Heavy Metal-Induced Assembly of DNA Network Biosensor from Double-Loop Hairpin Probes for Ultrasensitive Detection of UO22+ in Water and Soil Samples.

The uranyl ion (UO22+) is the most stable form of uranium, which exhibits high toxicity and bioavailability posing a severe risk to human health. The construction of ultrasensitive, reliable, and robust sensing techniques for UO22+ detection in water and soil samples remains a challenge. Herein, a DNA network biosensor was fabricated for UO22+ detection using DNAzyme as the heavy metal recognition element and double-loop hairpin probes as DNA assembly materials. UO22+-activated specific cleavage of the DNAzyme will liberate the triggered DNA fragment, which can be utilized to launch a double-loop hairpin probe assembly among Hab, Hbc, and Hca. Through multiple cyclic cross-hybridization reactions, hexagonal DNA duplex nanostructures (n[Hab•Hbc•Hca]) were formed. This DNA network sensing system generates a high fluorescence response for UO22+ monitoring. The biosensor is ultrasensitive, with a detection limit of 2 pM. This sensing system also displays an excellent selectivity and robustness, enabling the DNA network biosensor to work even in complex water and soil samples with excellent accuracy and reliability. With the advantages of enzyme-free operation, outstanding specificity, and high sensitivity, our proposed DNA network biosensor provides a reliable, simple, and robust method for trace levels of UO22+ detection in environmental samples.

Conformational equilibria in acrolein-CO2: the crucial contribution of n → π* interactions unveiled by rotational spectroscopy.

Using gas phase Fourier-transform microwave spectroscopy complemented by theoretical analysis, this study delivers a comprehensive depiction of the physical origin of the 'n → π* interaction' between CO2 and acrolein, one of the most reactive aldehydes. Three distinct isomers of the acrolein-CO2 complex, linked through a C⋯O tetrel bond (or n → π* interaction) and a C-H⋯O hydrogen bond, have been unambiguously identified in the pulsed jet. Relative intensity measurements allowed estimation on the population ratio of the three isomers to be T1/T2/C1 ≈ 25/5/1. Advanced theoretical analyses were employed to elucidate the intricacies of the noncovalent interactions within the examined complex. This study not only sheds light on the molecular underpinnings of n → π* interactions but also paves the way for future exploration in carbon dioxide capture and utilization, leveraging the fundamental principles uncovered in the study of acrolein-carbon dioxide interactions.

Elucidating the structural and conformational preferences of bioactive chromone and its monohydrate through advanced rotational spectroscopy.

Chromones are a class of naturally occurring compounds, renowned for their diverse biological activities with significant relevance in medicine and biochemistry. This study marks the first analysis of rotational spectra of both the chromone monomer and its monohydrate through Fourier transform microwave spectroscopy. The observation of nine mono-substituted 13C isotopologues facilitated a semi-experimental determination of the equilibrium structure of the chromone monomer. In the case of chromone monohydrate, two distinct isomers were identified, each characterized by a combination of O-H⋯O and C-H⋯O hydrogen bonds involving the chromone's carbonyl group. This study further delved into intermolecular non-covalent interactions, employing different theoretical approaches. The relative population ratio of the two identified isomers was estimated to be about 2:1 within the supersonic jet.

Decrypting the critical point of internal rotation of formaldehyde: A rotational study of the acrolein-formaldehyde complex.

The rotational spectrum of an acrolein-formaldehyde complex has been characterized using pulsed jet Fourier transform microwave spectroscopy complemented with quantum chemical calculations. One isomer has been observed in pulsed jets, which is stabilized by a dominant O=C⋯O tetrel bond (n → π* interaction) and a secondary C-H⋯O hydrogen bond. Splittings arising from the internal rotation of formaldehyde around its C2v axis were also observed, from which its V2 barrier was evaluated. It seems that when V2 equals or exceeds 4.61 kJ mol-1, no splitting of the spectral lines of the rotational spectrum was observed. The nature of the non-covalent interactions of the target complex is elucidated through natural bond orbital analysis. These findings contribute to a deeper understanding on the non-covalent interactions within the dimeric complex formed by two aldehydes.

The role of AMPK in macrophage metabolism, function and polarisation.

AMP-activated protein kinase (AMPK) is a ubiquitous sensor of energy and nutritional status in eukaryotic cells. It plays a key role in regulating cellular energy homeostasis and multiple aspects of cell metabolism. During macrophage polarisation, AMPK not only guides the metabolic programming of macrophages, but also counter-regulates the inflammatory function of macrophages and promotes their polarisation toward the anti-inflammatory phenotype. AMPK is located at the intersection of macrophage metabolism and inflammation. The metabolic characteristics of macrophages are closely related to immune-related diseases, infectious diseases, cancer progression and immunotherapy. This review discusses the structure of AMPK and its role in the metabolism, function and polarisation of macrophages. In addition, it summarises the important role of the AMPK pathway and AMPK activators in the development of macrophage-related diseases.

Accurate Geometry and Non-Covalent Interactions in 1-Phenylethanol and its Monohydrate: A Rotational Study.

The pure rotational spectra of 1-phenylethanol and its monohydrate were measured by using a pulsed jet Fourier transform microwave spectrometer. One conformer of the 1-phenylethanol monomer with the trans form was observed in the pulsed jet. The experimental values of rotational constants of ten isotopologues, including eight mono-substituted 13 C and one D isotopologues, allow an accurate structure determination of the skeleton of 1-phenylethanol. For its monohydrate, only one isomer has been observed, of which 1-phenylethanol adopts the trans form and binds with water through an O-H⋅⋅⋅Ow and an Ow -H⋅⋅⋅π hydrogen bond. Each rotational transition displays a doublet with a relative intensity ratio of 1 : 3, due to a hindered internal rotation of water around its C2 axis. This study provides the information on accurate geometry of 1-phenylethanol (PE) and large amplitude motion of water in the PE monohydrate.

Stepwise hydrations of anhydride tuned by hydrogen bonds: rotational study on maleic anhydride-(H2O)1-3.

The rotational spectra of maleic anhydride-(H2O)1-3 have been investigated for the first time by using pulsed jet Fourier transform microwave spectroscopy with complementary computational analyses. The experimental evidence points out that water tends to self-aggregate with hydrogen bonds and form homodromic cycles. Differences in bond lengths and charge distribution between the two carbonyl sites have been observed upon stepwise hydrations, which might further introduce a selectivity on the nucleophilic attack sites of hydrolysis. This study provides an important insight into the incipient solvation process (microsolvation) of maleic anhydride in water by understanding the cooperation and rearrangement of intermolecular hydrogen bonds in its stepwise hydrates.

Fluorination effects probed in 4-fluoroacetophenone and its monohydrate.

Rotational spectra of the 4-fluoroacetophenone monomer and its monohydrate were investigated by Fourier transform microwave spectroscopy complemented with quantum chemical calculations. One conformer of 4-fluoroacetophenone and two isomers of 4-fluoroacetophenone-H2O have been observed in the pulsed jets. The observation of all mono-substituted 13C isotopologues in natural abundance allows an accurate structural determination of the 4-fluoroacetophenone monomer. Both detected isomers of 4-fluoroacetophenone-H2O are stabilized by a dominant O-H⋯O and a secondary C-H⋯O hydrogen bond. The fluorination effects on the geometries, intermolecular non-covalent interactions and V3 barrier of the methyl internal rotation were analysed. The relative population ratio of the two observed isomers for 4-fluoroacetophenone-H2O was also estimated to be NI/NII ≈ 7/1.

Laboratory Rotational Spectrum and Radio-Astronomical Search of Acetoin.

The rotational spectrum of acetoin (3-hydroxy-2-butanone) was measured by using Fourier transform microwave spectroscopy with the aid of quantum chemical calculations. Only one conformer of acetoin was detected in the pulsed jet, whose spectrum featured the splittings raised from the internal rotation of the methyl top linking to the C═O group. Based on the spectroscopic result, radio-astronomical searches for acetoin were carried out toward the massive star-forming region Sgr B2(N) using the Shanghai Tianma 65 m and IRAM 30 m radio telescopes. No lines belonging to acetoin were detected toward Sgr B2(N). Its upper limit of column density was calculated.

Phylogenomic analysis of Syrphoidea (Diptera: Syrphidae, Pipunculidae) based on the expanded mitogenomic data.

The mitochondrial genome has become the most widely used genomic resource in resolving the insect phylogenetic relationships. In this study, we assess the interrelationships among the syrphid and pipunculid members of Syrphoidea using mitochondrial genome sequences of 152 taxa, 9 of which are newly reported and three are assembled from the existing transcriptome data. The Pipunculidae was found to be deeply nested members of Schizophora, which resulted in a nonmonophyletic Syrphoidea. In the monophyletic Syrphidae, unequivocal robust support was found for Microdontinae as the sister group of all other Syrphidae. The subfamily Eristalinae was nonmonophyletic. The Pipizinae was recovered as the sister group to the Syrphinae, albeit with strong support. As a whole, our results are concord with previously established hypotheses on Syrphoidea from the genome scale data. The mitochondrial genomes were successful in producing a robustly supported phylogenetic framework for the Syrphoidea.

Lightweight Helmet Detection Algorithm Using an Improved YOLOv4.

Safety helmet wearing plays a major role in protecting the safety of workers in industry and construction, so a real-time helmet wearing detection technology is very necessary. This paper proposes an improved YOLOv4 algorithm to achieve real-time and efficient safety helmet wearing detection. The improved YOLOv4 algorithm adopts a lightweight network PP-LCNet as the backbone network and uses deepwise separable convolution to decrease the model parameters. Besides, the coordinate attention mechanism module is embedded in the three output feature layers of the backbone network to enhance the feature information, and an improved feature fusion structure is designed to fuse the target information. In terms of the loss function, we use a new SIoU loss function that fuses directional information to increase detection precision. The experimental findings demonstrate that the improved YOLOv4 algorithm achieves an accuracy of 92.98%, a model size of 41.88 M, and a detection speed of 43.23 pictures/s. Compared with the original YOLOv4, the accuracy increases by 0.52%, the model size decreases by about 83%, and the detection speed increases by 88%. Compared with other existing methods, it performs better in terms of precision and speed.

Low-Valent-Tungsten-Catalyzed Aerobic Oxidative Cross-Dehydrogenative Coupling Reaction.

A straightforward and convenient protocol was established for the synthesis of thiophosphates and 3-sulfenylated indoles via low-valent-tungsten-catalyzed aerobic oxidative cross-dehydrogenative coupling reactions. These reactions occur under mild conditions and simple operations with commercially available starting materials, processing the advantage of excellent atom and step economy, broad substrate scope, and good functional groups tolerance. Moreover, this transformation could be practiced on the gram scale, which exhibits great potential in the preparation of drug-derived or bioactive molecules.

Tetrahedron-Based Constitutional Dynamic Network for COVID-19 or Other Coronaviruses Diagnostics and Its Logic Gate Applications.

Considering the large-scale outbreak of the coronavirus, it is essential to develop a versatile sensing system for different coronaviruses diagnostics, such as COVID-19, severe acute respiratory syndrome-related coronavirus (SARS-CoV), and bat SARS-like coronavirus (Bat-SL-CoVZC45). In this work, a tetrahedron-based constitutional dynamic network was built as the sensing platform for coronavirus detection. Four different DNA probes were used to construct the tetrahedron structure. DNAzyme and the fluorophore modified substrate strand were used to generate different fluorescence signals, which can be used to distinguish different coronaviruses. The coronavirus biosensor shows a high sensitivity for COVID-19, Bat-SL-CoVZC45, and SARS-CoV detection, with detection limits of 2.5, 3.1, and 2.9 fM, respectively. Also, the platform is robust, and the possible interference from clinical samples was negligible. Using different coronaviruses as inputs, we have fabricated several concatenated logic gates, such as "AND-OR", "INHIBIT-AND", "AND-AND-AND", and "AND-INHIBIT". Importantly, our logic system can also be used to identify SARS-CoV-2 Delta and Lambda variants in the logic operations. Due to the unique advantages of high sensitivity and selectivity, multiple logic biocomputing capabilities, and multireadout mode, this flexible sensing system provides a versatile sensing strategy for intelligent diagnostics of different coronaviruses with low false-negative rates.

Toehold-Mediated Cascade Catalytic Assembly for Mycotoxin Detection and Its Logic Applications.

In this work, an enzyme-free biosensor is reported for mycotoxin detection based on a toehold-mediated catalytic hairpin assembly (CHA) and a DNAzyme-cascaded hydrolysis reaction. In the presence of a mycotoxin, the recognition between an aptamer and the mycotoxin releases the trigger DNA. The trigger DNA initiates the toehold-mediated CHA, generating large amounts of partial duplex B/C with four toeholds, which can be used to assemble the DNAzyme-cascaded hydrolysis reaction. Furthermore, through a collaborative autoassembly reaction among the B/C duplex, DNA1, and DNA2, supramolecular nanostructures corresponding to Mg2+-dependent DNAzymes can be formed. With the incubation of Mg2+, the dual-modified (TAMRA/BHQ2) substrate strand DNA2 will be cleaved into two fragments, yielding a high TAMRA fluorescence signal for mycotoxin testing. Under optimal conditions, the sensing system was ultrasensitive and showed low detection limits of 0.2 pM for ochratoxin A (OTA), 0.13 pM for aflatoxin B1 (AFB1), and 0.17 pM for zearalenone (ZEN). The mycotoxin aptasensor also exhibited high selectivity and was successfully applied for the quantitative analysis of OTA, AFB1, and ZEN in wine samples. Due to the advantages of flexibility and versatility, this mycotoxin platform was used to fabricate several concatenated logic gates including "AND-INHIBIT", "INHIBIT-OR", "OR-AND", and "OR-INHIBIT" logic biocomputings. Such multiple functions of the logic system provided a universal sensing strategy for the intelligent detection of multiplex mycotoxins, demonstrating considerable potential in food safety and environmental monitoring.

Fancb deficiency causes premature ovarian insufficiency in mice†.

Fanconi anemia complementation group B (FANCB) protein is a major component of the Fanconi anemia (FA) core complex and plays an important role in hematopoiesis and germ cell development. Deletion of Fancb gene causes the defect of primordial germ cell (PGC) development and infertility in male mice. However, it remains unknown whether Fancb is required for female germ cell development. In this study, we found that the fertility of Fancb knockout male mice in C57/ICR mixed backgrounds was not affected. Female Fancb-/- mice were obtained by crossing Fancb+/- females with Fancb-/Y males. The number of PGCs was dramatically decreased in Fancb-/- females. Very few oocytes were observed after birth and the primordial follicle pool was completely depleted at 6 weeks of age in Fancb-/- females. However, the remained oocytes from Fancb-/- mice were normal in fertilization and embryonic development from 2-cell to the blastocyst stage. We also found that Fancb and Fancl double-knockout males were also fertile and the number of sperm in epididymis was not reduced as compared to that of Fancb-/- and Fancl-/- single-knockout mice. Taken together, these results showed that Fancb is also essential for female germ cell development. Inactivation of Fancb causes massive germ cell loss and infertility in adult females. We also found that Fancb and Fancl do not act synergistically in regulating germ cell development.

Palladium-Catalyzed Ring-Opening Reaction of Cyclopropenones with Vinyl Epoxides.

We report herein the Pd-catalyzed selective ring-opening reaction of cyclopropenones with vinyl epoxides. By using a commercially available Pd2(dba)3·CHCl3-BINAP catalyst, a wide range of conjugated alkadienyl carboxylates could be accessed in good yield and excellent regioselectivity. The new application of zwitterionic π-allyl palladium intermediates has been demonstrated in organic synthesis.

Target-mediated competitive hybridization of hairpin probes for kanamycin detection based on exonuclease III cleavage and DNAzyme catalysis.

Based on aptamer recognition and target-mediated competitive hybridization of hairpin probes, we developed a fluorescence sensor for kanamycin (KAN) detection. The aptamer and KAN binding will open hairpin H1 to release the trigger DNA fragment, which can initiate the competitive hybridization between hairpins H2 and H3. Then, exonuclease III (Exo III) can cleave H2 and H3 to produce numerous DNA3 and DNA4. Through the synergetic hybridization among DNA1, DNA2, DNA3, and DNA4, an active Mg2+-DNAzyme can be formed. The cleavage reaction toward FAM-BHQ-modified DNA2 will produce a high fluorescence signal for KAN assay. Through Exo III-guided cleavage and Mg2+-DNAzyme-based catalysis, the sensor exhibits high sensitivity, with a detection limit of 3.1 fM. This method is robust and has been applied to the detection of KAN in milk and water samples with good accuracy and reliability. Our developed fluorescence sensor exhibits the advantages of simple operation, high sensitivity, and good robustness, which are beneficial for KAN detection in food samples.

Sp2- and sp3-C⋯O tetrel bonds in the 3-oxetanone homodimer.

The structures and non-covalent interactions at play in the 3-oxetanone homodimer have been investigated using a pulsed jet Fourier transform microwave spectrometer supplemented with quantum chemical calculations. Two isomers were identified in the pulsed jet. With the analyses of non-covalent intermolecular interactions including the quantum theory of atoms, Johnson's non-covalent interactions and natural bond orbital, the observed global minimum is stabilized by a combination of one sp2-C⋯O tetrel bond and a network of multiple C-H⋯O weak hydrogen bonds. The second isomer is characterized by carbonyl-carbonyl interactions, with the formation of one sp2- and one sp3-C⋯O tetrel bond. The conformational population of the two observed isomers in the supersonic expansion was estimated to be NCE1/NCC1 ≈ 7/5.

Rotational Spectra of 2-Ethynylpyridine and Its Monohydrate: Influence of the Ortho-Substitution on Ring Geometry and Intermolecular Hydrogen Bonds.

Rotational spectra of the 2-ethynylpyridine monomer and its monohydrate have been characterized by pulsed jet Fourier transform microwave spectroscopy complemented with quantum chemical calculations. The measurements of rotational transitions of the 2-ethynylpyridine monomer and its eight monosubstituted isotopologues (15N and 13C) in natural abundances allow an accurate structural description of the skeleton of 2-ethynylpyridine. For the monohydrate, only the most stable isomer, stabilized by an O-H···N and a secondary C-H···O hydrogen bonds, has been observed in the supersonic jet. Johnson's noncovalent interaction and quantum theory of atoms in molecules analyses have been performed and compared with results for several ortho-substituted pyridine derivatives to elucidate the general trend in their binding energies.

Laboratory Measurements and Astronomical Search for Methoxyacetone and Methyl Methoxyacetate.

High-resolution pure rotational spectra of methoxyacetone and methyl methoxyacetate have been recorded and analyzed by using pulsed jet-expansion Fourier transform microwave spectroscopy with the aid of quantum calculations. The global minima for both target molecules have been detected in pulsed jet, whose spectra are featured with the splittings raised from the methyl internal rotations. On the basis of the spectroscopic results, a radio-astronomical search of methoxyacetone and methyl methoxyacetate was carried out toward the high-mass star-forming region Sgr B2(N) using the Shanghai Tianma 65 m radio telescope. No lines belonging to either of the target molecules were detected, and the upper limits to the column density were derived.