Radically Rethinking Agriculture for the 21st Century Fedoroff, N. V.; Battisti, D. S.; Beachy, R. N. ...
Science (American Association for the Advancement of Science),
02/2010, Letnik:
327, Številka:
5967
Journal Article
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Odprti dostop
Population growth, arable land and fresh water limits, and climate change have profound implications for the ability of agriculture to meet this century's demands for food, feed, fiber, and fuel ...while reducing the environmental impact of their production. Success depends on the acceptance and use of contemporary molecular techniques, as well as the increasing development of farming systems that use saline water and integrate nutrient flows.
The purpose of this study was to examine whether the expression of two chitin synthase genes, AgCHS1 and AgCHS2, can be repressed by chitosan/AgCHS dsRNA-based nanoparticles through larval feeding in ...Anopheles gambiae. The AgCHS1 transcript level and chitin content were reduced by 62.8 and 33.8%, respectively, in the larvae fed on chitosan/AgCHS1 dsRNA nanoparticles compared with those of the control larvae fed on chitosan/GFP dsRNA nanoparticles. Our study suggested for the first time that RNA interference (RNAi) in mosquito larvae is systemic, and demonstrated that the larvae fed on the nanoparticles assembled from AgCHS1 and AgCHS2 dsRNA increased larval susceptibilities to diflubenzuron, and calcofluor white (CF) or dithiothreitol, respectively. These results suggest great potential for using such a nanoparticle-based RNAi technology for high-throughput screening of gene functions and for developing novel strategies for pest management.
Drought, high salinity and freezing impose osmotic stress on plants. Plants respond to the stress in part by modulating gene expression, which eventually leads to the restoration of cellular ...homeostasis, detoxification of toxins and recovery of growth. The signal transduction pathways mediating these adaptations can be dissected by combining forward and reverse genetic approaches with molecular, biochemical and physiological studies. Arabidopsis is a useful genetic model system for this purpose and its relatives including the halophyte Thellungiella halophila, can serve as valuable complementary genetic model systems.
The ubiquitin-proteasome and lysosome-autophagy pathways are the two major intracellular protein degradation systems that work cooperatively to maintain homeostasis. Proteasome inhibitors (PIs) have ...clinical activity in hematological tumors, and inhibitors of autophagy are also being evaluated as potential antitumor therapies. In this study, we found that chemical PIs and small interfering RNA-mediated knockdown of the proteasome's enzymatic subunits promoted autophagosome formation, stimulated autophagic flux, and upregulated expression of the autophagy-specific genes (ATGs) (ATG5 and ATG7) in some human prostate cancer cells and immortalized mouse embryonic fibroblasts (MEFs). Upregulation of ATG5 and ATG7 only occurred in cells displaying PI-induced phosphorylation of the eukaryotic translation initiation factor 2 alpha (eIF2alpha), an important component of the unfolded protein responses. Furthermore, PIs did not induce autophagy or upregulate ATG5 in MEFs expressing a phosphorylation-deficient mutant form of eIF2alpha. Combined inhibition of autophagy and the proteasome induced an accumulation of intracellular protein aggregates reminiscent of neuronal inclusion bodies and caused more cancer cell death than blocking either degradation pathway alone. Overall, our data show that proteasome inhibition activates autophagy through a phospho-eIF2alpha-dependent mechanism to eliminate protein aggregates and alleviate proteotoxic stress.
Summary
Background
Studies on the relation between alcohol consumption and risk of colorectal adenoma (CRA), a precursor of colorectal cancer, have been inconsistent.
Aim
A systematic review with ...meta‐analysis was conducted to investigate the association and the dose–response of alcohol with CRA.
Methods
A literature search was performed on PubMed to identify relevant studies published up to January 2014. A fixed or random effects model was used to estimate summarised relative risks (RRs) and 95% confidence intervals (CIs) for the association between alcohol intake and CRA risk. Statistical heterogeneity between studies was assessed with the χ2 statistic and quantified by I².
Results
Twenty‐three case–control studies and two cohort studies were included in the meta‐analysis. All drinkers were associated with 17% increased risk for CRA, compared with nondrinkers or occasional alcohol drinkers. The dose–response analysis demonstrated that for drinkers of 10, 25, 50 and 100 g/day alcohol consumption, the estimated RRs of CRA were 1.02 (95% CI 0.89–1.16), 1.06 (95% CI 0.92–1.20), 1.16 (95% CI 1.02–1.33) and 1.61 (95% CI 1.42–1.84) respectively, in comparison with non‐/occasional drinkers. The risks were consistent in the subgroup analyses of gender and site of adenoma, while it was stronger in European studies than the studies in the US and Asia.
Conclusions
This study suggests that alcohol intake is related to a significant increase of risk for colrectal adenoma.
A nanostructured surface layer up to 50 μm thick was produced on commercially pure titanium using surface mechanical attrition treatment (SMAT). The microstructural features of the surface layer ...produced by SMAT were systematically characterized by cross-sectional optical microscopy observations, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) investigations. The grain refinement process, accompanied by an increase in strain in the surface layer, involves: (1) the onset of twins and the intersection of twin systems, (2) the formation of dislocation walls, (3) the nucleation of microbands associated with the splitting of dislocation walls, (4) the subdivision of microbands into low angle disoriented blocks and then highly disoriented polygonal submicronic grains, and (5) further breakdown of submicronic polygonal grains into randomly oriented nanograins. The final grain refinement step to form nanograins has been discussed on the basis of a recrystallization process.
Active DNA demethylation regulates many vital biological processes, including early development and locus-specific gene expression in plants and animals. In Arabidopsis, bifunctional DNA glycosylases ...directly excise the 5-methylcytosine base and then cleave the DNA backbone at the abasic site. Recent evidence suggests that mammals utilize DNA glycosylases after 5-methylcytosine is oxidized and/or deaminated. In both cases, the resultant single-nucleotide gap is subsequently filled with an unmodified cytosine through the DNA base excision repair pathway. The enzymatic removal of 5-methylcytosine is tightly integrated with histone modifications and possibly noncoding RNAs. Future research will increase our understanding of the mechanisms and critical roles of active DNA demethylation in various cellular processes as well as inspire novel genetic and chemical therapies for epigenetic disorders.
At constant rotating speed, localized faults in rotating machine tend to result in periodic shocks and thus arouse periodic transients in the vibration signal. The transient feature analysis has ...always been a crucial problem for localized fault detection, and the key aim for transient feature analysis is to identify the model and its parameters (frequency, damping ratio and time index) of the transient, and the time interval, i.e. period, between transients. Based on wavelet and correlation filtering, a technique incorporating transient modeling and parameter identification is proposed for rotating machine fault feature detection. With the proposed method, both parameters of a single transient and the period between transients can be identified from the vibration signal, and localized faults can be detected based on the parameters, especially the period. First, a simulation signal is used to test the performance of the proposed method. Then the method is applied to the vibration signals of different types of bearings with localized faults in the outer race, the inner race and the rolling element, respectively, and all the results show that the period between transients, representing the localized fault characteristic, is successfully detected. The method is also utilized in gearbox fault diagnosis and the effectiveness is verified through identifying the parameters of the transient model and the period. Moreover, it can be drawn that for bearing fault detection, the single-side wavelet model is more suitable than double-side one, while the double-side model for gearbox fault detection. This research proposed an effective method of localized fault detection for rotating machine fault diagnosis through transient modeling and parameter detection.
Summary
Background
There have been inconsistent results reported for leptin levels in patients with psoriasis.
Aim
To evaluate leptin levels in patients with psoriasis using a meta‐analysis of ...studies comparing leptin levels in controls and in patients with psoriasis.
Methods
PubMed (MEDLINE), EMBASE and the Cochrane Library were searched for relevant papers published in English. Pooled weighted mean differences (WMDs) and 95% CIs were calculated using random‐effects and fixed‐effects models. Heterogeneity between studies was assessed using the Cochran Q and I2 statistics.
Results
In total, 11 studies, comprising 773 patients with psoriasis and 570 healthy controls, were identified. Leptin levels were significantly higher in patients with psoriasis compared with controls (WMD = 7.24, 95% CI 4.55–9.93; P < 0.001). On stratified analysis, significant differences in leptin levels between patients with psoriasis and controls were reported only in serum samples (P < 0.001), and not in plasma samples (P = 0.025). Sensitivity analysis showed that there were no changes in the direction of effect when any one study was excluded. No publication bias was detected.
Conclusions
Leptin levels are higher in patients with psoriasis compared with those in controls. Future studies are warranted to clarify the association between leptin levels and the pathomechanism of psoriasis.
Hydrolysis of sodium borohydride (NaBH sub(4)) is one of the most attractive methods for energy generation of mobile systems used as hydrogen source because of the high gravimetric density and ...controllable hydrogen generation of NaBH sub(4). However, regeneration of NaBH sub(4) is a key issue that remains to be solved, and the energy efficiency of NaBH sub(4) is unknown. In the present study, the energy efficiency of NaBH sub(4) hydrolysis and the entire process of sodium metaborate (NaBO sub(2)) regeneration via reaction with magnesium hydride (MgH sub(2)) is determined through thermodynamics calculations. The maximum energy efficiency is 49.91%, indicating that NaBH sub(4) generation by reaction between MgH sub(2) and NaBO sub(2) during ball milling is feasible. An inexpensive high-energy ball milling method is employed to regenerate NaBH sub(4) by reaction of NaBO sub(2) with magnesium-lanthanum hydrides (H-Mg sub(3)La). Products after ball milling are characterized through Fourier transform infrared spectroscopy and X-ray diffraction measurements. In the reaction of NaBO sub(2) with H-Mg sub(3)La, MgH sub(2) reacts with NaBO sub(2) and then lanthanum hydride (LaH sub(3)) reacts with NaBO sub(2) to produce NaBH sub(4).
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