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Prithiviraj, Balakrishnan

Permanent URI for this collectionhttps://hdl.handle.net/10222/37761

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    Liuwei Dihuang (LWDH), a Traditional Chinese Medicinal Formula, Protects against beta-Amyloid Toxicity in Transgenic Caenorhabditis elegans
    (2012-08) Sangha, Jatinder S.; Sun, Xiaoli; Wally, Owen S. D.; Zhang, Kaibin; Ji, Xiuhong; Wang, Zhimin; Wang, Yanwen; Zidichouski, Jeffrey; Prithiviraj, Balakrishnan; Zhang, Junzeng
    Liuwei Dihuang (LWDH), a classic Chinese medicinal formula, has been used to improve or restore declined functions related to aging and geriatric diseases, such as impaired mobility, vision, hearing, cognition and memory. Here, we report on the effect and possible mechanisms of LWDH mediated protection of beta-amyloid (A beta) induced paralysis in Caenorhabditis elegans using ethanol extract (LWDH-EE) and water extract (LWDH-WE). Chemical profiling and quantitative analysis revealed the presence of different levels of bioactive components in these extracts. LWDH-WE was rich in polar components such as monosaccharide dimers and trimers, whereas LWDH-EE was enriched in terms of phenolic compounds such as gallic acid and paeonol. In vitro studies revealed higher DPPH radical scavenging activity for LWDH-EE as compared to that found for LWDH-WE. Neither LWDH-EE nor LWDH-WE were effective in inhibiting aggregation of Ab in vitro. By contrast, LWDH-EE effectively delayed A beta induced paralysis in the transgenic C. elegans (CL4176) model which expresses human A beta 1-42. Western blot revealed no treatment induced reduction in Ab accumulation in CL4176 although a significant reduction was observed at an early stage with respect to beta-amyloid deposition in C. elegans strain CL2006 which constitutively expresses human A beta 1-42. In addition, LWDH-EE reduced in vivo reactive oxygen species (ROS) in C. elegans (CL4176) that correlated with increased survival of LWDH-EE treated N2 worms under juglone-induced oxidative stress. Analysis with GFP reporter strain TJ375 revealed increased expression of hsp16.2::GFP after thermal stress whereas a minute induction was observed for sod3::GFP. Quantitative gene expression analysis revealed that LWDH-EE repressed the expression of amy1 in CL4176 while up-regulating hsp16.2 induced by elevating temperature. Taken together, these results suggest that LWDH extracts, particularly LWDH-EE, alleviated beta-amyloid induced toxicity, in part, through up-regulation of heat shock protein, antioxidant activity and reduced ROS in C. elegans.
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    Carrageenans, Sulphated Polysaccharides of Red Seaweeds, Differentially Affect Arabidopsis thaliana Resistance to Trichoplusia ni (Cabbage Looper)
    (2011-10) Sangha, Jatinder S.; Khan, Wajahatullah; Ji, Xiuhong; Zhang, Junzeng; Mills, Aaron A. S.; Critchley, Alan T.; Prithiviraj, Balakrishnan
    Carrageenans are a collective family of linear, sulphated galactans found in a number of commercially important species of marine red alga. These polysaccharides are known to elicit defense responses in plant and animals and possess anti-viral properties. We investigated the effect of foliar application of iota-, kappa- and lambda-carrageenans (representing various levels of sulphation) on Arabidopsis thaliana in resistance to the generalist insect Trichoplusia ni (cabbage looper) which is known to cause serious economic losses in crop plants. Plants treated with iota- and kappa-carrageenan showed reduced leaf damage, whereas those treated with lambda-carrageenan were similar to that of the control. In a no-choice test, larval weight was reduced by more than 20% in iota- and kappa-carrageenan treatments, but unaffected by lambda-carrageenan. In multiple choice tests, carrageenan treated plants attracted fewer T. ni larvae by the fourth day following infestation as compared to the control. The application of carrageenans did not affect oviposition behaviour of T. ni. Growth of T. ni feeding on an artificial diet amended with carrageenans was not different from that fed with untreated control diet. iota-carrageenan induced the expression of defense genes; PR1, PDF1.2, and TI1, but kappa- and lambda-carrageenans did not. Besides PR1, PDF1.2, and TI1, the indole glucosinolate biosynthesis genes CYP79B2, CYP83B1 and glucosinolate hydrolysing QTL, ESM1 were up-regulated by i-carrageenan treatment at 48 h post infestation. Gas chromatography-mass spectrometry analysis of carrageenan treated leaves showed increased concentrations of both isothiocyanates and nitriles. Taken together, these results show that carrageenans have differential effects on Arabidopsis resistance to T. ni and that the degree of sulphation of the polysaccharide chain may well mediate this effect.
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    Tasco®: A Product of Ascophyllum nodosum Enhances Immune Response of Caenorhabditis elegans Against Pseudomonas aeruginosa Infection
    (MDPI Publishing, 2012-03) Kandasamy, Saveetha; Khan, Wajahatullah; Evans, Franklin; Critchley, Alan T.; Prithiviraj, Balakrishnan
    No abstract available.
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    Tasco (R), a Product of Ascophyllum nodosum, Imparts Thermal Stress Tolerance in Caenorhabditis elegans
    (2011-11) Kandasamy, Saveetha; Fan, Di; Sangha, Jatinder Singh; Khan, Wajahatullah; Evans, Franklin; Critchley, Alan T.; Prithiviraj, Balakrishnan
    Tasco (R), a commercial product manufactured from the brown alga Ascophyllum nodosum, has been shown to impart thermal stress tolerance in animals. We investigated the physiological, biochemical and molecular bases of this induced thermal stress tolerance using the invertebrate animal model, Caenorhabiditis elegans. Tasco (R) water extract (TWE) at 300 mu g/mL significantly enhanced thermal stress tolerance as well as extended the life span of C. elegans. The mean survival rate of the model animals under thermal stress (35 degrees C) treated with 300 mu g/mL and 600 mu g/mL TWE, respectively, was 68% and 71% higher than the control animals. However, the TWE treatments did not affect the nematode body length, fertility or the cellular localization of daf-16. On the contrary, TWE under thermal stress significantly increased the pharyngeal pumping rate in treated animals compared to the control. Treatment with TWE also showed differential protein expression profiles over control following 2D gel-electrophoresis analysis. Furthermore, TWE significantly altered the expression of at least 40 proteins under thermal stress; among these proteins 34 were up-regulated while six were down-regulated. Mass spectroscopy analysis of the proteins altered by TWE treatment revealed that these proteins were related to heat stress tolerance, energy metabolism and a muscle structure related protein. Among them heat shock proteins, superoxide dismutase, glutathione peroxidase, aldehyde dehydrogenase, saposin-like proteins 20, myosin regulatory light chain 1, cytochrome c oxidase RAS-like, GTP-binding protein RHO A, OS were significantly up-regulated, while eukaryotic translation initiation factor 5A-1 OS, 60S ribosomal protein L18 OS, peroxiredoxin protein 2 were down regulated by TWE treatment. These results were further validated by gene expression and reporter gene expression analyses. Overall results indicate that the water soluble components of Tasco (R) imparted thermal stress tolerance in the C. elegans by altering stress related biochemical pathways.