Modular Construction of Unnatural α-Tertiary Amino Acid Derivatives by Multicomponent Radical Cross-Couplings.

Although the synthesis of α-tertiary amino acids (ATAAs) has been extensively studied, the development of an inexpensive and facile methodology to incorporate multifunctionality on ATAAs remains challenging. In this article, we present a single-step radical approach for the modular synthesis of functionally diverse ATAAs. This synthesis takes place under mild conditions with an absence of metals, photocatalysts, and all other additives. We demonstrate the broad applications of this approach on a variety of aliphatic and aromatic carboxylic acids, alkenes, 1,3-enynes, and oxazolones. The results prove that our method provides excellent functional group tolerance and late-stage applicability, as well as gram-scale synthesis via flow chemistry. Additionally, we include mechanistic studies which reveal that the excited state of oxazolone enolate upon light excitation is a key intermediate that acts as a radical precursor and an efficient reductant.

A survey of transcriptome complexity using PacBio single-molecule real-time analysis combined with Illumina RNA sequencing for a better understanding of ricinoleic acid biosynthesis in Ricinus communis.

BACKGROUND: Ricinus communis is a highly economically valuable oil crop plant from the spurge family, Euphorbiaceae. However, the available reference genomes are incomplete and to date studies on ricinoleic acid biosynthesis at the transcriptional level are limited. RESULTS: In this study, we combined PacBio single-molecule long read isoform and Illumina RNA sequencing to identify the alternative splicing (AS) events, novel isoforms, fusion genes, long non-coding RNAs (lncRNAs) and alternative polyadenylation (APA) sites to unveil the transcriptomic complexity of castor beans and identify critical genes related to ricinoleic acid biosynthesis. Here, we identified 11,285 AS-variants distributed in 21,448 novel genes and detected 520 fusion genes, 320 lncRNAs and 9511 (APA-sites). Furthermore, a total of 6067, 5983 and 4058 differentially expressed genes between developing beans of the R. communis lines 349 and 1115 with extremely different oil content were identified at 7, 14 and 21 days after flowering, respectively. Specifically, 14, 18 and 11 DEGs were annotated encoding key enzymes related to ricinoleic acid biosynthesis reflecting the higher castor oil content of 1115 compared than 349. Quantitative real-time RT-PCR further validated fifteen of these DEGs at three-time points. CONCLUSION: Our results significantly improved the existed gene models of R. communis, and a putative model of key genes was built to show the differences between strains 349 and 1115, illustrating the molecular mechanism of castor oil biosynthesis. A multi-transcriptome database and candidate genes were provided to further improve the level of ricinoleic acid in transgenic crops.

Fluorescent aliphatic hyperbranched polyether: chromophore-free and without any N and P atoms.

The strong fluorescence, in both the solution and the bulk state, of a chromophore-free aliphatic hyperbranched polyether which does not contain N and P atoms was reported for the first time. Effects of concentration and solvent solubility were measured. Its ethanol solution shows a strong blue-green fluorescence (Yu = 0.11-0.39), and its fluorescence shows a strong selective quenching with respect to Fe(3+).

Structure-activity relationship of Cr/Ti-PILC catalysts using a pre-modification method for NO oxidation and their surface species study.

The performances of Cr/Ti-PILC catalysts, which were prepared by the pre-modification method, are studied for the selective catalytic oxidation of NO. The aim of this paper is to elucidate the detailed relationship between physical nanoparticle structure and chemical properties. The maximum NO conversion over the Cr-HP(3)/TP catalyst reached 71.4% at 280 °C. The catalysts were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction of H2 (H2-TPR), temperature-programmed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) techniques. The characterization results demonstrated that the enhanced catalytic activity was ascribed to several beneficial effects, which were caused by the pre-modification such as the inhibition of crystallite size, improvement of Cr species dispersion and increase of the amount of active sites. XPS and FTIR experiments indicated that two Cr(VI) species, oxidized state CrO3 and chromate species with the anionic form, were generated via pre-modification, which played different roles in the catalytic reaction. In addition, the TPR and TPD results suggest that the increased active sites (Cr(VI) species) were conducive for the preferential adsorption and activation of NO. Furthermore, DRIFTS results revealed that the intermediates, NO(+) and nitrates, interacted quickly to generate gaseous NO2.

[Study on detoxication and mechanism of vinegar-processed Euphorbia pekinensis on normal liver cells LO2].

OBJECTIVE: To compare the toxicity of Euphorbia pekinensis before and after being processed by vinegar on normal liver cells LO2, and discuss its possible mechanism. METHOD: LO2 cells were cultured in vitro, and processed with different concentrations of crude and vinegar-processed E. pekinensis. MTT assay was used to measure the inhibitory effect of LO2 cell; Hoechst 33258 staining was used to observe the morphological changes in apoptosis cell; Annexin V-FITC flow cytometry was used to analyze the apoptotic rate of LO2 cell; PI staining flow cytometry was used to analyze its impact on cell cycle. The level or content of ALT, AST, LDH, SOD, MDA and GSH were observed as well. RESULT: Compared with the negative control group, crude E. pekinensis at all concentrations could obviously inhibit LO2 cell proliferation, induce LO2 cell apoptosis and cause cell arrest in S phase, with significant differences (P <0.05). E. pekinensis could significantly increase the levels of ALT, AST and LDH (P <0.05) in the supernatant of cell culture fluid, significantly decrease the level of SOD and the content of GSH (P <0.05) , and significantly increase the content of MDA (P <0.05). Compared with the crude E. pekinensis group, E. pekinensis after being vinegar-processed can significantly reduce cell apoptotic rate, cell cycle arrest, activities of ALT, AST, LDH in the supernatant of cell culture fluid (P <0.05) , and remarkably increase the level of SOD and the content of GSH, but reduce the content of MDA in the supernatant of cell culture fluid. CONCLUSION: Vinegar-processed E. pekinensis can release the cytotoxicity of LO2 cell. Its mechanism may be related to the decrease in the oxidative damage of LO2 cells, thereby reducing the cell cycle arrest and apoptosis.

Enhanced Fog Harvesting through Capillary-Assisted Rapid Transport of Droplet Confined in the Given Microchannel.

A novel integrated bioinspired surface is fabricated by using an innovative capillarity-induced selective oxidation method, to achieve the combination of the fog-collecting characteristics of a variety of creatures, i.e., the micronanostructures of spider silk, the wettable patterns of desert beetle, the conical structure of cactus spine, and the hierarchical microchannel of Sarracenia trichome. The fog is captured effectively via multistructures on the cone tips, and captured droplet is collected and confined in the microchannel to realize rapid transport via the formation of wettable pattern on the surface and the introduction of wettable gradient in the microchannel. Consequently, the fog harvest efficiency reaches 2.48 g/h, increasing to nearly 320% compared to the normal surface. More interestingly, similar to Sarracenia trichome, the surface also presents two transport modes, namely, Mode I (water transport along dry microchannel) and Mode II (succeeding water slippage on the water film). In Mode II, the velocity of 34.10 mm/s is about three times faster than that on the Sarracenia trichome. Such a design of integrated bioinspired surface may present potential applications in high-efficiency water collection systems, microfluidic devices, and others.

Alternative Oxidase Inhibition Impairs Tobacco Root Development and Root Hair Formation.

Alternative oxidase (AOX) is the terminal oxidase of the mitochondrial respiratory electron transport chain in plant cells and is critical for the balance of mitochondrial hemostasis. In this study, the effect of inhibition of AOX with different concentrations of salicylhydroxamic acid (SHAM) on the tobacco root development was investigated. We show here that AOX inhibition significantly impaired the development of the main root and root hair formation of tobacco. The length of the main root of SHAM-treated tobacco was significantly shorter than that of the control, and no root hairs were formed after treatment with a concentration of 1 mM SHAM or more. The transcriptome analysis showed that AOX inhibition by 1 mM SHAM involved in the regulation of gene expression related to root architecture. A total of 5,855 differentially expressed genes (DEGs) were obtained by comparing SHAM-treated roots with control. Of these, the gene expression related to auxin biosynthesis and perception were significantly downregulated by 1 mM SHAM. Similarly, genes related to cell wall loosening, cell cycle, and root meristem growth factor 1 (RGF1) also showed downregulation on SHAM treatment. Moreover, combined with the results of physiological measurements, the transcriptome analysis demonstrated that AOX inhibition resulted in excessive accumulation of reactive oxygen species in roots, which further induced oxidative damage and cell apoptosis. It is worth noting that when indoleacetic acid (20 nM) and dimethylthiourea (10 mM) were added to the medium containing SHAM, the defects of tobacco root development were alleviated, but to a limited extent. Together, these findings indicated that AOX-mediated respiratory pathway plays a crucial role in the tobacco root development, including root hair formation.

Construction of sterically congested oxindole derivatives via visible-light-induced radical-coupling.

The oxindole scaffold represents an important structural feature in many natural products and pharmaceutically relevant molecules. Herein, we report a visible-light-induced modular methodology for the synthesis of complex 3,3'-disubstituted oxindole derivatives. A library of valuable fluoroalkyl-containing highly sterically congested oxindole derivatives can be synthesized by a catalytic three-component radical coupling reaction under mild conditions (metal & photocatalyst free, >80 examples). This strategy shows high functional group tolerance and broad substrate compatibility (including a wide variety of terminal or non-terminal alkenes, conjugated dienes and enynes, and a broad array of polyfluoroalkyl iodide and oxindoles), which enables modular modification of complex drug-like compounds in one chemical step. The success of solar-driven transformation, large-scale synthesis, and the late-stage functionalization of bioactive molecules, as well as promising tumor-suppressing biological activities, highlights the potential for practical applications of this strategy. Mechanistic investigations, including a series of control experiments, UV-vis spectroscopy and DFT calculations, suggest that the reaction underwent a sequential two-step radical-coupling process and the photosensitive perfluoroalkyl benzyl iodides are key intermediates in the transformation.

Correction: RNA-seq transcriptome analysis of the immature seeds of two Brassica napus lines with extremely different thousand-seed weight to identify the candidate genes related to seed weight.

[This corrects the article DOI: 10.1371/journal.pone.0191297.].

RNA-seq transcriptome analysis of the immature seeds of two Brassica napus lines with extremely different thousand-seed weight to identify the candidate genes related to seed weight.

Brassica napus is an important oilseed crop worldwide. Although seed weight is the main determinant of seed yield, few studies have focused on the molecular mechanisms that regulate seed weight in B. napus. In this study, the immature seeds of G-42 and 7-9, two B. napus doubled haploid (DH) lines with extremely different thousand-seed weight (TSW), were selected for a transcriptome analysis to determine the regulatory mechanisms underlying seed weight at the whole gene expression level and to identify candidate genes related to seed weight. A total of 2,251 new genes and 2,205 differentially expressed genes (DEGs) were obtained via RNA-seq (RNA sequencing). Among these genes, 1,747 (77.61%) new genes and 2020 (91.61%) DEGs were successfully annotated. Of these DEGs, 1,118 were up-regulated and 1,087 were down-regulated in the large-seed line. The Kyoto Encyclopedia of Genes and Genomes (KEGG) database analysis indicated that 15 DEGs were involved in ubiquitin-mediated proteolysis and proteasome pathways, which might participate in regulating seed weight. The Gene Ontology (GO) database indicated that 222 DEGs were associated with the biological process or molecular function categories related to seed weight, such as cell division, cell size and cell cycle regulation, seed development, nutrient reservoir activity, and proteasome-mediated ubiquitin-dependent protein catabolic processes. Moreover, 50 DEGs encoding key enzymes or proteins were identified that likely participate in regulating seed weight. A DEG (GSBRNA2T00037121001) identified by the transcriptome analysis was also previously identified in a quantitative trait locus (QTL) region for seed weight via SLAF-seq (Specific Locus Amplified Fragment sequencing). Finally, the expression of 10 DEGs with putative roles in seed weight and the expression of the DEG GSBRNA2T00037121001 were confirmed by a quantitative real-time reverse transcription PCR (qRT-PCR) analysis, and the results were consistent with the RNA sequencing data. This work has provided new insights on the molecular mechanisms underlying seed weight-related biosynthesis and has laid a solid foundation for further improvements to the seed yield of oil crops.

Small RNA and degradome profiling involved in seed development and oil synthesis of Brassica napus.

MicroRNAs (miRNAs) play a prominent role in post-transcriptional gene expression regulation and have been involved in various biological and metabolic processes to regulate gene expression. For Brassica napus, improving seed-weight and oil-content is the main breeding goal. In order to better understand the regulation mechanism of miRNAs during seed-weight formation and oil-content accumulation in B. napus, in this study, a high-throughput sequencing technology was used to profile miRNAs expression of Brassica napus immature seeds from one to six weeks after flowering. A total of 1,276 miRNAs, including 1,248 novel and 28 known miRNAs, were obtained from both the high-seed-weight with low-oil-content RNA pool (S03) and the low-seed-weight with high-oil-content RNA pool (S04). Analysis of their expression profiles disclosed that 300 novel and two known miRNAs were differentially expressed between S03 and S04. For degradome analysis, 57 genes with 64 degradation sites were predicted to be targeted for degradation by these miRNAs. Further bioinformatics analysis indicated that these differentially expressed miRNAs might participate in regulation of myriad cellular and molecular processes, during seed development and oil synthesis. Finally, 6 target genes with potential roles in regulation of seed development and 9 other targets in seed oil synthesis, were further confirmed as candidate genes from small RNA and degradome sequencing.

Rapid Identification of Candidate Genes for Seed Weight Using the SLAF-Seq Method in Brassica napus.

Seed weight is a critical and direct trait for oilseed crop seed yield. Understanding its genetic mechanism is of great importance for yield improvement in Brassica napus breeding. Two hundred and fifty doubled haploid lines derived by microspore culture were developed from a cross between a large-seed line G-42 and a small-seed line 7-9. According to the 1000-seed weight (TSW) data, the individual DNA of the heaviest 46 lines and the lightest 47 lines were respectively selected to establish two bulked DNA pools. A new high-throughput sequencing technology, Specific Locus Amplified Fragment Sequencing (SLAF-seq), was used to identify candidate genes of TSW in association analysis combined with bulked segregant analysis (BSA). A total of 1,933 high quality polymorphic SLAF markers were developed and 4 associated markers of TSW were procured. A hot region of ~0.58 Mb at nucleotides 25,401,885-25,985,931 on ChrA09 containing 91 candidate genes was identified as tightly associated with the TSW trait. From annotation information, four genes (GSBRNA2T00037136001, GSBRNA2T00037157001, GSBRNA2T00037129001 and GSBRNA2T00069389001) might be interesting candidate genes that are highly related to seed weight.