A tissue-like neurotransmitter sensor for the brain and gut.

Neurotransmitters play essential roles in regulating neural circuit dynamics both in the central nervous system as well as at the peripheral, including the gastrointestinal tract1-3. Their real-time monitoring will offer critical information for understanding neural function and diagnosing disease1-3. However, bioelectronic tools to monitor the dynamics of neurotransmitters in vivo, especially in the enteric nervous systems, are underdeveloped. This is mainly owing to the limited availability of biosensing tools that are capable of examining soft, complex and actively moving organs. Here we introduce a tissue-mimicking, stretchable, neurochemical biological interface termed NeuroString, which is prepared by laser patterning of a metal-complexed polyimide into an interconnected graphene/nanoparticle network embedded in an elastomer. NeuroString sensors allow chronic in vivo real-time, multichannel and multiplexed monoamine sensing in the brain of behaving mouse, as well as measuring serotonin dynamics in the gut without undesired stimulations and perturbing peristaltic movements. The described elastic and conformable biosensing interface has broad potential for studying the impact of neurotransmitters on gut microbes, brain-gut communication and may ultimately be extended to biomolecular sensing in other soft organs across the body.

Structurally distinct bacterial TBC-like GAPs link Arf GTPase to Rab1 inactivation to counteract host defenses.

Rab GTPases are frequent targets of vacuole-living bacterial pathogens for appropriate trafficking of the vacuole. Here we discover that bacterial effectors including VirA from nonvacuole Shigella flexneri and EspG from extracellular Enteropathogenic Escherichia coli (EPEC) harbor TBC-like dual-finger motifs and exhibits potent RabGAP activities. Specific inactivation of Rab1 by VirA/EspG disrupts ER-to-Golgi trafficking. S. flexneri intracellular persistence requires VirA TBC-like GAP activity that mediates bacterial escape from autophagy-mediated host defense. Rab1 inactivation by EspG severely blocks host secretory pathway, resulting in inhibited interleukin-8 secretion from infected cells. Crystal structures of VirA/EspG-Rab1-GDP-aluminum fluoride complexes highlight TBC-like catalytic role for the arginine and glutamine finger residues and reveal a 3D architecture distinct from that of the TBC domain. Structure of Arf6-EspG-Rab1 ternary complex illustrates a pathogenic signaling complex that rewires host Arf signaling to Rab1 inactivation. Structural distinctions of VirA/EspG further predict a possible extensive presence of TBC-like RabGAP effectors in counteracting various host defenses.

From Quaternary Carbon to Tertiary C(sp3)-Si and C(sp3)-Ge Bonds: Decyanative Coupling of Malononitriles with Chlorosilanes and Chlorogermanes Enabled by Ni/Ti Dual Catalysis.

Transition-metal-catalyzed C-Si/Ge cross-coupling offers promising avenues for the synthesis of organosilanes/organogermanes, yet it is fraught with long-standing challenges. A Ni/Ti-catalyzed strategy is reported here, allowing the use of disubstituted malononitriles as tertiary C(sp3) coupling partners to couple with chlorosilanes and chlorogermanes, respectively. This method enables the catalytic cleavage of the C(sp3)-CN bond of the quaternary carbon followed by the formation of C(sp3)-Si/C(sp3)-Ge bonds from ubiquitously available starting materials. The efficiency and generality are showcased by a broad scope for both of the coupling partners, therefore holding the potential to synthesize structurally diverse quaternary organosilanes and organogermanes that were difficult to access previously.

Spätzle maintains homeostasis of hemolymph microbiota in Scylla paramamosain through Toll2.

The Toll pathway is crucial for innate immune responses in organisms (including Drosophila and mammals). The Spätzle protein outside of cells acts as a ligand for Toll receptors, enabling the transfer of signals from outside the cell to the inside. However, the function of Spätzle in the immune system of mud crab (Scylla paramamosain) remains unclear. This research discovered a novel Spätzle gene (Sp-Spz) in mud crab, which showed extensive expression in all the tissues that were examined. The RNA interference exhibited the correlation between Sp-Spz and the anti-lipopolysaccharide factors (ALFs). Knockdown of Sp-Spz decreased the expression of Sp-Toll2 but not Sp-Toll1. In Drosophila Schneider 2 cells, Sp-Spz was found interacted with Sp-Toll2. Moreover, the depletion of Sp-Spz caused the separation of hepatic lobules from the basement membrane, resulting in the disruption of the structural coherence of hepatopancreatic cells. Additionally, the knockdown of Sp-Spz resulted in changes to the composition of the hemolymph microbiota, specifically affecting the proportions of different phylum and family levels. The findings indicated that Sp-Spz may promote the synthesis of ALFs via Sp-Toll2, thereby influencing the homeostasis of microbiota in the hemolymph. In this study, novel insights into mud crab immunity are provided.

Reductive Aza-Pauson-Khand Reaction of Nitriles.

γ-Lactams are valuable heterocycles in synthetic chemistry and drug development. Here, we report a reductive aza-Pauson-Khand reaction (aza-PKR) of an alkyne, a nitrile, and Co2(CO)8. A wide array of bicyclic α,ß-unsaturated γ-lactams containing two adjacent stereocenters, including an all-carbon quaternary center, from alkyne-tethered malononitriles are efficiently accessed in high diastereoselectivity. Preliminary mechanistic investigations by experiments and DFT calculations reveal that the reaction undergoes an aza-PKR process followed by a in situ reduction. The reducing reagent generated in situ from water also provides a practical tool for deuterium incorporation into the γ-position of lactams using D2O as the deuterium source. This study represents a new mode for [2 + 2 + 1] cycloaddition that enables the direct use of nitrile in aza-heterocycle synthesis.

[Research summary of chemical constituents and pharmacological effects of Panax notoginseng and predictive analysis on its Q-markers].

Panax notoginseng contains triterpene saponins, flavonoids, amino acids, polysaccharides, volatile oil and other active components, which have the effects of promoting blood circulation, stopping bleeding, removing blood stasis, etc. This study summarized the herbal research, chemical constituents and main pharmacological activities of P. notoginseng, and based on the theory of Q-markers of traditional Chinese medicine, predicted and analyzed the Q-markers of P. notoginseng from the aspects of plant kinship, efficacy, drug properties, measurability of chemical components, etc. It was found that ginsenosides Rg_1, Re, and Rb_1 with specific content ratio, ginsenosides Rb_2, Rb_3, Rc, Rd, Rh_2, and Rg_3, notoginseng R_1, dencichine and quercetin could be used as potential Q-markers of P. notoginseng, which facilitated the formulation of quality standards reflecting the efficacy of P. notoginseng.

Core rhizosphere microbiome of Panax notoginseng and its associations with belowground biomass and saponin contents.

The core rhizosphere microbiome is critical for plant fitness. However, its contribution to the belowground biomass and saponin contents of Panax notoginseng remains unclear. High-throughput sequencing of amplicon and metagenome was performed to obtain the microbiome profiles and functional traits in P. notoginseng rhizosphere across a large spatial scale. We obtained 639 bacterial and 310 fungal core OTUs, which were mainly affected by soil pH and organic matter (OM). The core taxa were grouped into four ecological clusters (i.e. high pH, low pH, high OM and low OM) for sharing similar habitat preferences. Furthermore, structural equation modelling (SEM) and correlation analyses revealed that the diversity and composition of core microbiomes, as well as the metagenome-derived microbial functions, were related to belowground biomass and saponin contents. Key microbial genera related to the two plant indicators were also identified. In short, this study explored the main driving environmental factors of core microbiomes in the P. notoginseng rhizosphere and revealed that the core microbiomes and microbial functions potentially contributed to the belowground biomass and saponin contents of the plant. This work may enhance our understanding of interactions between microbes and perennial plants and improve our ability to manage root microbiota for the sustainable production of herbal medicine.

DFT Study of Mechanism and Stereochemistry of Nickel-Catalyzed trans-Arylative Desymmetrizing Cyclization of Alkyne-Tethered Malononitriles.

Present here is a density functional theory (DFT) study of the mechanism and origin of enantioselectivity of Ni-catalyzed desymmetric cyclization of alkyne-tethered malononitriles and aryl boronic acids. The reaction starts from transmetalation and arylnickel addition, followed by trans to cis isomerization to give cis-alkenyl nickel species. The stereodetermining step is the CN insertion, which prefers a transition state with the bystander CN group staying away from the ligand to reduce steric repulsion, and gives the final (R)-product.

Consumer Preferences for E-cigarette Flavor, Nicotine Strength, and Type: Evidence from Nielsen Scanner Data.

INTRODUCTION: Many countries regulate e-cigarette attributes such as flavors and nicotine strength. Despite a large literature on consumer preferences for e-cigarette attributes, none used consumer-level longitudinal purchase data. We therefore use a unique large dataset on U.S. adults' e-cigarette purchases as to gain insight into real-world consumer choices and purchasing patterns. METHODS: A total of 7098 purchase transactions, made by 1239 households on e-cigarette from various retail outlets for 2013 through 2017, were collected from Nielsen scanner data. We then apply an innovative multinomial logit model to examine which factors affected adult choices over 23 e-cigarettes products broken down by eight brands, three flavors, three nicotine strength levels, and two types. RESULTS: We found that tobacco flavor, medium nicotine strength (12< mg/ml ≤18), or disposables lead to higher adult purchases and such preference can vary over cigarette smoking status, purchase frequency, gender, race, and age. Specifically, smokers tend to purchase tobacco flavor, non-smokers or female vapers tend to purchase medium strength, and infrequent vapers tend to purchase disposables. Vapers are quite responsive to e-cigarette prices and also display loyalty (inertia) to e-cigarette brands, flavor, and nicotine strength. CONCLUSIONS: When modeled together, e-cigarette flavors, strength, type, price, and previous choice were all found to influence vapers' current purchase decision in the actual retail environment. IMPLICATIONS: The evidence presented here indicates that the impacts of certain restrictions on e-cigarette attributes, such as a flavor ban or maximum level of nicotine content, might have heterogeneous impacts on adults.

A Computational Mechanistic Study of Cp*Co(III)-Catalyzed Three-Component C-H Bond Addition to Terpenes and Formaldehydes: Insights into the Origins of Regioselectivity.

Transition metal-catalyzed three-component reactions of arenes, dienes, and carbonyls enable the convergent synthesis of homoallylic alcohols. Controlling regioselectivity is a central challenge for the difunctionalization of substituted 1,3-dienes in which multiple unbiased C═C bonds exist. Here, the mechanisms of Cp*Co(III)-catalyzed three-component C-H bond addition to terpenes and formaldehydes were investigated by density functional theory calculations. The reaction proceeds via sequential C(sp2)-H activation, migratory insertion, ß-hydride elimination, hydride reinsertion, and C-C bond formation to yield the final product. The migratory insertion is the rate- and regioselectivity-determining step of the overall reaction. We employed an energy decomposition approach to quantitatively dissect the contributions of different types of interactions to regioselectivity. For the 2-alkyl substituted 1,3-dienes, the orbital interactions in the 3,4-insertion are intrinsically more favorable as compared to that in the 4,3-insertion, while the stronger steric effects between metallacycle and 1,3-diene override the intrinsic electronic preference. However, the steric effects failed to rationalize the unfavorable 1,2-insertion that is analogous to 4,3-insertion and even bears smaller steric effects. The donor-acceptor interaction analysis indicates that orbital interactions between σCo-C and πC═C decreased significantly in the 1,2-insertion transition state, which leads to higher activation energy barriers. These insights into the dominant effects controlling regioselectivity will enable rational design of new catalysts for selective functionalization of dienes.

Transcription factor OsMADS25 improves rice tolerance to cold stress.

Cold stress is the limiting factor of rice growth and production, and it is important to clone cold stress tolerant genes and cultivate cold tolerance rice varieties. The MADS transcription factors play an important role in abiotic stress signaling in rice. This study showed that OsMADS25 was up-regulated by low temperature and abscisic acid (ABA), suggesting that OsMADS25 may be involved in ABA-dependent signaling. The OsMADS25 overexpression vector, pCambia1300-221-OsMADS25-Flag, was constructed and introduced into the rice variety Zhonghua 11 (ZH11) through Agrobacterium tumefacian-mediated genetic transformation. Two homozygous lines with high expression levels were selected for phenotypic identification. OsMADS25 overexpression lines show significantly improved cold stress tolerance and the sensitivity to ABA at the seedling stage of rice. Reactive oxygen species (ROS) was detected by diaminobenzidine (DAB) staining and nitroblue tetrazolium (NBT) staining. After treatment with cold stress, little ROS accumulation was observed in OsMADS25 overexpression lines compared to wild-type ZH11. In conclusion, OsMADS25 plays a role in scavenging reactive oxygen species (ROS) and could improve rice tolerance to cold stress involved in ABA-dependent pathway.

[Herbal textual research on Chuanxiong Rhizoma in Chinese classical prescriptions].

Fourteen classical prescriptions in the Catalog of 100 Ancient Classical Prescriptions(First Batch) promulgated in 2018 contain Chuanxiong Rhizoma, which reveals the high medicinal value and wide application of Chuanxiong Rhizoma. This paper systematically reviews the ancient herbal books and modern literature to explore the name, origin, genuine producing area, medicinal part, harvesting, and processing of Chuanxiong Rhizoma, thus facilitating the development of classical prescriptions containing Chuan-xiong Rhizoma. It is confirmed that Chuanxiong Rhizoma, formerly known as "Xiongqiong" in Chinese, was first called "Chuanxiong" in late Tang Dynasty, which has been gradually accepted as its official name due to the rise of the status of Chuanxiong Rhizoma produced in Sichuan. The main original plant of Chuanxiong Rhizoma in past dynasties has always been deemed to be Ligusticum chuan-xiong(Umbellifera), whose rhizome serves as the medicinal part. In general, it is best harvested in summer but the harvesting time can vary with different growth environments. Since the Song Dynasty, Sichuan province has been recognized as the genuine producing area of Chuanxiong Rhizoma in light of the high yield and good quality. It is suggested that Chuanxiong Rhizoma from Sichuan be used preferentially in the development of classical prescriptions. There are multiple processing methods of Chuanxiong Rhizoma recorded in ancient medical classics, and the raw(after purifying and slicing) or wine-processed or stir-fried Chuanxiong Rhizoma is still in use today. In the development of classical prescriptions containing Chuanxiong Rhizoma, Chuanxiong Rhizoma is advised to be processed in accordance with current processing standards if the specific processing method is described in the medical classics. If not, the raw Chuanxiong Rhizoma is preferred and then processed following the processing standards of Chuanxiong Rhizoma decoction pieces in Chinese Pharmacopoeia.

Multi-scale ordering in highly stretchable polymer semiconducting films.

Stretchable semiconducting polymers have been developed as a key component to enable skin-like wearable electronics, but their electrical performance must be improved to enable more advanced functionalities. Here, we report a solution processing approach that can achieve multi-scale ordering and alignment of conjugated polymers in stretchable semiconductors to substantially improve their charge carrier mobility. Using solution shearing with a patterned microtrench coating blade, macroscale alignment of conjugated-polymer nanostructures was achieved along the charge transport direction. In conjunction, the nanoscale spatial confinement aligns chain conformation and promotes short-range π-π ordering, substantially reducing the energetic barrier for charge carrier transport. As a result, the mobilities of stretchable conjugated-polymer films have been enhanced up to threefold and maintained under a strain up to 100%. This method may also serve as the basis for large-area manufacturing of stretchable semiconducting films, as demonstrated by the roll-to-roll coating of metre-scale films.

Organic Semiconducting Alloys with Tunable Energy Levels.

Continuous band structure tuning, e.g., doping with different atoms, is one of the most important features of inorganic semiconductors. However, this can hardly be realized in organic semicondutors. Here, we report the first example of fine-tuning organic semiconductor band structures by alloying structurally similar derivatives into one single phase. By incorporating halogen atoms on different positions of the backbone, BDOPV derivatives with complementary intramolecular or intermolecular charge distributions were obtained. To maximize the Coloumbic attractive interactions and minimize repulsive interactions, they form antiparallel cofacial stacking in monocomponent or in alloy single crystals, resulting in efficient π orbital overlap. Benefiting from self-assembly induced solid state "olefin metathesis" reaction, it was observed, for the first time, that three BDOPV derivatives cocrystallized in one single crystal. Molecules with different energy levels serve like the dopants in inorganic semiconductors. Consequently, as the total number of halogen atoms increased, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the alloy single crystals decreased monotonously in the range from -5.94 to -6.96 eV and -4.19 to -4.48 eV, respectively.

Skip residues modulate the structural properties of the myosin rod and guide thick filament assembly.

The rod of sarcomeric myosins directs thick filament assembly and is characterized by the insertion of four skip residues that introduce discontinuities in the coiled-coil heptad repeats. We report here that the regions surrounding the first three skip residues share high structural similarity despite their low sequence homology. Near each of these skip residues, the coiled-coil transitions to a nonclose-packed structure inducing local relaxation of the superhelical pitch. Moreover, molecular dynamics suggest that these distorted regions can assume different conformationally stable states. In contrast, the last skip residue region constitutes a true molecular hinge, providing C-terminal rod flexibility. Assembly of myosin with mutated skip residues in cardiomyocytes shows that the functional importance of each skip residue is associated with rod position and reveals the unique role of the molecular hinge in promoting myosin antiparallel packing. By defining the biophysical properties of the rod, the structures and molecular dynamic calculations presented here provide insight into thick filament formation, and highlight the structural differences occurring between the coiled-coils of myosin and the stereotypical tropomyosin. In addition to extending our knowledge into the conformational and biological properties of coiled-coil discontinuities, the molecular characterization of the four myosin skip residues also provides a guide to modeling the effects of rod mutations causing cardiac and skeletal myopathies.

Microscopic mechanisms that govern the titration response and pKa values of buried residues in staphylococcal nuclease mutants.

To probe the microscopic mechanisms that govern the titration behavior of buried ionizable groups, microsecond explicit solvent molecular dynamics simulations are carried out for several mutants of Staphylococcal nuclease using both fixed charge and polarizable force fields. While the ionization of Asp 66, Glu 66, and Lys 125 lead to enhanced structural fluctuations and partial unfolding of adjacent α-helical regions, the ionization of Lys 25 causes local unfolding of adjacent ß sheets. Using the sampled conformational ensembles, good agreement with experimental pKa values is obtained with Poisson-Boltzmann calculations using a protein dielectric constant of 2-4 for V66D/E; slightly larger dielectric constants are needed for Lys mutants especially L25K, suggesting that structural responses beyond microseconds are involved in ionization of Lys 25. Overall, the set of unbiased simulations provides insights into the spatial and temporal scales of protein and solvent motions that dictate the diverse titration behaviors of buried protein residues. Proteins 2017; 85:268-281. © 2016 Wiley Periodicals, Inc.

U.S. Demand for Tobacco Products in a System Framework.

This study estimated a system of demand for cigarettes, little cigars/cigarillos, large cigars, e-cigarettes, smokeless tobacco, and loose smoking tobacco using market-level scanner data for convenience stores. We found that the unconditional own-price elasticities for the six categories are -1.188, -1.428, -1.501, -2.054, -0.532, and -1.678, respectively. Several price substitute (e.g., cigarettes and e-cigarettes) and complement (e.g., cigarettes and smokeless tobacco) relationships were identified. Magazine and television advertising increased demand for e-cigarettes, and magazine advertising increased demand for smokeless tobacco and had spillover effects on demand for other tobacco products. We also reported the elasticities by U.S. census regions and market size. These results may have important policy implications, especially viewed in the context of the rise of electronic cigarettes and the potential for harm reduction if combustible tobacco users switch to non-combustible tobacco products. Copyright © 2016 John Wiley & Sons, Ltd.

Fine-Tuning of Crystal Packing and Charge Transport Properties of BDOPV Derivatives through Fluorine Substitution.

Molecular packing in organic single crystals greatly influences their charge transport properties but can hardly be predicted and designed because of the complex intermolecular interactions. In this work, we have realized systematic fine-tuning of the single-crystal molecular packing of five benzodifurandione-based oligo(p-phenylenevinylene) (BDOPV)-based small molecules through incorporation of electronegative fluorine atoms on the BDOPV backbone. While these molecules all exhibit similar column stacking configurations in their single crystals, the intermolecular displacements and distances can be substantially modified by tuning of the amounts and/or the positions of the substituent fluorine atoms. Density functional theory calculations showed that the subtle differences in charge distribution or electrostatic potential induced by different fluorine substitutions play an important role in regulating the molecular packing of the BDOPV compounds. Consequently, the electronic couplings for electron transfer can vary from 71 meV in a slipped stack to 201 meV in a nearly cofacial antiparallel stack, leading to an increase in the electron mobility of the BDOPV derivatives from 2.6 to 12.6 cm(2) V(-1) s(-1). The electron mobility of the five molecules did not show a good correlation with the LUMO levels, indicating that the distinct difference in charge transport properties is a result of the molecular packing. Our work not only provides a series of high-electron-mobility organic semiconductors but also demonstrates that fluorination is an effective approach for fine-tuning of single-crystal packing modes beyond simply lowering the molecular energy levels.

Cyclopentapeptides from Dianthus chinensis.

A new cyclopentapeptide dianthin I (1), together with two known ones pseudostellarin A (2) and heterophyllin J (3), was isolated from the aerial parts of Dianthus chinensis. The structure of 1 was elucidated as cyclo-(Gly(1)-L-Phe(2)-L-Pro(3)-L-Ser(4)-L-Phe(5)) on the basis of extensive spectroscopic analyses and chemical methods.

The histone H3 N-terminal tail: a computational analysis of the free energy landscape and kinetics.

Histone tails are the short peptide protrusions outside of the nucleosome core particle and they play a critical role in regulating chromatin dynamics and gene activity. A histone H3 N-terminal tail, like other histone tails, can be covalently modified on different residues to activate or repress gene expression. Previous studies have indicated that, despite its intrinsically disordered nature, the histone H3 N-terminal tail has regions of notable secondary structural propensities. To further understand the structure-dynamics-function relationship in this system, we have carried out 75.6 µs long implicit solvent simulations and 29.3 µs long explicit solvent simulations. The extensive samplings allow us to better characterize not only the underlying free energy landscape but also kinetic properties through Markov state models (MSM). Dihedral principal component analysis (dPCA) and locally scaled diffusion map (LSDMap) analysis yield consistent results that indicate an overall flat free energy surface with several shallow basins that correspond to conformations with a high α-helical propensity in two regions of the peptide. Kinetic information extracted from Markov state models reveals rapid transitions between different metastable states with mean first passage times spanning from several hundreds of nanoseconds to hundreds of microseconds. These findings shed light on how the dynamical nature of the histone H3 N-terminal tail is related to its function. The complementary nature of dPCA, LSDMap and MSM for the analysis of biomolecules is also discussed.