75 research outputs found
Evaluating Rockefeller Foundation research on drought tolerant rice in China
No full textThis research utilizes economic surplus model and cost-benefit analysis to investigate the justifiability and profitability of drought tolerant (DT) rice research investments by Rockefeller Foundation together with Chinese Government. The research focuses on a sample of 160 rice farmers in Guangxi and Zhejiang who were instructed to plant DT rice. Then another 144 amongst them planted both DT rice and Non-DT rice in the same plot. The impacts of DT rice on yield, irrigation, and farmer’s income are evaluated using both nonparametric and regression analyses. Results show that DT rice variety significantly increases the yield while decreasing the irrigation. This allows farmers to minimize cost and maximize their income. The research investment has paid off and consumers benefit more than producers from development of drought-tolerant rice variety.M.S.Includes bibliographical referencesby Shuchi Zhan
Structural and functional characterization of a Xanthomonas Type III effector
No full textRice bacterial leaf streak disease caused by Xanthomonas oryzae pv. oryzicola (Xoc) is one of the most important rice bacterial diseases. Xanthomonas type III effector gene avrRxo1 is conserved in diverse Xoc strains and its homologues have been identified from several other gram-negative bacteria species such as Burkholderia and Acidovorax. In this research, we studied the protein structure of AvrRxo1 and illustrated its virulence mechanism.We determined the three-dimensional structure of the complex of AvrRxo1 and its cognate chaperone Arc1 (AvrRxo1 required chaperone 1). The AvrRxo1: Arc1 complex is structurally similar to the Zeta-epsilon family of toxin: antitoxin systems from the human bacterial pathogen Streptococcus pyogenes. AvrRxo1 and Arc1 have toxin: antitoxin-like activity in bacteria, and the toxin activity of AvrRxo1 is required for its virulence function in planta. These findings suggest that AvrRxo1 evolved from an endogenous bacterial toxin-antitoxin system.Furthermore, AvrRxo1 was shown to have virulence functions in diverse host plants including Arabidopsis thaliana. The ectopic expression of wild type avrRxo1 in Arabidopsis suppresses plant basal defense. AtVOZ (Arabidopsis vascular one zinc-finger transcription factor), which has two homologues in the Arabidopsis genome, VOZ1 and VOZ2, was identified as one of AvrRxo1 candidate interactor. The knockout of voz1/voz2 renders the plants more susceptible to the virulent pathogen Pseudomonas syringae pv. tomato (Pst) DC3000, but compromises the virulence function of AvrRxo1. The expression profiling of transgenic Arabidopsis plants expressing the avrRxo1 gene allowed us to identify Arabidopsis genes regulated by AvrRxo1 and VOZ1/2. AvrRxo1 interacts with and stabilizes VOZ2 in vivo and directly binds to the promoter region of AtCYS2 (Arabidopsis phytoCYStatin 2) to induce its expression. The overexpression of CYS2 in increased stomatal aperture size, and enhanced plant susceptibility to Pst. Therefore one of AvrRxo1 virulent functions is to regulate the expression of CYS2 by manipulating VOZ2, resulting in increased stomatal aperture. Presumably, this renders the host leaf more susceptible to colonization via the stomata. Another component of my dissertation was based on a genome-wide survey of Arabidopsis papin-like cysteine protease genes (PLCPs). The Arabidopsis genome has 31 PLCP and 7 cystatin genes, and they often worked in pairs to regulate signaling pathways in response to biotic and abiotic stress. The coordinated transcriptional regulation of all Arabidopsis PLCP and cystatin genes has never been systematically investigated. In order to unveil the mechanism of stomata-related plant immunity regulated by CYS2, we analyzed the expression patterns of 28 PLCPs and 7 cystatins in Arabidopsis in response to biotic or abiotic stress, by reprocessing and integrating microarray data from the AtGenExpress database. We also performed enzyme assays and evaluated the inhibition specificity of seven cystatins to the five most abundant PLCPs in Arabidopsis. Finally, we utilized the SVMs (support vector machines) package in R software to predict a functional network of PLCP-cystatin interplay in Arabidopsis. We identified the PLCP protein PAP4 as one of the putative targets of CYS2. The co-expression profiling indicated that the expression patterns of PAP4 and CYS2 were strongly correlated during virulent bacterial infection, and weakly correlated under drought stress. Therefore, PAP4 was determined to be a promising gene in regulating stomatal aperture size. Further research on the interplay of PAP4-CYS2 could be important for understanding AvrRxo1's virulence mechanism and regulation of plant stomatal immunity.Ph. D
Using Clear Nail Polish to Make Arabidopsis Epidermal Impressions for Measuring the Change of Stomatal Aperture Size in Immune Response
No full textAdsorption of CO and O2 molecules on Li metal adsorbed graphene: Search for graphene based gas sensors
No full textIn-vitro efficacy analysis of aqueous extract of Zingiber officinale, Boswellia serrata and Coleus aromaticus against pathogenic Staphylococcus aureus
No full textIn the present study aqueous extracts of Zingiber officinale, Boswellia serrata and Coleus aromaticus were investigated for the presence of various phytochemicals. Their antioxidant and antimicrobial activities were also determined against Staphylococcus aureus. Phytochemical analyses revealed the presence of phenols, flavonoids, terpenoids, proteins, carbohydrates and saponins in different extracts. The susceptibility of bacterial strain against the aqueous extracts was determined using the well diffusion method. The zone of inhibition of different concentrations of the aqueous extracts against microbe was found to be in the range of 7-27 mm. The results showed that the aqueous extract taken in the concentrations of 50μg/ml (Coleus aromaticus), 100μg/ml (Boswellia serrata) and 200μg/ml (Zingiber officinale) were effective in antimicrobial activity against the test pathogen. Highest antibacterial activity was observed with Coleus aromaticus extract with 27 mm diameter of zone of inhibition while minimum activity was observed with aqueous extract of Zingiber officinale. The antioxidant activity was revealed by reducing power assay method and showed that aqueous extract of Coleus aromaticus has good reducing power which leads to potential antioxidant activity
Methyl Laurate Production in Synechocystis
No full textabstract: To efficiently produce biofuels and meet the planet’s rising energy demands, different biofuel production methods need to be developed and improved. One of the ways is to produce fatty acid methyl esters (FAMEs) in Synechocystis sp. PCC 6803, a versatile strain of cyanobacteria. In this thesis, Synechocystis was engineered to produce and excrete methyl laurate. In this pathway, first, lauroyl-ACP from fatty acid biosynthesis is converted to laurate by a thioesterase (TE) from Umbellularia californica. Then, the laurate is methylated to methyl laurate by a juvenile hormone acid O-methyltransferase (DmJHAMT) from Drosophila melanogaster. The TE/∆slr1609 strain of Synechocystis sp. PCC 6803 contains the TE gene and lacks the slr1609 gene encoding an acyl–acyl carrier protein synthetase, which functions in free fatty acid reuptake. The DmJHAMT gene was introduced into this strain for FAME production.
The DmJHAMT gene was cloned into a vector that contains neutral sites from the Synechocystis genome, making it suitable for homologous recombination, and a kanamycin resistance gene, for selection. The obtained plasmid was verified using restriction digests and Sanger sequencing. The sequence analysis and comparison of the cDNA in the obtained plasmid and the mRNA transcript of the same gene revealed three amino acid differences. Subsequent comparison with homologous genes in other Drosophila species revealed the differences in the cDNA match those of the other species, and thus, the gene most likely is functional.
The plasmid was transformed into Synechocystis, and PCRs were used to confirm proper integration and segregation. The TE/∆slr1609/DmJHAMT strain produced 62 mg/L methyl laurate in 12 days under a light intensity of 150 µmol photons m-2 s-1, bubbled with 0.5% CO2 at a rate of 30 mL/min, and supplemented with 0.5 mM methionine. The laurate levels did not decrease over time, but instead, remained stagnant after day 3. When the strain was grown in the same conditions without methionine, the laurate concentrations continued to increase above 400 µM, suggesting minimal methyl laurate production and thus a strong need for methionine supplementation. This work provides further evidence of the viability and success of the introduced FAME production pathway, and improved efficiency may be gained in the future
A Matching-adjusted Indirect Comparison of Nivolumab Plus Cabozantinib Versus Pembrolizumab Plus Axitinib in Patients with Advanced Renal Cell Carcinoma
No full textBackground: The comparative efficacy and health-related quality of life (HRQoL) outcomes of nivolumab plus cabozantinib versus pembrolizumab plus axitinib as first-line treatments for advanced renal cell carcinoma (aRCC) have not been assessed in head-to-head trials. Objective: To assess the efficacy and HRQoL outcomes of nivolumab plus cabozantinib versus pembrolizumab plus axitinib. Design, setting, and participants: Patient-level data for nivolumab plus cabozantinib from the CheckMate 9ER trial and published data for pembrolizumab plus axitinib from the KEYNOTE-426 trial were used. CheckMate 9ER data were reweighted to match the key baseline characteristics as reported in KEYNOTE-426. Intervention: Nivolumab (240 mg every 2 wk) plus cabozantinib (40 mg once daily) and pembrolizumab (200 mg every 3 wk) plus axitinib (5 mg twice daily, initially). Outcome measurements and statistical analysis: Hazard ratios (HRs) for progression-free survival (PFS), duration of response, overall survival (OS), and deterioration in HRQoL were assessed using weighted Cox proportional-hazard models, with sunitinib as a common anchor. Objective response rates (ORRs) and changes in HRQoL scores from baseline were assessed as difference-in-differences for the two treatments relative to sunitinib. Results and limitations: After balancing patient characteristics between the trials, nivolumab plus cabozantinib was associated with significantly improved PFS (HR [95% confidence interval {CI}] 0.70 [0.53-0.93]; p = 0.01) and a significantly decreased risk of confirmed deterioration in HRQoL (Functional Assessment of Cancer Therapy-Kidney Symptom Index-Disease-related Symptoms: HR [95% CI] 0.48 [0.34-0.69]) versus pembrolizumab plus axitinib. OS was similar between treatments (HR [95% CI] 0.99 [0.67-1.44]; p = 0.94). Nivolumab plus cabozantinib was associated with numerically greater ORRs (difference-in-difference [95% CI] 8.4% [-1.7 to 18.4]; p = 0.10) and longer duration of response (HR [95% CI] 0.79 [0.47-1.31]; p = 0.36) than pembrolizumab plus axitinib. Comparative studies using data with a longer duration of follow-up are warranted. Conclusions: Nivolumab plus cabozantinib significantly improved PFS and HRQoL compared with pembrolizumab plus axitinib as first-line treatment for aRCC. Patient summary: This study was conducted to indirectly compare the results of two immunotherapy-based combinations-nivolumab plus cabozantinib versus pembrolizumab plus axitinib-for patients who have not received any treatment for advanced renal cell carcinoma. Patients who received nivolumab plus cabozantinib had a significant improvement in the length of time without worsening of their disease and in their perceived physical and mental health compared with pembrolizumab plus axitinib; patients remained alive for a similar length of time from the start of either treatment. This analysis further adds to our current knowledge of the relative benefits of these two treatment regimens and will help with physician and patient treatment decisions
- …
