Resistance-gene-directed discovery of a natural-product herbicide with a new mode of action.

Bioactive natural products have evolved to inhibit specific cellular targets and have served as lead molecules for health and agricultural applications for the past century1-3. The post-genomics era has brought a renaissance in the discovery of natural products using synthetic-biology tools4-6. However, compared to traditional bioactivity-guided approaches, genome mining of natural products with specific and potent biological activities remains challenging4. Here we present the discovery and validation of a potent herbicide that targets a critical metabolic enzyme that is required for plant survival. Our approach is based on the co-clustering of a self-resistance gene in the natural-product biosynthesis gene cluster7-9, which provides insight into the potential biological activity of the encoded compound. We targeted dihydroxy-acid dehydratase in the branched-chain amino acid biosynthetic pathway in plants; the last step in this pathway is often targeted for herbicide development10. We show that the fungal sesquiterpenoid aspterric acid, which was discovered using the method described above, is a sub-micromolar inhibitor of dihydroxy-acid dehydratase that is effective as a herbicide in spray applications. The self-resistance gene astD was validated to be insensitive to aspterric acid and was deployed as a transgene in the establishment of plants that are resistant to aspterric acid. This herbicide-resistance gene combination complements the urgent ongoing efforts to overcome weed resistance11. Our discovery demonstrates the potential of using a resistance-gene-directed approach in the discovery of bioactive natural products

High Curie temperature and perpendicular magnetic anisotropy in homoepitaxial InMnAs films

We have prepared the dilute magnetic semiconductor (DMS) InMnAs with different Mn concentrations by ion implantation and pulsed laser melting. The Curie temperature of the In1-xMnxAs epilayer depends on the Mn concentration x, reaching 82 K for x=0.105. The substitution of Mn ions at the Indium sites induces a compressive strain perpendicular to the InMnAs layer and a tensile strain along the in-plane direction. This gives rise to a large perpendicular magnetic anisotropy, which is often needed for the demonstration of electrical control of magnetization and for spin-transfer-torque induced magnetization reversal.Comment: 16 pages, 5 figure

Effects of Full-Length Borealin on the Composition and Protein-Protein Interaction Activity of a Binary Chromosomal Passenger Complex

The chromosomal passenger complex (CPC) comprises at least four protein components and functions at various cellular localizations during different mitotic stages to ensure correct chromosome segregation and completion of cytokinesis. Borealin, the most recently identified member of the CPC, is an intrinsically unstructured protein of low solubility and stability. Recent reports have demonstrated the formation binary or ternary CPC sub-complexes incorporating short Borealin fragments in vitro. Using isothermal titration calorimetry, we show that full-length Borealin, instead of a Borealin fragment possessing the complete Survivin and INCENP-recognition sequence, is required for the composition of a Borealin-Survivin complex competent to interact with INCENP. In addition, we show evidence that full-length Borealin, which forms high-order oligomers in its isolated form, is a monomer in the Borealin-Survivin CPC sub-complex

Extended Infrared Photoresponse in Te-Hyperdoped Si at Room Temperature

Presently, silicon photonics requires photodetectors that are sensitive in a broad infrared range, can operate at room temperature, and are suitable for integration with the existing Si-technology process. Here, we demonstrate strong room-temperature sub-band-gap photoresponse of photodiodes based on Si hyperdoped with tellurium. The epitaxially recrystallized Te-hyperdoped Si layers are developed by ion implantation combined with pulsed-laser melting and incorporate Te-dopant concentrations several orders of magnitude above the solid solubility limit. With increasing Te concentration, the Te-hyperdoped layer changes from insulating to quasi-metallic behavior with a finite conductivity as the temperature tends to zero. The optical absorptance is found to increase monotonically with increasing Te concentration and extends well into the mid-infrared range. Temperature-dependent optoelectronic photoresponse unambiguously demonstrates that the extended infrared photoresponsivity from Te-hyperdoped Si p-n photodiodes is mediated by a Te intermediate band within the upper half of the Si band gap. This work contributes to pave the way toward establishing a Si-based broadband infrared photonic system operating at room temperature.Comment: 18 pages, 7 figure

The Association between Family and Parental Factors and Obesity among Children in Nanchang, China

Background: With rapid economic development in China, traditional patterns of health behaviors are changing, concurrent with a rise in childhood obesity. While the home environment and parenting behaviors are modifiable factors that could be targeted for intervention, little is known about their relationship with children’s health behaviors. Therefore, the purpose of this study was to investigate the relationship between obesity and home and parenting factors in Chinese children. Methods: A cross-sectional survey was conducted in Nanchang, China in 2013 with caregivers (N = 470) of a child between the ages of 2-10 years. Regression analyses were conducted to determine risk factors for childhood obesity. Results: Obesity prevalence (21.7%) did not differ by demographic variables. Eight physical activity, nutrition, and sedentary variables had significant relationships to obesity status. Logistic regression analysis revealed three significant predictors of obesity: the number of days the family eats meals together (odds ratio = 0.84, 95% CI 0.73-0.96) and parental home computer use time (odds ratio = 0.83, 95% CI 0.72-0.96) were related to lower levels of obesity, while parental television time (odds ratio = 1.25 95% CI 1.07-1.47) was related to higher levels of obesity. Conclusions: The prevalence of obesity among children is high in Nanchang. Family and environmental risk factors are significantly related to obesity

Merger Dynamics of the Pair of Galaxy Clusters -- A399 and A401

Convincing evidence of a past interaction between two rich clusters A399 and A401 was recently found by the X-ray imaging observations. In this paper we examine the structure and dynamics of this pair of galaxy clusters. A mixture-modeling algorithm has been applied to obtain a robust partition into two clusters, which allows us to discuss the virial mass and velocity distribution for each cluster. Assuming that these two clusters follow a linear orbit and they have once experienced a close encounter, we model the binary cluster as a two-body system. As a result, four gravitationally bound solutions are obtained. The recent X-ray observations seem to favor a scenario in which the two clusters with a true separation of $5.4h^{-1}$ Mpc are currently expanding at 583 km/s along the direction with a projection angle of 67.5 degree, and they will reach a maximum extent of $5.65h^{-1}$ Mpc in about $1.0h^{-1}$ Gyr.Comment: 11 pages, including 6 EPS figures and 4 tables, uses chjaa.cls, Accepted by the ChJA

Resistance distance, information centrality, node vulnerability and vibrations in complex networks

We discuss three seemingly unrelated quantities that have been introduced in different fields of science for complex networks. The three quantities are the resistance distance, the information centrality and the node displacement. We first prove various relations among them. Then we focus on the node displacement, showing its usefulness as an index of node vulnerability.We argue that the node displacement has a better resolution as a measure of node vulnerability than the degree and the information centrality

Non-Markovian dynamics in a spin star system: The failure of thermalization

In most cases, a small system weakly interacting with a thermal bath will finally reach the thermal state with the temperature of the bath. We show that this intuitive picture is not always true by a spin star model where non-Markov effect predominates in the whole dynamical process. The spin star system consists a central spin homogeneously interacting with an ensemble of identical noninteracting spins. We find that the correlation time of the bath is infinite, which implies that the bath has a perfect memory, and that the dynamical evolution of the central spin must be non- Markovian. A direct consequence is that the final state of the central spin is not the thermal state equilibrium with the bath, but a steady state which depends on its initial state.Comment: 8 page

Principle and recent development in photonic time-stretch imaging

Inspiring development in optical imaging enables great applications in the science and engineering industry, especially in the medical imaging area. Photonic time-stretch imaging is one emerging innovation that attracted a wide range of attention due to its principle of one-to-one-to-one mapping among space-wavelength-time using dispersive medium both in spatial and time domains. The ultrafast imaging speed of the photonics time-stretch imaging technique achieves an ultrahigh frame rate of tens of millions of frames per second, which exceeds the traditional imaging methods in several orders of magnitudes. Additionally, regarding ultrafast optical signal processing, it can combine several other optical technologies, such as compressive sensing, nonlinear processing, and deep learning. In this paper, we review the principle and recent development of photonic time-stretch imaging and discuss the future trends