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51.
We report the formation and appearance of loosely stacked extended grana like structures along with plastoglobuli in the chloroplasts
isolated from 27-day old senescing cucumber cotyledons. The origin and the nature of these extended grana structures have
not been elucidated earlier. We isolated Photosystem I complexes from 6-day-old control and 27-day-old senescing cotyledons.
The chlorophyll a/b ratio of the isolated Photosystem I complex obtained from 6-day cotyledons was 5–5.5 as against a ratio of 2.9 was found
in Photosystem I complexes obtained from 27-day-old senescing cotyledons. We also found that the presence of LHC II in the
Photosystem I complexes isolated from 27-day cotyledonary chloroplasts. The presence of LHC II in Photosystem I complexes
in senescing and not in control samples, clearly suggest the detachment and diffusion of LHC II complexes from stacked grana
region to Photosystem I enriched stroma lamellar region thereby, forming loose disorganized extended grana structures seen
in the transmission electron microscope. Furthermore, we show that under in vitro condition the senescing cotyledon chloroplasts exhibited lower extent of light induced phosphorylation of LHC II than the
control samples suggesting a possible irreversible phosphorylation and diffusion of LHC II in vivo during the progress of senescence in Cucumis cotyledons. From these findings, we suggest that the senescence induced phosphorylation of LHC II and its migration towards
Photosystem I may be a programmed one some how causing the destruction of the thylakoid membrane. The released membrane components
may be stored in the plastoglobuli prior to their mobilization to the younger plant parts.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
52.
53.
Chokkalingam Uvarani Karuppannan Arumugasamy Kumarasamy Chandraprakash Mathan Sankaran Athar Ata Palathurai Subramaniam Mohan 《化学与生物多样性》2015,12(3):358-370
Phytochemical investigation of the CHCl3 fraction of Swertia corymbosa resulted in the isolation of a new 3‐allyl‐2,8‐dihydroxy‐1,6‐dimethoxy‐9H‐xanthen‐9‐one ( 1 ), along with four known xanthones, gentiacaulein ( 3 ), norswertianin ( 4 ), 1,3,6,8‐tetrahydroxyxanthone ( 5 ), and 1,3‐dihydroxyxanthone ( 6 ). Structure of compound 1 was elucidated with the aid of IR, UV, NMR, and MS data, and chemical transformation via new allyloxy xanthone derivative ( 2 ). Compounds 1 – 6 exhibited various levels of antioxidant and anti‐α‐glucosidase activities. Absorption and fluorescence spectroscopic studies on 1 – 6 indicated that these compounds could interact with calf thymus DNA (CT‐DNA) through intercalation and with bovine serum albumin (BSA) in a static quenching process. Compound 1 was found to be significantly cytotoxic against human cancer cell lines HeLa, HCT116, and AGS, and weakly active against normal NIH 3T3 cell line. 相似文献
54.
55.
FCRL5 Delineates Functionally Impaired Memory B Cells Associated with Plasmodium falciparum Exposure
56.
Michelle J. Boyle Prasanna Jagannathan Lila A. Farrington Ijeoma Eccles-James Samuel Wamala Tara I McIntyre Hilary M. Vance Katherine Bowen Felistas Nankya Ann Auma Mayimuna Nalubega Esther Sikyomu Kate Naluwu John Rek Agaba Katureebe Victor Bigira James Kapisi Jordan Tappero Mary K Muhindo Bryan Greenhouse Emmanuel Arinaitwe Grant Dorsey Moses R. Kamya Margaret E. Feeney 《PLoS pathogens》2015,11(7)
FoxP3+ regulatory CD4 T cells (Tregs) help to maintain the delicate balance between pathogen-specific immunity and immune-mediated pathology. Prior studies suggest that Tregs are induced by P. falciparum both in vivo and in vitro; however, the factors influencing Treg homeostasis during acute and chronic infections, and their role in malaria immunopathogenesis, remain unclear. We assessed the frequency and phenotype of Tregs in well-characterized cohorts of children residing in a region of high malaria endemicity in Uganda. We found that both the frequency and absolute numbers of FoxP3+ Tregs in peripheral blood declined markedly with increasing prior malaria incidence. Longitudinal measurements confirmed that this decline occurred only among highly malaria-exposed children. The decline of Tregs from peripheral blood was accompanied by reduced in vitro induction of Tregs by parasite antigen and decreased expression of TNFR2 on Tregs among children who had intense prior exposure to malaria. While Treg frequencies were not associated with protection from malaria, there was a trend toward reduced risk of symptomatic malaria once infected with P. falciparum among children with lower Treg frequencies. These data demonstrate that chronic malaria exposure results in altered Treg homeostasis, which may impact the development of antimalarial immunity in naturally exposed populations. 相似文献
57.
Vijayasree V. Giridharan Rajarajan A. Thandavarayan Somasundaram Arumugam Makoto Mizuno Hiroyuki Nawa Kenji Suzuki Kam M. Ko Prasanna Krishnamurthy Kenichi Watanabe Tetsuya Konishi 《PloS one》2015,10(11)
Amyloid β (Aβ)-induced neurotoxicity is a major pathological mechanism of Alzheimer’s disease (AD). Our previous studies have demonstrated that schisandrin B (Sch B), an antioxidant lignan from Schisandra chinensis, could protect mouse brain against scopolamine- and cisplatin-induced neuronal dysfunction. In the present study, we examined the protective effect of Sch B against intracerebroventricular (ICV)-infused Aβ-induced neuronal dysfunction in rat cortex and explored the potential mechanism of its action. Our results showed that 26 days co-administration of Sch B significantly improved the behavioral performance of Aβ (1–40)-infused rats in step-through test. At the same time, Sch B attenuated Aβ-induced increases in oxidative and nitrosative stresses, inflammatory markers such as inducible nitric oxide syntheses, cyclooxygenase-2, interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α, and DNA damage. Several proteins such as receptor for advanced glycation end products (RAGE), nuclear factor-κB, mitogen-activated protein kinases, and apoptosis markers were over expressed in Aβ-infused rats but were significantly inhibited by Sch B treatment. Furthermore, Sch B negatively modulated the Aβ level with simultaneous up-regulation of HSP70 and beclin, autophagy markers in Aβ-infused rats. The aforementioned effects of Sch B suggest its protective role against Aβ-induced neurotoxicity through intervention in the negative cycle of RAGE-mediated Aβ accumulation during AD patho-physiology. 相似文献
58.
Nithya BabuRajendran Paaventhan Palasingam Kamesh Narasimhan Wenjie Sun Shyam Prabhakar Ralf Jauch Prasanna R. Kolatkar 《Nucleic acids research》2010,38(10):3477-3488
Smad1 is a downstream effector of the BMP signaling pathway that binds regulatory DNA to execute gene expression programs leading to, for example, the maintenance of pluripotency in mice. On the contrary, the TGF-β-activated Smad3 triggers strikingly different programs such as mesodermal differentiation in early development. Because Smad1 and Smad3 contain identical amino acids at the DNA contact interface it is unclear how they elicit distinctive bioactivities. Here, we report the crystal structure of the MH1 domain of Smad1 bound to a palindromic Smad binding element. Surprisingly, the DNA contact interface of Smad1 is drastically rearranged when compared to Smad3. The N-terminal helix 1 of Smad1 is dislodged from its intramolecular binding site and adopts a domain swapped arrangement with a symmetry-related molecule. As a consequence, helix 2 kinks away from the double helix disabling several key phosphate backbone interactions. Thermal melting analysis corroborates a decompacted conformation of Smad1 and DNA binding assays indicate a lower overall affinity of Smad1 to DNA but increased cooperativity when binding to palindromic DNA motifs. These findings suggest that Smad1 and Smad3 evolved differential qualities to assemble on composite DNA elements and to engage in co-factor interactions by remodeling their N-termini. 相似文献
59.
Sukanta K. Sabut Prasanna K. Lenka Ratnesh Kumar Manjunatha Mahadevappa 《Journal of electromyography and kinesiology》2010,20(6):1170-1177
ObjectiveTo investigate the effects of functional electrical stimulation (FES) combined with conventional rehabilitation program on the effort and speed of walking, the surface electromyographic (sEMG) activity and metabolic responses in the management of drop foot in stroke subjects.MethodsFifteen patients with a drop foot resulting from stroke at least 3 months prior to the start of the trial took part in this study. All subjects were treated 1 h a day, 5 days a week, for 12 weeks, including conventional stroke rehabilitation program and received 30 min of FES to the tibialis anterior (TA) muscle of the paretic leg in clinical settings. Baseline and post-treatment measurements were made for temporal and spectral EMG parameters of TA muscle, walking speed, the effort of walking as measured by physiological cost index (PCI) and metabolic responses.ResultsThe experimental results showed a significant improvement in mean-absolute-value (21.7%), root-mean-square (66.3%) and median frequency (10.6%) of TA muscle EMG signal, which reflects increased muscle strength. Mean increase in walking speed was 38.7%, and a reduction in PCI of 34.6% between the beginning and at end of the trial. Improvements were also found in cardiorespiratory responses with reduction in oxygen consumption (24.3%), carbon dioxide production (19.9%), heart rate (7.8%) and energy cost (22.5%) while walking with FES device.ConclusionsThe results indicate that the FES may be a useful therapeutic tool combined with conventional rehabilitation program to improve the muscle strength, walking ability and metabolic responses in the management of drop foot with stroke patients. 相似文献
60.
Purushothaman S Prasanna R Niranjana P Raghunathan R Nagaraj S Rengasamy R 《Bioorganic & medicinal chemistry letters》2010,20(24):7288-7291
Synthesis of a series of novel hexahydrochromenopyrrole analogues has been accomplished through an intramolecular 1,3-dipolar cycloaddition (1,3-DC reaction) of azomethine ylides, generated by the aldehyde induced decarboxylation of secondary amino acids. These compounds were screened for antibacterial and antifungal activities against six human pathogenic bacteria and three human pathogenic fungi and found to have good antimicrobial properties against most of the microorganisms. 相似文献