Previously, two riboswitch classes have been identified that sense and respond to the hypermodified nucleobase called prequeuosine1 (preQ1). The enormous expansion of available genomic DNA sequence ...data creates new opportunities to identify additional representatives of the known riboswitch classes and to discover novel classes. We conducted bioinformatics searches on microbial genomic DNA data sets to discover numerous additional examples belonging to the two previously known riboswitch classes for preQ1 (classes preQ1-I and preQ1-II), including some structural variants that further restrict ligand specificity. Additionally, we discovered a third preQ1-binding riboswitch class (preQ1-III) that is structurally distinct from previously known classes. These findings demonstrate that numerous organisms monitor the concentrations of this modified nucleobase by exploiting one or more riboswitch classes for this widespread compound.
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•Additional variant types of class I and II preQ1 riboswitches have been discovered•A third riboswitch class that senses preQ1 has been discovered and validated•Our findings expand the bacterial lineages that exploit preQ1-sensing riboswitches
McCown et al. identify variants within two known riboswitch classes and a previously unknown riboswitch class that sense prequeuosine1, a nearly ubiquitous nucleobase with an unclear biological role. Phylogenetic analysis of these RNAs suggests they use distinct recognition strategies for this ancient compound.
ABSTRACTThis paper presents an empirical method for converting reflectivity from Ku‐band (13.8 GHz) to S‐band (2.8 GHz) for several hydrometeor species, which facilitates the incorporation of ...Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) measurements into quantitative precipitation estimation (QPE) products from the U.S. Next‐Generation Radar (NEXRAD). The development of empirical dual‐frequency relations is based on theoretical simulations, which have assumed appropriate scattering and microphysical models for liquid and solid hydrometeors (raindrops, snow, and ice/hail). Particle phase, shape, orientation, and density (especially for snow particles) have been considered in applying the T‐matrix method to compute the scattering amplitudes. Gamma particle size distribution (PSD) is utilized to model the microphysical properties in the ice region, melting layer, and raining region of precipitating clouds. The variability of PSD parameters is considered to study the characteristics of dual‐frequency reflectivity, especially the variations in radar dual‐frequency ratio (DFR). The empirical relations between DFR and Ku‐band reflectivity have been derived for particles in different regions within the vertical structure of precipitating clouds. The reflectivity conversion using the proposed empirical relations has been tested using real data collected by TRMM‐PR and a prototype polarimetric WSR‐88D (Weather Surveillance Radar 88 Doppler) radar, KOUN. The processing and analysis of collocated data demonstrate the validity of the proposed empirical relations and substantiate their practical significance for reflectivity conversion, which is essential to the TRMM‐based vertical profile of reflectivity correction approach in improving NEXRAD‐based QPE.
Key PointsInvestigate the vertical structure of precipitationDevelop empirical relations for space‐borne and ground radarsProvide an approach of TRMM‐based VPR correction
Abstract
Kinase signaling in the tiered activation of inflammasomes and associated pyroptosis is a prime therapeutic target for inflammatory diseases. While MAPKs subsume pivotal roles during ...inflammasome priming, specifically the MAP3K7/JNK1/NLRP3 licensing axis, their involvement in successive steps of inflammasome activation is poorly defined. Using live–cell MAPK biosensors to focus on the inflammasome triggering event allowed us to identify a subsequent biphasic JNK activation. We find that post–trigger JNK signaling distinctly facilitates both mitochondrial reactive oxygen species generation needed to support core inflammasome formation, and gasdermin–mediated cell permeation leading to release of active IL–1β from human macrophages. We further identify and characterize a xanthine oxidase–ROS activated MAP3K5/JNK2 substrate licensing complex as a novel regulator of GSDMD mobilization preceding pyroptosis. We find that inhibitors targeting this MAP3K5 cascade alleviate morbidity in mouse models of colitis and dampen both augmented IL–1β release and cell permeation in monocytes derived from patients with gain–of–function inflammasomopathies.
This work was supported by the Intramural Research Program of NIAID, NIH.
The topographic wetness index (TWI), frequently used in approximately characterizing the spatial distribution of soil moisture and surface saturation within a watershed, has been widely applied in ...topography-related geographical processes and hydrological models. However, it is still questionable whether the current algorithms of TWI can adequately model the spatial distribution of topographic characteristics. Based upon the widely-used multiple flow direction approach (MFD), a novel MFD algorithm (NMFD) is proposed for improving the TWI derivation using a Digital Elevation Model (DEM) in this study. Compared with MFD, NMFD improves the mathematical equations of the contributing area and more precisely calculates the effective contour length. Additionally, a varying exponent strategy is adopted to dynamically determine the downslope flow-partition exponent. Finally, a flow-direction tracking method is employed to address grid cells in flat terrain. The NMFD algorithm is first applied to a catchment located upstream of the Hanjiang River in China to demonstrate its accuracy and improvements. Then NMFD is quantitatively evaluated by using four types of artificial mathematical surfaces. The results indicate that the error generated by NMFD is generally lower than that computed by MFD, and NMFD is able to more accurately represent the hydrological similarity of watersheds.
Deep ultraviolet (DUV) optical wireless communications have seen increased interest in recent years due to the unique properties of light in this spectral region. However, the reported DUV data rates ...remain significantly lower than comparable demonstrations at visible wavelengths due to lower modulation bandwidths and/or output power of the sources. Here, we present a wavelength division multiplexing demonstration using three UV micro-light-emitting diodes emitting at nominal peak wavelengths of 285, 317, and 375 nm, respectively, each with an emitting area of approximately
1369
μm
2
(equivalent to circular device pixels of diameter
∼
40
μm
). Using orthogonal frequency division multiplexing, data rates of 4.17, 3.02, and 3.13 Gbps were achieved from the 285, 317, and 375 nm devices, respectively, for a combined data rate of 10.32 Gbps transmitted over a distance of 0.5 m.
Phosphorous-containing heterocycles have attracted particular interest because they exhibit markedly different properties than common oxygen-, nitrogen-, and/or sulfur-based heterocyclic compounds. ...However, the study of such molecules remains difficult because of a lack of synthetic methods with which to synthesize them, especially with respect to the construction of P-stereogenic centers. Here, we present a simple, versatile method for the synthesis of PN-heterocycles bearing P(V) centers from phosphanamines through palladium-catalyzed intramolecular C–P coupling. Under the developed catalytic systems, chiral PN-heterocycles can be produced from P(III)-stereogenic precursors without loss of stereochemical integrity. Computational studies revealed the detailed reaction pathway and the origin of stereospecificity. The methods showed excellent functional-group tolerance, allowing access to diverse, optoelectronically relevant products that are stable under air and moisture.
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•Facile construction of PN-heterocycles with excellent functional-group tolerance•NH/PH tautomeric equilibrium between the P(III) and P(V) atom•Cross-couplings of P-stereogenic precursors without loss of stereochemical integrity•Mechanistic probes of stereospecific C–P bond formation
A strategy for constructing heterocycles bearing phosphorous and nitrogen is presented. The approach entails a Pd-catalyzed intramolecular C–P phosphanamine coupling that undergoes NH/PH tautomeric equilibrium between the P(III) and P(V) species. Importantly, the P(III)-stereogenic precursors can be used for stereospecific transformation for facile formation of diverse enantioenriched P(V)-phosphacycles. The protocol uses readily available substrates under simple reaction conditions to construct PN-heterocycles, which would be challenging by means of traditional cross-coupling methods.
Diverse stable heterocycles bearing phosphorous (V) and nitrogen centers were generated by palladium-catalyzed intramolecular C–P coupling of aryl chlorides, in which NH/PH undergoes tautomeric equilibrium between the P(III) and P(V) with no loss of optical information.
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