver in insulin-resistant rats.

Hepatoprotective effect of chrysin on prooxidant-antioxidant status during ethanol-induced toxicity in female albino rats.

Abstract: Objectives To evaluate the effect of chrysin, a natural, biologically active compound extracted from many plants, honey and propolis, on the tissue and circulatory antioxidant status, and lipid peroxidation in ethanol-induced hepatotoxicity in rats. Methods Rats were divided into four groups. Groups 1 and 2 received isocaloric glucose. Groups 3 and 4 received 20% ethanol, equivalent to 5 g/kg bodyweight every day. Groups 2 and 4 received chrysin (20 mg/kg bodyweight) dissolved in 0.5% dimethylsulfoxide. Key findings The results showed significantly elevated levels of tissue and circulatory thiobarbituric acid reactive substances, conjugated dienes and lipid hydroperoxides, and significantly lowered enzymic and non-enzymic antioxidant activity of superoxide dismutase, catalase and glutathione-related enzymes such as glutathione peroxidase, glutathione reductase, glutathione-S-transferase, reduced glutathione, vitamin C and vitamin E in ethanol-treated rats compared with the control. Chrysin administration to rats with ethanol-induced liver injury significantly decreased the levels of thiobarbituric acid reactive substances, lipid hydroperoxides and conjugated dienes, and significantly elevated the activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase and the levels of reduced glutathione, vitamin C and vitamin E in the tissues and circulation compared with those of the unsupplemented ethanol-treated rats. The histological changes observed in the liver and kidney correlated with the biochemical findings. Conclusions Chrysin offers protection against free radical-mediated oxidative stress in rats with ethanol-induced liver injury.

The neem limonoids azadirachtin and nimbolide inhibit hamster cheek pouch carcinogenesis by modulating xenobiotic-metabolizing enzymes, DNA damage, antioxidants, invasion and angiogenesis.

Abstract: The neem tree has attracted considerable research attention as a rich source of limonoids that have potent antioxidant and anti-cancer properties. The present study was designed to evaluate the chemopreventive potential of the neem limonoids azadirachtin and nimbolide based on in vitro antioxidant assays and in vivo inhibitory effects on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis. Both azadirachtin and nimbolide exhibited concentration-dependent anti-radical scavenging activity and reductive potential in the order: nimbolide > azadirachtin > ascorbate. Administration of both azadirachtin and nimbolide inhibited the development of DMBA-induced HBP carcinomas by influencing multiple mechanisms including prevention of procarcinogen activation and oxidative DNA damage, upregulation of antioxidant and carcinogen detoxification enzymes and inhibition of tumour invasion and angiogenesis. On a comparative basis, nimbolide was found to be a more potent antioxidant and chemopreventive agent and offers promise as a candidate agent in multitargeted prevention and treatment of cancer.

Effect of morin on tissue lipid peroxidation and antioxidant status in 1, 2-dimethylhydrazine induced experimental colon carcinogenesis

Abstract: Colon cancer is the third most malignant neoplasm in the world and it remains today an important cause of death, especially in western countries. In this study, we have evaluated the chemopreventive efficacy of morin on tissue lipid peroxidation and antioxidant status, which are used as biomarkers in 1,2-dimethylhydrazine-induced colon carcinogenesis in a rat model. Male Wistar rats were divided into four groups and received high fat diet. Group 1 served as control, groups 2 and 4 were given a daily treatment of morin (50 mg/kg body weight) orally, everyday for a total period of 30 weeks. Groups 3 and 4 were given weekly subcutaneous injections of DMH at a dose of 20 mg/kg body weight in the groin for 15 weeks. Animals were sacrificed at the end of 30 weeks. The liver, intestine, colon and caecum from different groups were subjected to histopathological studies, determination of lipid peroxidation and antioxidant status. Our results showed decreased levels of liver enzymic and non-enzymic antioxidants and increased levels of lipid peroxidation (LPO) products such as tissue thiobarbituricacid substances (TBARS), lipid hydroperoxides (LOOH) and conjugated dienes (CD) in DMH treated rats, which were significantly (P < 0.05) reversed on morin supplementation. Moreover, intestinal, colonic and caecal TBARS, LOOH, CD and also the antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GR) and reduced glutathione (GSH) were significantly diminished in DMH treated rats, which were significantly (P < 0.05) elevated on simultaneous morin supplementation. Moreover, enhanced activity of intestinal, colonic and caecal ascorbic acid and α-tocopherol levels were also observed in DMH alone treated rats, which were significantly (P < 0.05) reduced on morin supplementation. These results indicate that morin could exert a significant chemopreventive effect on colon carcinogenesis induced by DMH.