Observation of Chiral Channels in Helical Covalent Organic Frameworks.

Unraveling the mechanism of chirality transfer across length scales is crucial to the rational development of functional materials with hierarchical chirality. The key obstacle is the lack of structural information, especially at the mesoscopic level. We report herein the structural identification of helical covalent organic frameworks (heliCOFs) with hierarchical chirality, which integrate molecular chirality, channel chirality, and morphology chirality into one crystalline entity. Specifically, benefiting from the highly ordered structure of heliCOFs, the existence of chiral channels at the mesoscopic level has been confirmed by electron crystallography, and the handedness of these chiral channels has been directly determined through the stereopair imaging technique. Accordingly, the chirality transfer in heliCOFs from microscopic to macroscopic levels could be rationalized with a layer-rotating model that has been supported by both crystal structure analysis and theoretical calculations. Observation of chiral channels in heliCOFs not only provides unprecedented data for the understanding of the chirality transfer process but also sheds new light on the rational construction of highly ordered polymeric materials with hierarchical chirality.

Role of miRNAs in glucose metabolism of mouse cumulus cells†.

It is known that the oocyte has a limited capacity to acquire and metabolize glucose, and it must rely on cumulus cells (CCs) to take up glucose and produce pyruvate for use to produce ATP through oxidative phosphorylation. We therefore propose that miRNAs might regulate glucose metabolism (GM) in CCs and might be used as markers for oocyte quality assessment. Here, mouse CC models with impaired glycolysis or pentose phosphate pathway (PPP) were established, and miRNAs targeting the key enzymes in glycolysis/PPP were predicted using the miRNA target prediction databases. Expression of the predicted miRNAs was compared between CCs with normal and impaired glycolysis/PPP to identify candidate miRNAs. Function of the candidate miRNAs was validated by transfecting CCs or cumulus-oocyte-complexes (COCs) with miRNA inhibitors and observing effects on glucose metabolites of CCs and on competence of oocytes. The results validated that miR-23b-3p, let-7b-5p, 34b-5p and 145a-5p inhibited glycolysis, and miR-24-3p, 3078-3p,183-5p and 7001-5p inhibited PPP of CCs. Our observation using a more physiologically relevant model (intact cultured COCs) further validated the four glycolysis-targeting miRNAs we identified. Furthermore, miR-let-7b-5p, 34b-5p and 145a-5p may also inhibit PPP, as they decreased the production of glucose-6-phosphate. In conclusion, miRNAs play critical roles in GM of CCs and may be used as markers for oocyte quality assessment. Summary sentence:  We identified and validated eight new miRNAs that inhibit glycolysis and/or pentose phosphate pathways in cumulus cells (CCs) suggesting that miRNAs play critical roles in glucose metabolism of CCs and may be used for oocyte quality markers.

Bottom-Up Construction of Ni(II)-Incorporated Covalent Organic Framework for Metallaphotoredox Catalysis.

The construction of an all-in-one catalyst, in which the photosensitizer and the transition metal site are close to each other, is important for improving the efficiency of metallaphotoredox catalysis. However, the development of convenient synthetic strategies for the precise construction of an all-in-one catalyst remains a challenging task due to the requirement of precise installation of the catalytic sites. Herein, we have successfully established a facile bottom-up strategy for the direct synthesis of Ni(II)-incorporated covalent organic framework (COF), named LZU-713@Ni, as a versatile all-in-one metallaphotoredox catalyst. LZU-713@Ni showed excellent activity and recyclability in the photoredox/nickel-catalyzed C-O, C-S, and C-P cross-coupling reactions. Notably, this catalyst displayed a better catalytic activity than its homogeneous analogues, physically mixed dual catalyst system, and, especially, LZU-713/Ni which was prepared through post-synthetic modification. The improved catalytic efficiency of LZU-713@Ni should be attributed to the implementation of bottom-up strategy, which incorporated the fixed, ordered, and abundant catalytic sites into its framework. This work sheds new light on the exploration of concise and effective strategies for the construction of multifunctional COF-based photocatalysts.

Delivery Strategies, Structural Modification, and Pharmacological Mechanisms of Honokiol: A Comprehensive Review.

Honokiol (HK) is a traditional Chinese herbal bioactive compound that originates mainly from the Magnolia species, traditionally used to treat anxiety and stroke, as well as alleviation of flu symptoms. This natural product and its derivatives displayed diverse biological activities, including anticancer, antioxidant, anti-inflammatory, neuroprotective, and antimicrobial activities. However, its poor bioavailability and pharmacological activity require primary consideration in the development of HK-based drugs. Recent innovative HK formulations based on the nanotechnology approach allowed for improvement in both bioavailability and therapeutic efficacy. Chemical derivation and drug combination are also effective strategies to ameliorate the drawbacks of HK. In recent years, studies on HK derivatives and compositions have made great progress in the treatment of cancer, inflammation, bacterial infection, cardiovascular, and cerebrovascular diseases, demonstrating better activity than HK. The objective of this review is an examination of the recent developments in the field of pharmacological activity of HK and its drug-related issues, and approaches to improve its physicochemical and biological properties, including solubility, stability, and bioavailability. Recent patents and the ongoing clinical trials in HK are also summarized.

Fused-Ring-Linked Covalent Organic Frameworks.

The development of linkage chemistry in the research area of covalent organic frameworks (COFs) is fundamentally important for creating robust structures with high crystallinity and diversified functionality. We reach herein a new level of complexity and controllability in linkage chemistry by achieving the first synthesis of fused-ring-linked COFs. A series of bicyclic pyrano[4,3-b]pyridine COFs have been constructed via a cascade protocol involving Schiff-base condensation, intramolecular [4 + 2] cycloaddition, and dehydroaromatization. With a broad scope of Brønsted or Lewis acids as the catalyst, the designed monomers, that is, O-propargylic salicylaldehydes and multitopic anilines, were converted into the fused-ring-linked frameworks in a one-pot fashion. The obtained COFs exhibited excellence in terms of purity, stability, and crystallinity, as comprehensively characterized by solid-state nuclear magnetic resonance (NMR) spectroscopy, powder X-ray diffraction, high-resolution transmission electron microscopy, and so on. Specifically, the highly selective formation (>94%) of pyrano[4,3-b]pyridine linkage was verified by quantitative NMR measurements combined with 13C-labeling synthesis. Moreover, the fused-ring linkage possesses fully locked conformation, which benefits to the high crystallinity observed for these COFs. Advancing the linkage chemistry from the formation of solo bonds or single rings to that of fused rings, this study has opened up new possibilities for the concise construction of sophisticated COF structures with high controllability.

Drug Repurposing by Siderophore Conjugation: Synthesis and Biological Evaluation of Siderophore-Methotrexate Conjugates as Antibiotics.

Drug repurposing is considered a promising strategy to fight antimicrobial resistance (AMR). Methotrexate (Mtx), a classical anticancer drug, could strongly inhibit bacterial dihydrofolate reductase (DHFR). However, its poor permeability into bacteria and potent human cytotoxicity make it unsuitable as an antibacterial. Herein, we reported the conjugation of Mtx with a siderophore to construct "Trojan horse" antibacterials. The most potent conjugate 8 with nanomolar minimum inhibitory concentration (MIC) values exhibited over 1.00×103 -fold improved activity against Gram-positive Streptococcus pneumoniae (S. pneumoniae) and Gram-negative Yersinia enterocolitica (Y. enterocolitica) compared with Mtx, while possessing 2.31×103 -fold reduced human cytotoxicity, resulting in 2.08×106 -fold improvements in the therapeutic index. This proof-of-principle study verifies that siderophore conjugation is an effective strategy for developing new antibacterials from anticancer drugs.

Expression and Characterization of a Novel Cold-Adapted Chitosanase from Marine Renibacterium sp. Suitable for Chitooligosaccharides Preparation.

(1) Background: Chitooligosaccharides (COS) have numerous applications due to their excellent properties. Chitosan hydrolysis using chitosanases has been proposed as an advisable method for COS preparation. Although many chitosanases from various sources have been identified, the cold-adapted ones with high stability are still rather rare but required. (2) Methods: A novel chitosanase named CsnY from marine bacterium Renibacterium sp. Y82 was expressed in Escherichia coli, following sequence analysis. Then, the characterizations of recombinant CsnY purified through Ni-NTA affinity chromatography were conducted, including effects of pH and temperature, effects of metal ions and chemicals, and final product analysis. (3) Results: The GH46 family chitosanase CsnY possessed promising thermostability at broad temperature range (0-50 °C), and with optimal activity at 40 °C and pH 6.0, especially showing relatively high activity (over 80% of its maximum activity) at low temperatures (20-30 °C), which demonstrated the cold-adapted property. Common metal ions or chemicals had no obvious effect on CsnY except Mn2+ and Co2+. Finally, CsnY was determined to be an endo-type chitosanase generating chitodisaccharides and -trisaccharides as main products, whose total concentration reached 56.74 mM within 2 h against 2% (w/v) initial chitosan substrate. (4) Conclusions: The results suggest the cold-adapted CsnY with favorable stability has desirable potential for the industrial production of COS.

Pyrimidazole-Based Covalent Organic Frameworks: Integrating Functionality and Ultrastability via Isocyanide Chemistry.

Development of new chemistry to simultaneously meet the demands for topology, connectivity, and functionality is highly desired in the research area of covalent organic frameworks (COFs). We explore herein the isocyanide chemistry so as to establish a facile paradigm to integrate functionality and ultrastability in COFs. Using the representative Groebke-Blackburn-Bienaymé (GBB) reaction based on isocyanide chemistry, we are able to construct a series of pyrimidazole-based COFs in one step from isocyanide, aminopyridine, and aldehyde monomers. Diversified functionalities have been bottom-up integrated by the simple replacement of readily available 2-aminopyridine monomers. Meanwhile, the ubiquitous formation of fused imidazole rings within the frameworks has guaranteed their ultrastability. In view of the rich synthetic possibilities provided by isocyanide chemistry, we expect that this contribution opens up a new avenue toward the divergent construction of robust COFs for practical applications.

Characterization of a Robust and pH-Stable Tannase from Mangrove-Derived Yeast Rhodosporidium diobovatum Q95.

Tannase plays a crucial role in many fields, such as the pharmaceutical industry, beverage processing, and brewing. Although many tannases derived from bacteria and fungi have been thoroughly studied, those with good pH stabilities are still less reported. In this work, a mangrove-derived yeast strain Rhodosporidium diobovatum Q95, capable of efficiently degrading tannin, was screened to induce tannase, which exhibited an activity of up to 26.4 U/mL after 48 h cultivation in the presence of 15 g/L tannic acid. The tannase coding gene TANRD was cloned and expressed in Yarrowia lipolytica. The activity of recombinant tannase (named TanRd) was as high as 27.3 U/mL. TanRd was purified by chromatography and analysed by SDS-PAGE, showing a molecular weight of 75.1 kDa. The specific activity of TanRd towards tannic acid was 676.4 U/mg. Its highest activity was obtained at 40 °C, with more than 70% of the activity observed at 25-60 °C. Furthermore, it possessed at least 60% of the activity in a broad pH range of 2.5-6.5. Notably, TanRd was excellently stable at a pH range from 3.0 to 8.0; over 65% of its maximum activity remained after incubation. Besides, the broad substrate specificity of TanRd to esters of gallic acid has attracted wide attention. In view of the above, tannase resources were developed from mangrove-derived yeasts for the first time in this study. This tannase can become a promising material in tannin biodegradation and gallic acid production.

Characterization of a New Intracellular Alginate Lyase with Metal Ions-Tolerant and pH-Stable Properties.

Alginate lyases play an important role in alginate oligosaccharides (AOS) preparation and brown seaweed processing. Many extracellular alginate lyases have been characterized to develop efficient degradation tools needed for industrial applications. However, few studies focusing on intracellular alginate lyases have been conducted. In this work, a novel intracellular alkaline alginate lyase Alyw202 from Vibrio sp. W2 was cloned, expressed and characterized. Secretory expression was performed in a food-grade host, Yarrowia lipolytica. Recombinant Alyw202 with a molecular weight of approximately 38.3 kDa exhibited the highest activity at 45 °C and more than 60% of the activity in a broad pH range of 3.0 to 10.0. Furthermore, Alyw202 showed remarkable metal ion-tolerance, NaCl independence and the capacity of degrading alginate into oligosaccharides of DP2-DP4. Due to the unique pH-stable and high salt-tolerant properties, Alyw202 has potential applications in the food and pharmaceutical industries.

Cloning, Secretory Expression and Characterization of a Unique pH-Stable and Cold-Adapted Alginate Lyase.

Cold-adapted alginate lyases have unique advantages for alginate oligosaccharide (AOS) preparation and brown seaweed processing. Robust and cold-adapted alginate lyases are urgently needed for industrial applications. In this study, a cold-adapted alginate lyase-producing strain Vibrio sp. W2 was screened. Then, the gene ALYW201 was cloned from Vibrio sp. W2 and expressed in a food-grade host, Yarrowia lipolytica. The secreted Alyw201 showed the activity of 64.2 U/mL, with a molecular weight of approximate 38.0 kDa, and a specific activity of 876.4 U/mg. Alyw201 performed the highest activity at 30 °C, and more than 80% activity at 25-40 °C. Furthermore, more than 70% of the activity was obtained in a broad pH range of 5.0-10.0. Alyw201 was also NaCl-independent and salt-tolerant. The degraded product was that of the oligosaccharides of DP (Degree of polymerization) 2-6. Due to its robustness and its unique pH-stable property, Alyw201 can be an efficient tool for industrial production.

One-step utilization of inulin for docosahexaenoic acid (DHA) production by recombinant Aurantiochytrium sp. carrying Kluyveromyces marxianus inulinase.

This study aimed to express an inulinase gene from the yeast Kluyveromyces marxianus (KmINU) in Aurantiochytrium sp. and realized one-step utilization of inulin resource for DHA production without any chemical pretreatment. An expression cassette with a length of 6052 bp for expressing the inulinase gene was constructed by a fast two-step PCR method and then was transferred into the Aurantiochytrium sp. cells. The Aurantiochytrium sp. recombinant T39 was selected with an inulinase activity up to 50.1 U/mL in 72 h. In a 5-l fed-batch fermentation, as high as 148.9 g/L of inulin was directly used within 120 h, and only 1.2 g/L of total sugar was left in the medium at the end of fermentation. The biomass of 51.4 g/L with a lipid content of 69.2% DCW and a DHA yield of 14.9 g/L was obtained.

Characterization of Nuclear and Mitochondrial Genomes of Two Tobacco Endophytic Fungi Leptosphaerulina chartarum and Curvularia trifolii and Their Contributions to Phylogenetic Implications in the Pleosporales.

The symbiont endophytic fungi in tobacco are highly diverse and difficult to classify. Here, we sequenced the genomes of Curvularia trifolii and Leptosphaerulina chartarum isolated from tobacco plants. Finally, 41.68 Mb and 37.95 Mb nuclear genomes were sequenced for C. trifolii and L. chartarum with the scaffold N50, accounting for 638.94 Kb and 284.12 Kb, respectively. Meanwhile, we obtained 68,926 bp and 59,100 bp for their mitochondrial genomes. To more accurately classify C. trifolii and L. chartarum, we extracted seven nuclear genes and 12 mitochondrial genes from these two genomes and their closely related species. The genes were then used for calculation of evolutionary rates and for phylogenetic analysis. Results showed that it was difficult to achieve consistent results using a single gene due to their different evolutionary rates, while the phylogenetic trees obtained by combining datasets showed stable topologies. It is, therefore, more accurate to construct phylogenetic relationships for endophytic fungi based on multi-gene datasets. This study provides new insights into the distribution and characteristics of endophytic fungi in tobacco.

Lrrc34 Is Highly Expressed in SSCs and Is Necessary for SSC Expansion In Vitro.

Objective To discover critical genes contributing to the stemness and maintenance of spermatogonial stem cells (SSCs) and provide new insights into the function of the leucine-rich repeat (LRR) family member Lrrc34 (leucine-rich repeat-containing 34) in SSCs from mice. Methods Bioinformatic methods, including differentially expressed gene (DEG), gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, were used to uncover latent pluripotency-related genes. Reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence analyses were utilized to verify the mRNA and protein expression levels, respectively. RNA interference of Lrrc34 using siRNA was performed to detect its transient impact on SSCs. Results Eight DEGs between ID4-EGFP+ (G) and ID4-EGFP+/TSPAN8High (TH), eight DEGs between G and ID4-EGFP+/TSPAN8Low (TL) and eleven DEGs between TH and TL were discovered, and eleven protein-protein interaction (PPI) modules were found to be significant in the PPI network of DEGs. One of the DEGs, Lrrc34, was selected as a potential pluripotency-related gene due to its differential expression among ID4-EGFP+ spermatogonia subsets and its interaction with fibroblast growth factor 2 in the fifth module. Immunofluorescence experiments exhibited specific expression of Lrrc34 in a subpopulation of undifferentiated spermatogonia marked by LIN28A, and RT-PCR experiments confirmed the high expression of Lrrc34 in SSCs from P7 and adult mice. The transient knockdown of Lrrc34 in SSCs resulted in reduced colony sizes and significant changes in the transcriptome and apoptotic pathways. Conclusion Lrrc34 is highly expressed in mouse SSCs and is required for SSC proliferation in vitro through effects on transcriptome and signaling transduction pathways.

Non-Interpenetrated Single-Crystal Covalent Organic Frameworks.

Growth of covalent organic frameworks (COFs) as single crystals is extremely challenging. Inaccessibility of open-structured single-crystal COFs prevents the exploration of structure-oriented applications. Herein we report for the first time a non-interpenetrated single-crystal COF, LZU-306, which possesses the open structure constructed exclusively via covalent assembly. With a high void volume of 80 %, LZU-306 was applied to investigate the intrinsic dynamics of reticulated tetraphenylethylene (TPE) as the individual aggregation-induced-emission moiety. Solid-state 2 H NMR investigation has determined that the rotation of benzene rings in TPE, being the freest among the reported cases, is as fast as 1.0×104  Hz at 203 K to 1.5×107  Hz at 293 K. This research not only explores a new paradigm for single-crystal growth of open frameworks, but also provides a unique matrix-isolation platform to reticulate functional moieties into a well-defined and isolated state.

Constructing Robust Covalent Organic Frameworks via Multicomponent Reactions.

Methodology development of robust linkages is fundamentally important for the synthesis and application of covalent organic frameworks (COFs). We report herein a new strategy based on multicomponent reactions (MCRs) to construct ultrastable COFs. With the one-pot formation of five covalent bonds in each cyclic joint, a series of imidazole-linked COFs were robustly constructed through the Debus-Radziszewski MCR from three easily available components. By reaching a higher level of complexity and precision in covalent assembly, this research explores a new direction in integrating sophisticated reversible/irreversible reactions to construct crystalline porous frameworks.

Toward the Total Synthesis of Scabrosins: Synthesis of a Desulfur-scabrosin Skeleton and Its Stereoisomers.

The enantioselective synthesis of a desulfur-scabrosin skeleton was reported. The synthesis began from 3-(hydroxymethyl)phenol, and key steps include asymmetric nucleophilic epoxidation, a Mitsunobu reaction using a sulfonamide as the nucleophile, the construction of a pyrrolidine ring by intramolecular nucleophilic substitution, and inversion of configuration through base-induced keto-enol isomerization. Additionally, two isomers of the carbon skeleton were also obtained via an alternative ring-closing strategy.

Clinical outcomes of botulinum toxin A management for neurogenic detrusor overactivity: meta-analysis.

The aim of this work was to evaluate the efficacy and safety of botulinum toxin A (BTX-A) treatment in patients with neurogenic detrusor overactivity. PUBMED, EMBASE, and Cochrane Library were identified on 13 May 2017 to identify relevant randomized controlled trials. All data obtained were analyzed using Stata 12.0. Five randomized controlled trials were included in this study. Compared to placebo, the BTX-A groups had significantly fewer urinary incontinence (UI) episodes per day and per week (BTX-A with 300 U for frequency of UI per day at week 2, mean difference (MD): -1.13, 95% confidence interval (CI): -1.89 to -0.37; 200 U; BTX-A with 300 U for frequency of UI per week at week 6, MD: -11.42, 95% CI: -13.91 to -8.93; BTX-A with 200 U for frequency of UI per week at week 6, MD: -10.72, 95% CI: -13.40 to -8.04), increased in maximum cystometric capacity at week 6 (BTX-A with 300 U, MD: 154.88, 95% CI: 133.92-175.84; BTX-A with 200 U, MD: 141.30, 95% CI: 121.28-161.33), decreased maximum detrusor pressure at week 6 (BTX-A with 300 U, MD: -31.72, 95% CI: -37.69 to -25.75; BTX-A with 200 U, MD: -33.47, 95% CI: -39.20 to -27.73). For adverse effects, BTX-A was often associated with more complications and urinary tract infections (BTX-A with 300 U: relative risk (RR):1.42, 95% CI: 1.15-1.76; BTX-A with 200 U: RR: 1.42, 95% CI: 1.11-1.82). This meta-analysis suggests that treatment with BTX-A is effective and safe for neurogenic detrusor overactivity, and recommends using BTX-A with 300 U or with 200 U, as suitable dosage.

Efficient Conversion of Cane Molasses Towards High-Purity Isomaltulose and Cellular Lipid Using an Engineered Yarrowia lipolytica Strain in Fed-Batch Fermentation.

: Cane molasses is one of the main by-products of sugar refineries, which is rich in sucrose. In this work, low-cost cane molasses was introduced as an alternative substrate for isomaltulose production. Using the engineered Yarrowia lipolytica, the isomaltulose production reached the highest (102.6 g L-¹) at flask level with pretreated cane molasses of 350 g L-¹ and corn steep liquor of 1.0 g L-¹. During fed-batch fermentation, the maximal isomaltulose concentration (161.2 g L-¹) was achieved with 0.96 g g-¹ yield within 80 h. Simultaneously, monosaccharides were completely depleted, harvesting the high isomaltulose purity (97.4%) and high lipid level (12.2 g L-¹). Additionally, the lipids comprised of 94.29% C16 and C18 fatty acids, were proved suitable for biodiesel production. Therefore, the bioprocess employed using cane molasses in this study was low-cost and eco-friendly for high-purity isomaltulose production, coupling with valuable lipids.

High-Throughput Biochemical Fingerprinting of Oleaginous Aurantiochytrium sp. Strains by Fourier Transform Infrared Spectroscopy (FT-IR) for Lipid and Carbohydrate Productions.

The traditional biochemical methods for analyzing cellular composition of oleaginous microorganisms are time-consuming, polluting, and expensive. In the present study, an FT-IR method was used to analyze the cellular composition of the marine oleaginous protist Aurantiochytrium sp. during various research processes, such as strains screening, medium optimization, and fermentation, and was evaluated as a green, low-cost, high throughput, and accurate method compared with the traditional methods. A total of 109 Aurantiochytrium sp. strains were screened for lipid and carbohydrate production and the best results were found for the strains No. 6 and No. 32. The yields and productivities could reach up to 47.2 g/L and 0.72 g/L/h for lipid, 21.6 g/L and 0.33 g/L/h for docosahexaenoic acid (DHA) in the strain No. 6, and 15.4 g/L and 0.18 g/L/h for carbohydrate in the strain No. 32, under the optimal conditions, respectively. These results confirmed potentials of the two Aurantiochytrium sp. strains for lipid, DHA, and carbohydrate productions at industrial scales. The FT-IR method in this study will facilitate research on the oleaginous Aurantiochytrium sp., and the obtained two strains for lipid and carbohydrate productions will provide the foundations for their applications in medical, food, and feed industries.