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901.
902.
Ramar Manikandan Raman Thiagarajan Sivagnanam Beulaja Ganapasam Sudhandiran Munuswamy Arumugam 《Free radical biology & medicine》2010,48(4):483-492
The generation of free radicals has been implicated in the causation of cataract, and compounds that can scavenge free radicals ameliorate the disease process. This study investigated the possible free radical scavenging potential of curcumin at a dose of 75 mg/kg body wt on selenium-induced cataract in rat pups. Intraperitoneal injection of sodium selenite (15 μmol/kg body wt) into 8- to 10-day-old rat pups led to severe oxidative stress in the eye lens as evidenced by increased nitric oxide, superoxide anion, and hydroxyl radical generation and inducible nitric oxide synthase expression that probably led to cataract formation. Selenium exposure also caused an increase in total calcium in the eye lens and significantly inhibited the activity of Ca2+ ATPase but not Na+/K+ ATPase or Mg2+ ATPase. On the other hand, pretreatment with curcumin, but not simultaneous or posttreatment, led to a decrease in oxidative stress and also rescued the selenium-mediated increase in lens Ca2+ and inhibition of Ca2+ ATPase activity in the eye lens. The results of this study demonstrate that an increase in free radical generation triggered by selenium could cause inactivation of lens Ca2+ ATPase leading to Ca2+ accumulation. This enhanced Ca2+ can cause activation of calpain-mediated proteolysis in the lens, resulting in lens opacification. Curcumin in this study was able to prevent selenium-induced oxidative stress leading to activation of Ca2+ ATPase and inhibition of lens opacification. Thus, curcumin has the potential to function as an anticataractogenic agent, possibly by preventing free radical-mediated accumulation of Ca2+ in the eye lens. 相似文献
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Sagrario Gámez-Virués Ronald S Bonifacio Geoff M Gurr Cilla Kinross Anantanarayanan Raman Helen I Nicol 《Australian Journal of Entomology》2007,46(4):325-331
Abstract The value of insectivorous birds as agents for biological control of arthropod pests has been little studied, especially in Australia. This paper reports on the extent to which arthropods from various pest and non-pest taxa feature in the diets of birds captured in farm shelterbelts in central western New South Wales. The parameters examined were the types of arthropod fragments in bird faeces and percentage volume and frequency of occurrence of each component. The faecal data were compared with samples of the arthropod fauna trapped in shelterbelts during the period the birds were captured. In 26 of 29 faecal samples, arthropod fragments were the predominant components, the most common being from Coleoptera, Hymenoptera (especially Formicidae), Orthoptera and Araneae. The recognisable pest taxa in faecal samples were Scarabaeidae and wingless grasshopper Phaulacridium vittatum (Sjöstedt) (Orthoptera: Acrididae). The results indicate that the native bird species common in farm shelterbelts preyed on a range of arthropod taxa including several that are pests of crops and pastures. Accordingly, conservation of birds in farmlands could contribute to suppression of arthropod pests. 相似文献
904.
Xiangjie Sun Akila Jayaraman Pavithra Maniprasad Rahul Raman Katherine V. Houser Claudia Pappas Hui Zeng Ram Sasisekharan Jacqueline M. Katz Terrence M. Tumpey 《Journal of virology》2013,87(15):8756-8766
The hemagglutinin (HA) protein is a major virulence determinant for the 1918 pandemic influenza virus; however, it encodes no known virulence-associated determinants. In comparison to seasonal influenza viruses of lesser virulence, the 1918 H1N1 virus has fewer glycosylation sequons on the HA globular head region. Using site-directed mutagenesis, we found that a 1918 HA recombinant virus, of high virulence, could be significantly attenuated in mice by adding two additional glycosylation sites (asparagine [Asn] 71 and Asn 286) on the side of the HA head. The 1918 HA recombinant virus was further attenuated by introducing two additional glycosylation sites on the top of the HA head at Asn 142 and Asn 172. In a reciprocal experimental approach, deletion of HA glycosylation sites (Asn 142 and Asn 177, but not Asn 71 and Asn 104) from a seasonal influenza H1N1 virus, A/Solomon Islands/2006 (SI/06), led to increased virulence in mice. The addition of glycosylation sites to 1918 HA and removal of glycosylation sites from SI/06 HA imposed constraints on the theoretical structure surrounding the glycan receptor binding sites, which in turn led to distinct glycan receptor binding properties. The modification of glycosylation sites for the 1918 and SI/06 viruses also caused changes in viral antigenicity based on cross-reactive hemagglutinin inhibition antibody titers with antisera from mice infected with wild-type or glycan mutant viruses. These results demonstrate that glycosylation patterns of the 1918 and seasonal H1N1 viruses directly contribute to differences in virulence and are partially responsible for their distinct antigenicity. 相似文献
905.
Pathogenic and Genetic Variation among the Isolates of Rhizoctonia solani (AG 1‐IA), the Rice Sheath Blight Pathogen 下载免费PDF全文
Arra Yugander Duraisamy Ladhalakshmi Vellaichamy Prakasham Satendra K. Mangrauthia Madamsetty S. Prasad Donempudi Krishnaveni Maganti Sheshu Madhav Raman M. Sundaram Gouri Sankar Laha 《Journal of Phytopathology》2015,163(6):465-474
Sheath blight disease of rice caused by Rhizoctonia solani is one of the most dreaded plant diseases faced by the rice farmers all over the world. None of the commercially cultivated rice varieties have sufficient level of field resistance, and the disease is presently being managed by chemical pesticides. In this study, 40 isolates of rice sheath blight pathogen, collected from diverse rice ecosystems from 12 different states of India, were characterized for their morphological, pathological and genetic variation. The isolates showed wide morphological variation in terms of size of sclerotia and abundance of sclerotia production. The virulence of each pathogen isolate was studied on four rice varieties, that is TN1, IR 64, Tetep and Swarnadhan in glasshouse, and observations were taken by measuring the relative lesion height. The relative lesion heights produced by these isolates on four different rice varieties varied widely. Genetic variation of the isolates was analysed using ISSR markers. The primers based on AG, GA, AC and CA repeats were informative and revealed polymorphism among the isolates. The polymorphism information content (PIC) of the primers ranged from 0.80 to 0.96, while the resolving power (Rp) ranged from 3.7 to 15.35. Largely, grouping of the isolates happened based on their geographical origin. One isolate from Titabar, Assam, and another from Adialabad, Telangana, were quite distinct from rest of the isolates. 相似文献
906.
S. Muthuramkumar N. Ayyappan N. Parthasarathy Divya Mudappa T. R. Shankar Raman M. Arthur Selwyn L. Arul Pragasan 《Biotropica》2006,38(2):143-160
Changes in tree, liana, and understory plant diversity and community composition in five tropical rain forest fragments varying in area (18–2600 ha) and disturbance levels were studied on the Valparai plateau, Western Ghats. Systematic sampling using small quadrats (totaling 4 ha for trees and lianas, 0.16 ha for understory plants) enumerated 312 species in 103 families: 1968 trees (144 species), 2250 lianas (60 species), and 6123 understory plants (108 species). Tree species density, stem density, and basal area were higher in the three larger (> 100 ha) rain forest fragments but were negatively correlated with disturbance scores rather than area per se. Liana species density, stem density, and basal area were higher in moderately disturbed and lower in heavily disturbed fragments than in the three larger fragments. Understory species density was highest in the highly disturbed 18‐ha fragment, due to weedy invasive species occurring with rain forest plants. Nonmetric multidimensional scaling and Mantel tests revealed significant and similar patterns of floristic variation suggesting similar effects of disturbance on community compositional change for the three life‐forms. The five fragments encompassed substantial plant diversity in the regional landscape, harbored at least 70 endemic species (3.21% of the endemic flora of the Western Ghats–Sri Lanka biodiversity hotspot), and supported many endemic and threatened animals. The study indicates the significant conservation value of rain forest fragments in the Western Ghats, signals the need to protect them from further disturbances, and provides useful benchmarks for restoration and monitoring efforts. 相似文献
907.
Federated distributed systems present new challenges to resource management. Conventional resource managers are based on a
relatively static resource model and a centralized allocator that assigns resources to customers. Distributed environments,
particularly those built to support high-throughput computing (HTC), are often characterized by distributed management and
distributed ownership. Distributed management introduces resource heterogeneity: Not only the set of available resources,
but even the set of resource types is constantly changing. Distributed ownership introduces policy heterogeneity: Each resource
may have its own idiosyncratic allocation policy. To address these problems, we designed and implemented the Matchmaking resource
management framework. Customers and resources are all described by classified advertisements (classads) written in a simple
but powerful formal language that describes their attributes and allocation policies. A Matchmaker server uses a policy-independent
matching operation to discover pairings. It notifies the parties to the match, which use a separate, bilateral claiming protocol
to confirm the allocation. The resulting framework is robust, scalable and flexible, and can evolve with changing resources.
Matchmaking is the core of the Condor High Throughput Computing System developed at the University of Wisconsin — Madison.
Condor is a production-quality system used by scientists and engineers at sites around the world. Condor derives much of its
flexibility, robustness and efficiency from the matchmaking architecture. We describe the use of matchmaking in Condor, presenting
several examples that illustrate its flexibility and expressiveness.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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