Selective Construction of C-S/S-N Bonds from N-Substituted O-Thiocarbamates and Indoles under Transition-Metal-Free Conditions.

A method for the selective construction of S-N/C(sp2)-S bonds using N-substituted O-thiocarbamates and indoles as substrates is reported. This protocol features good atom utilization, mild conditions, short reaction time, and wide substrate scope, which can provide a convenient path for the functionalization of indoles. In addition, the reaction could be scaled up on gram scale, showing potential application value in industry synthesis.

Effect of Passivating Molecules and Antisolvents on Lifetime of Green Dion-Jacobson Perovskite Light-Emitting Diodes.

We investigated the influence of two passivating molecules containing a P═O group on the performance of quasi-2D Dion-Jacobson halide perovskite light-emitting diodes, namely, triphenylphosphine oxide (TPPO) and diphenyl-4-triphenylsilylphenyl phosphine oxide (TSPO1). We found that both passivating molecules lead to increased efficiency compared to control devices, while they had opposite effects on device lifetime, with a decrease observed for TPPO and an increase observed for TSPO1. The two passivating molecules resulted in differences in energy-level alignment, electron injection, film morphology and crystallinity, and ion migration during operation. While TPPO resulted in improved photoluminescence decay times, overall higher maximum external quantum efficiency (EQE) and device lifetime were obtained for TSPO1 compared to TPPO (14.4% vs 12.4% EQE, 341 min vs 42 min T50).

Characterization of two novel knock-in mouse models of syndromic retinal ciliopathy carrying hypomorphic Sdccag8 mutations.

Mutations in serologically defined colon cancer autoantigen protein 8 ( SDCCAG8) were first identified in retinal ciliopathy families a decade ago with unknown function. To investigate the pathogenesis of SDCCAG8-associated retinal ciliopathies in vivo, we employed CRISPR/Cas9-mediated homology-directed recombination (HDR) to generate two knock-in mouse models, Sdccag8Y236X/Y236X and Sdccag8E451GfsX467/E451GfsX467 , which carry truncating mutations of the mouse Sdccag8, corresponding to mutations that cause Bardet-Biedl syndrome (BBS) and Senior-Løken syndrome (SLS) (c.696T>G p.Y232X and c.1339-1340insG p.E447GfsX463) in humans, respectively. The two mutant Sdccag8 knock-in mice faithfully recapitulated human SDCCAG8-associated BBS phenotypes such as rod-cone dystrophy, cystic renal disorder, polydactyly, infertility, and growth retardation, with varied age of onset and severity depending on the hypomorphic strength of the Sdccag8 mutations. To the best of our knowledge, these knock-in mouse lines are the first BBS mouse models to present with the polydactyly phenotype. Major phototransduction protein mislocalization was also observed outside the outer segment after initiation of photoreceptor degeneration. Impaired cilia were observed in the mutant photoreceptors, renal epithelial cells, and mouse embryonic fibroblasts derived from the knock-in mouse embryos, suggesting that SDCCAG8 plays an essential role in ciliogenesis, and cilium defects are a primary driving force of SDCCAG8-associated retinal ciliopathies.

Divergent Conversion of Double Isocyanides with Alkenyl Bromide to Polysubstituted Pyrroles and 4-Imino-4,5-dihydropyrrolo[3,4-b]pyrrol-6(1H)-one Derivatives by Pd-Catalyzed Tandem Cyclization Reactions.

Herein a novel and concise approach to pyrrole skeletons via Pd-catalyzed tandem cyclization reactions is investigated. The substrates for the transformation could be readily prepared by phosphoric acid-catalyzed Ugi reactions with available starting materials. In this strategy, two isocyanides participate in sequential isocyanide insertion reactions, and the chemoselectivity of the products is regulated by the steric hindrance of the isocyanide. A plausible mechanism for the formation of the corresponding adducts is proposed.

[A consensus recommendation for the interpretation and reporting of exome sequencing in prenatal genetic diagnosis].

With the rapid development and adaptation of high-throughput sequencing in clinical settings, application of exome sequencing (ES) has been gradually expanded from pediatric to prenatal diagnosis in recent years. There is an urgent need to establish criteria for clinical grade ES in order to facilitate such a complex testing. The standardization of pre- and post-test consultation, quality control for sample processing process and validation of bioinformatics data analysis, and more importantly data interpretation and reporting, as well as appropriate reporting scope, is of great importance for health care stakeholders. To achieve this, a committee composed of a wide range of healthcare professionals has proposed an ES standard for prenatal diagnosis. This has provided expert opinion on the genetic counseling and reporting standards of prenatal ES for the purpose of applying ES technology in prenatal setting.

C(sp2)-H Functionalization of Imidazole at the C2- and C4-Position via Palladium-Catalyzed Isocyanide Insertion Leading to Indeno[1,2-d]imidazole and Imidazo[1,2-a]indole Derivatives.

An efficient strategy for the construction of fused imidazole derivatives through a palladium-catalyzed isocyanide insertion reaction has been accomplished. The methodology provides an operationally simple and versatile route for the synthesis of indeno[1,2-d]imidazole and imidazo[1,2-a]indole skeletons which are rarely reported. The key features of the protocol are construction of sequential C-C/C-C/C-N bonds via C(sp2)-H functionalization of imidazole at the C2- and C4-position, respectively. The compounds can be synthesized with diverse scaffolds, easily accessible starting materials, and moderate to good yields.

Improving Detection Efficiency of SARS-CoV-2 Nucleic Acid Testing.

Background: SARS-CoV-2 nucleic acid testing (NAT) has been routinely used for COVID-19 diagnosis during this pandemic; however, there have been concerns about its high false negative rate. We dissected its detection efficiency with a large COVID-19 cohort study. Methods: We analyzed SARS-CoV-2 NAT positive rates of 4,275 specimens from 532 COVID-19 patients in Sichuan Province with different disease severities, statuses, and stages, as well as different types and numbers of specimens. Results: The total positive rate of the 4,275 specimens was 37.5%. Among seven specimen types, BALF generated a 77.8% positive rate, followed by URT specimens (38.5%), sputum (39.8%), and feces/rectal swabs (34.1%). Specimens from critical cases generated a 43.4% positive rate, which was significantly higher than that of other severities. With specimens from patients at stable status, the SARS-CoV-2 positive rate was 40.6%, which was significantly higher than that of improved status (17.1%), but lower than that of aggravated status (61.5%). Notably, the positive rate of specimens from COVID-19 patients varied significantly from 85 to 95% during 3 days before and after symptom onset, to 20% at around 18 days after symptom onset. In addition, the detection rate increased from 72.1% after testing one throat swab, to 93.2% after testing three consecutive respiratory specimens from each patient. Conclusions: SARS-CoV-2 NAT detection rates vary with patient disease severity and status, specimen type, number of specimens, and especially disease progression. Sampling as close to symptom onset as possible, and consecutively collecting more than one respiratory specimen could effectively improve SARS-CoV-2 NAT detection efficiency.

Isocyano(triphenylphosphoranylidene)acetates: Key to the One-Pot Synthesis of Oxazolo[4,5-c]quinoline Derivatives via a Sequential Ugi/Wittig/aza-Wittig Cyclization Process.

A one-pot novel strategy is described for the construction of various oxazolo[4,5-c]quinoline derivatives starting from the isocyano(triphenylphosphoranylidene)acetates, aldehydes, amines, and 2-azidobenzoic acids. The reactions generated the target products directly in moderate to good yields via a sequential Ugi/Wittig/aza-Wittig cyclization process. The salient features of the method are that all three groups of the multifunctional isocyanides were involved in the reaction with broad substituent scopes and mild reaction conditions, making the protocol a useful contribution to the synthesis of oxazolo[4,5-c]quinoline heterocycles.

Delicate structural coordination of the Severe Acute Respiratory Syndrome coronavirus Nsp13 upon ATP hydrolysis.

To date, an effective therapeutic treatment that confers strong attenuation toward coronaviruses (CoVs) remains elusive. Of all the potential drug targets, the helicase of CoVs is considered to be one of the most important. Here, we first present the structure of the full-length Nsp13 helicase of SARS-CoV (SARS-Nsp13) and investigate the structural coordination of its five domains and how these contribute to its translocation and unwinding activity. A translocation model is proposed for the Upf1-like helicase members according to three different structural conditions in solution characterized through H/D exchange assay, including substrate state (SARS-Nsp13-dsDNA bound with AMPPNP), transition state (bound with ADP-AlF4-) and product state (bound with ADP). We observed that the ß19-ß20 loop on the 1A domain is involved in unwinding process directly. Furthermore, we have shown that the RNA dependent RNA polymerase (RdRp), SARS-Nsp12, can enhance the helicase activity of SARS-Nsp13 through interacting with it directly. The interacting regions were identified and can be considered common across CoVs, which provides new insights into the Replication and Transcription Complex (RTC) of CoVs.

Synthesis of iminoisoindolinones via a cascade of the three-component Ugi reaction, palladium catalyzed isocyanide insertion, hydroxylation and an unexpected rearrangement reaction.

A robust ligand-free palladium-catalyzed cascade reaction for the synthesis of diversely substituted iminoisoindolinones has been developed. The cascade reaction involves isocyanide insertion into Ugi-3CR adducts, accompanied by unexpected hydroxylation and rearrangement.

Prospective chromosome analysis of 3429 amniocentesis samples in China using copy number variation sequencing.

BACKGROUND: Next-generation sequencing is emerging as a viable alternative to chromosome microarray analysis for the diagnosis of chromosome disease syndromes. One next-generation sequencing methodology, copy number variation sequencing, has been shown to deliver high reliability, accuracy, and reproducibility for detection of fetal copy number variations in prenatal samples. However, its clinical utility as a first-tier diagnostic method has yet to be demonstrated in a large cohort of pregnant women referred for fetal chromosome testing. OBJECTIVE: We sought to evaluate copy number variation sequencing as a first-tier diagnostic method for detection of fetal chromosome anomalies in a general population of pregnant women with high-risk prenatal indications. STUDY DESIGN: This was a prospective analysis of 3429 pregnant women referred for amniocentesis and fetal chromosome testing for different risk indications, including advanced maternal age, high-risk maternal serum screening, and positivity for an ultrasound soft marker. Amniocentesis was performed by standard procedures. Amniocyte DNA was analyzed by copy number variation sequencing with a chromosome resolution of 0.1 Mb. Fetal chromosome anomalies including whole chromosome aneuploidy and segmental imbalances were independently confirmed by gold standard cytogenetic and molecular methods and their pathogenicity determined following guidelines of the American College of Medical Genetics for sequence variants. RESULTS: Clear interpretable copy number variation sequencing results were obtained for all 3429 amniocentesis samples. Copy number variation sequencing identified 3293 samples (96%) with a normal molecular karyotype and 136 samples (4%) with an altered molecular karyotype. A total of 146 fetal chromosome anomalies were detected, comprising 46 whole chromosome aneuploidies (pathogenic), 29 submicroscopic microdeletions/microduplications with known or suspected associations with chromosome disease syndromes (pathogenic), 22 other microdeletions/microduplications (likely pathogenic), and 49 variants of uncertain significance. Overall, the cumulative frequency of pathogenic/likely pathogenic and variants of uncertain significance chromosome anomalies in the patient cohort was 2.83% and 1.43%, respectively. In the 3 high-risk advanced maternal age, high-risk maternal serum screening, and ultrasound soft marker groups, the most common whole chromosome aneuploidy detected was trisomy 21, followed by sex chromosome aneuploidies, trisomy 18, and trisomy 13. Across all clinical indications, there was a similar incidence of submicroscopic copy number variations, with approximately equal proportions of pathogenic/likely pathogenic and variants of uncertain significance copy number variations. If karyotyping had been used as an alternate cytogenetics detection method, copy number variation sequencing would have returned a 1% higher yield of pathogenic or likely pathogenic copy number variations. CONCLUSION: In a large prospective clinical study, copy number variation sequencing delivered high reliability and accuracy for identifying clinically significant fetal anomalies in prenatal samples. Based on key performance criteria, copy number variation sequencing appears to be a well-suited methodology for first-tier diagnosis of pregnant women in the general population at risk of having a suspected fetal chromosome abnormality.

Characterization of chromosomal abnormalities in pregnancy losses reveals critical genes and loci for human early development.

Detailed characterization of chromosomal abnormalities, a common cause for congenital abnormalities and pregnancy loss, is critical for elucidating genes for human fetal development. Here, 2,186 product-of-conception samples were tested for copy-number variations (CNVs) at two clinical diagnostic centers using whole-genome sequencing and high-resolution chromosomal microarray analysis. We developed a new gene discovery approach to predict potential developmental genes and identified 275 candidate genes from CNVs detected from both datasets. Based on Mouse Genome Informatics (MGI) and Zebrafish model organism database (ZFIN), 75% of identified genes could lead to developmental defects when mutated. Genes involved in embryonic development, gene transcription, and regulation of biological processes were significantly enriched. Especially, transcription factors and gene families sharing specific protein domains predominated, which included known developmental genes such as HOX, NKX homeodomain genes, and helix-loop-helix containing HAND2, NEUROG2, and NEUROD1 as well as potential novel developmental genes. We observed that developmental genes were denser in certain chromosomal regions, enabling identification of 31 potential genomic loci with clustered genes associated with development.

Complete mitochondrial genome sequence of the Sichuan digging frog Kaloula rugifera (Anura: Microhylidae).

The Sichuan Digging Frog (Kaloula rugifera) belongs to the family Dicroglossidae, which is endemic to northeastern Sichuan and southernmost Gansu provinces, in southwestern China. In this study, the complete mitochondrial genome of K. rugifera was sequenced. The mitogenome was 17 074 bp in length, consisting of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and a non-coding control region. As in other vertebrates, most mitochondrial genes are encoded on the heavy strand, except for ND6 and eight tRNA genes which are encoded on the light strand. The overall base composition of the K. rugifera is 29.7% A, 30.3% T, 25.8% C, and 14.2% G. The alignment of the Kaloula species control regions exhibited high genetic variability and rich A + T content. Phylogenetic tree demonstrated that K. rugifera was clustered together with K. borealis and K. verrucosa and they had a close relationship with each other. The complete mitogenome of K. rugifera can provide an important data for the studies on phylogenetic relationship to further explore the taxonomic status of Kaloula species.

Synthesis of 2,3-Dihydro-1H-2-benzazepin-1-ones and 3H-2-Benzoxepin-1-ones by Isocyanide-Based Multicomponent Reaction/Wittig Sequence Starting from Phosphonium Salt Precursors.

A one-pot synthesis of multisubstituted 2,3-dihydro-1H-2-benzazepin-1-ones and 3H-2-benzoxepin-1-ones by an I-MCR/Wittig sequence was developed. The reaction of phosphonium salt 3, arylglyoxals 4, amine 5 (or without), and isocyanide 6 produced the 2,3-dihydro-1H-2-benzazepin-1-ones 8 or 3H-2-benzoxepin-1-ones 10 in good yields via a sequential Ugi or Passerini condensation and intramolecular Wittig reaction in the presence of NEt3.

Purification, crystallization and preliminary X-ray analysis of nonstructural protein 2 (nsp2) from avian infectious bronchitis virus.

Avian infectious bronchitis virus (IBV) is a member of the group III coronaviruses, which differ from the other groups of coronaviruses in that they do not encode the essential pathogenic factor nonstructural protein 1 (nsp1) and instead start with nsp2. IBV nsp2 is one of the first replicase proteins to be translated and processed in the viral life cycle; however, it has an entirely unknown function. In order to better understand the structural details and functional mechanism of IBV nsp2, the recombinant protein was cloned, overexpressed in Escherichia coli, purified and crystallized. The crystals diffracted to 2.8 Å resolution and belonged to space group P2(1), with unit-cell parameters a = 57.0, b = 192.3, c = 105.7 Å, ß = 90.8°. Two molecules were found in the asymmetric unit; the Matthews coefficient was 3.9 Å(3) Da(-1), corresponding to a solvent content of 68.2%.

Expression, crystallization and preliminary crystallographic study of the C-terminal half of nsp2 from SARS coronavirus.

SARS coronavirus (SARS-CoV) is the aetiological agent of the highly infectious severe acute respiratory syndrome (SARS). To gain a better understanding of SARS-CoV replication and transcription proteins, a preliminary X-ray crystallographic study of the C-terminal domain of SARS-CoV nonstructural protein 2 (nsp2) is reported here. The C-terminal domain of SARS-CoV nsp2 was cloned, overexpressed, purified and crystallized using polyethylene glycol 5000 monomethyl ether as the precipitant; the crystals diffracted to 2.5 Šresolution. The crystals belonged to space group P6(5), with unit-cell parameters a=b=112.8, c=91.1 Å, α=ß=90, γ=120°. One molecule is assumed to be present per asymmetric unit, which gives a Matthews coefficient of 2.89 Å3 Da(-1) and a solvent content of 56.2%.